os.loadAPI("/lib/util")

function prettyPrintSize(tokens)
	if type(tokens) == "number" then
		return tostring(tokens)
	end

	local str = "( "
	for key, token in pairs(tokens) do
		if token.tokentype == "list" then
			str = str .. prettyPrintSize(token)
		elseif token.tokentype == "num" then
			str = str .. token.val .. " "
		elseif token.tokentype == "percent" then
			str = str .. token.val .. "% "
		elseif token.tokentype == "selfpercent" then
			str = str .. token.val .. "$ "
		elseif token.tokentype == "auto" then
			str = str .. "& "
		elseif token.tokentype == "add" then
			str = str .. "+ "
		elseif token.tokentype == "sub" then
			str = str .. "- "
		elseif token.tokentype == "multiply" then
			str = str .. "* "
		elseif token.tokentype == "divide" then
			str = str .. "/ "
		end
	end
	return str .. ")"
end

function parseSize(size)
	if type(size) == "number" then
		return size
	end

	size = size .. " "
	size = string.gsub(size, "center", "50%% - 50$")
	print(size)

	local res = {
		tokentype = "list"
	}
	local current = ""
	local parsing = true
	local i = 1
	while i <= #size do
		local c = string.sub(size, i, i)

		if tonumber(c) ~= nil then
			current = current .. c
		elseif current ~= "" then
			local cur = tonumber(current)
			if cur == nil or current == "+" or current == "-" then
				 -- Don't do anything because there's no number
			elseif c == "%" then
				table.insert(res, {
					tokentype = "percent";
					val = cur;
				})
			elseif c == "$" then
					table.insert(res, {
						tokentype = "selfpercent";
						val = cur;
					})
			else
				table.insert(res, {
					tokentype = "num";
					val = cur;
				})
			end
			current = ""
		end

		if c == "(" then
			local substr = ""
			local depth = 1

			while depth > 0 do
				i = i + 1
				local cc = string.sub(size, i, i)
				if cc == "(" then
					depth = depth + 1
				elseif cc == ")" then
					depth = depth - 1
				end

				if depth > 0 then
					substr = substr .. cc
				end
			end
			table.insert(res, parseSize(substr))
		elseif c == "&" then
			table.insert(res, {
				tokentype = "auto"
			})
		elseif c == "+" then
			table.insert(res, {
				tokentype = "add"
			})
		elseif c == "-" then
			table.insert(res, {
				tokentype = "sub"
			})
		elseif c == "*" then
			table.insert(res, {
				tokentype = "multiply"
			})
		elseif c == "/" then
			table.insert(res, {
				tokentype = "divide"
			})
		end

		i = i + 1
	end

	return res
end

function calcSize(tokens, parentSizeArg, selfSizeArg, autoSizeArg)
	if type(tokens) == "number" then
		return tokens
	elseif tokens == nil then
		return nil
	end

	local parentSize = 0
	if type(parentSizeArg) == "function" then
		parentSize = parentSizeArg()
	elseif type(parentSizeArg) == "number" then
		parentSize = parentSizeArg
	end
	local selfSize = 0
	if type(selfSizeArg) == "function" then
		selfSize = selfSizeArg()
	elseif type(selfSizeArg) == "number" then
		selfSize = selfSizeArg
	end
	local autoSize = 0
	if type(autoSizeArg) == "function" then
		autoSize = autoSizeArg()
	elseif type(autoSizeArg) == "number" then
		autoSize = autoSizeArg
	end

	function getVal(token)
		if token.tokentype == "num" then
			return token.val
		elseif token.tokentype == "percent" then
			return util.percentOf(token.val, parentSize)
		elseif token.tokentype == "selfpercent" then
			return util.percentOf(token.val, selfSize) - 1
		elseif token.tokentype == "auto" then
			return autoSize
		elseif token.tokentype == "list" then
			return calcSize(token, parentSize, selfSize)
		else
			return 0
		end
	end

	local sum = 0
	local opr = "add"

	local i = 1
	while i <= #tokens do
		local num = getVal(tokens[i])
		if opr == "add" then
			sum = sum + num
		elseif opr == "sub" then
			sum = sum - num
		elseif opr == "multiply" then
			sum = sum * num
		elseif opr == "divide" then
			sum = sum / num
		else
			error("Unexpected operator: "..opr)
			return 0
		end

		local oprToken = tokens[i + 1]
		if oprToken ~= nil then
			opr = oprToken.tokentype
		else
			opr = ""
		end

		i = i + 2
	end

	return math.floor(sum)
end

function Widget()
	local self = util.newObject()
	util.makeEventListener(self)

