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package org.jooby.internal.apitool;

import com.fasterxml.jackson.databind.BeanDescription;
import com.fasterxml.jackson.databind.Module;
import com.fasterxml.jackson.databind.introspect.BeanPropertyDefinition;
import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
import com.google.common.base.Splitter;
import com.google.common.base.Strings;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Maps;
import com.google.inject.TypeLiteral;
import com.google.inject.internal.MoreTypes;
import io.swagger.converter.ModelConverter;
import io.swagger.converter.ModelConverterContext;
import io.swagger.converter.ModelConverters;
import io.swagger.jackson.AbstractModelConverter;
import io.swagger.models.Model;
import io.swagger.models.Operation;
import io.swagger.models.Path;
import io.swagger.models.Response;
import io.swagger.models.Swagger;
import io.swagger.models.Tag;
import io.swagger.models.parameters.AbstractSerializableParameter;
import io.swagger.models.parameters.BodyParameter;
import io.swagger.models.parameters.FormParameter;
import io.swagger.models.parameters.HeaderParameter;
import io.swagger.models.parameters.Parameter;
import io.swagger.models.parameters.PathParameter;
import io.swagger.models.parameters.QueryParameter;
import io.swagger.models.parameters.SerializableParameter;
import io.swagger.models.properties.ArrayProperty;
import io.swagger.models.properties.FileProperty;
import io.swagger.models.properties.Property;
import io.swagger.models.properties.PropertyBuilder;
import io.swagger.models.properties.PropertyBuilder.PropertyId;
import io.swagger.models.properties.RefProperty;
import io.swagger.util.Json;
import io.swagger.util.Yaml;
import org.jooby.MediaType;
import org.jooby.Upload;
import org.jooby.apitool.RouteMethod;
import org.jooby.apitool.RouteParameter;
import org.jooby.apitool.RouteResponse;

import java.lang.annotation.Annotation;
import java.lang.reflect.Array;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.EnumMap;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.function.BiConsumer;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class SwaggerBuilder {

  static {
    /** Convert Upload to Swagger FileProperty: */
    ModelConverters.getInstance().addConverter(new AbstractModelConverter(Json.mapper()) {
      @Override public Property resolveProperty(Type type, ModelConverterContext context,
          Annotation[] annotations, Iterator<ModelConverter> chain) {
        if (type == null) {
          return null;
        }
        try {
          TypeLiteral<?> typeLiteral = TypeLiteral.get(type);
          String typeName = typeLiteral.getType().getTypeName();
          if (typeName.equals("java.util.List<org.jooby.Upload>") ||
              typeName.equals("java.util.Set<org.jooby.Upload>")) {
            return new ArrayProperty(new FileProperty());
          }
          if (typeName.equals(Upload.class.getName())) {
            return new FileProperty();
          }
          return super.resolveProperty(type, context, annotations, chain);
        } catch (IllegalArgumentException x) {
          // shhh
          return super.resolveProperty(type, context, annotations, chain);
        }
      }
    });
    /** Kotlin module? */
    try {
      Module module = (Module) SwaggerBuilder.class.getClassLoader()
          .loadClass("com.fasterxml.jackson.module.kotlin.KotlinModule").newInstance();
      Json.mapper().registerModule(module);
      Yaml.mapper().registerModule(module);
    } catch (ClassNotFoundException | InstantiationException | IllegalAccessException x) {
      // Nop
    }
    /** Java8/Optional: */
    Jdk8Module jdk8 = new Jdk8Module();
    Json.mapper().registerModule(jdk8);
    Yaml.mapper().registerModule(jdk8);
  }

  private static class ResponseWithStatusCode {
    String statusCode;

    Response response;

    public ResponseWithStatusCode(String statusCode, Response response) {
      this.statusCode = statusCode;
      this.response = response;
    }
  }

  private Function<RouteMethod, String> tagger;

  public SwaggerBuilder(Function<RouteMethod, String> tagger) {
    this.tagger = tagger;
  }

  public Swagger build(Swagger base, final List<RouteMethod> routes) throws Exception {
    Swagger swagger = Optional.ofNullable(base).orElseGet(Swagger::new);

    /** Tags: */
    Function<String, Tag> tagFactory = value ->
        Optional.ofNullable(swagger.getTag(value))
            .orElseGet(() -> {
              Tag tag = new Tag().name(value);
              swagger.addTag(tag);
              return tag;
            });

    /** Paths: */
    Function<String, Path> pathFactory = pattern ->
        Optional.ofNullable(swagger.getPath(pattern))
            .orElseGet(() -> {
              Path path = new Path();
              swagger.path(pattern, path);
              return path;
            });

    ModelConverters converter = ModelConverters.getInstance();
    /** Model factory: */
    Function<Type, Model> modelFactory = type -> {
      for (Map.Entry<String, Model> entry : converter.readAll(type).entrySet()) {
        swagger.addDefinition(entry.getKey(), doModel(type, entry.getValue()));
      }
      // reference:
      Property property = converter.readAsProperty(type);
      Map<PropertyId, Object> args = new EnumMap<>(PropertyId.class);
      return PropertyBuilder.toModel(PropertyBuilder.merge(property, args));
    };

    Map<String, Integer> opIds = new HashMap<>();

    for (RouteMethod route : routes) {
      /** Find or create tag: */
      List<Tag> tags = tags(route, tagFactory);

      /** Find or create path: */
      Path path = pathFactory.apply(route.pattern());

      /** Operation: */
      Operation op = new Operation();

      tags.forEach(it -> op.addTag(it.getName()));

      op.operationId(operationId(route, tags.get(0), opIds));

      /** Doc and summary: */
      op.summary(summary(route));
      op.description(description(route, op.getSummary()));

      /** Consumes/Produces . */
      consumes(route, op::addConsumes);
      produces(route, op::addProduces);

      /** Parameters: */
      route.parameters().stream().flatMap(it -> {
        Type type = it.type();
        final Property property = converter.readAsProperty(type);
        Parameter parameter = it.accept(new RouteParameter.Visitor<Parameter>() {
          @Override public Parameter visitBody(final RouteParameter parameter) {
            return new BodyParameter().schema(modelFactory.apply(parameter.type()));
          }

          @Override public Parameter visitFile(final RouteParameter parameter) {
            return complement(property, parameter, new FormParameter());
          }

          @Override public Parameter visitForm(final RouteParameter parameter) {
            return complement(property, parameter, new FormParameter());
          }

          @Override public Parameter visitHeader(final RouteParameter parameter) {
            return complement(property, parameter, new HeaderParameter());
          }

          @Override public Parameter visitPath(final RouteParameter parameter) {
            return complement(property, parameter, new PathParameter());
          }

          @Override public Parameter visitQuery(final RouteParameter parameter) {
            return complement(property, parameter, new QueryParameter());
          }
        });
        if (it.kind() == RouteParameter.Kind.FILE) {
          op.setConsumes(ImmutableList.of(MediaType.multipart.name()));
        } else if (it.kind() == RouteParameter.Kind.FORM) {
          op.setConsumes(ImmutableList.of(MediaType.form.name(), MediaType.multipart.name()));
        }
        if (property instanceof RefProperty && (it.kind() == RouteParameter.Kind.QUERY
            || it.kind() == RouteParameter.Kind.FORM)) {
          return expandParameter(converter, it, it.type(), it.optional())
              .stream();
        } else {
          parameter.setName(it.name());
          parameter.setRequired(!it.optional());
          parameter.setDescription(property.getDescription());
          it.description().ifPresent(parameter::setDescription);
          return Stream.of(parameter);
        }
      }).forEach(op::addParameter);

      /** Response: */
      buildResponse(route, modelFactory, rsp -> op.addResponse(rsp.statusCode, rsp.response));

