let initialize_a_star = ( dom_container, theme ) => {
	// kinda enums
	let cell = { WALL: '#', BALL: '@', CUBE: 'H', EMPTY: ' ', GIFT: 'x' }
	let direction = { UP: 38, DOWN: 40, LEFT: 37, RIGHT: 39 }

	let assets = {
		levels: [
			"#################@##        x#H##          x ####       ##x    ##   ## x      #### x  x     x  ## x      x## x ##     ##x     x#################",
			" #  # # #   # ###   x         @#   #x  #x   x   # # x     x  # #      #   x   # #    #H#  x    #   #  # #   #xx##             #  #  #        #  ",
			"#################           x#@##   ##      ##H##   #x     x   ## x     x##   x## #x  x  x#  x### ##x #x  x x####x    ##x      #################",
			"#################            #H##     #        ###x#x x#x#x#x#x## # #x x# # # ####x#x#x x#x#x#x##     #        ##   #       #@ #################",
			" ############## #@  #   #  #   ##  #x # x  x # ###      #  #   ##x #x#        ####     # x #   ##x#  # # #   #H##   #    x#  #x# ############## ",
			"    ############   #   x   #x x#  #    x    # ## #     x       ##@     x       ###     x  #   ###      x    #  ##H #   x  ##x  #################",
			"#################              # ## ###  #x ##x# #x  #x # # # #   #  #  ### ##   ##  #  #x# #x# #              ##  @#x    H  #x#################",
			"############### #  x##        ###  #x  ## x    ##  x## # #x    ###     ##  #x# ### #       x#x ##xHx#   x  #@# ###             # ###############",
			"  # ###########  #x#x      #  @##x x#    x    #  # #  x##  x#  ##  #x #xHx    x##     x##     # #x#x         #  #           #   ############    ",
			"    ########### #### x         ##   H ###x x# x## x   #x #x   # #     #  x  # x##x#x  # x#  #@#  #x   ###  ###  #         # # #  #########  #  #",
			"#################      #      @##  #xx     xx ####   x   ##   x##x    #x#xx  ##### ##    ##    ##x  x# x    H x###x###    #   ## ## ########### ",
			"##     ##  #### #@#####x ### x###    xx     x  ## ##  ##x  #x# ## # x ###x ##  ## ##  ##   #H# ##     x        ##        x     #################",
			" ############## # @#        x ### #   #x   x## ##       x    # ## x          #x## #      x     ###      x x  #x##H  #    x # # # ############## ",
			"#################x#x        x#x## x#@      ##  ## H        x   ##        x#    ##      x       ## x#        #  ##x#x        x#x#################",
			" ###### ####### #     x#     x ## # x #  #   x ##  @#   #xx #x # # #   # x  H# ##x       #  #x # #      x     # #x            x# ############## ",
			"################## H#x x      x##x @x#x       #### ###    x   ####     x#x#    ##xx       x#x  ### x    ####x  ###x#  #        #################",
			"################# x#        #@ ## #  x#xx#x  # ##    #x##x# x  ## x#       x#  ##  x#x    x#   ## #  # ##x#  # ##    x #x   H  #################",
			"################# x    x  H#   ##  #x#x   #x   ##   #x#    #x  ##   x  #   x#x ## #x#   # x#   ## x#x # x #    ##x#@  #     #  #################",
			"#################x   ##     ##x## #  #      #x ## x#   x##  x  ## #    #x      ##    #   x#    ## ## x# ##x  #H## x# #x     ##@#################",
			"#################   x#x        ###x  x# ##x   ### # # x   #  # ## H #  ##  # @x## #  #   x # # ###   x## #x  x###        x#x   #################",
			"################# ###     x   ###   #       # ###   ##x      x ##  x    x   x ###    #    ###x ##  x x @ H x xx#################                ",
			"#################x#  #x# #x  # ##    #         ##x   #  #x  x  ### #x      x #### x #   ###x   ##     #@#H  x  #################                ",
			" ############## # #  #x# #x  # ##    x  #      ###   #   x #x  ##  #x  #  xx x ###x #   ## x   ##     #@#H  x  # ##############                 ",
			"#################     #       ### ##x x    ##x### #x     x#  #### xx  x# ##    ## #x x #    ## ## ##   @#H###xx#################                ",
			"#################            # ## x ##x   x    ##   #x  x  ##  ## x    ##  #x  ## #x   x#    x ## ##x #@ H     #################                "
		]
	}

