text: // Go support for Protocol Buffers - Google's data interchange format
  //
  // Copyright 2016 The Go Authors.  All rights reserved.
  // https://github.com/golang/protobuf
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  package types
  
  // This file implements conversions between google.protobuf.Duration
  // and time.Duration.
  
  import (
  	"errors"
  	"fmt"
  	"time"
  )
  
  const (
  	// Range of a Duration in seconds, as specified in
  	// google/protobuf/duration.proto. This is about 10,000 years in seconds.
  	maxSeconds = int64(10000 * 365.25 * 24 * 60 * 60)
  	minSeconds = -maxSeconds
  )
  
  // validateDuration determines whether the Duration is valid according to the
  // definition in google/protobuf/duration.proto. A valid Duration
  // may still be too large to fit into a time.Duration (the range of Duration
  // is about 10,000 years, and the range of time.Duration is about 290).
  func validateDuration(d *Duration) error {
  	if d == nil {
  		return errors.New("duration: nil Duration")
  	}
  	if d.Seconds < minSeconds || d.Seconds > maxSeconds {
  		return fmt.Errorf("duration: %#v: seconds out of range", d)
  	}
  	if d.Nanos <= -1e9 || d.Nanos >= 1e9 {
  		return fmt.Errorf("duration: %#v: nanos out of range", d)
  	}
  	// Seconds and Nanos must have the same sign, unless d.Nanos is zero.
  	if (d.Seconds < 0 && d.Nanos > 0) || (d.Seconds > 0 && d.Nanos < 0) {
  		return fmt.Errorf("duration: %#v: seconds and nanos have different signs", d)
  	}
  	return nil
  }
  
  // DurationFromProto converts a Duration to a time.Duration. DurationFromProto
  // returns an error if the Duration is invalid or is too large to be
  // represented in a time.Duration.
  func DurationFromProto(p *Duration) (time.Duration, error) {
  	if err := validateDuration(p); err != nil {
  		return 0, err
  	}
  	d := time.Duration(p.Seconds) * time.Second
  	if int64(d/time.Second) != p.Seconds {
  		return 0, fmt.Errorf("duration: %#v is out of range for time.Duration", p)
  	}
  	if p.Nanos != 0 {
  		d += time.Duration(p.Nanos) * time.Nanosecond
  		if (d < 0) != (p.Nanos < 0) {
  			return 0, fmt.Errorf("duration: %#v is out of range for time.Duration", p)
  		}
  	}
  	return d, nil
  }
  
  // DurationProto converts a time.Duration to a Duration.
  func DurationProto(d time.Duration) *Duration {
  	nanos := d.Nanoseconds()
  	secs := nanos / 1e9
  	nanos -= secs * 1e9
  	return &Duration{
  		Seconds: secs,
  		Nanos:   int32(nanos),
  	}
  }
  