package x

import "image"

import "github.com/jezek/xgbutil"
import "github.com/jezek/xgb/xproto"
import "git.tebibyte.media/tomo/xgbkb"
import "github.com/jezek/xgbutil/xevent"
import "git.tebibyte.media/tomo/tomo/input"

type scrollSum struct {
	x, y int
}

// TODO: this needs to be configurable, we need a config api
const scrollDistance = 16

func (sum *scrollSum) add (button xproto.Button, window *window, state uint16) {
	if xgbkb.StateToModifiers(state).Shift {
		switch button {
		case 4: sum.x -= scrollDistance
		case 5: sum.x += scrollDistance
		case 6: sum.y -= scrollDistance
		case 7: sum.y += scrollDistance
		}
	} else {
		switch button {
		case 4: sum.y -= scrollDistance
		case 5: sum.y += scrollDistance
		case 6: sum.x -= scrollDistance
		case 7: sum.x += scrollDistance
		}
	}
}

var buttonCodeTable = map[xproto.Keysym] input.Key {
	0xFFFFFF: input.KeyNone,

	0xFF63: input.KeyInsert,
	0xFF67: input.KeyMenu,
	0xFF61: input.KeyPrintScreen,
	0xFF6B: input.KeyPause,
	0xFFE5: input.KeyCapsLock,
	0xFF14: input.KeyScrollLock,
	0xFF7F: input.KeyNumLock,
	0xFF08: input.KeyBackspace,
	0xFF09: input.KeyTab,
	0xFE20: input.KeyTab,
	0xFF0D: input.KeyEnter,
	0xFF1B: input.KeyEscape,
	
	0xFF52: input.KeyUp,
	0xFF54: input.KeyDown,
	0xFF51: input.KeyLeft,
	0xFF53: input.KeyRight,
	0xFF55: input.KeyPageUp,
	0xFF56: input.KeyPageDown,
	0xFF50: input.KeyHome,
	0xFF57: input.KeyEnd,
	
	0xFFE1: input.KeyLeftShift,
	0xFFE2: input.KeyRightShift,
	0xFFE3: input.KeyLeftControl,
	0xFFE4: input.KeyRightControl,

	0xFFE7: input.KeyLeftMeta,
	0xFFE8: input.KeyRightMeta,
	0xFFE9: input.KeyLeftAlt,
	0xFFEA: input.KeyRightAlt,
	0xFFEB: input.KeyLeftSuper,
	0xFFEC: input.KeyRightSuper,
	0xFFED: input.KeyLeftHyper,
	0xFFEE: input.KeyRightHyper,
	
	0xFFFF: input.KeyDelete,
	
	0xFFBE: input.KeyF1,
	0xFFBF: input.KeyF2,
	0xFFC0: input.KeyF3,
	0xFFC1: input.KeyF4,
	0xFFC2: input.KeyF5,
	0xFFC3: input.KeyF6,
	0xFFC4: input.KeyF7,
	0xFFC5: input.KeyF8,
	0xFFC6: input.KeyF9,
	0xFFC7: input.KeyF10,
	0xFFC8: input.KeyF11,
	0xFFC9: input.KeyF12,

	0xFF20: input.KeyDead,
}

var keypadCodeTable = map[xproto.Keysym] input.Key {
	0xff80: input.Key(' '),
	0xff89: input.KeyTab,
	0xff8d: input.KeyEnter,
	0xff91: input.KeyF1,
	0xff92: input.KeyF2,
	0xff93: input.KeyF3,
	0xff94: input.KeyF4,
	0xff95: input.KeyHome,
	0xff96: input.KeyLeft,
	0xff97: input.KeyUp,
	0xff98: input.KeyRight,
	0xff99: input.KeyDown,
	0xff9a: input.KeyPageUp,
	0xff9b: input.KeyPageDown,
	0xff9c: input.KeyEnd,
	0xff9d: input.KeyHome,
	0xff9e: input.KeyInsert,
	0xff9f: input.KeyDelete,
	0xffbd: input.Key('='),
	0xffaa: input.Key('*'),
	0xffab: input.Key('+'),
	0xffac: input.Key(','),
	0xffad: input.Key('-'),
	0xffae: input.Key('.'),
	0xffaf: input.Key('/'),

	0xffb0: input.Key('0'),
	0xffb1: input.Key('1'),
	0xffb2: input.Key('2'),
	0xffb3: input.Key('3'),
	0xffb4: input.Key('4'),
	0xffb5: input.Key('5'),
	0xffb6: input.Key('6'),
	0xffb7: input.Key('7'),
	0xffb8: input.Key('8'),
	0xffb9: input.Key('9'),
}

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
	configureEvent = window.compressConfigureNotify(configureEvent)
	
	oldBounds := window.metrics.bounds
	window.updateBounds()
	newBounds := window.metrics.bounds

	sizeChanged :=
		oldBounds.Dx() != newBounds.Dx() ||
		oldBounds.Dy() != newBounds.Dy()

	if sizeChanged {
		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 keycodeToKey (keycode xproto.Keycode, state uint16) (input.Key, bool) {
	keysym, char := xgbkb.KeycodeToKeysym(keycode, state)

	if xgbkb.IsOnNumpad(keysym) {
		// look up in keypad table
		key := keypadCodeTable[keysym]
		return key, true
	} else {		
		// look up in control code table
		key, isControl := buttonCodeTable[keysym]
		if isControl {
			return key, false
		} else {
			// return as rune
			return input.Key(char), false
		}
	}
}

func (window *window) handleKeyPress (
	connection *xgbutil.XUtil,
	event xevent.KeyPressEvent,
) {
	if window.hasModal { return }
	
	keyEvent := *event.KeyPressEvent
	key, numberPad := keycodeToKey(keyEvent.Detail, keyEvent.State)
	window.updateModifiers(keyEvent.State)

