/ld28

-- Class: Cached

-- This helps you re-use assets in your app instead of creating extraneous

-- copies of them. It also hides Love-related calls so that your code is

-- more portable.

--

-- If you're using a class built into Zoetrope, you do not need to use

-- this class directly. They take care of setting things up for you

-- appropriately. However, if you're rolling your own, you'll want to use

-- this to save memory.

--

-- This class is not meant to be created directly. Instead, call

-- methods on Cached directly, e.g. Cached:sound(), Cached:image(), and so on.

--

-- Extends:

--		<Class>

Cached = Class:extend

{

	-- Property: defaultGlyphs

	-- The default character order of a bitmap font, if none is specified

	-- in a <font> call.

	defaultGlyphs = ' !"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`' ..

					'abcdefghijklmnopqrstuvwxyz{|}~',

	-- private property: library

	-- a table to store already-instantiated assets

	_library = { image = {}, text = {}, sound = {}, font = {}, binds = {}, },

	-- Method: image

	-- Returns a cached image asset.

	--

	-- Arguments:

	--		path - pathname to image file

	--

	-- Returns:

	--		Love image object

	image = function (self, path)

		if STRICT then

			assert(type(path) == 'string', 'path must be a string')

		end

		local realPath = self:_absolutePath(path)

		if not self._library.image[realPath] then

			self._library.image[realPath] = love.graphics.newImage(realPath)

		end

		return self._library.image[realPath]

	end,

	-- Method: text

	-- Returns a cached text asset.

	--

	-- Arguments:

	--		path - pathname to text file

	--

	-- Returns:

	--		string

	text = function (self, path)

		if STRICT then

			assert(type(path) == 'string', 'path must be a string')

		end

		local realPath = self:_absolutePath(path)

		if not self._library.text[realPath] then

			self._library.text[realPath] = love.filesystem.read(realPath)

		end

		return self._library.text[realPath]

	end,

	-- Method: sound

	-- Returns a cached sound asset.

	--

	-- Arguments:

	--		path - pathname to sound file

	--		length - either 'short' or 'long'. *It's very important to pass

	--				 the correct option here.* A short sound is loaded entirely

	--				 into memory, while a long one is streamed from disk. If you

	--				 mismatch, you'll either hear a delay in the sound (short sounds

	--				 played from disk) or your app will freeze (long sounds played from

	--				 memory).

	-- 

	-- Returns:

	--		Either a Love SoundData object (for short sounds) or a

	--		Love Decoder object (for long sounds). Either can be used to

	--		create a Love Source object.

	--

	-- See Also:

	--		<playSound>, <sound>

	sound = function (self, path, length)

		if STRICT then

			assert(type(path) == 'string', 'path must be a string')

		end

		local realPath = self:_absolutePath(path)

		if not self._library.sound[realPath] then

			if length == 'short' then

				self._library.sound[realPath] = love.sound.newSoundData(realPath)

			elseif length == 'long' then

				self._library.sound[realPath] = love.sound.newDecoder(realPath)

			else

				error('length must be either "short" or "long"')

			end

		end

		return self._library.sound[path]

	end,

	-- Method: font

	-- Returns a cached font asset.

	--

	-- Arguments:

	-- Can be:

	--		* A single number. This uses Love's default outline font at that point size.

	--		* A single string. This uses a bitmap font given by this pathname, and assumes that

	--		  the characters come in

	--		  <printable ASCII order at https://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters>.

	--		* A string, then a number. This uses an outline font whose pathname is the first argument,

	--		  at the point size given in the second argument.

	--		* Two strings. The first is treated as a pathname to a bitmap font, the second

	--		  as the character order in the font.

	--

	-- Returns:

	--		Love font object

	font = function (self, ...)

		local arg = {...}

		local libKey = arg[1]

		if type(libKey) == 'string' then

			libKey = self:_absolutePath(libKey)

		end

		if #arg > 1 then libKey = libKey .. arg[2] end

		if not self._library.font[libKey] then

			local font, image

			if #arg == 1 then

				if type(arg[1]) == 'number' then

					font = love.graphics.newFont(arg[1])

				elseif type(arg[1]) == 'string' then

					image = Cached:image(arg[1])

					font = love.graphics.newImageFont(image, self.defaultGlyphs)

				else

					error("don't understand single argument: " .. arg[1])

				end

			elseif #arg == 2 then

				if type(arg[2]) == 'number' then

					font = love.graphics.newFont(arg[1], arg[2])

				elseif type(arg[2]) == 'string' then

					image = Cached:image(arg[1])

					font = love.graphics.newImageFont(image, arg[2])

				else

					error("don't understand arguments: " .. arg[1] .. ", " .. arg[2])

				end

			else

				error("too many arguments; should be at most two")

			end

			self._library.font[libKey] = font

		end

		return self._library.font[libKey]

	end,

	-- Function: bind

	-- Returns a function that's bound to an object so it can be later called with

	-- the correct context. This can be abbreviated as just bind().

	--

	-- Arguments:

	--		obj - object to use as function owner

	--		func - either a string name of a property of obj, or a free-standing

	--			   function.

	--		... - any number of extra arguments 

	bind = function (self, obj, func, ...)

		local arg = {...}

		if STRICT and type(func) == 'string' then

			assert(type(obj[func]) == 'function', 'asked to bind an object to a non-existent method named ' .. func)

		end

		-- look for previous bind

		for key, value in pairs(self._library.binds) do

			if key[1] == func and key[2] == obj then

				local match = true

				for i = 1, #arg do

					if key[i + 2] ~= arg[i] then

						match = false

						break

					end

				end

				if match then

					return value

				end

			end

		end

		-- have to create a new one

		-- note that we have to create a compound key, hence the loop above

		local result = function()

			if type(func) == 'string' then

				return obj[func](obj, unpack(arg))

			else

				return func(obj, unpack(arg))

			end

		end

		self._library.binds[{func, obj, arg}] = result

		return result

	end,

	-- internal function: _absolutePath

	-- Replaces any .. references in a path, where possible. 

	--

	-- Arguments:

	--		rawPath - string path to expand

	--

	-- Returns:

	--		string

	_absolutePath = function (self, rawPath)

		local matches

		local result = rawPath

		repeat

			result, matches = string.gsub(result, '[^/]+/%.%./', '')

		until matches == 0

		return result

	end

}