	////// FUNCTIONS //////
	let count_gifts = () => (state.board.match( new RegExp( cell.GIFT, 'g' ) ) || []).length

	let get_pos = ( actor ) => {
		let p = state.board.indexOf( actor, state.board )
		let pos = []
		pos[ 1 ] = Math.floor( p / level_infos.width ) /* y */
		pos[ 0 ] = p - ( pos[ 1 ] * level_infos.width ) /* x */

		return pos
	}

	let get_cell = ( x, y ) => state.board[ x + ( y * level_infos.width ) ]

	let set_cell = ( x, y, value ) => {
		let p = x + ( y * level_infos.width )
		state.board = [ state.board.substring( 0, p ), value, state.board.substring( p+1, state.board.length ) ].join( '' )
	}

	let switch_actor = () => state.moving = ( state.moving == cell.BALL ) ? cell.CUBE : cell.BALL

	let won_or_not = () => count_gifts() === 0

	let load_level = ( index ) => {
		return( { moving:             cell.BALL,
							distance_travelled: 0,
							level:              index,
							board:              assets.levels[ index ],
							it_s_over:          false } )
	}

	let make_a_move = ( where ) => {
		let motion = [ 0, 0 ]
		let item_coord = get_pos( state.moving )

		/* Setup the motion vector according to direction.*/
		switch( where ) {
		case direction.UP:
			motion[ 1 ]--
			break
		case direction.DOWN:
			motion[ 1 ]++
			break
		case direction.LEFT:
			motion[ 0 ]--
			break
		case direction.RIGHT:
			motion[ 0 ]++
			break
		default: break
		}

		let path = []
		path[ 0 ] = []
		path[ 0 ][ 0 ] = item_coord[ 0 ]
		path[ 0 ][ 1 ] = item_coord[ 1 ]
		/* Calculating arrival coordinates */
		while (                      /* Hairy conditions ahead */
			/* target cell is within level's boundaries */
			( ( item_coord[ 0 ] + motion[ 0 ] >= 0 ) && ( item_coord[ 0 ] + motion[ 0 ] < level_infos.width ) ) &&
				( ( item_coord[ 1 ] + motion[ 1 ] >= 0 ) && ( item_coord[ 1 ] + motion[ 1 ] < level_infos.height ) ) &&
				/* and target cell is empty */
			( get_cell( item_coord[ 0 ] + motion[ 0 ], item_coord[ 1 ] + motion[ 1 ] ) == cell.EMPTY )
			/* or, the ball will eat gifts so we can move it on one */
				|| ( state.moving == cell.BALL && ( get_cell( item_coord[ 0 ] + motion[ 0 ], item_coord[ 1 ] + motion[ 1 ] ) == cell.GIFT ) )
		)
		{
			set_cell( item_coord[ 0 ], item_coord[ 1 ], cell.EMPTY ) /* empty the origin cell */
			item_coord[ 0 ] += motion[ 0 ]           /* move coordinate */
			item_coord[ 1 ] += motion[ 1 ]           /* to those of target cells */

			let push_pos = path.length
			path[ push_pos ] = []
			path[ push_pos ][ 0 ] = item_coord[ 0 ]
			path[ push_pos ][ 1 ] = item_coord[ 1 ]

			set_cell( item_coord[ 0 ], item_coord[ 1 ], state.moving ) /* move actor into target cell */
		}

