--- Yet another badly designed and implemented GUI library, but this time I wrote it so it's the best.
-- Part of daccord. See daccord.can for more information.

-- Copyright 2017-2018 Étienne "Reuh" Fildadut
--
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
--     http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.

let curses = require("curses")
let class = require("classtoi")
let sleep = require("socket").sleep

let screen

os.setlocale("")

let everyWidget = {}

let widget = class {
	_exit = false,

	_redraw = true,
	x = 0,
	y = 0,
	w = 0,
	h = 0,

	parent = {},
	focused = false,

	updateInterval = -1,
	_nextUpdate = os.time(), -- -1 = no update

	new = :(data)
		table.insert(everyWidget, self)

		-- Copy properties
		for k, v in pairs(data) do
			@[k] = v
		end

		-- Dimensions
		if not @parent._firstX then @parent._firstX, @parent._firstY = 0, 0 end
		@x, @y = @parent._firstX, @parent._firstY

		if     @width == "extend" @w = @parent.w - @x
		elseif @width:match("%d+em$") @w = tonumber(@width:match("%d+"))
		if     @height == "extend" then
			@h = @parent.h - @y
			@parent._lastVerticalExtend = self -- will be resized if vertical space is needed
			@parent._afterLastVerticalExtend = {}
		elseif @height:match("%d+em$") @h = tonumber(@height:match("%d+"))

		if @y >= @parent.h then -- resize
			@parent._lastVerticalExtend:_resize(@parent._lastVerticalExtend.w, @parent._lastVerticalExtend.h - @h)
			@parent._firstY -= @h
			@y -= @h
			for _, el in ipairs(@parent._afterLastVerticalExtend) do -- move widgets
				el.y -= @h
			end
		end

		@parent._firstX += @w
		if @parent._firstX >= @parent.w then @parent._firstX = 0 end -- newline
		@parent._firstY += @h
		if @parent._lastVerticalExtend ~= self and @parent._afterLastVerticalExtend then table.insert(@parent._afterLastVerticalExtend, self) end

		-- Setup
		if @_setup then @_setup() end

		screen:move(@parent.y + @y + @h, @parent.x + @x + @w)
	end,

	exit = :()
		@_exit = true
	end,

	byId = :(id)
		for _, el in ipairs(everyWidget) do
			if el.id == id return el
		end
		error("no element with id "..tostring(id))
	end,

	updateAfter = :(time)
		@_nextUpdate = os.time() + time
	end
}

let widgets = setmetatable({
	fill = widget {
		_draw = :()
			if type(@fill) == "string" then @fill = curses[@fill] end
			for y = @parent.y + @y, @parent.y + @y + @h - 1 do
				screen:move(y, @parent.x + @x)
				for x = @parent.x + @x, @parent.x + @x + @w - 1 do
					screen:addch(@fill or 32)
				end
			end
		end
	},

	input = widget {
		content = "",
		cursorPosition = 1,
		_input = :(charbuffer, control)
			let y, x = @parent.y + @y, @parent.x + @x + @cursorPosition-1
			if control == "backspace" then
				screen:mvdelch(y, x-1)
				if @cursorPosition > 1 then
					if @cursorPosition == 2 then -- utf8.offset(s, 0) returns the start of the last character, ie something we don't want
						@content = @content:sub(utf8.offset(@content, @cursorPosition))
					else
						@content = @content:sub(1, utf8.offset(@content, @cursorPosition-1)-1)
									.. @content:sub(utf8.offset(@content, @cursorPosition))
					end
					@cursorPosition -= 1
					@onTextInput()
				end
			elseif control == "delete" then
				screen:mvdelch(y, x)
				if @cursorPosition <= utf8.len(@content) then
					if @cursorPosition == 1 then -- utf8.offset(s, 0) returns the start of the last character, ie something we don't want
						@content = @content:sub(utf8.offset(@content, @cursorPosition+1))
					else
						@content = @content:sub(1, utf8.offset(@content, @cursorPosition)-1)
									.. @content:sub(utf8.offset(@content, @cursorPosition+1))
					end
					@onTextInput()
				end
			elseif control == "right" then
				if @cursorPosition <= utf8.len(@content) then
					screen:addstr(@content:sub(utf8.offset(@content, @cursorPosition), utf8.offset(@content, @cursorPosition+1)-1))
					@cursorPosition += 1
				end
			elseif control == "left" then
				if @cursorPosition > 1 then
					screen:move(y, x-1)
					@cursorPosition -= 1
				end
			elseif charbuffer then
				screen:move(y, x)
				screen:winsstr(charbuffer)
				screen:move(y, x+1)
				@content = @content:sub(1, utf8.offset(@content, @cursorPosition)-1)
								.. charbuffer
								.. @content:sub(utf8.offset(@content, @cursorPosition))
				@cursorPosition += 1
				@onTextInput()
			end
		end,
		_draw = :()
			for y = @parent.y + @y, @parent.y + @y + @h - 1 do
				screen:move(y, @parent.x + @x)
				for x = @parent.x + @x, @parent.x + @x + @w - 1 do
					screen:addch(32)
				end
			end
			screen:mvaddstr(@parent.y + @y, @parent.x + @x, @content)
		end,
		_placeCursor = :()
			screen:move(@parent.y + @y, @parent.x + @x + @cursorPosition-1)
			return true
		end,
		sub = :(start, stop=utf8.len(@content))
			if stop < 1 or start >= utf8.len(@content) then
				return ""
			else
				return @content:sub(utf8.offset(@content, start), (utf8.offset(@content, stop+1) or (#@content+1))-1)
			end
		end,
		replace = :(start, stop, newText)
			if @cursorPosition >= stop then
				@cursorPosition += utf8.len(newText) - (stop - start)
			end
			@content = @sub(1, start-1) .. newText .. @sub(stop+1)
			@onTextInput()
			@_redraw = true
		end,
		onTextInput = :() end
	},