      /** Done: */
      path.set(method(route), op);
    }

    Function<Function<RouteMethod, List<String>>, List<String>> mediaTypes = types ->
        routes.stream().flatMap(it -> types.apply(it).stream()).collect(Collectors.toList());
    /** Default consumes/produces: */
    List<String> consumes = mediaTypes.apply(RouteMethod::consumes);
    if (consumes.size() == 0) {
      swagger.consumes(MediaType.json.name());
    } else if (consumes.size() == 1) {
      swagger.consumes(consumes);
    }
    List<String> produces = mediaTypes.apply(RouteMethod::produces);
    if (produces.size() == 0) {
      swagger.produces(MediaType.json.name());
    } else if (produces.size() == 1) {
      swagger.produces(produces);
    }
    return swagger;
  }

  private void buildResponse(RouteMethod route, Function<Type, Model> modelFactory,
      Consumer<ResponseWithStatusCode> consumer) {
    Object[] apiResponses = (Object[]) route.attributes().get("apiResponses");
    if (apiResponses != null) {
      /** ApiResponses annotation: */
      Set<Integer> codes = new HashSet<>();
      Stream.of(apiResponses)
          .map(it -> buildResponse(modelFactory, (Map) it, c -> !codes.add(c)))
          .forEach(consumer);
    } else {
      Integer code = (Integer) route.attributes().get("apiResponse.code");
      if (code != null) {
        /** Single ApiResponse annotation: */
        consumer.accept(buildResponse(modelFactory, route.attributes(), c -> false));
      } else {
        /** Default response: */
        RouteResponse returns = route.response();
        Map<Integer, String> status = returns.status();
        Integer statusCode = (Integer) route.attributes()
            .getOrDefault("apiOperation.code", returns.statusCode());

        Response response = new Response();
        String doc = returns.description()
            .orElseGet(() -> FriendlyTypeName.name(returns.type()));
        response.description(doc);

        Type responseType = (Type) route.attributes()
            .getOrDefault("apiOperation.response", returns.type());
        if (!isVoid(responseType)) {
          response.responseSchema(modelFactory.apply(responseType));
        }
        buildResponseHeader(route.attributes(), "apiOperation.responseHeaders",
            response::addHeader);

        consumer.accept(new ResponseWithStatusCode(statusCode.toString(), response));
        status.entrySet().stream()
            .filter(it -> !statusCode.equals(it.getKey()))
            .forEach(it -> consumer.accept(
                new ResponseWithStatusCode(it.getKey().toString(),
                    new Response().description(it.getValue())))
            );
      }
    }
  }

  private boolean isVoid(Type type) {
    return "void".equals(type.getTypeName()) || Void.class.getName().equals(type.getTypeName());
  }

  private ResponseWithStatusCode buildResponse(Function<Type, Model> modelFactory,
      Map<String, Object> attributes, Predicate<Integer> statusCode) {
    Response response = new Response();
    String description = (String) attributes.get("apiResponse.message");
    Class type = (Class) attributes.get("apiResponse.response");

    if (!isVoid(type)) {
      response.setResponseSchema(modelFactory.apply(type));
    }
    response.setDescription(description);

    buildResponseHeader(attributes, "apiResponse.responseHeaders", response::addHeader);

    Integer code = (Integer) attributes.get("apiResponse.code");
    String key = code.toString();
    if (statusCode.test(code)) {
      key += "(" + type.getSimpleName() + ")";
    }
    return new ResponseWithStatusCode(key, response);
  }

  private void buildResponseHeader(Map<String, Object> attributes, String name,
      BiConsumer<String, Property> consumer) {
    Object[] headers = (Object[]) attributes.get(name);
    if (headers != null) {
      ModelConverters converter = ModelConverters.getInstance();
      Stream.of(headers)
          .map(Map.class::cast)
          .filter(it -> ((String) it.get("responseHeader.name")).length() > 0)
          .forEach(header -> {
            String hname = header.get("responseHeader.name").toString();
            Property htype = converter.readAsProperty((Type) header.get("responseHeader.response"));
            consumer.accept(hname, htype);
          });
    }
  }

  private String method(RouteMethod route) {
    String method = stringAttribute(route, "httpMethod");
    if (method == null) {
      method = route.method();
    }
    return method.toLowerCase();
  }

  private void consumes(RouteMethod route, Consumer<String> consumer) {
    String consumes = stringAttribute(route, "consumes");
    if (consumes == null) {
      route.consumes().forEach(consumer::accept);
    } else {
      Stream.of(consumes.split(",")).forEach(consumer);
    }
  }

  private void produces(RouteMethod route, Consumer<String> consumer) {
    String produces = stringAttribute(route, "produces");
    if (produces == null) {
      route.produces().forEach(consumer::accept);
    } else {
      Stream.of(produces.split(",")).forEach(consumer);
    }
  }

  private String description(RouteMethod route, String summary) {
    String notes = stringAttribute(route, "notes");
    if (notes == null) {
      return route.description().map(description -> {
        String prefix = Optional.ofNullable(summary).orElse("");
        return description.replace(prefix + ".", "");
      }).orElse(null);
    }
    return notes;
  }

  private String summary(RouteMethod route) {
    String summary = stringAttribute(route, "apiOperation");
    if (summary == null) {
      return route.description().map(description -> {
        int dot = description.indexOf('.');
        if (dot > 0) {
          return description.substring(0, dot);
        }
        return null;
      }).orElse(null);
    }
    return summary;
  }

  private String operationId(RouteMethod route, Tag tag, Map<String, Integer> opIds) {
    String operationId = stringAttribute(route, "nickname");
    if (operationId == null) {
      operationId = route.name().orElseGet(() -> {
        String args = "";
        if (route.method().equals("GET") && route.parameters().size() > 0) {
          args = route.parameters().stream()
              .filter(p -> p.kind() == RouteParameter.Kind.QUERY
                  || p.kind() == RouteParameter.Kind.PATH)
              .map(p -> p.name())
              .map(this::ucase)
              .reduce(new StringBuilder("By"), StringBuilder::append, StringBuilder::append)
              .toString();
        }
        return route.method().toLowerCase() + ucase(tag.getName().replace("/", "")) + args;
      });
    }
    int c = opIds.getOrDefault(operationId, 0);
    opIds.put(operationId, c + 1);
    if (c == 0) {
      return operationId;
    }
    return operationId + c;
  }

  private List<Tag> tags(RouteMethod route, Function<String, Tag> tagFactory) {
    String[] tags = arrayAttribute(route, "tags");
    if (tags != null) {
      List<Tag> result = Stream.of(tags)
          .filter(it -> it.length() > 0)
          .map(tagFactory)
          .collect(Collectors.toList());
      if (result.size() > 0) {
        return result;
      }
    }
    Tag tag = tagFactory.apply(tagger.apply(route));
    route.summary().ifPresent(tag::description);
    return ImmutableList.of(tag);
  }

  private String stringAttribute(RouteMethod route, String name) {
    return (String) swaggerAttribute(route, name, it -> it.toString().length() > 0);
  }

  private <T> T[] arrayAttribute(RouteMethod routeMethod, String name) {
    return (T[]) swaggerAttribute(routeMethod, "tags", v -> Array.getLength(v) > 0);
  }

  private Object swaggerAttribute(RouteMethod route, String name, Predicate<Object> filter) {
    String[] prefix = {"apiOperation", "swagger"};
    for (String p : prefix) {
      String key = p.equalsIgnoreCase(name) ? name : p + "." + name;
      Object value = route.attributes().get(key);
      if (value != null && filter.test(value)) {
        return value;
      }
    }
    return null;
  }

  private void apiOperation(Map<String, Object> attributes, Operation op,
      Response response, Function<Type, Model> modelFactory,
      Function<String, Tag> tagFactory) {
    attributes.forEach((name, value) -> {
      switch (name) {
        case "apiOperation":
          String summary = Strings.emptyToNull((String) value);
          if (summary != null) {
            op.summary(summary);
          }
          break;
        case "tags":
          Stream.of((String[]) value)
              .filter(it -> it != null && it.trim().length() > 0)
              .map(tagFactory)
              .forEach(tag -> op.addTag(tag.getName()));
          break;
        case "response":
          Class responseType = (Class) value;
          if (responseType != Void.class) {
            response.responseSchema(modelFactory.apply(responseType));
          }
          break;
        case "nickname":
          String operationId = Strings.emptyToNull((String) value);
          if (operationId != null) {
            op.setOperationId(operationId);
          }
          break;
        case "produces":
          String produces = Strings.emptyToNull((String) value);
          if (produces != null) {
            op.produces(Splitter.on(",").trimResults().omitEmptyStrings().splitToList(produces));
          }
          break;
        case "consumes":
          String consumes = Strings.emptyToNull((String) value);
          if (consumes != null) {
            op.consumes(Splitter.on(",").trimResults().omitEmptyStrings().splitToList(consumes));
          }
          break;
        case "code":
          int code = (Integer) value;
          if (code != 200) {
            op.addResponse(value.toString(), response);
          }
          break;
        case "responseHeaders":
          break;
      }
    });
  }