		return path
	}

	////// HTML/Canvas version specific functions
	let load_sprites = ( theme ) => {
		assets.sprites = {  }
		assets.sprites.ball = new Image()
		assets.sprites.ball.src = "themes/" + theme + "/tex_ball.png"
		assets.sprites.ball_selected = new Image()
		assets.sprites.ball_selected.src = "themes/" + theme + "/tex_ball_selected.png"
		assets.sprites.cube = new Image()
		assets.sprites.cube.src = "themes/" + theme + "/tex_cube.png"
		assets.sprites.cube_selected = new Image()
		assets.sprites.cube_selected.src = "themes/" + theme + "/tex_cube_selected.png"
		assets.sprites.wall = new Image()
		assets.sprites.wall.src = "themes/" + theme + "/tex_wall.png"
		assets.sprites.empty = new Image()
		assets.sprites.empty.src = "themes/" + theme + "/tex_empty.png"
		assets.sprites.gift = new Image()
		assets.sprites.gift.src = "themes/" + theme + "/tex_gift.png"
	}

	let draw_cell = ( sprite, x, y ) => DOM_infos.canvas.context.drawImage( sprite,
																																					x * level_infos.cell.width,
																																					y * level_infos.cell.height,
																																					level_infos.cell.width,
																																					level_infos.cell.height )

	let display_switch_actor = () => {
		let ball_pos = get_pos( cell.BALL )
		let cube_pos = get_pos( cell.CUBE )

		// redraw ball
		draw_cell( ( state.moving == cell.BALL ) ? assets.sprites.ball_selected : assets.sprites.ball, ball_pos[ 0 ], ball_pos[ 1 ] )
		// redraw cube
		draw_cell( ( state.moving == cell.CUBE ) ? assets.sprites.cube_selected : assets.sprites.cube, cube_pos[ 0 ], cube_pos[ 1 ] )
	}

	let full_display_on_canvas = () => {
		for ( let i=0 ; i < level_infos.height ; i++ ) {
			for ( let j=0 ; j < level_infos.width ; j++ ) {
				let c = get_cell( j, i )
				let sprite

				switch( c ) {
				case "@": sprite = ( state.moving == cell.BALL ) ? assets.sprites.ball_selected : assets.sprites.ball
					break
				case "H": sprite = ( state.moving == cell.CUBE ) ? assets.sprites.cube_selected : assets.sprites.cube
					break
				case "#": sprite = assets.sprites.wall
					break
				case "x": sprite = assets.sprites.gift
					break
				case " ": sprite = assets.sprites.empty
					break
				default:
					break
				}
				draw_cell( sprite, j, i )
			}
		}
	}

	let update_infos = () => {
		let infos = "<h1>Star5</h1><br />"
		infos += "Level <em>" + (state.level+1) + "</em> of <em>" + assets.levels.length + "</em><br />"
		infos += "<em>" + count_gifts() + "</em> gifts left<br />"
		infos += "<em>" + state.distance_travelled + "</em> meters travelled"

		document.querySelector( DOM_infos.container + " .gstar #infos" ).innerHTML = infos
	}

	let format_help = () => {
		let help = "<em>←↑→↓</em> to move around<br />"
		help += "<em>Space</em> to switch actor<br />"
		help += "<em>r</em> to reload<br />"
		help += "<em>n</em> to pass to the next level<br />"
		help += "<em>p</em> to go back to the previous level<br />"
		return help
	}

	let display_level = () => {
		update_infos()
		full_display_on_canvas()
	}

	let display_move_actor = ( path ) => {
		for ( let i=0 ; i < path.length-1 ; i++ ) {
			draw_cell( assets.sprites.empty, path[ i ][ 0 ], path[ i ][ 1 ] )
			draw_cell( ( state.moving == cell.BALL ) ? assets.sprites.ball_selected : assets.sprites.cube_selected,
						 path[ i+1 ][ 0 ], path[ i+1 ][ 1 ] )

