player

type Backend struct {
	// Commands can be used to send commands to the UI.
	Commands chan Command

	// UIStates receives updates to the UI state non-blockingly.
	UIStates chan UIState
	// contains filtered or unexported fields
}

type Command struct {
	// Exit exits all current playbacks and returns to waiting state.
	Exit bool

	// Quit quits the entire main loop.
	Quit bool

	// PlayOne plays the given file.
	PlayOne string

	// PlayPrelude enters prelude player mode.
	PlayPrelude bool

	// New list of tags for prelude selection.
	PreludeTags map[string]bool

	// Tempo sets the tempo to a new factor.
	Tempo float64

	// NumVerses is an override for the verse count.
	NumVerses int

	// Answer continues the current playback (exits a Prompt state).
	Answer bool

	// Skip skips the current playback (exits a Prompt state).
	Skip bool

	// Config contains a new configuration. Will be applied on next hymn.
	Config *processor.Config

	// OutPort contains a new, not yet opened, MIDI port. Will be applied once silent.
	OutPort drivers.Out
}

type Options struct {
	// FSys is the virtual file system to use.
	FSys fs.FS

	// Config is the global configuration to use.
	Config *processor.Config

	// OutPort is the MIDI output port to use. OK to change later.
	OutPort drivers.Out

	// PlayOnly is the single file to play.
	PlayOnly string
}

type UIState struct {
	// Err is set to show an error message. The backend is dead, but can be
	// restarted by sending a PlayOne or PlayPrelude message.
	Err error

	// PlayOne is the name of the currently playing file.
	PlayOne string

	// PlayPrelude indicates if we're in the prelude player.
	PlayPrelude bool

	// List of tags for prelude selection.
	PreludeTags map[string]bool

	// Tempo is the current tempo as a factor of normal.
	Tempo float64

	// Number of verses to play.
	NumVerses int

	// HavePostlude tells if a postlude is pending.
	HavePostlude bool

	// Prompt is the text to prompt the user with.
	// To clear a prompt, send the Answer or Skip message.
	Prompt string

	// SkipPrompt is nonempty is when the skip button should be available.
	// To clear a prompt, send the Answer or Skip message.
	SkipPrompt string

	// CurrentFile is the currently being played file.
	CurrentFile string

	// CurrentPart is the currently being played part.
	CurrentPart processor.OutputKey

	// CurrentMessage is a message for what is currently playing.
	CurrentMessage string

	// Playing is whether we are currently playing.
	Playing bool

	// PlaybackPosTime is the wall time PlaybackPos was last updated.
	PlaybackPosTime time.Time

	// PlaybackPos is the current playback position.
	PlaybackPos time.Duration

	// PlaybackLen is the length of the current file.
	PlaybackLen time.Duration

	// Verse is the current verse.
	Verse int

	// Comment is the hymn comment string.
	Comment string

	// UnrolledNumVerses of real verses in hymn. Only useful if NumVerses == 1.
	UnrolledNumVerses int
}