/**
 * Copyright (c) 2016 rxi
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the MIT license. See LICENSE for details.
 */

#include <stdlib.h>
#include <string.h>
#include <dos.h>
#include "luaobj.h"
#include "mouse.h"

#define BUFFER_SIZE 32
#define BUFFER_MASK (BUFFER_SIZE - 1)

int mouse_inited;
int mouse_x, mouse_y;
int mouse_lastX, mouse_lastY;
int mouse_buttonStates[MOUSE_BUTTON_MAX];

struct {
  mouse_Event data[BUFFER_SIZE];
  int writei, readi;
} mouse_events;


void mouse_init(void) {
  union REGS regs = {};
  int86(0x33, &regs, &regs);
  mouse_inited = regs.x.ax ? 1 : 0;
}


void mouse_update(void) {
  if (!mouse_inited) {
    return;
  }

  /* Update mouse position */
  union REGS regs = {};
  regs.x.ax = 3;
  int86(0x33, &regs, &regs);
  mouse_x = regs.x.cx >> 1;
  mouse_y = regs.x.dx;

  /* Do moved event if mouse moved */
  if (mouse_x != mouse_lastX || mouse_y != mouse_lastY) {
    mouse_Event e;
    e.type = MOUSE_MOVED;
    e.x = mouse_x;
    e.y = mouse_y;
    e.dx = mouse_x - mouse_lastX;
    e.dy = mouse_y - mouse_lastY;
    mouse_events.data[mouse_events.writei++ & BUFFER_MASK] = e;
  }

  /* Update last position */
  mouse_lastX = mouse_x;
  mouse_lastY = mouse_y;

  /* Update button states and push pressed/released events */
  int i, t;
  for (i = 0; i < MOUSE_BUTTON_MAX; i++) {
    for (t = 0; t < 2; t++) {
      memset(&regs, 0, sizeof(regs));
      regs.x.ax = 5 + t;
      regs.x.bx = i;
      int86(0x33, &regs, &regs);
      if (regs.x.bx) {
        /* Push event */
        mouse_Event e;
        e.type = t == 0 ? MOUSE_PRESSED : MOUSE_RELEASED;
        e.button = i;
        e.x = mouse_x;
        e.y = mouse_y;
        mouse_events.data[mouse_events.writei++ & BUFFER_MASK] = e;
        /* Set state */
        mouse_buttonStates[i] = t == 0 ? 1 : 0;
      }
    }
  }
}


int mouse_poll(mouse_Event *e) {
retry:
  /* Event in event buffer? Store and return */
  if (mouse_events.readi != mouse_events.writei) {
    *e = mouse_events.data[mouse_events.readi++ & BUFFER_MASK];
    return 1;
  }

  /* No events in buffer -- update; return `0` if no new events were pushed by
   * the update */
  mouse_update();
  if (mouse_events.readi != mouse_events.writei) {
    goto retry;
  }

  return 0;
}


int mouse_isDown(int button) {
  return mouse_buttonStates[button];
}


int mouse_getX(void) {
  return mouse_x;
}


int mouse_getY(void) {
  return mouse_y;
}