/traderous

-- Class: Keys

-- This tracks the state of the keyboard, i.e. if a key

-- was just pressed or released this frame. You can look

-- up a key either by its name or its Unicode number.

-- Not all keys sensed have Unicode equivalents (e.g. modifiers

-- like Control or Alt).

--

-- Only one Keys object can be active at one time. The one currently

-- listening to the keyboard can be accessed globally via <the>.keys.

--

-- See http://love2d.org/wiki/KeyConstant for a list of key names.

-- This class aliases modifiers for you, so that if you want to check

-- whether either the left or right Control key is pressed, you can check

-- on 'ctrl' instead of both 'lctrl' and 'rctrl'.

--

-- Extends:

--		<Sprite>

Keys = Sprite:extend

{

	visible = false,

	-- Property: typed

	-- This is literally what is being typed during the current frame.

	-- e.g. if the user holds the shift key and presses the 'a' key,

	-- this will be set to 'A'. Consult <allPressed()> if you

	-- want to know what specific keys are being pressed.

	typed = '',

	-- private property: _thisFrame

	-- what keys are pressed this frame

	-- if you are interested in this, use allPressed() instead

	_thisFrame = {},

	-- private property: _lastFrame

	-- what keys were pressed last frame

	_lastFrame = {},

	new = function (self, obj)

		obj = self:extend(obj)

		the.keys = obj

		love.keypressed = function (key, unicode) obj:keyPressed(key, unicode) end

		love.keyreleased = function (key, unicode) obj:keyReleased(key, unicode) end

		if obj.onNew then obj:onNew() end

		return obj

	end,

	-- Method: pressed

	-- Are *any* of the keys passed held down this frame?

	--

	-- Arguments:

	--		string key descriptions passed as individual arguments

	--

	-- Returns:

	-- 		boolean

	pressed = function (self, ...)

		local keys = {...}

		for _, value in pairs(keys) do

			if STRICT then

				assert(type(value) == 'string', 'all keys are strings; asked to check a ' .. type(value))

			end

			if self._thisFrame[value] then

				return true

			end

		end

		return false

	end,

	-- Method: justPressed

	-- Are *any* of the keys passed pressed for the first time this frame?

	--

	-- Arguments:

	--		string key descriptions passed as individual arguments

	--

	-- Returns:

	-- 		boolean

	justPressed = function (self, ...)

		local keys = {...}

		for _, value in pairs(keys) do

			if STRICT then

				assert(type(value) == 'string', 'all keys are strings; asked to check a ' .. type(value))

			end

			if self._thisFrame[value] and not self._lastFrame[value] then

				return true

			end

		end

		return false

	end,

	-- Method: released

	-- Are *all* of the keys passed not held down this frame?

	-- 

	-- Arguments:

	--		string key descriptions passed as individual arguments

	--

	-- Returns:

	-- 		boolean

	released = function (self, ...)

		local keys = {...}

		for _, value in pairs(keys) do

			if STRICT then

				assert(type(value) == 'string', 'all keys are strings; asked to check a ' .. type(value))

			end

			if self._thisFrame[value] then

				return false

			end

		end

		return true

	end,

	-- Method: justReleased

	-- Are *any* of the keys passed released after being held last frame?

	--

	-- Arguments:

	--		string key descriptions passed as individual arguments

	--

	-- Returns:

	-- 		boolean

	justReleased = function (self, ...)

		local keys = {...}

		for _, value in pairs(keys) do

			if STRICT then

				assert(type(value) == 'string', 'all keys are strings; asked to check a ' .. type(value))

			end

			if self._lastFrame[value] and not self._thisFrame[value] then

				return true

			end

		end

		return false

	end,

	-- Method: allPressed

	-- Returns all buttons currently pressed this frame.

	--

	-- Arguments:

	--		none

	--

	-- Returns:

	--		string key descriptions; if nothing is pressed, nil

	allPressed = function (self)

		local result = {}

		for key, value in pairs(self._thisFrame) do

			if value then table.insert(result, key) end

		end

		return unpack(result)

	end,

	-- Method: allJustPressed

	-- Returns all keys just pressed this frame.

	--

	-- Arguments:

	--		none

	--

	-- Returns:

	--		string key descriptions; if nothing is just pressed, nil

	allJustPressed = function (self)

		local result = {}

		for key, value in pairs(self._thisFrame) do

			if value and not self._lastFrame[key] then table.insert(result, key) end

		end

		return unpack(result)

	end,

	-- Method: allJustReleased

	-- Returns all keys just released this frame.

	--

	-- Arguments:

	--		none

	--

	-- Returns:

	--		string key descriptions; if nothing is just pressed, nil

	allJustReleased = function (self)

		local result = {}

		for key, value in pairs(self._thisFrame) do

			if not value and self._lastFrame[key] then table.insert(result, key) end

		end

		return unpack(result)

	end,

	-- Converts a character code to a Unicode string

	-- see http://stackoverflow.com/questions/7780179/what-is-the-way-to-represent-a-unichar-in-lua/7799843

	unicodeChar = function (self, code)

		if code == nil then return nil end

		if code < 32 then return string.format('\\x%02x', code) end

		if code < 126 then return string.char(code) end

		if code < 65539 then return string.format("\\u%04x", code) end

		if code < 1114111 then return string.format("\\u%08x", code) end

	end,

	-- Connects to the love.keypressed callback

	keyPressed = function (self, key, unicode)

		self._thisFrame[key] = true

		if unicode and unicode >= 0x20 and unicode ~= 127 and unicode < 0x3000 then

			self.typed = self.typed .. self:unicodeChar(unicode)

		end

		-- aliases for modifiers

		if key == 'rshift' or key == 'lshift' or

		   key == 'rctrl' or key == 'lctrl' or

		   key == 'ralt' or key == 'lalt' or

		   key == 'rmeta' or key == 'lmeta' or

		   key == 'rsuper' or key == 'lsuper' then

			self._thisFrame[string.sub(key, 2)] = true

		end

	end,

	-- Connects to the love.keyreleased callback

	keyReleased = function (self, key, unicode)

		self._thisFrame[key] = false

		-- aliases for modifiers

		if key == 'rshift' or key == 'lshift' or

		   key == 'rctrl' or key == 'lctrl' or

		   key == 'ralt' or key == 'lalt' or

		   key == 'rmeta' or key == 'lmeta' or

		   key == 'rsuper' or key == 'lsuper' then

			self._thisFrame[string.sub(key, 2)] = false

		end

	end,

	endFrame = function (self, elapsed)

		for key, value in pairs(self._thisFrame) do

			self._lastFrame[key] = value

		end

		self.typed = ''

		Sprite.endFrame(self, elapsed)

	end,

	update = function() end

}