/spacey

-- Class: Map

-- A map saves memory and CPU time by acting as if it were a grid of sprites.

-- Each different type of sprite in the grid is represented via a single

-- object. Each sprite must have the same size, however.

-- 

-- This works very similarly to a tilemap, but there is additional flexibility

-- in using a sprite, e.g. animation and other display effects. (If you want it

-- to act like a tilemap, use its loadTiles method.) However, changing a sprite's

-- x or y position has no effect. Changing the scale will have weird effects as

-- a map expects every sprite to be the same size.

--

-- Extends:

--		<Sprite>

Map = Sprite:extend

{

	-- Constant: NO_SPRITE

	-- Represents a map entry with no sprite.

	NO_SPRITE = -1,

	-- Property: sprites

	-- An ordered table of <Sprite> objects to be used in conjunction with the map property.

	sprites = {},

	-- Property: map

	-- A two-dimensional table of values, each corresponding to an entry in the sprites property.

	-- nb. The tile at (0, 0) visually is stored in [1, 1].

	map = {},

	-- Method: empty

	-- Creates an empty map.

	--

	-- Arguments:

	--		width - width of the map in sprites

	--		height - height of the map in sprites

	-- 

	-- Returns:

	--		self, for chaining

	empty = function (self, width, height)

		local x, y

		-- empty the map

		for x = 1, width do

			self.map[x] = {}

			for y = 1, height do

				self.map[x][y] = Map.NO_SPRITE

			end

		end

		-- set bounds

		self.width = width * self.spriteWidth

		self.height = height * self.spriteHeight

		return self

	end,

	-- Method: loadMap

	-- Loads map data from a file, typically comma-separated values.

	-- Each entry corresponds to an index in self.sprites, and all rows

	-- must have the same number of columns.

	--

	-- Arguments:

	--		file - filename of source text to use

	--		colSeparator - character to use as separator of columns, default ','

	--		rowSeparator - character to use as separator of rows, default newline

	--

	-- Returns:

	--		self, for chaining

	loadMap = function (self, file, colSeparator, rowSeparator)

		colSeparator = colSeparator or ','

		rowSeparator = rowSeparator or '\n'

		-- load data

		local x, y

		local source = Cached:text(file)

		local rows = split(source, rowSeparator)

		for y = 1, #rows do

			local cols = split(rows[y], colSeparator)

			for x = 1, #cols do

				if not self.map[x] then self.map[x] = {} end

				self.map[x][y] = tonumber(cols[x])

			end

		end

		-- set bounds

		self.width = #self.map * self.spriteWidth

		self.height = #self.map[1] * self.spriteHeight

		return self

	end,

	-- Method: loadTiles

	--- Loads the sprites group with slices of a source image.

	--  By default, this uses the Tile class for sprites, but you

	--  may pass as replacement class.

	--

	--  Arguments:

	--		image - source image to use for tiles

	--		class - class to create objects with; constructor

	--				  will be called with properties: image, width,

	--				  height, imageOffset (with x and y sub-properties)

	--		startIndex - starting index of tiles in self.sprites, default 0

	--

	--  Returns:

	--		self, for chaining

	loadTiles = function (self, image, class, startIndex)

		assert(self.spriteWidth and self.spriteHeight, 'sprite size must be set before loading tiles')

		if type(startIndex) ~= 'number' then startIndex = 0 end

		class = class or Tile

		self.sprites = self.sprites or {}

		local imageObj = Cached:image(image)

		local imageWidth = imageObj:getWidth()

		local imageHeight = imageObj:getHeight()

		local i = startIndex

		for y = 0, imageHeight - self.spriteHeight, self.spriteHeight do

			for x = 0, imageWidth - self.spriteWidth, self.spriteWidth do

				self.sprites[i] = class:new{ image = image, width = self.spriteWidth,

											  height = self.spriteHeight,

											  imageOffset = { x = x, y = y }}

				i = i + 1

			end

		end

		return self

	end,

	-- Method: getMapSize

	-- Returns the size of the map in map coordinates.

