clui/composer.go

package clui

import (
	term "github.com/nsf/termbox-go"
)

// Composer is a service object that manages Views and console, processes
// events, and provides service methods. One application must have only
// one object of this type
type Composer struct {
	// list of visible Views
	windows  []Control
	consumer Control
	// last pressed key - to make repeatable actions simpler, e.g, at first
	// one presses Ctrl+S and then just repeatedly presses arrow lest to
	// resize Window
	lastKey term.Key
	// coordinates when the mouse button was down, e.g to detect
	// mouse click
	mdownX, mdownY int
	// last processed coordinates: e.g, for mouse move
	lastX, lastY int
	// Type of dragging
	dragType DragType
}

var (
	comp *Composer
)

func initComposer() {
	comp = new(Composer)
	comp.windows = make([]Control, 0)
	comp.consumer = nil
	comp.lastKey = term.KeyEsc
}

func composer() *Composer {
	return comp
}

// GrabEvents makes control c as the exclusive event reciever. After calling
// this function the control will recieve all mouse and keyboard events even
// if it is not active or mouse is outside it. Useful to implement dragging
// or alike stuff
func GrabEvents(c Control) {
	comp.consumer = c
}

// ReleaseEvents stops a control being exclusive evetn reciever and backs all
// to normal event processing
func ReleaseEvents() {
	comp.consumer = nil
}

func termboxEventToLocal(ev term.Event) Event {
	e := Event{Type: EventType(ev.Type), Ch: ev.Ch,
		Key: ev.Key, Err: ev.Err, X: ev.MouseX, Y: ev.MouseY,
		Mod: ev.Mod, Width: ev.Width, Height: ev.Height}
	return e
}

// Repaints everything on the screen
func RefreshScreen() {
	term.Clear(ColorWhite, ColorBlack)

	for _, wnd := range comp.windows {
		wnd.Draw()
	}

	term.Flush()
}

// AddWindow constucts a new Window, adds it to the composer automatically,
// and makes it active
// posX and posY are top left coordinates of the Window
// width and height are Window size
// title is a Window title
func AddWindow(posX, posY, width, height int, title string) *Window {
	window := CreateWindow(posX, posY, width, height, title)

	comp.windows = append(comp.windows, window)
	window.Draw()

	comp.activateWindow(window)

	RefreshScreen()

	return window
}

func (c *Composer) checkWindowUnderMouse(screenX, screenY int) (Control, HitResult) {
	if len(c.windows) == 0 {
		return nil, HitOutside
	}

	for i := len(c.windows) - 1; i >= 0; i-- {
		window := c.windows[i]
		hit := window.HitTest(screenX, screenY)
		if hit != HitOutside {
			return window, hit
		}
	}

	return nil, HitOutside
}

func (c *Composer) activateWindow(window Control) bool {
	if c.topWindow() == window {
		for _, v := range c.windows {
			v.SetActive(false)
		}
		window.SetActive(true)
		return true
	}

	var wList []Control
	found := false

	for _, v := range c.windows {
		if v != window {
			v.SetActive(false)
			wList = append(wList, v)
		} else {
			found = true
		}
	}

	if !found {
		return false
	}

	window.SetActive(true)
	c.windows = append(wList, window)
	return true
}

func (c *Composer) moveActiveWindowToBottom() bool {
	if len(c.windows) < 2 {
		return false
	}

	if c.topWindow().Modal() {
		return false
	}

	event := Event{Type: EventActivate, X: 0} // send deactivated
	c.sendEventToActiveWindow(event)

	last := c.topWindow()

	for i := len(c.windows) - 1; i > 0; i-- {
		c.windows[i] = c.windows[i-1]
	}

	c.windows[0] = last
	if !c.activateWindow(c.topWindow()) {
		return false
	}

	event = Event{Type: EventActivate, X: 1} // send 'activated'
	c.sendEventToActiveWindow(event)
	RefreshScreen()

	return true
}

func (c *Composer) sendEventToActiveWindow(ev Event) bool {
	view := c.topWindow()
	if view != nil {
		return view.ProcessEvent(ev)
	}

	return false
}

func (c *Composer) topWindow() Control {
	if len(c.windows) == 0 {
		return nil
	}

