gistfile1.coffee

$ ->
  c = $("canvas").get(0)
  ctx = c.getContext "2d"
  #ctx.font="20px sans-serif"
  #mainLoop
  #running
  initial_sleep_length=250
  sleep_length=initial_sleep_length
  img_data_for_player=ctx.createImageData c.width,c.height
  tile_size=25
  player=snake c.width/2,c.height/2,img_data_for_player,tile_size
  #feed=[]
  player.up()
  window.onkeydown=readKey
  debug_out = $("#debug_area")

  readKey = (event) ->
    key_code = event.keyCode
    switch key_code
      when 27, 96 then (stop() if running else start())
      when 33, 93 then faster()
      when 34, 91 then slower()
      when 37, 97 then player.left()
      when 38, 119 then player.up()
      when 39, 100 then player.right()
      when 40, 115 then player.down()
      else debug_out.innerHTML="Unbinded key code: #{key_code}\n"

  draw = ->
    player.paint()
    null

  paintImgData = (img_data) ->
    ctx.putImageData img_data,0,0,0,0,c.width,c.height
    putFeed()
    null

  randomTile = (resolution) ->
    Math.floor Math.random * resolution/tile_size

  putFeed = ->
    if not feed[0]?
      feed[0]="waiting"
      setTimeout(
        ->
          feed=[randomTile c.width,randomTile c.height]
        Math.floor Math.random()*1000+200)
      console.log "timeout set"
    else if feed[0] is "waiting" #console.log "elseif: "+feed
    else
      console.log "else"
      ctx.fillStyle = "#ffff00"
      ctx.beginPath
      ctx.arc feed[0]*tile_size-tile_size/2,feed[1]*tile_size-tile_size/2,tile_size/2,0,2*Math.PI
      ctx.fill
      ctx.closePath
    null

  snake = (x,y,img_data,@tile_size) ->
    #variables
    max_snake_length=3
    #array stores x and y per each snake`s segment hence times two
    max_array_length=max_snake_length*2
    #move_x, move_y
    body_coordinates=new Array parseInt x/tile_size, parseInt y/tile_size
    grid_resolution_x=img_data.width/tile_size
    grid_resolution_y=img_data.height/tile_size
    #every_other_frame=false

    #functions
    addCoordinates = (x,y) ->
      if body_coordinates.length >= max_array_length
        body_coordinates.splice 0,2
      else body_coordinates.push x,y
      null
    currentCoordinates = ->
      body_coordinates.slice -2
    this.up = ->
      move_x=0
      move_y=-1
      null
    this.down = ->
      move_x=0
      move_y=1
      null
    this.right = ->
      move_x=1
      move_y=0
      null
    this.left = ->
      move_x = -1
      move_y = 0
      null
    isPartOfSnake = (a,b) ->
      if body_coordinates[i] is a and body_coordinates[i+1] is b then return true for body_coordinates in [0..body_coordinates.length] by 2
      false
    move = ->
      ###
        currentCoordinates return an array
        in form of (current_x,current_y)
      ###
      current_location = currentCoordinates()
      if (!(isPartOfSnake(current_location[0]+move_x,current_location[1]+move_y) || current_location[0]+move_x>=grid_resolution_x || current_location[0]+move_x < 0 || current_location[1]+move_y>=grid_resolution_y || current_location[1]+move_y < 0))
        addCoordinates(current_location[0]+move_x,current_location[1]+move_y)
      else
        stop()
        alert "Game Over"
      null
    this.paint = ->
      #we might someday move the player only the every other frame
      #if (every_other_frame) {
        move()
      ###every_other_frame=false;
      } else {
        every_other_frame=true;
      }###
      #TODO can be optimized a lot
      #clear img_data of previous paint
      for channel, i in img_data.data
        channel = if (i+1)%4 then 0 else 255
      ###for (i=0; i<img_data.width*img_data.height*4;i++) {
        img_data.data[i]=((i+1)%4) ? 0 : 255;
      }###
      #instead let's just be inefficient and draw as needed
      #NOTE each coordiante pair is stored as two values hence incriment by 2
      paintTile body_coordinates[i]*tile_size,body_coordinates[i+1]*tile_size,(body_coordinates[i]+1)*tile_size,(body_coordinates[i+1]+1)*tile_size
      paintImgData img_data
    paintTile = (x1,y1,x2,y2) ->
      original_x1=x1
      for y1 in [y1..y2]
        for x1 in [x1..x2]
          #paint it green
          img_data.data[(x1+y1*img_data.width)*4+1]=255
          #make it visible
          img_data.data[(x1+y1*img_data.width)*4+3]=255
        #we must restore x1 value before we can do new inner loop
        x1=original_x1

  stop = ->
      mainLoop=window.clearInterval mainLoop
      running = false

  start = ->
    if not running
      mainLoop=self.setInterval "draw()", sleep_length
      running = true

  refresh_timer = ->
    stop()
    start()
    updateStatusSpeed()

  faster = ->
    if sleep_length > 50
      sleep_length-=25
      refresh_timer()

  slower = ->
    if sleep_length < 400
      sleep_length+=25
      refresh_timer()

  updateStatusSpeed = ->
    $("#speed_value").innerHTML="#{(initial_sleep_length/sleep_length).toFixed 2}x"
    $("#speed_entry").style.visibility="visible"