	local prog = nil
	local focused = false
	local children = {}
	local parent = nil
	local top = 1
	local bottom = nil
	local left = 1
	local right = nil
	local width = parseSize("&")
	local height = parseSize("&")
	local background = "black"
	local foreground = "white"

	local x = 1
	local y = 1

	self.getset("prog",
		function() return prog end,
		function(val) prog = val end)

	self.getset("focused",
		function() return focused end)
	self.getset("children",
		function() return children end)

	self.getset("parent",
		function() return parent end)
	self.getset("_parent",
		function() return parent end,
		function(val) parent = val end)

	self.getset("width", 
		function() return calcSize(width, parent.width, 0, self.autoWidth) end,
		function(val) width = parseSize(val) end)
	self.getset("height", 
		function() return calcSize(height, parent.height, 0, self.autoHeight) end,
		function(val) height = parseSize(val) end)

	self.getset("background",
		function() return background end,
		function(val) background = val end)
	self.getset("foreground",
		function() return foreground end,
		function(val) foreground = val end)

	self.getset("top",
		function() return calcSize(top, parent.height, self.height, 0)  end,
		function(val) top = parseSize(val) end)
	self.getset("bottom",
		function() return calcSize(bottom, parent.height, self.height, 0)  end,
		function(val) bottom = parseSize(val) end)
	self.getset("left",
		function() return calcSize(left, parent.width, self.width, 0)  end,
		function(val) left = parseSize(val) end)
	self.getset("right",
		function() return calcSize(right, parent.width, self.width, 0)  end,
		function(val) right = parseSize(val) end)

	self.getset("x",
		function() return x end,
		function(val) x = val end)
	self.getset("y",
		function() return y end,
		function(val) y = val end)

	self.focus = function()
		focused = true
		self.emit("focus", self)
	end
	self.unfocus = function()
		focused = false
		self.emit("unfocus", self)
	end

	self.onclick = function(x, y)
		for key, child in pairs(self.children()) do
			local cx = child.x()
			local cy = child.y()
			local cw = child.width()
			local ch = child.height()

			if x >= cx and x < cx + cw
			and y >= cy and y < cy + ch then
				child.onclick(x, y)
			end
		end
	end

	self.onchar = function(char) end
	self.onkey = function(key) end

	self.setColors = function(screen)
		screen.setTextColor(colors[foreground])
		screen.setBackgroundColor(colors[background])

		local w = self.width()
		local h = self.height()

		local str = ""
		for i = 1, w do
			str = str .. " "
		end

		local x = self.x()
		local y = self.y()
		for i = 1, h do
			screen.setCursorPos(x, y + i - 1)
			screen.write(str)
		end
		screen.setCursorPos(x, y)
	end

	self.addChild = function(widget)
		if widget.parent() ~= nil then
			error("Widget already has a parent")
			return
		end
		table.insert(children, widget)
		widget._parent(self)
		widget.prog(prog)

		widget.on("mustreflow", function()
			self.emit("mustreflow")
		end)

		widget.on("mustredraw", function(elem)
			self.emit("mustredraw", elem)
		end)

		widget.on("focus", function(elem)
			self.emit("focus", elem)
		end)

		widget.on("unfocus", function(elem)
			self.emit("unfocus", elem)
		end)

		self.emit("mustreflow")
	end

	self.removeChild = function(child)
		local removed = false
		for key, val in pairs(children) do
			if val == child then
				removed = true
				child.unfocus()
				table.remove(children, key)
			end
		end
		if removed then
			self.emit("mustreflow")
		end
	end

	self.reflow = util.abstract

	self.draw = util.abstract

	return self
end

function LinearLayout()
	local self = Widget()

	local orientation = "vertical"
	local reversed = false

	self.getset("orientation",
		function() return orientation end,
		function(val) orientation = val end)
	self.getset("reversed",
		function() return reversed end,
		function(val) reversed = val end)

	self.draw = function(screen)
		self.setColors(screen)
		for key, child in pairs(self.children()) do
			child.draw(screen)
		end
	end

	self.reflow = function(screen, x, y)
		self.x(x)
		self.y(y)

		local selfw = self.width()
		local selfh = self.height()
		local offset = 0
		for key, child in pairs(self.children()) do
			local cx = x
			local cy = y
			local height = child.height()
			local width = child.width()
			local top = child.top()
			local bottom = child.bottom()
			local left = child.left()
			local right = child.right()

			if right ~= nil then
				cx = cx +
				selfw -
				width -
				right + 1
			else
				cx = cx + top - 1
			end
			if bottom ~= nil then
				cy = cy +
				selfh -
				height -
				bottom + 1
			else
				cy = cy + top - 1
			end

			if orientation == "vertical" then
				cy = y + offset + top - 1
				offset = offset +
				top - 1 +
				height +
				(bottom or 1) - 1