	return c.windows[len(c.windows)-1]
}

func (c *Composer) resizeTopWindow(ev Event) bool {
	view := c.topWindow()
	if view == nil {
		return false
	}

	w, h := view.Size()
	w1, h1 := w, h
	minW, minH := view.Constraints()
	if ev.Key == term.KeyArrowUp && minH < h {
		h--
	} else if ev.Key == term.KeyArrowLeft && minW < w {
		w--
	} else if ev.Key == term.KeyArrowDown {
		h++
	} else if ev.Key == term.KeyArrowRight {
		w++
	}

	if w1 != w || h1 != h {
		view.SetSize(w, h)
		event := Event{Type: EventResize, X: w, Y: h}
		c.sendEventToActiveWindow(event)
		RefreshScreen()
	}

	return true
}

func (c *Composer) moveTopWindow(ev Event) bool {
	if len(c.windows) > 0 {
		view := c.topWindow()
		if view != nil {
			x, y := view.Pos()
			w, h := view.Size()
			x1, y1 := x, y
			cx, cy := term.Size()
			if ev.Key == term.KeyArrowUp && y > 0 {
				y--
			} else if ev.Key == term.KeyArrowDown && y+h < cy {
				y++
			} else if ev.Key == term.KeyArrowLeft && x > 0 {
				x--
			} else if ev.Key == term.KeyArrowRight && x+w < cx {
				x++
			}

			if x1 != x || y1 != y {
				view.SetPos(x, y)
				event := Event{Type: EventMove, X: x, Y: y}
				c.sendEventToActiveWindow(event)
				RefreshScreen()
			}
		}
		return true
	}

	return false
}

func (c *Composer) closeTopWindow() {
	if len(c.windows) > 1 {
		view := c.topWindow()
		event := Event{Type: EventClose, X: 1}
		c.sendEventToActiveWindow(event)

		c.DestroyWindow(view)
		activate := c.topWindow()
		c.activateWindow(activate)
		event = Event{Type: EventActivate, X: 1} // send 'activated'
		c.sendEventToActiveWindow(event)

		RefreshScreen()
	} else {
		go Stop()
	}
}

func (c *Composer) processWindowDrag(ev Event) {
	if ev.Mod != term.ModMotion || c.dragType == DragNone {
		return
	}
	dx := ev.X - c.lastX
	dy := ev.Y - c.lastY
	if dx == 0 && dy == 0 {
		return
	}

	w := c.topWindow()
	newX, newY := w.Pos()
	newW, newH := w.Size()
	cw, ch := ScreenSize()

	switch c.dragType {
	case DragMove:
		newX = newX + dx
		newY = newY + dy
		if newX >= 0 && newY >= 0 && newX+newW < cw && newY+newH < ch {
			c.lastX = ev.X
			c.lastY = ev.Y

			w.SetPos(newX, newY)
			event := Event{Type: EventMove, X: newX, Y: newY}
			c.sendEventToActiveWindow(event)
			RefreshScreen()
		}
	case DragResizeLeft:
		newX = newX + dx
		newW = newW - dx
		if newX >= 0 && newY >= 0 && newX+newW < cw && newY+newH < ch {
			c.lastX = ev.X
			c.lastY = ev.Y

			w.SetPos(newX, newY)
			w.SetSize(newW, newH)
			event := Event{Type: EventMove, X: newX, Y: newY}
			c.sendEventToActiveWindow(event)
			event.Type = EventResize
			c.sendEventToActiveWindow(event)
			RefreshScreen()
		}
	case DragResizeRight:
		newW = newW + dx
		if newX >= 0 && newY >= 0 && newX+newW < cw && newY+newH < ch {
			c.lastX = ev.X
			c.lastY = ev.Y

			w.SetSize(newW, newH)
			event := Event{Type: EventResize}
			c.sendEventToActiveWindow(event)
			RefreshScreen()
		}
	case DragResizeBottom:
		newH = newH + dy
		if newX >= 0 && newY >= 0 && newX+newW < cw && newY+newH < ch {
			c.lastX = ev.X
			c.lastY = ev.Y

			w.SetSize(newW, newH)
			event := Event{Type: EventResize}
			c.sendEventToActiveWindow(event)
			RefreshScreen()
		}
	case DragResizeTopLeft:
		newX = newX + dx
		newW = newW - dx
		newY = newY + dy
		newH = newH - dy
		if newX >= 0 && newY >= 0 && newX+newW < cw && newY+newH < ch {
			c.lastX = ev.X
			c.lastY = ev.Y