	--

	-- Arguments:

	--		none

	--

	-- Returns:

	--		width and height in integers

	getMapSize = function (self)

		if #self.map == 0 then

			return 0, 0

		else

			return #self.map, #self.map[1]

		end

	end,

	-- Method: pixelToMap

	-- Converts pixels to map coordinates.

	--

	-- Arguments:

	--		x - x coordinate in pixels

	--		y - y coordinate in pixels

	--		clamp - clamp to map bounds? defaults to true

	--

	-- Returns:

	--		x, y map coordinates

	pixelToMap = function (self, x, y, clamp)

		if type(clamp) == 'nil' then clamp = true end

		-- remember, Lua tables start at index 1

		local mapX = math.floor(x / self.spriteWidth) + 1

		local mapY = math.floor(y / self.spriteHeight) + 1

		-- clamp to map bounds

		if clamp then

			if mapX < 1 then mapX = 1 end

			if mapY < 1 then mapY = 1 end

			if mapX > #self.map then mapX = #self.map end

			if mapY > #self.map[1] then mapY = #self.map[1] end

		end

		return mapX, mapY

	end,

	-- Method: spriteAtMap

	-- Returns the sprite at a given set of map coordinates, with

	-- the correct pixel position for that sprite. Remember that

	-- sprites in maps are shared, so any changes you make to one

	-- sprite will carry over to all instances of that sprite in the map.

	--

	-- Arguments:

	--		x - x coordinate in map units

	--		y - y coordinate in map units

	--

	-- Returns:

	--		<Sprite> instance. If no sprite is present at these

	--		coordinates, the method returns nil.

	spriteAtMap = function (self, x, y)

		if self.map[x] and self.map[x][y] then

			local spr = self.sprites[self.map[x][y]]

			if spr then 

				spr.x = (x - 1) * self.spriteWidth

				spr.y = (y - 1) * self.spriteHeight

				return spr

			end

		elseif STRICT then

			print('Warning: asked for map sprite at ' .. x .. ', ' .. y ' but map isn\'t that big')

		end

	end,

	-- Method: spriteAtPixel

	-- Returns the sprite at a given set of pixel coordinates, with

	-- the correct pixel position for that sprite. Remember that

	-- sprites in maps are shared, so any changes you make to one

	-- sprite will carry over to all instances of that sprite in the map.

	--

	-- Arguments:

	--		x - x coordinate in pixels

	--		y - y coordinate in pixels

	--

	-- Returns:

	--		<Sprite> instance. If no sprite is present at these

	--		coordinates, the method returns nil.

	spriteAtPixel = function (self, x, y)

		return self:spriteAtMap((x - 1) * self.spriteWidth, (y - 1) * self.spriteHeight)

	end,

	-- This overrides a method in <Sprite>, passing along

	-- collidedWith() calls to all sprites in the map touching a

	-- sprite.

	--

	-- Arguments:

	--		other - other <Sprite>

	--

	-- Returns:

	--		nothing

	collidedWith = function (self, other)

		local spriteWidth = self.spriteWidth

		local spriteHeight = self.spriteHeight

		local startX, startY = self:pixelToMap(other.x - self.x, other.y - self.y)

		local endX, endY = self:pixelToMap(other.x + other.width - self.x,

										   other.y + other.height - self.y)

		-- collect collisions against sprites

		local collisions = {}

		for x = startX, endX do 

			for y = startY, endY do

				local spr = self.sprites[self.map[x][y]]

				if spr and spr.solid then

					local sprX = self.x + (x - 1) * spriteWidth

					local sprY = self.y + (y - 1) * spriteHeight

					local xOverlap, yOverlap = other:overlap(sprX, sprY, spriteWidth, spriteHeight)

					if xOverlap ~= 0 or yOverlap ~= 0 then

						table.insert(collisions, { area = xOverlap * yOverlap, x = xOverlap, y = yOverlap,

												   a = spr, ax = sprX, ay = sprY })

					end

				end

			end

		end

		-- sort as usual and pass off collidedWith() calls

		table.sort(collisions, Collision.sortCollisions)