			state.distance_travelled++                /* increment distance_travelled */
		}

		update_infos()
	}

	let event_handler = ( e ) => {
		if ( !state.it_s_over ) {
			if ( e.type === "click" ) {
				let movingpos = get_pos( state.moving )
				let notmovingpos = get_pos( ( state.moving != cell.BALL ) ? cell.BALL : cell.CUBE )
				let click = {  }
				click.x = e.pageX - DOM_infos.canvas.offset.left
				click.y = e.pageY - DOM_infos.canvas.offset.top

				if ( ( 0 <= click.x && click.x < DOM_infos.canvas.width )
					&& ( 0 <= click.y && click.y < DOM_infos.canvas.height ) ) {
						// coordinates in cell indexes
						click.x	= Math.floor( click.x / level_infos.cell.width )
						click.y	= Math.floor( click.y / level_infos.cell.height )

						// We're inside the board
						if ( click.x == notmovingpos[0] && click.y == notmovingpos[1] ) {
							switch_actor()
							display_switch_actor()
						} else if ( click.x == movingpos[0] ) {
							if ( click.y > movingpos[1] ) {
								display_move_actor( make_a_move( direction.DOWN ) )
							} else if ( click.y < movingpos[1] ) {
								display_move_actor( make_a_move( direction.UP ) )
							}
						} else if ( click.y == movingpos[1] ) {
							if ( click.x > movingpos[0] ) {
								display_move_actor( make_a_move( direction.RIGHT ) )
							} else {
								display_move_actor( make_a_move( direction.LEFT ) )
							}
						}
					}
			} else if ( e.type === "keydown" ) {
				switch( e.keyCode ) {
				case 37: // LEFT
				case 38: // UP
				case 39: // RIGHT
				case 40: // DOWN
					display_move_actor( make_a_move( e.keyCode ) )
					break
				case 32: // SPACE
					switch_actor()
					display_switch_actor()
					break
				case 78: // n
					if ( state.level < assets.levels.length - 1 ) {
						state = load_level( state.level + 1 )
						display_level()
					}
					break
				case 80: // p
					if ( state.level > 0 ) {
						state = load_level( state.level - 1 )
						display_level()
					}
					break
				case 82: // r
					state = load_level( state.level )
					display_level()
					break
				default:
					break
				}
			}

			if ( won_or_not() ) {
				if ( state.level < assets.levels.length - 1 ) {
					state = load_level( state.level + 1 )
					display_level()
				}
				else {
					state.it_s_over = true
					alert( "You won!" )
				}
			}
		}
	}

	////// MAIN (so to speak) //////

	// First of all, setup our little DOM branch
	let starhtml = '<div class="gstar">'
	starhtml +=	'<aside id="help">' + format_help() + '</aside>'
	starhtml +=	'<canvas id="starboard" width="320" height="180"></canvas>'
	starhtml +=	'<aside id="infos"></aside>'
	starhtml +=	'</div>'
	document.querySelector( dom_container ).innerHTML = starhtml

	// Now we can collect some informations about this DOM branch we have
	load_sprites( theme )
	let DOM_infos = {
		container: dom_container,
		canvas: {
			context: document.querySelector( dom_container + " #starboard" ).getContext( '2d' ),
			offset:  document.querySelector( dom_container + " #starboard" ).offsetLeft,
			width:   document.querySelector( dom_container + " #starboard" ).width,
			height:  document.querySelector( dom_container + " #starboard" ).height
		}
	}

	let level_infos = {
		height: 9,
		width:  16,
		cell: {
			width:  DOM_infos.canvas.width / 16,
			height: DOM_infos.canvas.height / 9
		}
	}

	let state = load_level( 0 )

	// kinda ugly workaround around a mysterious bug causing the canvas
	// not to refresh the first time (before any event)
	setTimeout( () => display_level(), 100 ) // 1/10 second

	// Start main "loop"
	document.addEventListener('click', event_handler)
	document.addEventListener('keydown', event_handler)
}