	list = widget {
		content = {},
		columnWidth = {},
		selected = 1,
		scroll = 0,
		_redraw = true,
		_input = :(charbuffer, control)
			if control == "up" then
				@selected -= 1
				@_redraw = true
			elseif control == "down" then
				@selected += 1
				@_redraw = true
			elseif control == "pgup" then
				@selected -= 10
				@_redraw = true
			elseif control == "pgdown" then
				@selected += 10
				@_redraw = true
			end
			@selected = math.min(math.max(@selected, 1), math.max(#@content, 1))

			while @selected <= @scroll do
				@scroll -= 1
			end
			while @selected >= @scroll + @h + 1 do
				@scroll += 1
			end

			if control == "enter" then
				@onSelect({@selected})
			elseif control == "A" then
				let len = #@content
				@onSelect([for i=1, len do i end])
			end
		end,
		_draw = :()
			let oY, oX = screen:getyx()
			for y = @parent.y + @y, @parent.y + @y + @h -1 do -- clear
				screen:mvaddstr(y, @parent.x + @x, (" "):rep(@w))
			end
			screen:move(@parent.y + @y, @parent.x + @x)
			for i=@scroll+1, @scroll + @h do -- draw
				if i == @selected then
					screen:standout()
				end
				let colx = @parent.x+@x
				for c=1, #@columnWidth do
					screen:mvaddstr(@parent.y+@y+i-1-@scroll, colx, @content[i] and @content[i][c] or "") -- TODO: make sure it doesn't go too far right or something
					colx += @columnWidth[c]
				end
				if i == @selected then
					screen:standend()
				end
			end
			screen:move(oY, oX)
		end,
		insert = :(pos, item)
			if item then
				table.insert(@content, pos, item)
				if @selected > pos and @selected < #@content then
					@selected += 1
				end
			else
				item = pos
				table.insert(@content, item)
			end
			if #@content == 1 then -- column count is determined by 1st item (other items can do what they want, this isn't a dictatorship)
				@columnWidth = [for _=1,#item do 0 end]
			end
			if #item >= #@columnWidth then -- if the column fits into our dictatorship, update column width
				for c=1, #@columnWidth do
					let l = utf8.len(item[c]) -- if it isn't valid UTF8, ignore (can happen for files in Windows-made zipfiles). Should probably raise a warning or something... TODO.
					if l and l > @columnWidth[c] then
						@columnWidth[c] = utf8.len(item[c]) + 1
					end
				end
			end
			@_redraw = true
		end,
		remove = :(pos=#@content)
			table.remove(@content, pos)
			if @selected > pos and @selected > 1 then
				@selected -= 1
			end
			@selected = math.min(@selected, #@content)
			@_redraw = true
		end,
		replace = :(pos, item)
			@content[pos] = item
			@_redraw = true
		end,
		clear = :()
			@content = {}
			@columnWidth = {}
			@_redraw = true
			@selected = 1
			@scroll = 0
		end,
		onSelect = :() end
	},

	tabs = widget {
		selected = 1,
		children = {},
		_children = {},
		_setup = :()
			for i, tab in ipairs(@) do
				@children[i] = { x = @x, y = @y, w = @w, h = @h }
				for _, el in ipairs(tab) do
					el.parent = @children[i]
					table.insert(@children[i], widgets[el.type]:new(el))
				end
			end
			@_children = @children[@selected]
		end,
		_input = :(charbuffer, control)
			if control == "tab" then
				@selected += 1
				if @selected > #@ then @selected = 1 end
				@_children = @children[@selected]
				for _, el in ipairs(@_children) do -- Force redraw
					el._redraw = true
				end
			end
		end,
		_resize = :(w, h)
			@w, @h = w, h
			for i, tab in ipairs(@) do
				for _, el in ipairs(@children[i]) do
					if el.x + el.w > w then el.w = w - el.x end
					if el.y + el.h > h then el.h = h - el.y end
				end
			end
		end
	},