  private Map<String, Object> swaggerAttributes(Class annotation, Map<String, Object> attributes) {
    String name = annotation.getSimpleName();
    return attributes.entrySet().stream()
        .filter(it -> it.getKey().equalsIgnoreCase(name) || it.getKey().startsWith(name + "."))
        .filter(it -> {
          Object value = it.getValue();
          if (value instanceof String) {
            return !Strings.isNullOrEmpty(((String) value).trim());
          }
          return value != null;
        })
        .map(e -> {
          String key = e.getKey();
          Object value = attributes.get(key);
          if (key.equalsIgnoreCase(name)) {
            return Maps.immutableEntry(name, value);
          }

          return Maps.immutableEntry(key.replace("apiOperation.", ""), value);
        })
        .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
  }

  private List<Parameter> expandParameter(ModelConverters converter, RouteParameter it,
      Type type, boolean optional) {
    Supplier<SerializableParameter> factory =
        it.kind() == RouteParameter.Kind.FORM ? FormParameter::new : QueryParameter::new;
    return expandParameter(converter.readAll(type), it, factory, simpleClassName(type), "",
        optional);
  }

  private List<Parameter> expandParameter(Map<String, Model> models, RouteParameter it,
      Supplier<SerializableParameter> factory, String typeName, String prefix, boolean optional) {
    List<Parameter> parameters = new ArrayList<>();
    Model model = models.get(typeName);
    Map<String, Property> properties = model.getProperties();
    Optional.ofNullable(properties).ifPresent(props -> props.values().stream()
        .flatMap(p -> {
          SerializableParameter result = complement(p, it, factory.get());
          String name = prefix + p.getName();
          if (p instanceof RefProperty) {
            return expandParameter(models, it, factory, ((RefProperty) p).getSimpleRef(),
                name + ".", optional).stream();
          } else {
            result.setName(name);
            boolean required;
            if (optional) {
              required = false;
            } else {
              required = p.getRequired();
            }
            String desc = Strings.emptyToNull(p.getDescription());
            result.setRequired(required);
            result.setDescription(desc);
            return Stream.of(result);
          }
        })
        .forEach(parameters::add)
    );
    return parameters;
  }

  private String simpleClassName(Type type) {
    return MoreTypes.getRawType(type).getSimpleName();
  }

  private String ucase(String name) {
    if (name.length() > 0) {
      return Character.toUpperCase(name.charAt(0)) + name.substring(1);
    }
    return name;
  }

  /**
   * Mostly for kotlin null safe operator and immutable properties.
   *
   * @param type Target type.
   * @param model Model.
   * @return Input model.
   */
  private Model doModel(Type type, Model model) {
    Map<String, Property> properties = model.getProperties();
    if (properties != null) {
      BeanDescription desc = Json.mapper().getSerializationConfig()
          .introspect(Json.mapper().constructType(type));
      for (BeanPropertyDefinition beanProperty : desc.findProperties()) {
        Property property = properties.get(beanProperty.getName());
        if (property != null) {
          property.setRequired(beanProperty.isRequired());
        }
      }
    }
    return model;
  }

  private SerializableParameter complement(Property property, RouteParameter source,
      SerializableParameter param) {
    param.setType(property.getType());
    param.setFormat(property.getFormat());
    // array param:
    if (property instanceof ArrayProperty) {
      param.setItems(((ArrayProperty) property).getItems());
    }
    // enum values:
    List<String> enums = source.enums();
    if (enums.size() > 0) {
      param.setEnum(enums);
    }
    // default value:
    if (param instanceof AbstractSerializableParameter) {
      ((AbstractSerializableParameter) param).setDefault(source.defaultValue());
    }
    return param;
  }
}


