package playback

import (
	"errors"
	"fmt"
)

type SessionCommandKind uint8

const (
	CommandSetVideo SessionCommandKind = iota + 1
	CommandSetAudio
	CommandStopVideo
	CommandStopAudio
	CommandStopAll
	CommandResumeVideo
	CommandResumeAudio
	CommandResumeAll
	CommandRemoveVideo
	CommandRemoveAudio
	CommandEnableSync
	CommandDisableSync
	CommandSetSession
)

type SessionCommand struct {
	Kind    SessionCommandKind
	Config  FeedConfig    // Used only by SetVideo and SetAudio.
	Session SessionConfig // Used only by SetSession.
}

var (
	ErrUnknownSessionCommand = errors.New("unknown session command")
	ErrVideoNotConfigured    = errors.New("video feed is not configured")
	ErrAudioNotConfigured    = errors.New("audio feed is not configured")
)

func ApplySessionCommand(
	current SessionConfig,
	command SessionCommand,
) (SessionConfig, error) {
	next := current
	switch command.Kind {
	case CommandSetVideo:
		if !command.Config.IsConfigured() {
			return current, ErrVideoNotConfigured
		}
		if err := command.Config.Validate(); err != nil {
			return current, fmt.Errorf("validate video command: %w", err)
		}
		next.Video = command.Config

	case CommandSetAudio:
		if !command.Config.IsConfigured() {
			return current, ErrAudioNotConfigured
		}
		if err := command.Config.Validate(); err != nil {
			return current, fmt.Errorf("validate audio command: %w", err)
		}
		next.Audio = command.Config

	case CommandStopVideo:
		next.Video.Active = false
		next.SyncRequested = false

	case CommandStopAudio:
		next.Audio.Active = false
		next.SyncRequested = false

	case CommandStopAll:
		next.Video.Active = false
		next.Audio.Active = false

	case CommandResumeVideo:
		if !next.Video.IsConfigured() {
			return current, ErrVideoNotConfigured
		}
		next.Video.Active = true

	case CommandResumeAudio:
		if !next.Audio.IsConfigured() {
			return current, ErrAudioNotConfigured
		}
		next.Audio.Active = true

	case CommandResumeAll:
		next.Video.Active = next.Video.IsConfigured()
		next.Audio.Active = next.Audio.IsConfigured()

	case CommandRemoveVideo:
		next.Video = FeedConfig{}
		next.SyncRequested = false

	case CommandRemoveAudio:
		next.Audio = FeedConfig{}
		next.SyncRequested = false

	case CommandEnableSync:
		next.SyncRequested = true

	case CommandDisableSync:
		next.SyncRequested = false

	case CommandSetSession:
		next = command.Session
		// Retry policy belongs to the running controller configuration, not to
		// GUI or playlist session selections.
		next.Retry = current.Retry

	default:
		return current, ErrUnknownSessionCommand
	}

	if err := next.Validate(); err != nil {
		return current, fmt.Errorf("validate desired session: %w", err)
	}
	return next, nil
}