const Orientation = {
  UP: 'up',
  DOWN: 'down',
  LEFT: 'left',
  RIGHT: 'right'
}

// TODO: make these not global.
let upArrowPressed = false;
let downArrowPressed = false;
let leftArrowPressed = false;
let rightArrowPressed = false;

class Input {
  constructor() {
    this.up = false;
    this.down = false;
    this.left = false;
    this.right = false;
    this.a = false;
    this.b = false;
    this.x = false;
    this.y = false;
    this.l = false;
    this.r = false;
    this.select = false;
    this.start = false;

    window.addEventListener('gamepadconnected', this.gamepadConnected);
    window.addEventListener('gamepaddisconnected', this.gamepadDisconnected);
    document.addEventListener('keydown', this.keyDown);
    document.addEventListener('keyup', this.keyUp);
  }

  keyDown(e) {
    if (e.key == 'ArrowUp' || e.key == 'w') {
      upArrowPressed = true;
    }
    if (e.key == 'ArrowDown' || e.key == 's') {
      downArrowPressed = true;
    }
    if (e.key == 'ArrowLeft' || e.key == 'a') {
      leftArrowPressed = true;
    }
    if (e.key == 'ArrowRight' || e.key == 'd') {
      rightArrowPressed = true;
    }
  }

  keyUp(e) {
    if (e.key == 'ArrowUp' || e.key == 'w') {
      upArrowPressed = false;
    }
    if (e.key == 'ArrowDown' || e.key == 's') {
      downArrowPressed = false;
    }
    if (e.key == 'ArrowLeft' || e.key == 'a') {
      leftArrowPressed = false;
    }
    if (e.key == 'ArrowRight' || e.key == 'd') {
      rightArrowPressed = false;
    }
  }

  update() {
    // TODO: have a config screen instead of hard-coding the 8Bitdo SNES30 pad.
    // TODO: handle connects / disconnects more correctly.

    this.up = upArrowPressed;
    this.down = downArrowPressed;
    this.left = leftArrowPressed;
    this.right = rightArrowPressed;

    const gamepad = navigator.getGamepads()[0];
    if (gamepad == null || !gamepad.connected || gamepad.axes.length < 2 ||
        gamepad.buttons.length < 12) {
      return;
    }
    this.up |= gamepad.axes[1] < 0;
    this.down |= gamepad.axes[1] > 0;
    this.left |= gamepad.axes[0] < 0;
    this.right |= gamepad.axes[0] > 0;
    this.a = gamepad.buttons[0].pressed;
    this.b = gamepad.buttons[1].pressed;
    this.x = gamepad.buttons[3].pressed;
    this.y = gamepad.buttons[4].pressed;
    this.l = gamepad.buttons[6].pressed;
    this.r = gamepad.buttons[7].pressed;
    this.select = gamepad.buttons[10].pressed;
    this.start = gamepad.buttons[11].pressed;
    debug(this.toString());
  }

  gamepadConnected(e) {
    debug('gamepad connected! :)');
    console.log('gamepad connected @ index %d: %d buttons, %d axes\n[%s]',
        e.gamepad.index, e.gamepad.buttons.length, e.gamepad.axes.length,
        e.gamepad.id);
  }

  gamepadDisconnected(e) {
    debug('gamepad disconnected :(');
    console.log('gamepad disconnected @ index %d:\n[%s]', e.gamepad.index,
        e.gamepad.id);
  }

  toString() {
    let result = '';

    if (this.up) {
      result += '^';
    } else if (this.down) {
      result += 'v';
    } else {
      result += '-';
    }

    if (this.left) {
      result += '<';
    } else if (this.right) {
      result += '>';
    } else {
      result += '-';
    }

    result += ' ';

    if (this.a) {
      result += 'A';
    }
    if (this.b) {
      result += 'B';
    }
    if (this.x) {
      result += 'X';
    }
    if (this.y) {
      result += 'Y';
    }
    if (this.l) {
      result += 'L';
    }
    if (this.r) {
      result += 'R';
    }
    if (this.select) {
      result += 's';
    }
    if (this.start) {
      result += 'S';
    }
    return result;
  }
}