/**
 *                                  Apache License
 *                            Version 2.0, January 2004
 *                         http://www.apache.org/licenses/
 *
 *    TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
 *
 *    1. Definitions.
 *
 *       "License" shall mean the terms and conditions for use, reproduction,
 *       and distribution as defined by Sections 1 through 9 of this document.
 *
 *       "Licensor" shall mean the copyright owner or entity authorized by
 *       the copyright owner that is granting the License.
 *
 *       "Legal Entity" shall mean the union of the acting entity and all
 *       other entities that control, are controlled by, or are under common
 *       control with that entity. For the purposes of this definition,
 *       "control" means (i) the power, direct or indirect, to cause the
 *       direction or management of such entity, whether by contract or
 *       otherwise, or (ii) ownership of fifty percent (50%) or more of the
 *       outstanding shares, or (iii) beneficial ownership of such entity.
 *
 *       "You" (or "Your") shall mean an individual or Legal Entity
 *       exercising permissions granted by this License.
 *
 *       "Source" form shall mean the preferred form for making modifications,
 *       including but not limited to software source code, documentation
 *       source, and configuration files.
 *
 *       "Object" form shall mean any form resulting from mechanical
 *       transformation or translation of a Source form, including but
 *       not limited to compiled object code, generated documentation,
 *       and conversions to other media types.
 *
 *       "Work" shall mean the work of authorship, whether in Source or
 *       Object form, made available under the License, as indicated by a
 *       copyright notice that is included in or attached to the work
 *       (an example is provided in the Appendix below).
 *
 *       "Derivative Works" shall mean any work, whether in Source or Object
 *       form, that is based on (or derived from) the Work and for which the
 *       editorial revisions, annotations, elaborations, or other modifications
 *       represent, as a whole, an original work of authorship. For the purposes
 *       of this License, Derivative Works shall not include works that remain
 *       separable from, or merely link (or bind by name) to the interfaces of,
 *       the Work and Derivative Works thereof.
 *
 *       "Contribution" shall mean any work of authorship, including
 *       the original version of the Work and any modifications or additions
 *       to that Work or Derivative Works thereof, that is intentionally
 *       submitted to Licensor for inclusion in the Work by the copyright owner
 *       or by an individual or Legal Entity authorized to submit on behalf of
 *       the copyright owner. For the purposes of this definition, "submitted"
 *       means any form of electronic, verbal, or written communication sent
 *       to the Licensor or its representatives, including but not limited to
 *       communication on electronic mailing lists, source code control systems,
 *       and issue tracking systems that are managed by, or on behalf of, the
 *       Licensor for the purpose of discussing and improving the Work, but
 *       excluding communication that is conspicuously marked or otherwise
 *       designated in writing by the copyright owner as "Not a Contribution."
 *
 *       "Contributor" shall mean Licensor and any individual or Legal Entity
 *       on behalf of whom a Contribution has been received by Licensor and
 *       subsequently incorporated within the Work.
 *
 *    2. Grant of Copyright License. Subject to the terms and conditions of
 *       this License, each Contributor hereby grants to You a perpetual,
 *       worldwide, non-exclusive, no-charge, royalty-free, irrevocable
 *       copyright license to reproduce, prepare Derivative Works of,
 *       publicly display, publicly perform, sublicense, and distribute the
 *       Work and such Derivative Works in Source or Object form.
 *
 *    3. Grant of Patent License. Subject to the terms and conditions of
 *       this License, each Contributor hereby grants to You a perpetual,
 *       worldwide, non-exclusive, no-charge, royalty-free, irrevocable
 *       (except as stated in this section) patent license to make, have made,
 *       use, offer to sell, sell, import, and otherwise transfer the Work,
 *       where such license applies only to those patent claims licensable
 *       by such Contributor that are necessarily infringed by their
 *       Contribution(s) alone or by combination of their Contribution(s)
 *       with the Work to which such Contribution(s) was submitted. If You
 *       institute patent litigation against any entity (including a
 *       cross-claim or counterclaim in a lawsuit) alleging that the Work
 *       or a Contribution incorporated within the Work constitutes direct
 *       or contributory patent infringement, then any patent licenses
 *       granted to You under this License for that Work shall terminate
 *       as of the date such litigation is filed.
 *
 *    4. Redistribution. You may reproduce and distribute copies of the
 *       Work or Derivative Works thereof in any medium, with or without
 *       modifications, and in Source or Object form, provided that You
 *       meet the following conditions:
 *
 *       (a) You must give any other recipients of the Work or
 *           Derivative Works a copy of this License; and
 *
 *       (b) You must cause any modified files to carry prominent notices
 *           stating that You changed the files; and
 *
 *       (c) You must retain, in the Source form of any Derivative Works
 *           that You distribute, all copyright, patent, trademark, and
 *           attribution notices from the Source form of the Work,
 *           excluding those notices that do not pertain to any part of
 *           the Derivative Works; and
 *
 *       (d) If the Work includes a "NOTICE" text file as part of its
 *           distribution, then any Derivative Works that You distribute must
 *           include a readable copy of the attribution notices contained
 *           within such NOTICE file, excluding those notices that do not
 *           pertain to any part of the Derivative Works, in at least one
 *           of the following places: within a NOTICE text file distributed
 *           as part of the Derivative Works; within the Source form or
 *           documentation, if provided along with the Derivative Works; or,
 *           within a display generated by the Derivative Works, if and
 *           wherever such third-party notices normally appear. The contents
 *           of the NOTICE file are for informational purposes only and
 *           do not modify the License. You may add Your own attribution
 *           notices within Derivative Works that You distribute, alongside
 *           or as an addendum to the NOTICE text from the Work, provided
 *           that such additional attribution notices cannot be construed
 *           as modifying the License.
 *
 *       You may add Your own copyright statement to Your modifications and
 *       may provide additional or different license terms and conditions
 *       for use, reproduction, or distribution of Your modifications, or
 *       for any such Derivative Works as a whole, provided Your use,
 *       reproduction, and distribution of the Work otherwise complies with
 *       the conditions stated in this License.
 *
 *    5. Submission of Contributions. Unless You explicitly state otherwise,
 *       any Contribution intentionally submitted for inclusion in the Work
 *       by You to the Licensor shall be under the terms and conditions of
 *       this License, without any additional terms or conditions.
 *       Notwithstanding the above, nothing herein shall supersede or modify
 *       the terms of any separate license agreement you may have executed
 *       with Licensor regarding such Contributions.
 *
 *    6. Trademarks. This License does not grant permission to use the trade
 *       names, trademarks, service marks, or product names of the Licensor,
 *       except as required for reasonable and customary use in describing the
 *       origin of the Work and reproducing the content of the NOTICE file.
 *
 *    7. Disclaimer of Warranty. Unless required by applicable law or
 *       agreed to in writing, Licensor provides the Work (and each
 *       Contributor provides its Contributions) on an "AS IS" BASIS,
 *       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 *       implied, including, without limitation, any warranties or conditions
 *       of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
 *       PARTICULAR PURPOSE. You are solely responsible for determining the
 *       appropriateness of using or redistributing the Work and assume any
 *       risks associated with Your exercise of permissions under this License.
 *
 *    8. Limitation of Liability. In no event and under no legal theory,
 *       whether in tort (including negligence), contract, or otherwise,
 *       unless required by applicable law (such as deliberate and grossly
 *       negligent acts) or agreed to in writing, shall any Contributor be
 *       liable to You for damages, including any direct, indirect, special,
 *       incidental, or consequential damages of any character arising as a
 *       result of this License or out of the use or inability to use the
 *       Work (including but not limited to damages for loss of goodwill,
 *       work stoppage, computer failure or malfunction, or any and all
 *       other commercial damages or losses), even if such Contributor
 *       has been advised of the possibility of such damages.
 *
 *    9. Accepting Warranty or Additional Liability. While redistributing
 *       the Work or Derivative Works thereof, You may choose to offer,
 *       and charge a fee for, acceptance of support, warranty, indemnity,
 *       or other liability obligations and/or rights consistent with this
 *       License. However, in accepting such obligations, You may act only
 *       on Your own behalf and on Your sole responsibility, not on behalf
 *       of any other Contributor, and only if You agree to indemnify,
 *       defend, and hold each Contributor harmless for any liability
 *       incurred by, or claims asserted against, such Contributor by reason
 *       of your accepting any such warranty or additional liability.
 *
 *    END OF TERMS AND CONDITIONS
 *
 *    APPENDIX: How to apply the Apache License to your work.
 *
 *       To apply the Apache License to your work, attach the following
 *       boilerplate notice, with the fields enclosed by brackets "{}"
 *       replaced with your own identifying information. (Don't include
 *       the brackets!)  The text should be enclosed in the appropriate
 *       comment syntax for the file format. We also recommend that a
 *       file or class name and description of purpose be included on the
 *       same "printed page" as the copyright notice for easier
 *       identification within third-party archives.
 *
 *    Copyright 2014 Edgar Espina
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.jooby.run;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.lang.reflect.Field;
import java.net.MalformedURLException;
import java.net.URI;
import java.nio.file.Paths;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;
import java.util.jar.JarFile;

import org.jboss.modules.DependencySpec;
import org.jboss.modules.Module;
import org.jboss.modules.ModuleIdentifier;
import org.jboss.modules.ModuleLoadException;
import org.jboss.modules.ModuleLoader;
import org.jboss.modules.ModuleSpec;
import org.jboss.modules.ResourceLoaderSpec;
import org.jboss.modules.ResourceLoaders;

public class AppModuleLoader extends ModuleLoader {

  private Map<ModuleIdentifier, ModuleSpec> modules;

  public AppModuleLoader(final Map<ModuleIdentifier, ModuleSpec> modules) {
    this.modules = modules;
  }

  @Override
  protected ModuleSpec findModule(final ModuleIdentifier moduleId) throws ModuleLoadException {
    ModuleSpec spec = modules.get(moduleId);
    return spec == null ? super.findModule(moduleId) : spec;
  }

  public void unload(final Module module) {
    super.unloadModuleLocal(module);
  }

  /**
   * Build a flat jboss module, with some minor exceptions (like j2v8).
   *
   * @param name module name.
   * @param cp Classpath.
   * @return A new app module loader.
   * @throws Exception If something goes wrong.
   */
  public static AppModuleLoader build(final String name, final File... cp) throws Exception {
    Map<ModuleIdentifier, ModuleSpec> modules = newModule(name, 0, "", cp);
    return new AppModuleLoader(modules);
  }

  private static Map<ModuleIdentifier, ModuleSpec> newModule(final String name,
      final int level, final String prefix, final File... cp) throws Exception {
    Map<ModuleIdentifier, ModuleSpec> modules = new HashMap<>();

    String mId = name.replace(".jar", "");
    ModuleSpec.Builder builder = ModuleSpec.build(ModuleIdentifier.fromString(mId));
    if (level == 0) {
      String classurl = AppModuleLoader.class
          .getResource("/" + Main.JOOBY_REF.replace(".", "/") + ".class")
          .toString();
      String jartoken = ".jar!";
      File jar = new File(URI
          .create(classurl.substring(0, classurl.indexOf(jartoken) + jartoken.length() - 1)
              .replace("jar:", "")));
      Main.debug("loading hack: %s?%s", jar, jar.exists());
      builder.addResourceRoot(ResourceLoaderSpec
          .createResourceLoaderSpec(ResourceLoaders
              .createJarResourceLoader("jooby-run", new JarFile(jar))));
    }

    int l = (prefix.length() + mId.length() + level);
    Main.debug("%1$" + l + "s", prefix + mId);
    for (File file : cp) {
      if (file.getName().endsWith(".pom")) {
        // skip pom(s)
        continue;
      }
      if (!file.exists()) {
        // skip missing file/dir
        continue;
      }
      String fname = "└── " + file.getAbsolutePath();
      if (file.getName().startsWith("j2v8") && !name.equals(file.getName())) {
        ModuleSpec dependency = newModule(file.getName(), level + 2, "└── ", file)
            .values()
            .iterator()
            .next();
        builder.addDependency(
            DependencySpec.createModuleDependencySpec(dependency.getModuleIdentifier()));
        modules.put(dependency.getModuleIdentifier(), dependency);
      } else {
        Main.debug("%1$" + (fname.length() + level + 2) + "s", fname);
        if (file.getName().endsWith(".jar")) {
          builder.addResourceRoot(ResourceLoaderSpec
              .createResourceLoaderSpec(ResourceLoaders
                  .createJarResourceLoader(file.getName(), new JarFile(file))));
        } else {
          builder.addResourceRoot(ResourceLoaderSpec
              .createResourceLoaderSpec(ResourceLoaders
                  .createFileResourceLoader(file.getName(), file)));
        }
      }
    }
    Set<String> sysPaths = sysPaths();

