package imgui

import (
	"mxl-player/internal/sdl"
	"unsafe"

	cimgui "github.com/AllenDang/cimgui-go/imgui"
)

const (
	sdlKModShift uint16 = 0x0001 | 0x0002
	sdlKModCtrl  uint16 = 0x0040 | 0x0080
	sdlKModAlt   uint16 = 0x0100 | 0x0200
	sdlKModGUI   uint16 = 0x0400 | 0x0800
)

// SDL3 event (128 byte raw buffer) -> imgui
func (c *Context) ProcessEvent(event *[128]byte) {
	eventType := *(*uint32)(unsafe.Pointer(&event[0]))

	// CommonEvent (16 bytes: type uint32 + reserved uint32 + timestamp uint64)
	switch eventType {
	case sdl.EventKeyDown, sdl.EventKeyUp:
		scancode := *(*uint32)(unsafe.Pointer(&event[24]))
		modifiers := *(*uint16)(unsafe.Pointer(&event[32]))
		down := eventType == sdl.EventKeyDown
		c.addKeyModifiers(modifiers)
		key := sdlScancodeToImGuiKey(scancode)
		if key >= 0 {
			c.io.AddKeyEvent(key, down)
		}
	// MouseMotionEvent: +16 windowID(4), +20 which(4), +24 state(4), +28 x(float32), +32 y(float32)
	case sdl.EventMouseMotion:
		x := *(*float32)(unsafe.Pointer(&event[28]))
		y := *(*float32)(unsafe.Pointer(&event[32]))
		c.io.AddMousePosEvent(x, y)
	// MouseButtonEvent: +16 windowID(4), +20 which(4), +24 button(1), +25 down(bool)
	case sdl.EventMouseButtonDown, sdl.EventMouseButtonUp:
		button := *(*uint8)(unsafe.Pointer(&event[24]))
		down := eventType == sdl.EventMouseButtonDown
		c.io.AddMouseButtonEvent(int32(button-1), down)
	// MouseWheelEvent: +16 windowID(4), +20 which(4), +24 x(float32), +28 y(float32)
	case sdl.EventMouseWheel:
		x := *(*float32)(unsafe.Pointer(&event[24]))
		y := *(*float32)(unsafe.Pointer(&event[28]))
		c.io.AddMouseWheelEvent(x, y)
	// TextInputEvent: +16 windowID(4), +20 text(*char pointer, 8 bytes on 64-bit)
	case sdl.EventTextInput:
		// text pointer is at offset 24, 8 bytes (pointer)
		ptr := *(*uintptr)(unsafe.Pointer(&event[24]))
		if ptr != 0 {
			text := cstr(ptr)
			c.io.AddInputCharactersUTF8(text)
		}

	}
}

func (c *Context) addKeyModifiers(modifiers uint16) {
	c.io.AddKeyEvent(cimgui.ModCtrl, modifiers&sdlKModCtrl != 0)
	c.io.AddKeyEvent(cimgui.ModShift, modifiers&sdlKModShift != 0)
	c.io.AddKeyEvent(cimgui.ModAlt, modifiers&sdlKModAlt != 0)
	c.io.AddKeyEvent(cimgui.ModSuper, modifiers&sdlKModGUI != 0)
}

func sdlScancodeToImGuiKey(scancode uint32) cimgui.Key {
	switch scancode {
	case 40: // SDL_SCANCODE_RETURN
		return cimgui.KeyEnter
	case 42: // SDL_SCANCODE_BACKSPACE
		return cimgui.KeyBackspace
	case 41: // SDL_SCANCODE_ESCAPE
		return cimgui.KeyEscape
	case 43: // SDL_SCANCODE_TAB
		return cimgui.KeyTab
	case 44: // SDL_SCANCODE_SPACE
		return cimgui.KeySpace
	case 80: // SDL_SCANCODE_LEFT
		return cimgui.KeyLeftArrow
	case 79: // SDL_SCANCODE_RIGHT
		return cimgui.KeyRightArrow
	case 82: // SDL_SCANCODE_UP
		return cimgui.KeyUpArrow
	case 81: // SDL_SCANCODE_DOWN
		return cimgui.KeyDownArrow
	case 225: // SDL_SCANCODE_LSHIFT
		return cimgui.KeyLeftShift
	case 229: // SDL_SCANCODE_RSHIFT
		return cimgui.KeyRightShift
	case 224: // SDL_SCANCODE_LCTRL
		return cimgui.KeyLeftCtrl
	case 228: // SDL_SCANCODE_RCTRL
		return cimgui.KeyRightCtrl
	case 226: // SDL_SCANCODE_LALT
		return cimgui.KeyLeftAlt
	case 230: // SDL_SCANCODE_RALT
		return cimgui.KeyRightAlt
	case 227: // SDL_SCANCODE_LGUI
		return cimgui.KeyLeftSuper
	case 231: // SDL_SCANCODE_RGUI
		return cimgui.KeyRightSuper
	default:
		// Letters A-Z: scancodes 4-29 map to ImGui KeyA-KeyZ
		if scancode >= 4 && scancode <= 29 {
			return cimgui.Key(int(cimgui.KeyA) + int(scancode-4))
		}
		// Numbers 0-9: scancodes 30-39
		if scancode >= 30 && scancode <= 39 {
			return cimgui.Key(int(cimgui.Key0) + int(scancode-30))
		}
		return -1
	}
}

// cstr reads a NUL-terminated C string at p.
// TODO: same func used in Vulkan
// Maybe i should create something like "package common"
// for funcs like this
func cstr(p uintptr) string {
	if p == 0 {
		return ""
	}
	var n int
	for *(*byte)(unsafe.Pointer(p + uintptr(n))) != 0 {
		n++
	}
	return string(unsafe.Slice((*byte)(unsafe.Pointer(p)), n))
}