tty

type Tty interface {
	// Start is used to activate the Tty for use.  Upon return the terminal should be
	// in raw mode, non-blocking, etc.  The implementation should take care of saving
	// any state that is required so that it may be restored when Stop is called.
	// Start must be idempotent.
	Start() error

	// Stop is used to stop using this Tty instance.  This may be a suspend, so that other
	// terminal based applications can run in the foreground.  Implementations should
	// restore any state collected at Start(), and return to ordinary blocking mode, etc.
	// Drain is called first to drain the input.  Once this is called, no more Read
	// or Write calls will be made until Start is called again.
	Stop() error

	// Drain is called before Stop, and ensures that the reader will wake up appropriately
	// if it was blocked.  This workaround is required for /dev/tty on certain UNIX systems
	// to ensure that Read() does not block forever.  This typically arranges for the tty driver
	// to send data immediately (e.g. VMIN and VTIME both set zero) and sets a deadline on input.
	// Implementations may reasonably make this a no-op.  There will still be control sequences
	// emitted between the time this is called, and when Stop is called.
	Drain() error

	// NotifyResize is used to post a signal that will be written to (non-blocking) if the
	// system detects that a resize event happened.  If the channel is null, then the caller
	// does not desire such notifications (or no longer desires them.)
	// The standard UNIX implementation links this to a handler for SIGWINCH.
	//
	// If window resize events are delivered inline as part of Read, then the implementation may stub this.
	// If the caller determines that the underlying terminal can deliver notifications without OS support
	// (i.e. the terminal supports in-band resize notifications), then it may not call this function at all.
	NotifyResize(chan<- bool)

	// WindowSize is called to determine the terminal dimensions.  This might be determined
	// by an ioctl or other means.
	WindowSize() (WindowSize, error)

	io.ReadWriteCloser
}

type WindowSize struct {
	Width       int // Width in characters
	Height      int // Height in characters
	PixelWidth  int // Width in pixels (zero if not available or known)
	PixelHeight int // Height in pixels (zero if not available or known)
}