    Main.trace("system packages:");
    sysPaths.forEach(p -> Main.trace("  %s", p));

    builder.addDependency(DependencySpec.createSystemDependencySpec(sysPaths));
    builder.addDependency(DependencySpec.createLocalDependencySpec());

    ModuleSpec module = builder.create();
    modules.put(module.getModuleIdentifier(), builder.create());
    return modules;
  }

  @SuppressWarnings({"rawtypes", "unchecked" })
  private static Set<String> jdkPaths() throws Exception {
    Class jdkPath = AppModuleLoader.class.getClassLoader().loadClass("org.jboss.modules.JDKPaths");
    Field field = jdkPath.getDeclaredField("JDK");
    field.setAccessible(true);
    return (Set<String>) field.get(null);
  }

  private static Set<String> sysPaths() throws Exception {
    Set<String> pkgs = new LinkedHashSet<>();

    pkgs.addAll(jdkPaths());
    pkgs.addAll(pkgs(new InputStreamReader(Main.class.getResourceAsStream("pkgs"))));

    /**
     * Hack to let users to configure system packages, javax.transaction cause issues with
     * hibernate.
     */
    pkgs.addAll(pkgs(Paths.get("src", "etc", "jboss-modules", "pkgs.includes").toFile()));

    pkgs.removeAll(pkgs(Paths.get("src", "etc", "jboss-modules", "pkgs.excludes").toFile()));
    return pkgs;
  }

  private static Set<String> pkgs(final File file) throws IOException {
    if (file.exists()) {
      return pkgs(new FileReader(file));
    }
    return new LinkedHashSet<>();
  }

  private static Set<String> pkgs(final Reader reader) throws IOException {
    try (BufferedReader in = new BufferedReader(reader)) {
      Set<String> pkgs = new LinkedHashSet<>();
      String line = in.readLine();
      while (line != null) {
        pkgs.add(line.trim());
        line = in.readLine();
      }
      return pkgs;
    }
  }

}


/**
 *                                  Apache License
 *                            Version 2.0, January 2004
 *                         http://www.apache.org/licenses/
 *
 *    TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
 *
 *    1. Definitions.
 *
 *       "License" shall mean the terms and conditions for use, reproduction,
 *       and distribution as defined by Sections 1 through 9 of this document.
 *
 *       "Licensor" shall mean the copyright owner or entity authorized by
 *       the copyright owner that is granting the License.
 *
 *       "Legal Entity" shall mean the union of the acting entity and all
 *       other entities that control, are controlled by, or are under common
 *       control with that entity. For the purposes of this definition,
 *       "control" means (i) the power, direct or indirect, to cause the
 *       direction or management of such entity, whether by contract or
 *       otherwise, or (ii) ownership of fifty percent (50%) or more of the
 *       outstanding shares, or (iii) beneficial ownership of such entity.
 *
 *       "You" (or "Your") shall mean an individual or Legal Entity
 *       exercising permissions granted by this License.
 *
 *       "Source" form shall mean the preferred form for making modifications,
 *       including but not limited to software source code, documentation
 *       source, and configuration files.
 *
 *       "Object" form shall mean any form resulting from mechanical
 *       transformation or translation of a Source form, including but
 *       not limited to compiled object code, generated documentation,
 *       and conversions to other media types.
 *
 *       "Work" shall mean the work of authorship, whether in Source or
 *       Object form, made available under the License, as indicated by a
 *       copyright notice that is included in or attached to the work
 *       (an example is provided in the Appendix below).
 *
 *       "Derivative Works" shall mean any work, whether in Source or Object
 *       form, that is based on (or derived from) the Work and for which the
 *       editorial revisions, annotations, elaborations, or other modifications
 *       represent, as a whole, an original work of authorship. For the purposes
 *       of this License, Derivative Works shall not include works that remain
 *       separable from, or merely link (or bind by name) to the interfaces of,
 *       the Work and Derivative Works thereof.
 *
 *       "Contribution" shall mean any work of authorship, including
 *       the original version of the Work and any modifications or additions
 *       to that Work or Derivative Works thereof, that is intentionally
 *       submitted to Licensor for inclusion in the Work by the copyright owner
 *       or by an individual or Legal Entity authorized to submit on behalf of
 *       the copyright owner. For the purposes of this definition, "submitted"
 *       means any form of electronic, verbal, or written communication sent
 *       to the Licensor or its representatives, including but not limited to
 *       communication on electronic mailing lists, source code control systems,
 *       and issue tracking systems that are managed by, or on behalf of, the
 *       Licensor for the purpose of discussing and improving the Work, but
 *       excluding communication that is conspicuously marked or otherwise
 *       designated in writing by the copyright owner as "Not a Contribution."
 *
 *       "Contributor" shall mean Licensor and any individual or Legal Entity
 *       on behalf of whom a Contribution has been received by Licensor and
 *       subsequently incorporated within the Work.
 *
 *    2. Grant of Copyright License. Subject to the terms and conditions of
 *       this License, each Contributor hereby grants to You a perpetual,
 *       worldwide, non-exclusive, no-charge, royalty-free, irrevocable
 *       copyright license to reproduce, prepare Derivative Works of,
 *       publicly display, publicly perform, sublicense, and distribute the
 *       Work and such Derivative Works in Source or Object form.
 *
 *    3. Grant of Patent License. Subject to the terms and conditions of
 *       this License, each Contributor hereby grants to You a perpetual,
 *       worldwide, non-exclusive, no-charge, royalty-free, irrevocable
 *       (except as stated in this section) patent license to make, have made,
 *       use, offer to sell, sell, import, and otherwise transfer the Work,
 *       where such license applies only to those patent claims licensable
 *       by such Contributor that are necessarily infringed by their
 *       Contribution(s) alone or by combination of their Contribution(s)
 *       with the Work to which such Contribution(s) was submitted. If You
 *       institute patent litigation against any entity (including a
 *       cross-claim or counterclaim in a lawsuit) alleging that the Work
 *       or a Contribution incorporated within the Work constitutes direct
 *       or contributory patent infringement, then any patent licenses
 *       granted to You under this License for that Work shall terminate
 *       as of the date such litigation is filed.
 *
 *    4. Redistribution. You may reproduce and distribute copies of the
 *       Work or Derivative Works thereof in any medium, with or without
 *       modifications, and in Source or Object form, provided that You
 *       meet the following conditions:
 *
 *       (a) You must give any other recipients of the Work or
 *           Derivative Works a copy of this License; and
 *
 *       (b) You must cause any modified files to carry prominent notices
 *           stating that You changed the files; and
 *
 *       (c) You must retain, in the Source form of any Derivative Works
 *           that You distribute, all copyright, patent, trademark, and
 *           attribution notices from the Source form of the Work,
 *           excluding those notices that do not pertain to any part of
 *           the Derivative Works; and
 *
 *       (d) If the Work includes a "NOTICE" text file as part of its
 *           distribution, then any Derivative Works that You distribute must
 *           include a readable copy of the attribution notices contained
 *           within such NOTICE file, excluding those notices that do not
 *           pertain to any part of the Derivative Works, in at least one
 *           of the following places: within a NOTICE text file distributed
 *           as part of the Derivative Works; within the Source form or
 *           documentation, if provided along with the Derivative Works; or,
 *           within a display generated by the Derivative Works, if and
 *           wherever such third-party notices normally appear. The contents
 *           of the NOTICE file are for informational purposes only and
 *           do not modify the License. You may add Your own attribution
 *           notices within Derivative Works that You distribute, alongside
 *           or as an addendum to the NOTICE text from the Work, provided
 *           that such additional attribution notices cannot be construed
 *           as modifying the License.
 *
 *       You may add Your own copyright statement to Your modifications and
 *       may provide additional or different license terms and conditions
 *       for use, reproduction, or distribution of Your modifications, or
 *       for any such Derivative Works as a whole, provided Your use,
 *       reproduction, and distribution of the Work otherwise complies with
 *       the conditions stated in this License.
 *
 *    5. Submission of Contributions. Unless You explicitly state otherwise,
 *       any Contribution intentionally submitted for inclusion in the Work
 *       by You to the Licensor shall be under the terms and conditions of
 *       this License, without any additional terms or conditions.
 *       Notwithstanding the above, nothing herein shall supersede or modify
 *       the terms of any separate license agreement you may have executed
 *       with Licensor regarding such Contributions.
 *
 *    6. Trademarks. This License does not grant permission to use the trade
 *       names, trademarks, service marks, or product names of the Licensor,
 *       except as required for reasonable and customary use in describing the
 *       origin of the Work and reproducing the content of the NOTICE file.
 *
 *    7. Disclaimer of Warranty. Unless required by applicable law or
 *       agreed to in writing, Licensor provides the Work (and each
 *       Contributor provides its Contributions) on an "AS IS" BASIS,
 *       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 *       implied, including, without limitation, any warranties or conditions
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 *       PARTICULAR PURPOSE. You are solely responsible for determining the
 *       appropriateness of using or redistributing the Work and assume any
 *       risks associated with Your exercise of permissions under this License.
 *
 *    8. Limitation of Liability. In no event and under no legal theory,
 *       whether in tort (including negligence), contract, or otherwise,
 *       unless required by applicable law (such as deliberate and grossly
 *       negligent acts) or agreed to in writing, shall any Contributor be
 *       liable to You for damages, including any direct, indirect, special,
 *       incidental, or consequential damages of any character arising as a
 *       result of this License or out of the use or inability to use the
 *       Work (including but not limited to damages for loss of goodwill,
 *       work stoppage, computer failure or malfunction, or any and all
 *       other commercial damages or losses), even if such Contributor
 *       has been advised of the possibility of such damages.
 *
 *    9. Accepting Warranty or Additional Liability. While redistributing
 *       the Work or Derivative Works thereof, You may choose to offer,
 *       and charge a fee for, acceptance of support, warranty, indemnity,
 *       or other liability obligations and/or rights consistent with this
 *       License. However, in accepting such obligations, You may act only
 *       on Your own behalf and on Your sole responsibility, not on behalf
 *       of any other Contributor, and only if You agree to indemnify,
 *       defend, and hold each Contributor harmless for any liability
 *       incurred by, or claims asserted against, such Contributor by reason
 *       of your accepting any such warranty or additional liability.
 *
 *    END OF TERMS AND CONDITIONS
 *
 *    APPENDIX: How to apply the Apache License to your work.
 *
 *       To apply the Apache License to your work, attach the following
 *       boilerplate notice, with the fields enclosed by brackets "{}"
 *       replaced with your own identifying information. (Don't include
 *       the brackets!)  The text should be enclosed in the appropriate
 *       comment syntax for the file format. We also recommend that a
 *       file or class name and description of purpose be included on the
 *       same "printed page" as the copyright notice for easier
 *       identification within third-party archives.
 *
 *    Copyright 2014 Edgar Espina
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.jooby;

