/* Calcite, src/kernel/ps2.c
 * Copyright 2025-2026 Benji Dial
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <https://www.gnu.org/licenses/>.
 */

#include "input.h"
#include "ps2.h"

#include <kernel-public/input.h>
#include <stdint.h>

//defined in ps2.asm
//returns -1 if no byte available
int read_ps2_byte();

static uint8_t keyboard_packet[7];
static int keyboard_packet_length = 0;

void on_keyboard_irq() {

  int byte = read_ps2_byte();
  if (byte == -1)
    return;

  if (keyboard_packet_length == 0 && byte != 0xe0 && byte != 0xe1 && byte != 0xf0) {
    add_keyboard_packet(KEY_FLAG_MAKE | byte);
    return;
  }

  if (keyboard_packet_length == 1 && keyboard_packet[0] == 0xe0 && byte != 0xf0 && byte != 0x12) {
    add_keyboard_packet(KEY_FLAG_MAKE | 0x80 | byte);
    keyboard_packet_length = 0;
    return;
  }

  if (keyboard_packet_length == 1 && keyboard_packet[0] == 0xf0) {
    add_keyboard_packet(byte);
    keyboard_packet_length = 0;
    return;
  }

  if (keyboard_packet_length == 2 && keyboard_packet[0] == 0xe0 && keyboard_packet[1] == 0xf0 && byte != 0x7c) {
    add_keyboard_packet(0x80 | byte);
    keyboard_packet_length = 0;
    return;
  }

  if (keyboard_packet_length == 3 && keyboard_packet[0] == 0xe0 && keyboard_packet[1] == 0x12 &&
      keyboard_packet[2] == 0xe0 && byte == 0x7c) {
    add_keyboard_packet(KEY_FLAG_MAKE | KEY_PRINT_SCREEN);
    keyboard_packet_length = 0;
    return;
  }

  if (keyboard_packet_length == 5 && keyboard_packet[0] == 0xe0 && keyboard_packet[1] == 0xf0 &&
      keyboard_packet[2] == 0x7c && keyboard_packet[3] == 0xe0 && keyboard_packet[4] == 0xf0 && byte == 0x12) {
    add_keyboard_packet(KEY_PRINT_SCREEN);
    keyboard_packet_length = 0;
    return;
  }

  if (keyboard_packet_length == 7 && keyboard_packet[0] == 0xe1 && keyboard_packet[1] == 0x14 &&
      keyboard_packet[2] == 0x77 && keyboard_packet[3] == 0xe1 && keyboard_packet[4] == 0xf0 &&
      keyboard_packet[5] == 0x14 && keyboard_packet[6] == 0xf0 && byte == 0x77) {
    add_keyboard_packet(KEY_FLAG_MAKE | KEY_PAUSE_BREAK);
    add_keyboard_packet(KEY_PAUSE_BREAK);
    keyboard_packet_length = 0;
    return;
  }

  if (keyboard_packet_length == 7) {
    keyboard_packet_length = 0;
    return;
  }

  keyboard_packet[keyboard_packet_length++] = byte;

}

static uint8_t mouse_packet[3];
static int mouse_packet_length = 0;

void on_mouse_irq() {

  int byte = read_ps2_byte();
  if (byte == -1)
    return;

  mouse_packet[mouse_packet_length] = byte;
  if (mouse_packet_length < 2) {
    ++mouse_packet_length;
    return;
  }
  mouse_packet_length = 0;

  int x_change = mouse_packet[1];
  if (mouse_packet[0] & 0x10)
    x_change -= 256;

  int y_change = mouse_packet[2];
  if (mouse_packet[0] & 0x20)
    y_change -= 256;

  add_mouse_movement(x_change, y_change);

}