				if reversed then
					cy = selfh - cy - height + 2
				end
			elseif orientation == "horizontal" then
				cx = x + offset + left - 1
				offset = offset +
				left - 1 +
				width +
				(right or 1) - 1

				if reversed then
					cx = selfw - cx - width + 2
				end
			end

			child.reflow(screen, cx, cy)
		end
	end

	return self
end

function FloatingLayout()
	local self = Widget()

	self.draw = function(screen)
		self.setColors(screen)
		for key, child in pairs(self.children()) do
			child.draw(screen)
		end
	end

	self.reflow = function(screen, x, y)
		self.x(x)
		self.y(y)

		for key, child in pairs(self.children()) do
			local cx = x
			local cy = y
			if child.right() ~= nil then
				cx = cx +
				self.width() -
				child.width() -
				child.right() + 1
			else
				cx = cx + child.left() - 1
			end
			if child.bottom() ~= nil then
				cy = cy +
				self.height() -
				child.height() -
				child.bottom() + 1
			else
				cy = cy + child.top() - 1
			end

			child.reflow(screen, cx, cy)
		end
	end

	self.autoWidth = function()
		return self.parent().width()
	end
	self.autoHeight = function()
		return self.parent().height()
	end

	return self
end

function TextView()
	local self = Widget()

	local text = ""

	self.getset("text",
		function() return text end,
		function(val)
			local pre = text
			text = tostring(val)
			if #pre == #text then
				self.emit("mustredraw", self)
			else
				self.emit("mustreflow")
			end
		end)

	self.reflow = function(screen, x, y)
		self.x(x)
		self.y(y)
	end

	self.draw = function(screen)
		self.setColors(screen)

		screen.setCursorPos(self.x(), self.y())
		local w = self.width()
		local h = self.height()

		local offy = math.floor(h / 2)
		local offx = math.floor(w - #text - ((w - #text) / 2))
		screen.setCursorPos(self.x() + offx, self.y() + offy)
		screen.write(text)
	end

	self.autoWidth = function()
		return #text
	end
	self.autoHeight = function()
		return 1
	end

	self.onclick = function(x, y)
		-- TextViews don't have any interesting onclick actions
	end

	return self
end

function TextInput()
	local self = Widget()

	local backgroundInactive = "blue"
	local backgroundActive = "red"
	local foregroundInactive = "white"
	local foregroundActive = "white"

	local key_backspace = 14
	local key_left = 203
	local key_right = 205
	local key_delete = 211

	local text = ""
	local cursor = 0

	self.getset("text",
		function() return text end,
		function(val)
			local pre = text
			text = tostring(val)
			if #pre == #text then
				self.emit("mustredraw", self)
			else
				self.emit("mustreflow")
			end
		end)

	self.getset("backgroundInactive",
		function() return backgroundInactive end,
		function(val) backgroundInactive = val end)
	self.getset("backgroundActive",
		function() return backgroundActive end,
		function(val) backgroundActive = val end)
	self.getset("foregroundInactive",
		function() return foregroundInactive end,
		function(val) foregroundInactive = val end)
	self.getset("foregroundActive",
		function() return foregroundActive end,
		function(val) foregroundActive = val end)

	self.reflow = function(screen, x, y)
		self.x(x)
		self.y(y)
	end

	self.draw = function(screen)
		if self.focused() then
			self.background(backgroundActive)
			self.foreground(foregroundActive)
		else
			self.background(backgroundInactive)
			self.foreground(foregroundInactive)
		end

		self.setColors(screen)

		screen.setCursorPos(self.x(), self.y())
		screen.write("|")
		screen.setCursorPos(self.x() + self.width() - 1, self.y())
		screen.write("|")

		local len = self.width() - 2
		screen.setCursorPos(self.x() + 1, self.y())
		screen.write(string.sub(text, 1, len))

		if self.focused() then
			screen.setCursorPos(self.x() + 1 + cursor, self.y())
			screen.setBackgroundColor(colors.white)
			screen.write(" ")
		end
	end

	self.autoWidth = function()
		return #text + 2
	end
	self.autoHeight = function()
		return 1
	end

	self.onclick = function(x, y)
		local w = self.width()
		if x == self.x() or x == w then
			cursor = #text
		else
			cursor = math.min(x - self.x() - 1, #text)
		end
		self.focus()
	end

	self.onchar = function(char)
		local pre = string.sub(text, 1, cursor)
		local post = string.sub(text, cursor + 1, #text)
		text = pre .. char .. post
		cursor = cursor + 1
		self.emit("mustreflow")
	end

