/*
 * Copyright 2019 New Vector Ltd
 *
 * 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 im.vector.app.features.roomdirectory

import com.airbnb.epoxy.TypedEpoxyController
import com.airbnb.epoxy.VisibilityState
import com.airbnb.mvrx.Fail
import com.airbnb.mvrx.Incomplete
import com.airbnb.mvrx.Success
import im.vector.app.R
import im.vector.app.core.epoxy.errorWithRetryItem
import im.vector.app.core.epoxy.loadingItem
import im.vector.app.core.epoxy.noResultItem
import im.vector.app.core.error.ErrorFormatter
import im.vector.app.core.resources.StringProvider
import im.vector.app.features.home.AvatarRenderer
import org.matrix.android.sdk.api.MatrixPatterns
import org.matrix.android.sdk.api.session.room.members.ChangeMembershipState
import org.matrix.android.sdk.api.session.room.model.roomdirectory.PublicRoom
import org.matrix.android.sdk.api.util.MatrixItem
import org.matrix.android.sdk.api.util.toMatrixItem
import javax.inject.Inject

class PublicRoomsController @Inject constructor(private val stringProvider: StringProvider,
                                                private val avatarRenderer: AvatarRenderer,
                                                private val errorFormatter: ErrorFormatter) : TypedEpoxyController<PublicRoomsViewState>() {

    var callback: Callback? = null

    override fun buildModels(viewState: PublicRoomsViewState) {
        val publicRooms = viewState.publicRooms

        val unknownRoomItem = viewState.buildUnknownRoomIfNeeded()

        val noResult = publicRooms.isEmpty() && viewState.asyncPublicRoomsRequest is Success && unknownRoomItem == null
        if (noResult) {
            // No result
            noResultItem {
                id("noResult")
                text(stringProvider.getString(R.string.no_result_placeholder))
            }
        } else {
            publicRooms.forEach {
                buildPublicRoom(it, viewState)
            }

            unknownRoomItem?.addTo(this)

            if ((viewState.hasMore && viewState.asyncPublicRoomsRequest is Success)
                    || viewState.asyncPublicRoomsRequest is Incomplete) {
                loadingItem {
                    // Change id to avoid list to scroll automatically when first results are displayed
                    if (publicRooms.isEmpty()) {
                        id("loading")
                    } else {
                        id("loadMore")
                    }
                    onVisibilityStateChanged { _, _, visibilityState ->
                        if (visibilityState == VisibilityState.VISIBLE) {
                            callback?.loadMore()
                        }
                    }
                }
            }
        }

        if (viewState.asyncPublicRoomsRequest is Fail) {
            errorWithRetryItem {
                id("error")
                text(errorFormatter.toHumanReadable(viewState.asyncPublicRoomsRequest.error))
                listener { callback?.loadMore() }
            }
        }
    }

    private fun buildPublicRoom(publicRoom: PublicRoom, viewState: PublicRoomsViewState) {
        publicRoomItem {
            avatarRenderer(avatarRenderer)
            id(publicRoom.roomId)
            matrixItem(publicRoom.toMatrixItem())
            roomAlias(publicRoom.getPrimaryAlias())
            roomTopic(publicRoom.topic)
            nbOfMembers(publicRoom.numJoinedMembers)

            val roomChangeMembership = viewState.changeMembershipStates[publicRoom.roomId] ?: ChangeMembershipState.Unknown
            val isJoined = viewState.joinedRoomsIds.contains(publicRoom.roomId) || roomChangeMembership is ChangeMembershipState.Joined
            val joinState = when {
                isJoined                                                    -> JoinState.JOINED
                roomChangeMembership is ChangeMembershipState.Joining       -> JoinState.JOINING
                roomChangeMembership is ChangeMembershipState.FailedJoining -> JoinState.JOINING_ERROR
                else                                                        -> JoinState.NOT_JOINED
            }
            joinState(joinState)

            joinListener {
                callback?.onPublicRoomJoin(publicRoom)
            }
            globalListener {
                callback?.onPublicRoomClicked(publicRoom, joinState)
            }
        }
    }

    private fun PublicRoomsViewState.buildUnknownRoomIfNeeded(): UnknownRoomItem? {
        val roomIdOrAlias = currentFilter.trim()
        val isAlias = MatrixPatterns.isRoomAlias(roomIdOrAlias) && !publicRooms.any { it.canonicalAlias == roomIdOrAlias }
        val isRoomId = !isAlias && MatrixPatterns.isRoomId(roomIdOrAlias) && !publicRooms.any { it.roomId == roomIdOrAlias }
        val roomItem = when {
            isAlias  -> MatrixItem.RoomAliasItem(roomIdOrAlias, roomIdOrAlias)
            isRoomId -> MatrixItem.RoomItem(roomIdOrAlias)
            else     -> null
        }
        return roomItem?.let {
            UnknownRoomItem_().apply {
                id(roomIdOrAlias)
                matrixItem(it)
                avatarRenderer(this@PublicRoomsController.avatarRenderer)
                globalListener {
                    callback?.onUnknownRoomClicked(roomIdOrAlias)
                }
            }
        }
    }

    interface Callback {
        fun onUnknownRoomClicked(roomIdOrAlias: String)
        fun onPublicRoomClicked(publicRoom: PublicRoom, joinState: JoinState)
        fun onPublicRoomJoin(publicRoom: PublicRoom)
        fun loadMore()
    }
}