import com.google.common.collect.ImmutableList;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.TypeLiteral;
import com.google.inject.name.Names;
import static java.util.Objects.requireNonNull;
import org.jooby.Route.Chain;
import org.jooby.internal.SseRenderer;
import org.jooby.funzy.Throwing;
import org.jooby.funzy.Try;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.annotation.Nonnull;
import java.io.IOException;
import java.nio.channels.ClosedChannelException;
import java.nio.charset.StandardCharsets;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Optional;
import java.util.UUID;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;

/**
 *
Server Sent Events

 *

 * Server-Sent Events (SSE) is a mechanism that allows server to push the data from the server to
 * the client once the client-server connection is established by the client. Once the connection is
 * established by the client, it is the server who provides the data and decides to send it to the
 * client whenever new chunk of data is available.
 *

 *
 *
usage

 *
 *
{@code
 * {
 *   sse("/path", sse -> {
 *     // 1. connected
 *     sse.send("data"); // 2. send/push data
 *   });
 * }
 * }

 *
 *

 * Simple, effective and easy to use. The callback will be executed once when a new client is
 * connected. Inside the callback we can send data, listen for connection close events, etc.
 *

 *
 *

 * There is a factory method {@link #event(Object)} that let you set event attributes:
 *

 *
 *
{@code
 * {
 *   sse("/path", sse -> {
 *     sse.event("data")
 *         .id("id")
 *         .name("myevent")
 *         .retry(5000L)
 *         .send();
 *   });
 * }
 * }

 *
 *
structured data

 *

 * Beside raw/string data you can also send structured data, like json,
 * xml, etc..
 *

 *
 *

 * The next example will send two message one in json format and one in
 * text/plain format:
 *

 * :
 *
 *
{@code
 * {
 *   use(new MyJsonRenderer());
 *
 *   sse("/path", sse -> {
 *     MyObject object = ...
 *     sse.send(object, "json");
 *     sse.send(object, "plain");
 *   });
 * }
 * }

 *
 *

 * Or if your need only one format, just:
 *

 *
 *
{@code
 * {
 *   use(new MyJsonRenderer());
 *
 *   sse("/path", sse -> {
 *     MyObject object = ...
 *     sse.send(object);
 *   }).produces("json"); // by default always send json
 * }
 * }

 *
 *
request params

 *

 * We provide request access via two arguments callback:
 *

 *
 *
{@code
 * {
 *   sse("/events/:id", (req, sse) -> {
 *     String id = req.param("id").value();
 *     MyObject object = findObject(id);
 *     sse.send(object);
 *   });
 * }
 * }

 *
 *
connection lost

 *

 * The {@link #onClose(Throwing.Runnable)} callback allow you to clean and release resources on
 * connection close. A connection is closed by calling {@link #close()} or when the client/browser
 * close the connection.
 *

 *
 *
{@code
 * {
 *   sse("/events/:id", sse -> {
 *     sse.onClose(() -> {
 *       // clean up resources
 *     });
 *   });
 * }
 * }

 *
 *

 * The close event will be generated if you try to send an event on a closed connection.
 *

 *
 *
keep alive time

 *

 * The keep alive time feature can be used to prevent connections from timing out:
 *

 *
 *
{@code
 * {
 *   sse("/events/:id", sse -> {
 *     sse.keepAlive(15, TimeUnit.SECONDS);
 *   });
 * }
 * }

 *
 *

 * The previous example will sent a ':' message (empty comment) every 15 seconds to
 * keep the connection alive. If the client drop the connection, then the
 * {@link #onClose(Throwing.Runnable)} event will be fired it.
 *

 *
 *

 * This feature is useful when you want to detect {@link #onClose(Throwing.Runnable)} events without
 * waiting for the next time you send a new event. But for example, if your application already
 * generate events every 15s, then the use of keep alive is useless and you can avoid it.
 *

 *
 *
require

 *

 * The {@link #require(Class)} methods let you access to application services:
 *

 *
 *
{@code
 * {
 *   sse("/events/:id", sse -> {
 *     MyService service = sse.require(MyService.class);
 *   });
 * }
 * }

 *
 *
example

 *

 * The next example will generate a new event every 60s. It recovers from a server shutdown by using
 * the {@link #lastEventId()} and clean resources on connection close.
 *