class Graphics {
  constructor(canvas) {
    this.canvas_ = canvas;
    this.ctx_ = canvas.getContext('2d');
  }

  get width() {
    return this.canvas_.width;
  }

  get height() {
    return this.canvas_.height;
  }

  fill(color) {
    this.ctx_.fillStyle = color;
    this.ctx_.beginPath();
    this.ctx_.rect(0, 0, this.canvas_.width, this.canvas_.height);
    this.ctx_.fill();
    this.ctx_.closePath();
  }

  circle(x, y, radius, color) {
    this.ctx_.fillStyle = color;
    this.ctx_.beginPath();
    this.ctx_.arc(x, y, radius, 0, 2 * Math.PI)
    this.ctx_.fill();
    this.ctx_.closePath();
  }

  // TODO: replace with custom sprite-based text rendering.
  text(string, x, y, size, color) {
    this.ctx_.imageSmoothingEnabled = false;
    this.ctx_.fillStyle = color;
    this.ctx_.font = '' + size + 'px monospace';
    this.ctx_.fillText(string, x, y);
  }

  drawImage(image, dx, dy) {
    const src = image[0];
    const sx = image[1];
    const sy = image[2];
    const width = image[3];
    const height = image[4];
    this.ctx_.drawImage(
        src, sx, sy, width, height, dx, dy, width, height);
  }
}

class FpsCounter {
  constructor() {
    this.fps = 0;
    this.frameTimes_ = new Array(60);
    this.idx_ = 0;
  }

  update(timestampMs) {
    if (this.frameTimes_[this.idx_]) {
      const timeElapsed = (timestampMs - this.frameTimes_[this.idx_]) / 1000;
      this.fps = this.frameTimes_.length / timeElapsed;
    }
    this.frameTimes_[this.idx_] = timestampMs;
    this.idx_++;
    if (this.idx_ == this.frameTimes_.length) {
      this.idx_ = 0;
    }
  }

  draw(gfx) {
    const fpsDiv = document.getElementById('fps');
    fpsDiv.innerText = 'FPS: ' + Math.round(this.fps);
  }
}

class World {
  constructor() {
    this.state_ = null;
    this.fpsCounter_ = new FpsCounter();
    this.input_ = new Input();
    this.player_ = new Player();

    // TODO: move rendering stuff to a separate object.
    this.resources_ = new Resources();
    this.tileRenderer_ = new TileRenderer();
    this.playerRenderer_ = new PlayerRenderer();
    this.gamepadRenderer_ = new GamepadRenderer();
  }

  update(timestampMs) {
    this.fpsCounter_.update(timestampMs);
    this.input_.update();
    if (this.input_.left) {
      this.player_.moveLeft();
    }
    if (this.input_.right) {
      this.player_.moveRight();
    }
    if (this.input_.up) {
      this.player_.moveUp();
    }
    if (this.input_.down) {
      this.player_.moveDown();
    }
  }

  draw(gfx) {
    gfx.fill('black');
    this.tileRenderer_.draw(gfx, this.resources_.sprites);
    this.playerRenderer_.draw(gfx, this.resources_.sprites, this.player_);
    // this.gamepadRenderer_.draw(gfx, this.input_);
    this.fpsCounter_.draw(gfx);
  }
}

