/*
    * Keyboard.hpp
    * PS/2 Keyboard driver
    * Copyright (c) 2025 Daniel Hammer
*/

#pragma once
#include <cstdint>

namespace Drivers::PS2::Keyboard {

    // Key event structure
    struct KeyEvent {
        uint8_t Scancode;
        char    Ascii;
        bool    Pressed;
        bool    Shift;
        bool    Ctrl;
        bool    Alt;
        bool    CapsLock;
        // Right Alt held. Reported separately from Alt so keyboard layouts can
        // use it as AltGr without swallowing left-Alt shortcuts.
        bool    AltGr;
        // Key came from an E0-prefixed (extended) scancode. The prefix is not
        // part of Scancode, so without this flag keypad "/" is indistinguishable
        // from the main "/" key and layout translation would rewrite it.
        bool    Extended;
    };

    // Modifier key state
    struct ModifierState {
        bool LeftShift;
        bool RightShift;
        bool LeftCtrl;
        bool RightCtrl;
        bool LeftAlt;
        bool RightAlt;
        bool CapsLock;
        bool NumLock;
        bool ScrollLock;
    };

    // Ring buffer size (must be power of 2)
    constexpr uint32_t KeyBufferSize = 256;

    void Initialize();

    // Interrupt handler -- called from IRQ dispatch (EOI is sent automatically)
    void HandleIRQ(uint8_t irq, bool fromUser);

    // Public interface for consuming key events
    bool IsKeyAvailable();
    KeyEvent GetKey();
    char GetChar();

    // Modifier state query
    const ModifierState& GetModifiers();

    // Inject a key event from an external source (e.g., USB HID keyboard)
    void InjectKeyEvent(const KeyEvent& event);

    // Current Caps Lock state. Injecting drivers (USB HID) need this to
    // compute ASCII, since the lock is toggled centrally here.
    bool GetCapsLock();

    // Current Num Lock state, owned here like Caps Lock. On (the default), the
    // keypad types digits; off, it acts as the navigation keys printed on it.
    bool GetNumLock();

    // Set-1 scancodes of the keypad keys that are a digit/'.' with Num Lock on
    // and Home/arrows/PgUp/End/PgDn/Ins/Del with it off (not '-' and '+').
    inline bool IsKeypadNavScancode(uint8_t keycode) {
        return keycode >= 0x47 && keycode <= 0x53 && keycode != 0x4A && keycode != 0x4E;
    }

};