 *
{@code
 * {
 *   // creates an executor service
 *   ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
 *
 *   sse("/events", sse -> {
 *     // if we go down, recover from last event ID we sent. Otherwise, start from zero.
 *     int lastId = sse.lastEventId(Integer.class).orElse(0);
 *
 *     AtomicInteger next = new AtomicInteger(lastId);
 *
 *     // send events every 60s
 *     ScheduledFuture<?> future = executor.scheduleAtFixedRate(() -> {
 *        Integer id = next.incrementAndGet();
 *        Object data = findDataById(id);
 *
 *        // send data and id
 *        sse.event(data).id(id).send();
 *      }, 0, 60, TimeUnit.SECONDS);
 *
 *      // on connection lost, cancel 60s task
 *      sse.onClose(() -> {
 *       future.cancel(true);
 *      });
 *   });
 * }
 *
 * }

 *
 * @author edgar
 * @since 1.0.0.CR
 */
public abstract class Sse implements AutoCloseable {

  /**
   * Event representation of Server sent event.
   *
   * @author edgar
   * @since 1.0.0.CR
   */
  public static class Event {
    private Object id;

    private String name;

    private Object data;

    private Long retry;

    private MediaType type;

    private String comment;

    private Sse sse;

    private Event(final Sse sse, final Object data) {
      this.sse = sse;
      this.data = data;
    }

    /**
     * @return Event data (if any).
     */
    public Optional<Object> data() {
      return Optional.ofNullable(data);
    }

    /**
     * Event media type helps to render or format event data.
     *
     * @return Event media type (if any).
     */
    public Optional<MediaType> type() {
      return Optional.ofNullable(type);
    }

    /**
     * Set event media type. Useful for sengin json, xml, etc..
     *
     * @param type Media Type.
     * @return This event.
     */
    public Event type(final MediaType type) {
      this.type = requireNonNull(type, "Type is required.");
      return this;
    }

    /**
     * Set event media type. Useful for sengin json, xml, etc..
     *
     * @param type Media Type.
     * @return This event.
     */
    public Event type(final String type) {
      return type(MediaType.valueOf(type));
    }

    /**
     * @return Event id (if any).
     */
    public Optional<Object> id() {
      return Optional.ofNullable(id);
    }

    /**
     * Set event id.
     *
     * @param id An event id.
     * @return This event.
     */
    public Event id(final Object id) {
      this.id = requireNonNull(id, "Id is required.");
      return this;
    }

    /**
     * @return Event name (a.k.a type).
     */
    public Optional<String> name() {
      return Optional.ofNullable(name);
    }

    /**
     * Set event name (a.k.a type).
     *
     * @param name Event's name.
     * @return This event.
     */
    public Event name(final String name) {
      this.name = requireNonNull(name, "Name is required.");
      return this;
    }

    /**
     * Clients (browsers) will attempt to reconnect every 3 seconds. The retry option allow you to
     * specify the number of millis a browser should wait before try to reconnect.
     *
     * @param retry Retry value.
     * @param unit Time unit.
     * @return This event.
     */
    public Event retry(final int retry, final TimeUnit unit) {
      this.retry = unit.toMillis(retry);
      return this;
    }

    /**
     * Clients (browsers) will attempt to reconnect every 3 seconds. The retry option allow you to
     * specify the number of millis a browser should wait before try to reconnect.
     *
     * @param retry Retry value in millis.
     * @return This event.
     */
    public Event retry(final long retry) {
      this.retry = retry;
      return this;
    }

    /**
     * @return Event comment (if any).
     */
    public Optional<String> comment() {
      return Optional.ofNullable(comment);
    }

    /**
     * Set event comment.
     *
     * @param comment An event comment.
     * @return This event.
     */
    public Event comment(final String comment) {
      this.comment = requireNonNull(comment, "Comment is required.");
      return this;
    }

    /**
     * @return Retry event line (if any).
     */
    public Optional<Long> retry() {
      return Optional.ofNullable(retry);
    }

    /**
     * Send an event and optionally listen for success confirmation or error:
     *
     *
{@code
     * sse.event(data).send().onSuccess(id -> {
     *   // success
     * }).onFailure(cause -> {
     *   // handle error
     * });
     * }

     *
     * @return A future callback.
     */
    public CompletableFuture<Optional<Object>> send() {
      CompletableFuture<Optional<Object>> future = sse.send(this);
      this.id = null;
      this.name = null;
      this.data = null;
      this.type = null;
      this.sse = null;
      return future;
    }

  }

  /**
   * Server-sent event handler.
   *
   * @author edgar
   * @since 1.0.0.CR
   */
  public interface Handler extends Route.Filter {

    @Override
    default void handle(final Request req, final Response rsp, final Chain chain) throws Throwable {
      Sse sse = req.require(Sse.class);
      String path = req.path();
      rsp.send(new Deferred(deferred -> {
        try {
          sse.handshake(req, () -> {
            Try.run(() -> handle(req, sse))
                .onSuccess(() -> deferred.resolve(null))
                .onFailure(ex -> {
                  deferred.reject(ex);
                  Logger log = LoggerFactory.getLogger(Sse.class);
                  log.error("execution of {} resulted in error", path, ex);
                });
          });
        } catch (Exception ex) {
          deferred.reject(ex);
        }
      }));
    }

    /**
     * Event handler.
     *
     * @param req Current request.
     * @param sse Sse object.
     * @throws Exception If something goes wrong.
     */
    void handle(Request req, Sse sse) throws Exception;
  }

  /**
   * Single argument event handler.
   *
   * @author edgar
   * @since 1.0.0.CR
   */
  public interface Handler1 extends Handler {
    @Override
    default void handle(final Request req, final Sse sse) throws Exception {
      handle(sse);
    }

    void handle(Sse sse) throws Exception;
  }

  /* package */static class KeepAlive implements Runnable {

    /** The logging system. */
    private final Logger log = LoggerFactory.getLogger(Sse.class);

    private Sse sse;

    private long retry;

    public KeepAlive(final Sse sse, final long retry) {
      this.sse = sse;
      this.retry = retry;
    }

    @Override
    public void run() {
      String sseId = sse.id();
      log.debug("running heart beat for {}", sseId);
      Try.run(() -> sse.send(Optional.of(sseId), HEART_BEAT).whenComplete((id, x) -> {
        if (x != null) {
          log.debug("connection lost for {}", sseId, x);
          sse.fireCloseEvent();
          Try.run(sse::close);
        } else {
          log.debug("reschedule heart beat for {}", id);
          // reschedule
          sse.keepAlive(retry);
        }
      }));
    }

  }

  /** Keep alive scheduler. */
  private static final ScheduledExecutorService scheduler = Executors
      .newSingleThreadScheduledExecutor(r -> {
        Thread thread = new Thread(r, "sse-heartbeat");
        thread.setDaemon(true);
        return thread;
      });

  /** Empty comment. */
  static final byte[] HEART_BEAT = ":\n".getBytes(StandardCharsets.UTF_8);

  /** The logging system. */
  protected final Logger log = LoggerFactory.getLogger(Sse.class);

  private Injector injector;

  private List<Renderer> renderers;

  private final String id;

  private List<MediaType> produces;

  private Map<String, Object> locals;

  private AtomicReference<Throwing.Runnable> onclose = new AtomicReference<>(null);

  private Mutant lastEventId;

  private boolean closed;

  private Locale locale;

  public Sse() {
    id = UUID.randomUUID().toString();
  }

  protected void handshake(final Request req, final Runnable handler) throws Exception {
    this.injector = req.require(Injector.class);
    this.renderers = ImmutableList.copyOf(injector.getInstance(Renderer.KEY));
    this.produces = req.route().produces();
    this.locals = req.attributes();
    this.lastEventId = req.header("Last-Event-ID");
    this.locale = req.locale();
    handshake(handler);
  }

  protected abstract void handshake(Runnable handler) throws Exception;

  /**
   * A unique ID (like a session ID).
   *
   * @return Sse unique ID (like a session ID).
   */
  @Nonnull
  public String id() {
    return id;
  }

  /**
   * Server sent event will send a Last-Event-ID header if the server goes down.
   *
   * @return Last event id.
   */
  @Nonnull
  public Optional<String> lastEventId() {
    return lastEventId(String.class);
  }