	self.onkey = function(key)
		if key == key_backspace then
			local pre = string.sub(text, 1, cursor - 1)
			local post = string.sub(text, cursor + 1, #text)
			text = pre .. post
			if cursor > 0 then
				cursor = cursor - 1
			end
			self.emit("mustreflow")
		elseif key == key_delete then
			local pre = string.sub(text, 1, cursor)
			local post = string.sub(text, cursor + 2, #text)
			text = pre .. post
			self.emit("mustreflow")
		elseif key == key_left then
			if cursor > 0 then
				cursor = cursor - 1
			end
			self.emit("mustredraw", self)
		elseif key == key_right then
			if cursor < #text then
				cursor = cursor + 1
			end
			self.emit("mustredraw", self)
		end
	end

	self.on("focus", function() self.emit("mustredraw", self) end)
	self.on("unfocus", function() self.emit("mustredraw", self) end)

	return self
end

function Button()
	local self = TextView()

	local backgroundInactive = "blue"
	local backgroundActive = "red"
	local foregroundInactive = "white"
	local foregroundActive = "white"

	self.getset("backgroundInactive",
		function() return backgroundInactive end,
		function(val) backgroundInactive = val end)
	self.getset("backgroundActive",
		function() return backgroundActive end,
		function(val) backgroundActive = val end)
	self.getset("foregroundInactive",
		function() return foregroundInactive end,
		function(val) foregroundInactive = val end)
	self.getset("foregroundActive",
		function() return foregroundActive end,
		function(val) foregroundActive = val end)

	self.background(backgroundInactive)
	self.foreground(foregroundInactive)

	local resetTimeout

	self.onclick = function(x, y)
		if resetTimeout ~= nil then
			self.prog().cancelTimeout(resetTimeout)
		end
		self.background(backgroundActive)
		self.foreground(foregroundActive)
		self.emit("mustredraw", self)

		self.emit("focus", self)
		self.emit("click")

		resetTimeout = self.prog().setTimeout(0.3, function()
			self.background(backgroundInactive)
			self.foreground(foregroundInactive)
			self.emit("mustredraw", self)
		end)
	end

	return self
end

function DummyScreen()
	local self = {}

	self.getSize = function()
		return term.getSize()
	end
	self.clear = function() end
	self.write = function() end
	self.setCursorPos = function() end
	self.setTextColor = function() end
	self.setBackgroundColor = function() end

	return self
end

function Gui(prog, screen)
	local self = util.newObject()

	if screen == nil then
		screen = term
	end

	local focusedWidget = nil
	local rootWidget = nil

	self.getset("width",
		function()
			local x, y = screen.getSize()
			return x
		end)
	self.getset("height",
		function()
			local x, y = screen.getSize();
			return y
		end)

	self.getset("screen",
		function() return screen end,
		function(val) screen = val end)

	self.getset("focused",
		function() return focusedWidget end)

	 -- Handle focusing and unfocusing of widgets
	local function onRootChildFocus(widget)
		if focusedWidget ~= nil then
			focusedWidget.unfocus()
		end
		focusedWidget = widget
	end

	local function onRootChildUnfocus(widget)
		if widget == focusedWidget then
			focusedWidget = nil
		end
	end

	local function onRootChildRedraw(widget)
		widget.draw(screen)
	end

	self.setRoot = function(root)
		if rootWidget ~= nil then
			rootWidget.removeListener("focus", onRootChildFocus)
			rootWidget.removeListener("unfocus", onRootChildUnfocus)
			rootWidget.removeListener("mustreflow", self.reflow)
			rootWidget.removeListener("mustredraw", onRootChildRedraw)
		end
		rootWidget = root
		root._parent(self)
		root.on("focus", onRootChildFocus)
		root.on("unfocus", onRootChildUnfocus)
		root.on("mustreflow", self.reflow)
		root.on("mustredraw", onRootChildRedraw)
		root.prog(prog)
	end

	self.reflow = function()
		if rootWidget == nil then
			return
		end
		screen.clear()
		screen.setCursorPos(1, 1)
		rootWidget.reflow(screen, 1, 1)
		rootWidget.draw(screen)
	end

	self.exit = function()
		prog.exit()
	end

	prog.on("init", self.draw)

	prog.on("exit", function()
		screen.setTextColor(colors.white)
		screen.setBackgroundColor(colors.black)
		screen.clear()
		screen.setCursorPos(1, 1)
	end)

	prog.on("mouse_click", function(button, x, y)
		if focusedWidget ~= nil then
			focusedWidget.unfocus()
		end
		if rootWidget ~= nil then
			rootWidget.onclick(x, y)
		end
	end)
	prog.on("char", function(char)
		if focusedWidget ~= nil then
			focusedWidget.onchar(char)
		end
	end)
	prog.on("key", function(key)
		if focusedWidget ~= nil then
			focusedWidget.onkey(key)
		end
	end)

	return self
end