class Resources {
  constructor() {
    const atlantis = document.getElementById('atlantis');
    const ghost = document.getElementById('ghost');
    const ts = 16;
    this.sprites = {
      'ground0': [atlantis, 2 * ts, 1 * ts, 16, 16],
      'ground1': [atlantis, 3 * ts, 1 * ts, 16, 16],
      'ground2': [atlantis, 4 * ts, 1 * ts, 16, 16],
      'ground3': [atlantis, 5 * ts, 1 * ts, 16, 16],
      'ground4': [atlantis, 6 * ts, 1 * ts, 16, 16],
      'ground5': [atlantis, 7 * ts, 1 * ts, 16, 16],
      'ground6': [atlantis, 8 * ts, 1 * ts, 16, 16],
      'rock0': [atlantis, 1 * ts, 2 * ts, 16, 16],
      'rock1': [atlantis, 2 * ts, 2 * ts, 16, 16],
      'rock2': [atlantis, 3 * ts, 2 * ts, 16, 16],
      'anchor0': [atlantis, 21 * ts, 1 * ts, 16, 16],
      'seaweed0': [atlantis, 20 * ts, 2 * ts, 16, 32],
      'seaweed1': [atlantis, 16 * ts, 2 * ts, 16, 32],
      'coral0': [atlantis, 15 * ts, 9 * ts, 32, 16],
      'rockpile0': [atlantis, 17 * ts, 10 * ts, 32, 32],

      'ghostdown0': [ghost, 0, 0, 24, 36],
      'ghostdown1': [ghost, 26, 0, 24, 36],
      'ghostdown2': [ghost, 52, 0, 24, 36],
      'ghostleft0': [ghost, 0, 36, 24, 36],
      'ghostleft1': [ghost, 26, 36, 24, 36],
      'ghostleft2': [ghost, 52, 36, 24, 36],
      'ghostright0': [ghost, 0, 72, 24, 36],
      'ghostright1': [ghost, 26, 72, 24, 36],
      'ghostright2': [ghost, 52, 72, 24, 36],
      'ghostup0': [ghost, 0, 108, 24, 36],
      'ghostup1': [ghost, 26, 108, 24, 36],
      'ghostup2': [ghost, 52, 108, 24, 36],
    }
  }
}

class Player {
  constructor() {
    this.x = (256 - 26) / 2;
    this.y = (224 - 36) / 2;
    this.orientation = Orientation.DOWN;
  }

  moveLeft() {
    this.orientation = Orientation.LEFT;
    this.x -= 2;
    if (this.x < -4) {
      this.x = -4;
    }
  }

  moveRight() {
    this.orientation = Orientation.RIGHT;
    this.x += 2;
    if (this.x > 256 - 21) {
      this.x = 256 - 21;
    }
  }

  moveUp() {
    this.orientation = Orientation.UP;
    this.y -= 2;
    if (this.y < -7) {
      this.y = -7;
    }
  }

  moveDown() {
    this.orientation = Orientation.DOWN;
    this.y += 2;
    if (this.y > 224 - 36) {
      this.y = 224 - 36;
    }
  }
}

class PlayerRenderer {
  constructor() {
    this.frameNum = 0;
  }

  draw(gfx, sprites, player) {
    let spriteIndex = Math.floor((this.frameNum % 40) / 10);
    if (spriteIndex == 3) { spriteIndex = 1; }
    const spriteName = 'ghost' + player.orientation + spriteIndex;
    gfx.drawImage(sprites[spriteName], player.x, player.y);
    this.frameNum++;
  }
}