  /**
   * Server sent event will send a Last-Event-ID header if the server goes down.
   *
   * @param type Last event id type.
   * @param <T> Event id type.
   * @return Last event id.
   */
  @Nonnull
  public <T> Optional<T> lastEventId(final Class<T> type) {
    return lastEventId.toOptional(type);
  }

  /**
   * Listen for connection close (usually client drop the connection). This method is useful for
   * resources cleanup.
   *
   * @param task Task to run.
   * @return This instance.
   */
  @Nonnull
  public Sse onClose(final Throwing.Runnable task) {
    onclose.set(task);
    return this;
  }

  /**
   * Send an event and set media type.
   *
   *
{@code
   *   sse.send(new MyObject(), "json");
   * }

   *
   *
{@code
   *   sse.send(new MyObject(), "json").whenComplete((id, x) -> {
   *     if (x == null) {
   *       handleSuccess();
   *     } else {
   *       handleError(x);
   *     }
   *   });
   * }

   *
   * The id of the success callback correspond to the {@link Event#id()}.
   *
   * @param data Event data.
   * @param type Media type, like: json, xml.
   * @return A future. The success callback contains the {@link Event#id()}.
   */
  @Nonnull
  public CompletableFuture<Optional<Object>> send(final Object data, final String type) {
    return send(data, MediaType.valueOf(type));
  }

  /**
   * Send an event and set media type.
   *
   *
{@code
   *   sse.send(new MyObject(), "json");
   * }

   *
   *
{@code
   *   sse.send(new MyObject(), "json").whenComplete((id, x) -> {
   *     if (x == null) {
   *       handleSuccess();
   *     } else {
   *       handleError(x);
   *     }
   *   });
   * }

   *
   * The id of the success callback correspond to the {@link Event#id()}.
   *
   * @param data Event data.
   * @param type Media type, like: json, xml.
   * @return A future. The success callback contains the {@link Event#id()}.
   */
  @Nonnull
  public CompletableFuture<Optional<Object>> send(final Object data, final MediaType type) {
    return event(data).type(type).send();
  }

  /**
   * Send an event.
   *
   *
{@code
   *   sse.send(new MyObject());
   * }

   *
   *
{@code
   *   sse.send(new MyObject(), "json").whenComplete((id, x) -> {
   *     if (x == null) {
   *       handleSuccess();
   *     } else {
   *       handleError(x);
   *     }
   *   });
   * }

   *
   * The id of the success callback correspond to the {@link Event#id()}.
   *
   * @param data Event data.
   * @return A future. The success callback contains the {@link Event#id()}.
   */
  @Nonnull
  public CompletableFuture<Optional<Object>> send(final Object data) {
    return event(data).send();
  }

  /**
   * Factory method for creating {@link Event} instances.
   *
   * Please note event won't be sent unless you call {@link Event#send()}:
   *
   *
{@code
   *   sse.event(new MyObject()).send();
   * }

   *
   * The factory allow you to set event attributes:
   *
   *
{@code
   *   // send data
   *   MyObject data = ...;
   *   sse.event(data).send();
   *
   *   // send data with event name
   *   sse.event(data).name("myevent").send();
   *
   *   // send data with event name and id
   *   sse.event(data).name("myevent").id(id).send();
   *
   *   // send data with event name, id and retry interval
   *   sse.event(data).name("myevent").id(id).retry(1500).send();
   * }

   *
   * @param data Event data.
   * @return A new event.
   */
  @Nonnull
  public Event event(final Object data) {
    return new Event(this, data);
  }

  /**
   * Ask Guice for the given type.
   *
   * @param type A service type.
   * @param <T> Service type.
   * @return A ready to use object.
   */
  @Nonnull
  public <T> T require(final Class<T> type) {
    return require(Key.get(type));
  }

  /**
   * Ask Guice for the given type.
   *
   * @param name A service name.
   * @param type A service type.
   * @param <T> Service type.
   * @return A ready to use object.
   */
  @Nonnull
  public <T> T require(final String name, final Class<T> type) {
    return require(Key.get(type, Names.named(name)));
  }

  /**
   * Ask Guice for the given type.
   *
   * @param type A service type.
   * @param <T> Service type.
   * @return A ready to use object.
   */
  @Nonnull
  public <T> T require(final TypeLiteral<T> type) {
    return require(Key.get(type));
  }

  /**
   * Ask Guice for the given type.
   *
   * @param key A service key.
   * @param <T> Service type.
   * @return A ready to use object.
   */
  @Nonnull
  public <T> T require(final Key<T> key) {
    return injector.getInstance(key);
  }

  /**
   * The keep alive time can be used to prevent connections from timing out:
   *
   *
{@code
   * {
   *   sse("/events/:id", sse -> {
   *     sse.keepAlive(15, TimeUnit.SECONDS);
   *   });
   * }
   * }

   *
   *

   * The previous example will sent a ':' message (empty comment) every 15 seconds to
   * keep the connection alive. If the client drop the connection, then the
   * {@link #onClose(Throwing.Runnable)} event will be fired it.
   *

   *
   *

   * This feature is useful when you want to detect {@link #onClose(Throwing.Runnable)} events without
   * waiting until you send a new event. But for example, if your application already generate
   * events
   * every 15s, then the use of keep alive is useless and you should avoid it.
   *

   *
   * @param time Keep alive time.
   * @param unit Time unit.
   * @return This instance.
   */
  @Nonnull
  public Sse keepAlive(final int time, final TimeUnit unit) {
    return keepAlive(unit.toMillis(time));
  }

  /**
   * The keep alive time can be used to prevent connections from timing out:
   *
   *
{@code
   * {
   *   sse("/events/:id", sse -> {
   *     sse.keepAlive(15, TimeUnit.SECONDS);
   *   });
   * }
   * }

   *
   *

   * The previous example will sent a ':' message (empty comment) every 15 seconds to
   * keep the connection alive. If the client drop the connection, then the
   * {@link #onClose(Throwing.Runnable)} event will be fired it.
   *

   *
   *

   * This feature is useful when you want to detect {@link #onClose(Throwing.Runnable)} events without
   * waiting until you send a new event. But for example, if your application already generate
   * events
   * every 15s, then the use of keep alive is useless and you should avoid it.
   *

   *
   * @param millis Keep alive time in millis.
   * @return This instance.
   */
  @Nonnull
  public Sse keepAlive(final long millis) {
    scheduler.schedule(new KeepAlive(this, millis), millis, TimeUnit.MILLISECONDS);
    return this;
  }

  /**
   * Close the connection and fire an {@link #onClose(Throwing.Runnable)} event.
   */
  @Override
  public final void close() throws Exception {
    closeAll();
  }

  private void closeAll() {
    synchronized (this) {
      if (!closed) {
        closed = true;
        fireCloseEvent();
        closeInternal();
      }
    }
  }

  protected abstract void closeInternal();

  protected abstract CompletableFuture<Optional<Object>> send(Optional<Object> id, byte[] data);

  protected void ifClose(final Throwable cause) {
    if (shouldClose(cause)) {
      closeAll();
    }
  }

  protected void fireCloseEvent() {
    Throwing.Runnable task = onclose.getAndSet(null);
    if (task != null) {
      Try.run(task).onFailure(ex -> log.error("close callback resulted in error", ex));
    }
  }

  protected boolean shouldClose(final Throwable ex) {
    if (ex instanceof IOException) {
      // is there a better way?
      boolean brokenPipe = Optional.ofNullable(ex.getMessage())
          .map(m -> m.toLowerCase().contains("broken pipe"))
          .orElse(false);
      return brokenPipe || ex instanceof ClosedChannelException;
    }
    return false;
  }

  private CompletableFuture<Optional<Object>> send(final Event event) {
    List<MediaType> produces = event.type().<List<MediaType>>map(ImmutableList::of)
        .orElse(this.produces);
    SseRenderer ctx = new SseRenderer(renderers, produces, StandardCharsets.UTF_8, locale, locals);
    return Try.apply(() -> {
      byte[] bytes = ctx.format(event);
      return send(event.id(), bytes);
    }).recover(x -> {
      CompletableFuture<Optional<Object>> future = new CompletableFuture<>();
      future.completeExceptionally(x);
      return future;
    })
        .get();
  }

}