package asterisk

import (
	"context"
	"errors"
	"fmt"
	"time"

	"github.com/CyCoreSystems/ari/v5"
)

// awaitDialUp only runs after Dial was submitted. Create enters Stasis before
// any SIP request is sent, so StasisStart alone can never prove an answer.
func awaitDialUp(ctx context.Context, sub ari.Subscription, channelID string) (time.Time, error) {
	if ctx == nil || sub == nil || channelID == "" {
		return time.Time{}, errors.New("native answer wait has no channel subscription")
	}
	stasis, up := false, false
	var answeredAt time.Time
	for {
		select {
		case <-ctx.Done():
			return time.Time{}, ctx.Err()
		case event, ok := <-sub.Events():
			if !ok {
				return time.Time{}, errors.New("native answer subscription closed before confirmed answer")
			}
			if event == nil {
				continue
			}
			switch e := event.(type) {
			case *ari.StasisStart:
				if e.Channel.ID == channelID {
					stasis = true
				}
			case *ari.ChannelStateChange:
				if e.Channel.ID == channelID && e.Channel.State == "Up" {
					if !up {
						answeredAt = time.Time(e.Timestamp)
					}
					up = true
				}
			case *ari.ChannelDestroyed:
				if e.Channel.ID == channelID {
					return time.Time{}, fmt.Errorf("native outbound channel destroyed before verified answer: cause=%d", e.Cause)
				}
			case *ari.ChannelHangupRequest:
				if e.Channel.ID == channelID {
					return time.Time{}, fmt.Errorf("native outbound channel requested hangup before verified answer: cause=%d", e.Cause)
				}
			case *ari.StasisEnd:
				if e.Channel.ID == channelID {
					return time.Time{}, errors.New("native outbound channel left Stasis before verified answer")
				}
			}
			if stasis && up {
				return answeredAt, nil
			}
		}
	}
}

func eventBelongsToChannel(event ari.Event, channelID string) bool {
	for _, key := range event.Keys() {
		if key != nil && key.Kind == "channel" && key.ID == channelID {
			return true
		}
	}
	return false
}