package input

import (
	"runtime"
	"strings"
)

func PressKey(key, action string, modifiers []string) error {
	vk, ok := vkCode(key)
	if !ok {
		return ErrBadKey
	}

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()
	if err := attachInputDesktop(); err != nil {
		return err
	}

	modVKs := make([]uint16, 0, len(modifiers))
	for _, mod := range modifiers {
		modVK, ok := vkCode(mod)
		if !ok {
			return ErrBadKey
		}
		modVKs = append(modVKs, modVK)
	}

	var inputs []winInput
	for _, modVK := range modVKs {
		inputs = append(inputs, keyInput(modVK, false))
	}

	switch strings.ToLower(strings.TrimSpace(action)) {
	case "down":
		inputs = append(inputs, keyInput(vk, false))
	case "up":
		inputs = append(inputs, keyInput(vk, true))
	default:
		inputs = append(inputs, keyInput(vk, false), keyInput(vk, true))
		for i := len(modVKs) - 1; i >= 0; i-- {
			inputs = append(inputs, keyInput(modVKs[i], true))
		}
	}

	return sendKeyboardInputs(inputs)
}

func keyInput(vk uint16, keyUp bool) winInput {
	flags := uint32(0)
	if keyUp {
		flags |= keyeventfKeyup
	}
	if isExtendedVK(vk) {
		flags |= keyeventfExtended
	}
	return winInput{
		Type: inputKeyboard,
		Ki: keyboardData{
			Vk:    vk,
			Flags: flags,
		},
	}
}

func isExtendedVK(vk uint16) bool {
	switch vk {
	case 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x2D, 0x2E, 0x5B, 0x5C, 0x5D:
		return true
	default:
		return false
	}
}