#include "arch/Keyboard.h"
#include <luna/CType.h>

// PS/2 keyboard decoding routine.

static bool is_key_released(u8& scancode)
{
    if (scancode > 0x80)
    {
        scancode -= 0x80;
        return true;
    }
    return false;
}

constexpr static u8 print_screen_pressed[] = { 0xe0, 0x2a, 0xe0, 0x37 };
constexpr static u8 print_screen_released[] = { 0xe0, 0xb7, 0xe0, 0xaa };
constexpr static u8 pause[] = { 0xe1, 0x1d, 0x45, 0xe1, 0x9d, 0xc5 };

using namespace moon;

constexpr KeyCode keycode_table[] = {
    K_Unknown,    K_Esc,
    K_CH01, // 1
    K_CH02, // 2
    K_CH03, // 3
    K_CH04, // 4
    K_CH05, // 5
    K_CH06, // 6
    K_CH07, // 7
    K_CH08, // 8
    K_CH09, // 9
    K_CH10, // 0
    K_CH11, // -
    K_CH12, // =
    K_Backspace,  K_Tab,
    K_CH13, // Q
    K_CH14, // W
    K_CH15, // E
    K_CH16, // R
    K_CH17, // T
    K_CH18, // Y
    K_CH19, // U
    K_CH20, // I
    K_CH21, // O
    K_CH22, // P
    K_CH23, // [
    K_CH24, // ]
    K_Enter,      K_LeftControl,
    K_CH25, // A
    K_CH26, // S
    K_CH27, // D
    K_CH28, // F
    K_CH29, // G
    K_CH30, // H
    K_CH31, // J
    K_CH32, // K
    K_CH33, // L
    K_CH34, // ;
    K_CH35, // '
    K_CH00, // `
    K_LeftShift,
    K_CH36, // #
    K_CH38, // Z
    K_CH39, // X
    K_CH40, // C
    K_CH41, // V
    K_CH42, // B
    K_CH43, // N
    K_CH44, // M
    K_CH45, // ,
    K_CH46, // .
    K_CH47, // /
    K_RightShift, K_KeypadMul,   K_LeftAlt,
    K_CH48, // Space
    K_CapsLock,   K_F1,          K_F2,          K_F3,      K_F4,        K_F5,         K_F6,
    K_F7,         K_F8,          K_F9,          K_F10,     K_NumLock,   K_ScrollLock, K_Keypad7,
    K_Keypad8,    K_Keypad9,     K_KeypadMinus, K_Keypad4, K_Keypad5,   K_Keypad6,    K_KeypadPlus,
    K_Keypad1,    K_Keypad2,     K_Keypad3,     K_Keypad0, K_KeypadDot, K_Unknown,    K_Unknown,
    K_CH37, // Backslash
    K_F11,        K_F12,
};

constexpr KeyCode extended_keycode_table[] = {
    K_MediaPrev,     K_Unknown,   K_Unknown,      K_Unknown,    K_Unknown,    K_Unknown,     K_Unknown,
    K_Unknown,       K_Unknown,   K_MediaNext,    K_Unknown,    K_Unknown,    K_KeypadEnter, K_RightControl,
    K_Unknown,       K_Unknown,   K_MediaMute,    K_MediaCalc,  K_MediaPlay,  K_Unknown,     K_MediaStop,
    K_Unknown,       K_Unknown,   K_Unknown,      K_Unknown,    K_Unknown,    K_Unknown,     K_Unknown,
    K_Unknown,       K_Unknown,   K_MediaVolDown, K_Unknown,    K_MediaVolUp, K_Unknown,     K_WWWHome,
    K_Unknown,       K_Unknown,   K_KeypadDiv,    K_Unknown,    K_Unknown,    K_RightAlt,    K_Unknown,
    K_Unknown,       K_Unknown,   K_Unknown,      K_Unknown,    K_Unknown,    K_Unknown,     K_Unknown,
    K_Unknown,       K_Unknown,   K_Unknown,      K_Unknown,    K_Unknown,    K_Unknown,     K_Home,
    K_UpArrow,       K_PageUp,    K_Unknown,      K_LeftArrow,  K_Unknown,    K_RightArrow,  K_Unknown,
    K_End,           K_DownArrow, K_PageDown,     K_Insert,     K_Delete,     K_Unknown,     K_Unknown,
    K_Unknown,       K_Unknown,   K_Unknown,      K_Unknown,    K_Unknown,    K_Super,       K_Super,
    K_Menu,          K_ACPIPower, K_ACPISleep,    K_Unknown,    K_Unknown,    K_Unknown,     K_ACPIWake,
    K_Unknown,       K_WWWSearch, K_WWWFavorites, K_WWWRefresh, K_WWWStop,    K_WWWForward,  K_WWWBack,
    K_WWWMyComputer, K_WWWEmail,  K_WWWSelect
};

namespace Keyboard
{
    Option<KeyboardPacket> decode_scancode(u8 scancode, KeyboardState& state)
    {
        if (state.parsing_pause)
        {
            if (state.key_state.size() < 6) state.key_state.try_append(scancode).release_value();

            if (state.key_state.size() == 6)
            {
                state.parsing_pause = state.parsing_ext = false;
                if (!memcmp(state.key_state.data(), pause, 6))
                {
                    state.key_state.clear_data();
                    return KeyboardPacket { K_Pause, false };
                }

                state.key_state.clear_data();
                return KeyboardPacket { K_Unknown, false };
            }
        }

        if (state.parsing_ext)
        {
            if (scancode == 0xe0 && state.key_state.size() == 2)
            {
                state.key_state.try_append(scancode).release_value();
                return {};
            }

            if (state.key_state.size() == 3)
            {
                state.key_state.try_append(scancode).release_value();
                if (!memcmp(state.key_state.data(), print_screen_pressed, 4))
                {
                    state.parsing_ext = false;
                    state.key_state.clear_data();
                    return KeyboardPacket { K_PrtScr, false };
                }

                if (!memcmp(state.key_state.data(), print_screen_released, 4))
                {
                    state.parsing_ext = false;
                    state.key_state.clear_data();
                    return KeyboardPacket { K_PrtScr, true };
                }

                state.parsing_ext = false;
                state.key_state.clear_data();
                return KeyboardPacket { K_Unknown, false };
            }

            if (scancode == 0x2a || scancode == 0xb7)
            {
                state.key_state.try_append(scancode).release_value();
                return {};
            }

            bool released = is_key_released(scancode);

            KeyCode key = KeyCode::K_Unknown;

            if (scancode <= 0x6d) key = extended_keycode_table[scancode - 0x10];

            state.parsing_ext = false;
            state.key_state.clear_data();

            return KeyboardPacket { key, released };
        }

        if (scancode == 0xe0)
        {
            state.parsing_ext = true;
            state.key_state.try_append(scancode).release_value();
            return {};
        }

        if (scancode == 0xe1)
        {
            state.parsing_pause = true;
            state.key_state.try_append(scancode).release_value();
            return {};
        }

        bool released = is_key_released(scancode);

        KeyCode key = KeyCode::K_Unknown;

        if (scancode <= 0x58) key = keycode_table[scancode];

        return KeyboardPacket { key, released };
    }
}