	label = widget {
		content = "Label",
		_draw = :()
			screen:mvaddstr(@parent.y + @y, @parent.x + @x, @content .. (" "):rep(@w - #@content))
		end,
		set = :(str)
			@content = str
			@_redraw = true
		end
	},

	slider = widget {
		min = 0,
		max = 1,
		current = 0,
		head = "⏸",
		_draw = :()
			let len = math.ceil((@current - @min) / (@max - @min) * @w)
			screen:mvaddstr(@parent.y + @y, @parent.x + @x, ("="):rep(len-1))
			screen:addstr(@head .. (" "):rep(@w - len))
		end,
		set = :(current)
			@current = current
			@_redraw = true
		end,
		setMax = :(max)
			@max = max
			@_redraw = true
		end,
		setMin = :(min)
			@min = min
			@_redraw = true
		end,
		setHead = :(head)
			@head = head
			@_redraw = true
		end
	}
}, {
	__index = (t, k)
		error("unknown widget "..tostring(k))
	end
})

let recursiveApply = (list, fn)
	for _, el in ipairs(list) do
		if el._widget then
			el = el._widget
		end
		fn(el)
		if el._children then
			recursiveApply(el._children, fn)
		end
	end
end

return (ui)
	xpcall(()
		-- Init
		if not screen then
			screen = curses.initscr()
			curses.cbreak()
			curses.echo(false)
			screen:nodelay(true)
		end

		-- Create widgets
		screen:clear()
		let h, w = screen:getmaxyx()
		let parent = {
			x = 0, y = 0,
			w = w, h = h
		}
		for _, el in ipairs(ui) do
			el.parent = parent
			el._widget = widgets[el.type]:new(el)
		end

		-- Update loop
		while not widget._exit do
			-- Input
			local c = screen:getch()
			if c and c < 256 then
				let charbuffer = string.char(c)
				let control
				if c > 127 then -- multibyte char
					charbuffer ..= string.char(screen:getch())
					if c > 223 then
						charbuffer ..= string.char(screen:getch())
						if c > 239 then
							charbuffer ..= string.char(screen:getch())
						end
					end
				end
				if curses.unctrl(c):match("^%^") then -- control char
					charbuffer = nil
					let k = curses.unctrl(c)
					if k == "^?" then
						control = "backspace"
					elseif k == "^W" then
						control = "close"
					elseif k == "^J" then
						control = "enter"
					elseif k == "^I" then
						control = "tab"
					elseif k == "^@" then
						control = "space"
					elseif k == "^[" then
						let k = string.char(screen:getch()) .. string.char(screen:getch())
						if k == "[C" then
							control = "right"
						elseif k == "[D" then
							control = "left"
						elseif k == "[A" then
							control = "up"
						elseif k == "[B" then
							control = "down"
						elseif k == "[5" then
							control = "pgup"
						elseif k == "[6" then
							control = "pgdown"
						elseif k == "[3" then
							k ..= string.char(screen:getch())
							if k == "[3~" then
								control = "delete"
							elseif k == "[3;" then
								control = "clear"
							else
								error("unknown control "..tostring(k))
							end
						else
							error("unknown control "..tostring(k))
						end
					elseif k:match("^%^[A-Z]$") then
						control = k:match("^%^([A-Z])$")
					else
						error("unknown control "..tostring(k))
					end
				end

				recursiveApply(ui, (el)
					if el.focused and el._input then
						el:_input(charbuffer, control)
					end
					if el.focused and control and el.onControl then
						el:onControl(control)
					end
				end)

				if control == "close" then
					if ui.onClose then ui.onClose(widget) end
				end
			end

			-- Update
			recursiveApply(ui, (el)
				if el._nextUpdate ~= -1 and os.difftime(el._nextUpdate, os.time()) <= 0 then
					if el.onUpdate then el:onUpdate() end
					if el.updateInterval ~= -1 then
						el._nextUpdate += el.updateInterval
					else
						el._nextUpdate = -1
					end
				end
			end)

			-- Redraw
			recursiveApply(ui, (el)
				if el._redraw and el._draw then
					el._redraw = false
					el:_draw()
				end
			end)

			-- Place cursor
			let cursorVis = 0
			recursiveApply(ui, (el)
				if el._placeCursor and el:_placeCursor() then
					cursorVis = 2
				end
			end)
			curses.curs_set(cursorVis)

			-- Done
			screen:refresh()
			sleep(0.03)
		end

		curses.endwin()
	end, (err)
	  curses.endwin()
	  print(require("candran").messageHandler(err))
	  os.exit(2)
	end)
end