	if key == input.KeyTab && window.modifiers.Alt {
		if window.modifiers.Shift {
			window.focusPrevious()
		} else {
			window.focusNext()
		}
	} else if key == input.KeyEscape && window.shy {
		window.Close()
	} else if window.focused != nil {
		window.keyboardTarget().handleKeyDown(key, numberPad)
	}
}

func (window *window) handleKeyRelease (
	connection *xgbutil.XUtil,
	event xevent.KeyReleaseEvent,
) {
	if window.hasModal { return }
	
	keyEvent := *event.KeyReleaseEvent

	// do not process this event if it was generated from a key repeat
	nextEvents := xevent.Peek(window.backend.x)
	if len(nextEvents) > 0 {
		untypedEvent := nextEvents[0]
		if untypedEvent.Err == nil {
			typedEvent, ok :=
				untypedEvent.Event.(xproto.KeyPressEvent)
			
			if ok && typedEvent.Detail == keyEvent.Detail &&
				typedEvent.Event == keyEvent.Event &&
				typedEvent.State == keyEvent.State {

				return
			}
		}
	}
	
	key, numberPad := keycodeToKey(keyEvent.Detail, keyEvent.State)
	window.updateModifiers(keyEvent.State)

	if window.focused != nil {
		window.keyboardTarget().handleKeyUp(key, numberPad)
	}
}

func (window *window) handleButtonPress (
	connection *xgbutil.XUtil,
	event xevent.ButtonPressEvent,
) {
	if window.hasModal { return }
	
	buttonEvent  := *event.ButtonPressEvent
	point        := image.Pt(int(buttonEvent.EventX), int(buttonEvent.EventY))
	insideWindow := point.In(window.xCanvas.Bounds())
	scrolling    := buttonEvent.Detail >= 4 && buttonEvent.Detail <= 7
	window.updateModifiers(buttonEvent.State)
	window.updateMousePosition(buttonEvent.EventX, buttonEvent.EventY)

	if !insideWindow && window.shy && !scrolling {
		window.Close()
	} else if scrolling {
		underneath := window.boxUnder(point, eventCategoryScroll)
		if underneath != nil {
			sum := scrollSum { }
			sum.add(buttonEvent.Detail, window, buttonEvent.State)
			window.compressScrollSum(buttonEvent, &sum)
			underneath.handleScroll(float64(sum.x), float64(sum.y))
		}
	} else {
		underneath := window.boxUnder(point, eventCategoryMouse)
		window.drags[buttonEvent.Detail] = underneath
		if underneath != nil {
			underneath.handleMouseDown(input.Button(buttonEvent.Detail))
		}
	}
}

func (window *window) handleButtonRelease (
	connection *xgbutil.XUtil,
	event xevent.ButtonReleaseEvent,
) {
	if window.hasModal { return }
	
	buttonEvent := *event.ButtonReleaseEvent
	if buttonEvent.Detail >= 4 && buttonEvent.Detail <= 7 { return }
	window.updateModifiers(buttonEvent.State)
	window.updateMousePosition(buttonEvent.EventX, buttonEvent.EventY)
	dragging := window.drags[buttonEvent.Detail]
	window.drags[buttonEvent.Detail] = nil
	
	if dragging != nil {
		dragging.handleMouseUp(input.Button(buttonEvent.Detail))
	}
}

func (window *window) handleMotionNotify (
	connection *xgbutil.XUtil,
	event xevent.MotionNotifyEvent,
) {
	if window.hasModal { return }
	
	motionEvent := window.compressMotionNotify(*event.MotionNotifyEvent)
	window.updateMousePosition(motionEvent.EventX, motionEvent.EventY)
	x := int(motionEvent.EventX)
	y := int(motionEvent.EventY)

	handled := false
	for _, child := range window.drags {
		if child == nil { continue }
		child.handleMouseMove()
		handled = true
	}

	underneath := window.boxUnder(image.Pt(x, y), eventCategoryMouse)
	if underneath != nil {
		window.hover(underneath)
		if !handled {
			underneath.handleMouseMove()
		}
	}
	
}

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
}

func (window *window) compressScrollSum (
	firstEvent xproto.ButtonPressEvent,
	sum *scrollSum,
) {
	window.backend.x.Sync()
	xevent.Read(window.backend.x, false)
	
	for index, untypedEvent := range xevent.Peek(window.backend.x) {
		if untypedEvent.Err != nil { continue }
		
		typedEvent, ok := untypedEvent.Event.(xproto.ButtonPressEvent)
		if !ok { continue }

		if firstEvent.Event == typedEvent.Event &&
			typedEvent.Detail >= 4 &&
			typedEvent.Detail <= 7 {

			sum.add(typedEvent.Detail, window, typedEvent.State)
			defer func (index int) {
				xevent.DequeueAt(window.backend.x, index)
			} (index)
		}
	}

	return
}

func (window *window) compressMotionNotify (
	firstEvent xproto.MotionNotifyEvent,
) (
	lastEvent xproto.MotionNotifyEvent,
) {
	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.MotionNotifyEvent)
		if !ok { continue }

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

	return
}

func (window *window) updateModifiers (state uint16) {
	modifiers := xgbkb.StateToModifiers(state)
	window.modifiers.Shift   = modifiers.Shift || modifiers.ShiftLock
	window.modifiers.Control = modifiers.Control
	window.modifiers.Alt     = modifiers.Alt
	window.modifiers.Meta    = modifiers.Meta
	window.modifiers.Super   = modifiers.Super
	window.modifiers.Hyper   = modifiers.Hyper
}

func (window *window) updateMousePosition (x, y int16) {
	window.mousePosition = image.Pt(int(x), int(y))
}