class TileRenderer {
  draw(gfx, sprites) {
    const tileSize = 16;
    const rows = gfx.height / tileSize;
    const columns = gfx.width / tileSize;
    const layer1 = ["-,*-...*'.,-_'`o",
                    "_..'-_**,',_.'oo",
                    "-*-''_-'o,0O_```",
                    "o`0_._,*O'`--'-'",
                    "`0O-_'',`o*o*`-,",
                    "*,`'---o'O'_*''-",
                    "'-.**.'_'`.,'-.'",
                    ".O'``*``'`*,,_o`",
                    "_*_''*O'`_OO-_'o",
                    "0`0,*-,`_*'`O'*.",
                    ".o'-*.*_',`,,`.'",
                    "`o`O',.`OO,*-'**",
                    "-..*'-''',*'.'.O",
                    "*-_'-0.--__O`O`_",
                    "*-_,O_'*'`*'_._.",
                    "-.*,`OO'_`'*-0-O"];
    const layer2 = ["                ",
                    "                ",
                    "     iil        ",
                    "                ",
                    "   A            ",
                    "                ",
                    "                ",
                    "                ",
                    "                ",
                    "             i  ",
                    "     l          ",
                    "                ",
                    "  c         R   ",
                    "              c "];
    const spriteLookup = {
      '.': sprites.ground0,
      ',': sprites.ground1,
      '_': sprites.ground2,
      '`': sprites.ground3,
      '-': sprites.ground4,
      '*': sprites.ground5,
      "'": sprites.ground6,
      'o': sprites.rock0,
      'O': sprites.rock1,
      '0': sprites.rock2,
      'A': sprites.anchor0,
      'i': sprites.seaweed0,
      'l': sprites.seaweed1,
      'c': sprites.coral0,
      'R': sprites.rockpile0,
    };
    for (let j = 0; j < columns; j++) {
      for (let i = 0; i < rows; i++) {
        const dx = tileSize * j;
        const dy = tileSize * i;
        const sprite = spriteLookup[layer1[i][j]];
        if (sprite) {
          gfx.drawImage(sprite, dx, dy);
        }
      }
    }
    for (let j = 0; j < columns; j++) {
      for (let i = 0; i < rows; i++) {
        const dx = tileSize * j;
        const dy = tileSize * i;
        const sprite = spriteLookup[layer2[i][j]];
        if (sprite) {
          gfx.drawImage(sprite, dx, dy);
        }
      }
    }
  }

}

class GamepadRenderer {
  draw(gfx, input) {
    const centerX = gfx.width / 2;
    const centerY = gfx.height / 2;

    // Select & Start
    gfx.circle(centerX + 12, centerY, 8, input.start ? 'cyan' : 'grey');
    gfx.circle(centerX - 12, centerY, 8, input.select ? 'cyan' : 'grey');

    // Y X B A
    gfx.circle(centerX + 48, centerY, 8, input.y ? 'cyan' : 'grey');
    gfx.circle(centerX + 64, centerY - 16, 8, input.x ? 'cyan' : 'grey');
    gfx.circle(centerX + 64, centerY + 16, 8, input.b ? 'cyan' : 'grey');
    gfx.circle(centerX + 80, centerY, 8, input.a ? 'cyan' : 'grey');

    // dpad
    gfx.circle(centerX - 48, centerY, 8, input.right ? 'cyan' : 'grey');
    gfx.circle(centerX - 64, centerY - 16, 8, input.up ? 'cyan' : 'grey');
    gfx.circle(centerX - 64, centerY + 16, 8, input.down ? 'cyan' : 'grey');
    gfx.circle(centerX - 80, centerY, 8, input.left ? 'cyan' : 'grey');

    // L & R
    gfx.circle(centerX + 30, centerY - 32, 8, input.r ? 'cyan' : 'grey');
    gfx.circle(centerX - 30, centerY - 32, 8, input.l ? 'cyan' : 'grey');
  }
}

function debug(message) {
  const debugDiv = document.getElementById('debug');
  debugDiv.innerText = message;
}

function loop(world, gfx) {
  return timestampMs => {
    world.update(timestampMs);
    world.draw(gfx);
    window.requestAnimationFrame(loop(world, gfx));
  };
}

function setCanvasScale(scale) {
  const snesWidth = 256;
  const snesHeight = 224;
  const canvas = document.getElementById('canvas');
  canvas.style.width = '' + snesWidth * scale + 'px';
  canvas.style.height = '' + snesHeight * scale + 'px';
}

function init() {
  const world = new World();
  const gfx = new Graphics(document.getElementById('canvas'));

  document.getElementById('1x').onclick = () => setCanvasScale(1);
  document.getElementById('2x').onclick = () => setCanvasScale(2);
  document.getElementById('3x').onclick = () => setCanvasScale(3);
  document.getElementById('4x').onclick = () => setCanvasScale(4);
  document.getElementById('5x').onclick = () => setCanvasScale(5);
  setCanvasScale(3);
  window.requestAnimationFrame(loop(world, gfx));
  debug('initialized!');
}

init();