			w.SetPos(newX, newY)
			w.SetSize(newW, newH)
			event := Event{Type: EventMove, X: newX, Y: newY}
			c.sendEventToActiveWindow(event)
			event.Type = EventResize
			c.sendEventToActiveWindow(event)
			RefreshScreen()
		}
	case DragResizeBottomLeft:
		newX = newX + dx
		newW = newW - dx
		newH = newH + dy
		if newX >= 0 && newY >= 0 && newX+newW < cw && newY+newH < ch {
			c.lastX = ev.X
			c.lastY = ev.Y

			w.SetPos(newX, newY)
			w.SetSize(newW, newH)
			event := Event{Type: EventMove, X: newX, Y: newY}
			c.sendEventToActiveWindow(event)
			event.Type = EventResize
			c.sendEventToActiveWindow(event)
			RefreshScreen()
		}
	case DragResizeBottomRight:
		newW = newW + dx
		newH = newH + dy
		if newX >= 0 && newY >= 0 && newX+newW < cw && newY+newH < ch {
			c.lastX = ev.X
			c.lastY = ev.Y

			w.SetSize(newW, newH)
			event := Event{Type: EventResize}
			c.sendEventToActiveWindow(event)
			RefreshScreen()
		}
	case DragResizeTopRight:
		newY = newY + dy
		newW = newW + dx
		newH = newH - dy
		if newX >= 0 && newY >= 0 && newX+newW < cw && newY+newH < ch {
			c.lastX = ev.X
			c.lastY = ev.Y

			w.SetPos(newX, newY)
			w.SetSize(newW, newH)
			event := Event{Type: EventMove, X: newX, Y: newY}
			c.sendEventToActiveWindow(event)
			event.Type = EventResize
			c.sendEventToActiveWindow(event)
			RefreshScreen()
		}
	}
}

func (c *Composer) processMouse(ev Event) {
	if c.consumer != nil {
		tmp := c.consumer
		tmp.ProcessEvent(ev)
		tmp.Draw()
		term.Flush()
		return
	}

	view, hit := c.checkWindowUnderMouse(ev.X, ev.Y)
	if c.dragType != DragNone {
		view = c.topWindow()
	}

	if c.topWindow() == view {
		if ev.Key == term.MouseRelease && c.dragType != DragNone {
			c.dragType = DragNone
			return
		}

		if ev.Mod == term.ModMotion && c.dragType != DragNone {
			c.processWindowDrag(ev)
			return
		}

		if hit != HitInside && ev.Key == term.MouseLeft {
			if hit != HitButtonClose && hit != HitButtonBottom && hit != HitButtonMaximize {
				c.lastX = ev.X
				c.lastY = ev.Y
				c.mdownX = ev.X
				c.mdownY = ev.Y
			}
			switch hit {
			case HitButtonClose:
				c.closeTopWindow()
			case HitButtonBottom:
				c.moveActiveWindowToBottom()
			case HitButtonMaximize:
				v := c.topWindow().(*Window)
				maximized := v.Maximized()
				v.SetMaximized(!maximized)
			case HitTop:
				c.dragType = DragMove
			case HitBottom:
				c.dragType = DragResizeBottom
			case HitLeft:
				c.dragType = DragResizeLeft
			case HitRight:
				c.dragType = DragResizeRight
			case HitTopLeft:
				c.dragType = DragResizeTopLeft
			case HitTopRight:
				c.dragType = DragResizeTopRight
			case HitBottomRight:
				c.dragType = DragResizeBottomRight
			case HitBottomLeft:
				c.dragType = DragResizeBottomLeft
			}

			return
		}
	}

	if ev.Key == term.MouseLeft {
		c.lastX = ev.X
		c.lastY = ev.Y
		c.mdownX = ev.X
		c.mdownY = ev.Y
		c.sendEventToActiveWindow(ev)
		return
	} else if ev.Key == term.MouseRelease {
		c.sendEventToActiveWindow(ev)
		if c.lastX != ev.X && c.lastY != ev.Y {
			return
		}

		ev.Type = EventClick
		c.sendEventToActiveWindow(ev)
		return
	} else {
		c.sendEventToActiveWindow(ev)
		return
	}

	if view == nil {
		return
	}

	if c.topWindow() != view {
		if c.topWindow().Modal() {
			return
		}
		event := Event{Type: EventActivate, X: 0} // send 'deactivated'
		c.sendEventToActiveWindow(event)
		c.activateWindow(view)
		event = Event{Type: EventActivate, X: 1} // send 'activated'
		c.sendEventToActiveWindow(event)
	} else if hit == HitInside {
		c.sendEventToActiveWindow(ev)
	}
}

