package x

import "unicode"
import "github.com/jezek/xgb/xproto"
import "github.com/jezek/xgbutil/keybind"
import "git.tebibyte.media/sashakoshka/stone"

// when making changes to this file, look at keysymdef.h and
// https://tronche.com/gui/x/xlib/input/keyboard-encoding.html

var buttonCodeTable = map[xproto.Keysym] stone.Button {
	0xFFFFFF: stone.ButtonUnknown,

	0xFF63: stone.KeyInsert,
	0xFF67: stone.KeyMenu,
	0xFF61: stone.KeyPrintScreen,
	0xFF6B: stone.KeyPause,
	0xFFE5: stone.KeyCapsLock,
	0xFF14: stone.KeyScrollLock,
	0xFF7F: stone.KeyNumLock,
	0xFF08: stone.KeyBackspace,
	0xFF09: stone.KeyTab,
	0xFF0D: stone.KeyEnter,
	0xFF1B: stone.KeyEscape,
	
	0xFF52: stone.KeyUp,
	0xFF54: stone.KeyDown,
	0xFF51: stone.KeyLeft,
	0xFF53: stone.KeyRight,
	0xFF55: stone.KeyPageUp,
	0xFF56: stone.KeyPageDown,
	0xFF50: stone.KeyHome,
	0xFF57: stone.KeyEnd,
	
	0xFFE1: stone.KeyLeftShift,
	0xFFE2: stone.KeyRightShift,
	0xFFE3: stone.KeyLeftControl,
	0xFFE4: stone.KeyRightControl,
	0xFFE9: stone.KeyLeftAlt,
	0xFFEA: stone.KeyRightAlt,
	0xFFEB: stone.KeyLeftSuper,
	0xFFEC: stone.KeyRightSuper,
	
	0xFFFF: stone.KeyDelete,
	
	0xFFBE: stone.KeyF1,
	0xFFBF: stone.KeyF2,
	0xFFC0: stone.KeyF3,
	0xFFC1: stone.KeyF4,
	0xFFC2: stone.KeyF5,
	0xFFC3: stone.KeyF6,
	0xFFC4: stone.KeyF7,
	0xFFC5: stone.KeyF8,
	0xFFC6: stone.KeyF9,
	0xFFC7: stone.KeyF10,
	0xFFC8: stone.KeyF11,
	0xFFC9: stone.KeyF12,
}

func (backend *Backend) keycodeToButton (
	keycode xproto.Keycode,
	state   uint16,
) (
	button stone.Button,
) {
	// FIXME: also set shift to true if the lock modifier is on and the lock
	// modifier is interpreted as shiftLock
	shift    := state & xproto.ModMaskShift > 0

	// FIXME: only set this to true if the lock modifier is on and the lock
	// modifier is interpreted as capsLock
	capsLock := state & xproto.ModMaskLock  > 0

	symbol1 := keybind.KeysymGet(backend.connection, keycode, 0)
	symbol2 := keybind.KeysymGet(backend.connection, keycode, 1)
	symbol3 := keybind.KeysymGet(backend.connection, keycode, 2)
	symbol4 := keybind.KeysymGet(backend.connection, keycode, 3)

	cased := false

	// third paragraph
	switch {
	case symbol2 == 0 && symbol3 == 0 && symbol4 == 0:
		symbol3 = symbol1
	case symbol3 == 0 && symbol4 == 0:
		symbol3 = symbol1
		symbol2 = symbol2
	case symbol4 == 0:
		symbol4 = 0
	}

	symbol1Rune := keysymToRune(symbol1)
	symbol2Rune := keysymToRune(symbol2)
	symbol3Rune := keysymToRune(symbol3)
	symbol4Rune := keysymToRune(symbol4)

	// FIXME: we ignore mode switch stuff
	_ = symbol4Rune

	// fourth paragraph
	if symbol2 == 0 {
		upper := unicode.IsUpper(symbol1Rune)
		lower := unicode.IsLower(symbol1Rune)
		if upper || lower {
			symbol1Rune = unicode.ToLower(symbol1Rune)
			symbol2Rune = unicode.ToUpper(symbol1Rune)
			cased = true
		} else {
			symbol2 = symbol1
		}
	}
	if symbol4 == 0 {
		upper := unicode.IsUpper(symbol3Rune)
		lower := unicode.IsLower(symbol3Rune)
		if upper || lower {
			symbol3Rune = unicode.ToLower(symbol3Rune)
			symbol4Rune = unicode.ToUpper(symbol3Rune)
			cased = true
		} else {
			symbol4 = symbol3
		}
	}

	var selectedKeysym xproto.Keysym
	var selectedRune   rune
	
	// big ol list in the middle
	switch {
	// FIXME: take into account numlock
	case !shift && !capsLock:
		selectedKeysym = symbol1
		selectedRune   = symbol1Rune
		
	case !shift && capsLock:
		if cased && unicode.IsLower(symbol1Rune) {
			selectedRune = symbol2Rune
		} else {
			selectedKeysym = symbol1
			selectedRune   = symbol1Rune
		}
		
	case shift && capsLock:
		if cased && unicode.IsLower(symbol2Rune) {
			selectedRune = unicode.ToUpper(symbol2Rune)
		} else {
			selectedKeysym = symbol2
			selectedRune   = symbol2Rune
		}
		
	case shift:
		selectedKeysym = symbol2
		selectedRune   = symbol2Rune
	}

	// look up in table
	var isControl bool
	button, isControl = buttonCodeTable[selectedKeysym]

	// if it wasn't found, 
	if !isControl {
		button = stone.Button(selectedRune)
	}
	
	return
}

func keysymToRune (keysym xproto.Keysym) (character rune) {
	// X keysyms like 0xFF.. or 0xFE.. are non-character keys. these cannot
	// be converted so we return a zero.
	if (keysym >> 8) == 0xFF || (keysym >> 8) == 0xFE {
		character = 0
		return
	}
	
	// some X keysyms have a single bit set to 1 here. i believe this is to
	// prevent conflicts with existing codes. if we mask it off we will get
	// a correct utf-32 code point.
	if keysym & 0xF000000 == 0x1000000 {
		character = rune(keysym & 0x0111111)
		return
	}

	// if none of these things happened, we can safely (i think) assume that
	// the keysym is an exact utf-32 code point.
	character = rune(keysym)
	return
}