		for _, col in ipairs(collisions) do

			col.a.x, col.a.y = col.ax, col.ay

			col.a:collidedWith(other, col.x, col.y)

			other:collidedWith(col.a, col.x, col.y)

		end

	end,

	-- this is here mainly for completeness; it's better to specify displacement

	-- in individual map sprites

	displace = function (self, other, xHint, yHint)	

		if not self.solid or self == other or not other.solid then return end

		if STRICT then assert(other:instanceOf(Sprite), 'asked to displace a non-sprite') end

		local spriteWidth = self.spriteWidth

		local spriteHeight = self.spriteHeight

		local startX, startY = self:pixelToMap(other.x - self.x, other.y - self.y)

		local endX, endY = self:pixelToMap(other.x + other.width - self.x,

										   other.y + other.height - self.y)

		-- collect collisions against sprites

		local collisions = {}

		for x = startX, endX do 

			for y = startY, endY do

				local spr = self.sprites[self.map[x][y]]

				if spr and spr.solid then

					local sprX = self.x + (x - 1) * spriteWidth

					local sprY = self.y + (y - 1) * spriteHeight

					local xOverlap, yOverlap = other:overlap(sprX, sprY, spriteWidth, spriteHeight)

					if xOverlap ~= 0 or yOverlap ~= 0 then

						table.insert(collisions, { area = xOverlap * yOverlap, x = xOverlap, y = yOverlap,

												   a = spr, ax = sprX, ay = sprY })

					end

				end

			end

		end

		-- sort as usual and displace

		table.sort(collisions, Collision.sortCollisions)

		for _, col in ipairs(collisions) do

			col.a.x, col.a.y = col.ax, col.ay

			col.a:displace(other)

		end

	end,

	draw = function (self, x, y)

		-- lock our x/y coordinates to integers

		-- to avoid gaps in the tiles

		x = math.floor(x or self.x)

		y = math.floor(y or self.y)

		if not self.visible or self.alpha <= 0 then return end

		if not self.spriteWidth or not self.spriteHeight then return end

		-- determine drawing bounds

		-- we draw to fill the entire app windoow

		local startX, startY = self:pixelToMap(-x, -y)

		local endX, endY = self:pixelToMap(the.app.width - x, the.app.height - y)

		-- queue each sprite drawing operation

		local toDraw = {}

		for drawY = startY, endY do

			for drawX = startX, endX do

				local sprite = self.sprites[self.map[drawX][drawY]]

				if sprite and sprite.visible then

					if not toDraw[sprite] then

						toDraw[sprite] = {}

					end

					table.insert(toDraw[sprite], { x + (drawX - 1) * self.spriteWidth,

												   y + (drawY - 1) * self.spriteHeight })

				end

			end

		end

		-- draw each sprite in turn

		for sprite, list in pairs(toDraw) do

			for _, coords in pairs(list) do

				sprite:draw(coords[1], coords[2])

			end

		end

	end,

	-- makes sure all sprites receive startFrame messages

	startFrame = function (self, elapsed)

		for _, spr in pairs(self.sprites) do

			spr:startFrame(elapsed)

		end

		Sprite.startFrame(self, elapsed)

	end,

	-- makes sure all sprites receive update messages

	update = function (self, elapsed)

		for _, spr in pairs(self.sprites) do

			spr:update(elapsed)

		end

		Sprite.update(self, elapsed)

	end,

	-- makes sure all sprites receive endFrame messages

	endFrame = function (self, elapsed)

		for _, spr in pairs(self.sprites) do

			spr:endFrame(elapsed)

		end

		Sprite.endFrame(self, elapsed)

	end,

	__tostring = function (self)

		local result = 'Map (x: ' .. self.x .. ', y: ' .. self.y ..

					   ', w: ' .. self.width .. ', h: ' .. self.height .. ', '

		if self.active then

			result = result .. 'active, '

		else

			result = result .. 'inactive, '

		end

		if self.visible then

			result = result .. 'visible, '

		else

			result = result .. 'invisible, '

		end

		if self.solid then

			result = result .. 'solid'

		else

			result = result .. 'not solid'

		end

		return result .. ')'

	end

}