package x

import "image"

import "github.com/jezek/xgbutil"
import "github.com/jezek/xgb/xproto"
import "github.com/jezek/xgbutil/xevent"

func (window *window) handleExpose (
	connection *xgbutil.XUtil,
	event xevent.ExposeEvent,
) {
	if window.xCanvas == nil {
		window.reallocateCanvas()
	}
	window.compressExpose(*event.ExposeEvent)
	window.pushAll()
}

func (window *window) updateBounds () {
	// FIXME: some window managers parent windows more than once, we might
	// need to sum up all their positions.
	decorGeometry, _ := window.xWindow.DecorGeometry()
	windowGeometry, _ := window.xWindow.Geometry()
	origin := image.Pt(
		windowGeometry.X() + decorGeometry.X(),
		windowGeometry.Y() + decorGeometry.Y())
	window.metrics.bounds = image.Rectangle {
		Min: origin,
		Max: origin.Add(image.Pt(windowGeometry.Width(), windowGeometry.Height())),
	}
}

func (window *window) handleConfigureNotify (
	connection *xgbutil.XUtil,
	event xevent.ConfigureNotifyEvent,
) {
	if window.root == nil { return }
	
	configureEvent := *event.ConfigureNotifyEvent
	
	newWidth  := int(configureEvent.Width)
	newHeight := int(configureEvent.Height)
	sizeChanged :=
		window.metrics.bounds.Dx() != newWidth ||
		window.metrics.bounds.Dy() != newHeight
	window.updateBounds()

	if sizeChanged {
		configureEvent = window.compressConfigureNotify(configureEvent)
		window.reallocateCanvas()

		// TODO figure out what to do with this
		// if !window.exposeEventFollows(configureEvent) {
		// }
	}
}

func (window *window) exposeEventFollows (event xproto.ConfigureNotifyEvent) (found bool) {	
	nextEvents := xevent.Peek(window.backend.x)
	if len(nextEvents) > 0 {
		untypedEvent := nextEvents[0]
		if untypedEvent.Err == nil {
			typedEvent, ok :=
				untypedEvent.Event.(xproto.ConfigureNotifyEvent)
			
			if ok && typedEvent.Window == event.Window {
				return true
			}
		}
	}
	return false
}

func (window *window) compressExpose (
	firstEvent xproto.ExposeEvent,
) (
	lastEvent xproto.ExposeEvent,
	region image.Rectangle,
) {
	region = image.Rect (
		int(firstEvent.X), int(firstEvent.Y),
		int(firstEvent.X + firstEvent.Width),
		int(firstEvent.Y + firstEvent.Height))
	
	window.backend.x.Sync()
	xevent.Read(window.backend.x, false)
	lastEvent = firstEvent
	
	for index, untypedEvent := range xevent.Peek(window.backend.x) {
		if untypedEvent.Err != nil { continue }
		
		typedEvent, ok := untypedEvent.Event.(xproto.ExposeEvent)
		if !ok { continue }

		if firstEvent.Window == typedEvent.Window {
			region = region.Union (image.Rect (
				int(typedEvent.X), int(typedEvent.Y),
				int(typedEvent.X + typedEvent.Width),
				int(typedEvent.Y + typedEvent.Height)))
		
			lastEvent = typedEvent
			defer func (index int) {
				xevent.DequeueAt(window.backend.x, index)
			} (index)
		}
	}

	return
}

func (window *window) compressConfigureNotify (
	firstEvent xproto.ConfigureNotifyEvent,
) (
	lastEvent xproto.ConfigureNotifyEvent,
) {
	window.backend.x.Sync()
	xevent.Read(window.backend.x, false)
	lastEvent = firstEvent
	
	for index, untypedEvent := range xevent.Peek(window.backend.x) {
		if untypedEvent.Err != nil { continue }
		
		typedEvent, ok := untypedEvent.Event.(xproto.ConfigureNotifyEvent)
		if !ok { continue }
		
		if firstEvent.Event == typedEvent.Event &&
			firstEvent.Window == typedEvent.Window {

			lastEvent = typedEvent
			defer func (index int) {
				xevent.DequeueAt(window.backend.x, index)
			} (index)
		}
	}

	return
}