// Stop sends termination event to Composer. Composer should stop
// console management and quit application
func Stop() {
	ev := Event{Type: EventQuit}
	go PutEvent(ev)
}

// DestroyWindow removes the Window from the list of managed Windows
func (c *Composer) DestroyWindow(view Control) {
	ev := Event{Type: EventClose}
	c.sendEventToActiveWindow(ev)

	var newOrder []Control
	for i := 0; i < len(c.windows); i++ {
		if c.windows[i] != view {
			newOrder = append(newOrder, c.windows[i])
		}
	}
	c.windows = newOrder
	c.activateWindow(c.topWindow())
}

// IsDeadKey returns true if the pressed key is the first key in
// the key sequence understood by composer. Dead key is never sent to
// any control
func IsDeadKey(key term.Key) bool {
	if key == term.KeyCtrlS || key == term.KeyCtrlP ||
		key == term.KeyCtrlW || key == term.KeyCtrlQ {
		return true
	}

	return false
}

func (c *Composer) processKey(ev Event) {
	if ev.Key == term.KeyEsc {
		if IsDeadKey(c.lastKey) {
			c.lastKey = term.KeyEsc
			return
		}
	}

	if IsDeadKey(ev.Key) && !IsDeadKey(c.lastKey) {
		c.lastKey = ev.Key
		return
	}

	if !IsDeadKey(ev.Key) {
		if c.consumer != nil {
			tmp := c.consumer
			tmp.ProcessEvent(ev)
			tmp.Draw()
			term.Flush()
		} else {
			c.sendEventToActiveWindow(ev)
			c.topWindow().Draw()
			term.Flush()
		}
	}

	newKey := term.KeyEsc
	switch c.lastKey {
	case term.KeyCtrlQ:
		switch ev.Key {
		case term.KeyCtrlQ:
			Stop()
		default:
			newKey = ev.Key
		}
	case term.KeyCtrlS:
		switch ev.Key {
		case term.KeyArrowUp, term.KeyArrowDown, term.KeyArrowLeft, term.KeyArrowRight:
			c.resizeTopWindow(ev)
		default:
			newKey = ev.Key
		}
	case term.KeyCtrlP:
		switch ev.Key {
		case term.KeyArrowUp, term.KeyArrowDown, term.KeyArrowLeft, term.KeyArrowRight:
			c.moveTopWindow(ev)
		default:
			newKey = ev.Key
		}
	case term.KeyCtrlW:
		switch ev.Key {
		case term.KeyCtrlH:
			c.moveActiveWindowToBottom()
		case term.KeyCtrlM:
			w := c.topWindow().(*Window)
			maxxed := w.Maximized()
			w.SetMaximized(!maxxed)
			RefreshScreen()
		case term.KeyCtrlC:
			c.closeTopWindow()
		default:
			newKey = ev.Key
		}
	}

	if newKey != term.KeyEsc {
		event := Event{Key: c.lastKey, Type: EventKey}
		c.sendEventToActiveWindow(event)
		event.Key = newKey
		c.sendEventToActiveWindow(event)
		c.lastKey = term.KeyEsc
	}
}

func ProcessEvent(ev Event) {
	switch ev.Type {
	case EventRedraw:
		RefreshScreen()
	case EventResize:
		SetScreenSize(ev.Width, ev.Height)
		for _, c := range comp.windows {
			wnd := c.(*Window)
			if wnd.Maximized() {
				wnd.SetSize(ev.Width, ev.Height)
				wnd.ResizeChildren()
				wnd.PlaceChildren()
				RefreshScreen()
			}
		}
	case EventKey:
		comp.processKey(ev)
	case EventMouse:
		comp.processMouse(ev)
	}
}