// main.js
var draw = use('draw2d')
var render = use('render')
var graphics = use('graphics')
var input = use('input')
var config = use('config')
var color = use('color')

prosperon.camera.transform.pos = [0,0]

var cellSize = 20
var gridW = Math.floor(config.width / cellSize)
var gridH = Math.floor(config.height / cellSize)

var snake, direction, nextDirection, apple
var moveInterval = 0.1
var moveTimer = 0
var gameState = "playing"

function resetGame() {
  var cx = Math.floor(gridW / 2)
  var cy = Math.floor(gridH / 2)
  snake = [
    {x: cx,   y: cy},
    {x: cx-1, y: cy},
    {x: cx-2, y: cy}
  ]
  direction = {x:1, y:0}
  nextDirection = {x:1, y:0}
  spawnApple()
  gameState = "playing"
  moveTimer = 0
}

function spawnApple() {
  apple = {x:Math.floor(Math.random()*gridW), y:Math.floor(Math.random()*gridH)}
  // Re-spawn if apple lands on snake
  for (var i=0; i<snake.length; i++)
    if (snake[i].x === apple.x && snake[i].y === apple.y) { spawnApple(); return }
}

function wrap(pos) {
  if (pos.x < 0) pos.x = gridW - 1
  if (pos.x >= gridW) pos.x = 0
  if (pos.y < 0) pos.y = gridH - 1
  if (pos.y >= gridH) pos.y = 0
}

resetGame()

this.update = function(dt) {
  if (gameState !== "playing") return
  moveTimer += dt
  if (moveTimer < moveInterval) return
  moveTimer -= moveInterval

  // Update direction
  direction = {x: nextDirection.x, y: nextDirection.y}

  // New head
  var head = {x: snake[0].x + direction.x, y: snake[0].y + direction.y}
  wrap(head)

  // Check collision with body
  for (var i=0; i<snake.length; i++) {
    if (snake[i].x === head.x && snake[i].y === head.y) {
      gameState = "gameover"
      return
    }
  }

  // Place head
  snake.unshift(head)

  // Eat apple?
  if (head.x === apple.x && head.y === apple.y) spawnApple()
  else snake.pop()
}

this.hud = function() {
  // Optional clear screen
  draw.rectangle({x:0, y:0, width:config.width, height:config.height}, [0,0,0,1])
  
  // Draw snake
  for (var i=0; i<snake.length; i++) {
    var s = snake[i]
    draw.rectangle({x:s.x*cellSize, y:s.y*cellSize, width:cellSize, height:cellSize}, color.green)
  }

  // Draw apple
  draw.rectangle({x:apple.x*cellSize, y:apple.y*cellSize, width:cellSize, height:cellSize}, color.red)

  if (gameState === "gameover") {
    var msg = "GAME OVER! Press SPACE to restart."
    draw.text(msg, {x:0, y:config.height*0.5-10, width:config.width, height:20}, undefined, 0, color.white)
  }
}

// No immediate reversal
// "Up" means y=1, so going physically up on screen
this.inputs = {
  up: function() {
    if (direction.y !== -1) nextDirection = {x:0,y:1}
  },
  down: function() {
    if (direction.y !== 1) nextDirection = {x:0,y:-1}
  },
  left: function() {
    if (direction.x !== 1) nextDirection = {x:-1,y:0}
  },
  right: function() {
    if (direction.x !== -1) nextDirection = {x:1,y:0}
  },
  space: function() {
    if (gameState==="gameover") resetGame()
  }
}

input.player[0].control(this)