--- Yet another MPD client, but this time I wrote it so it's the best.
-- Focused on an instant and hopefully powerful search.
-- Currently only a console interface is available.
--
-- Dependencies: candran, luasocket, lcurses
--
-- Highly unintuitive keybinding:
-- * Up goes up, down goes down.
-- * Tab switch between search and current playlist.
-- * Control+W quits.
-- * Control+Space toggle play/pause.
-- * In search:
--   * Control+A add all the results to the playlist.
--   * Enter add currently selected song to the playlist.
--   * Type "TagName=" to trigger tag completion: select a tag and press Enter to select it. Or type it manually and exit tag completion by typing a space.
--   * Type "File=" to trigger filename search.
-- * In current playlist:
--   * Enter play currently selected song.
--   * Delete remove selected song from playlist.
--   * Control+Delete clear the playlist.
--
-- Most of what was initialy planned isn't implemented yet. Hopefully all will be finished before you're six feet under.
--
-- Curently implemented:
-- * Play/pause, current song status
-- * Current playlist, jump to song, remove song
-- * Instant search among all tags or specific tags
-- * Instant tag value completion
-- * Overly optimistic planned features list in a comment in the main file
--
-- Stuff which is planned:
-- * Sticker search
-- * Search requests where keyword and tag selectors can be assigned with a $probabilty, generating infinite playlists (composer=chopin$.5)
-- * Relational operators for tags and stickers (song ratings) (rating>.5)
-- * Random, single, consume and other MPD play mode are determined by :keywords in the search query (:rand, :limit=5, :asc=Track, etc.)
-- * The endgoal would be that playlists would be entirely determined and contained in a single search query (add some saved storage interface).
--   Which we would therfore mean we can regenerate them on the fly when the MPD database is updated, or probabilities where used in the query.
-- * A non-console GUI. Should be doable considering everything is neatly contained in gui.can, but damn are thoses text widget I made weird.
-- * A real documentation.
-- * Tag!=thing, modified since, and, not, or
-- * File browser
--
-- This version of the software is licensed under the terms of the Apache License, version 2 (https://www.apache.org/licenses/LICENSE-2.0.txt).

-- 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.

require("candran").setup()
let gui = require("gui")
let mpc = require("mpc")

-- Constants
let VERSION = "0.0.4" -- Major.Minor.IdkIChangedSomethingButLetsNotTalkAboutItTooMuch
-- Major bump means that everything major that was planned before I decided to keep programming this shit was implemented, and forms, like, a cohesive whole.
-- Minor bump means I implemented something that's actually useful. Stuff may break, because why not.
-- The other thing bump means I implemented or fixed something. But that's not worth excitement.

-- Configuration file. Yeah.
let config = {
	-- MPD server
	host = "localhost",
	port = 6600,
	password = "", -- leave empty if you don't use a password
	-- Default behaviour
	filenameSearch = true, -- instant search search also search in filenames for untitled tracks (not only when using the file= syntax), slightly slower when handling large searches
	-- Interface
	songDisplay = { "Track", { "Title", "Name", "file" }, "Artist", "Album" } -- list of tags or list of alternative tags (first one to exist will be used) to display for each song
}
(loadfile("config.lua", "t", config) or () end)() -- GATHER UP EVERYONE! I WANT YOU TO MEET... THE AMAZING CONFIG FILE LOADER!

-- Returns list of fields to display for the song s
let songTable = (s)
	let t = {}
	for i, field in ipairs(config.songDisplay) do
		if type(field) ~= "table" then field = { field } end
		t[i] = "∅"
		for _, option in ipairs(field) do
			if s[option] then
				t[i] = tostring(s[option])
				break
			end
		end
	end
	return t
end

-- Connect!
mpc.log = () end
mpc = mpc(config.host, config.port)
if config.password ~= "" then
	mpc:password(config.password)
end

-- Valid tags list
let tags = [
	let r, l = mpc:tagtypes()
	for _, t in ipairs(l) do
		push t.tagtype
	end
]

-- State
let tagCompleting = {
	tag = nil, -- tag name
	start = nil, -- start position in search input for tag=thing
	stop = nil -- end position
}

let results, playlist = {}, {} -- current result in the search view / playlist (list of songs)
let state = "stop" -- state

gui {
		{
			type = "tabs",
			focused = true,

			width = "extend",
			height = "extend",

			-- Search
			{
				{
					id = "prompt",

					type = "input",
					focused = true,

					width = "extend",
					height = "1em",

					onTextInput = :()
						let list = @byId("list")
						list:clear()

						-- Tag complete
						tagCompleting.tag = nil
						if @sub(1, @cursorPosition):match("[A-Za-z_]+=[^\" ]*$") or @sub(1, @cursorPosition):match("[A-Za-z_]+=\"[^\"]*$") then
							let start, sel, val, stop
							if @sub(1, @cursorPosition):match("[A-Za-z_]+=[^\" ]*$") then
								start, sel, val, stop = @sub(1, @cursorPosition):match("()([A-Za-z_]+)=([^\" ]*)()$")
							else
								start, sel, val, stop = @sub(1, @cursorPosition):match("()([A-Za-z_]+)=\"([^\"]*)()$")
							end

							-- music tags
							for _, tag in ipairs(tags) do
								if tag:lower() == sel:lower() then
									results = {}

									let r, songs = mpc:list(tag)
									if r then
										for _, s in ipairs(songs) do
											if s[tag]:lower():match(val:lower()) then -- filter val
												table.insert(results, s)
												list:insert{tostring(s[tag])}
											end
										end
									end

									tagCompleting.tag = tag
									tagCompleting.start = start
									tagCompleting.stop = stop

									break
								end
							end

							-- file search
							if sel:lower() == "file" then
								results = {}

								list:setPump(10, :(start, stop)
									let r, songs = mpc:search("(file == %q)":format(val), "window", "%s:%s":format(start-1, stop))
									if r then
										for _, s in ipairs(songs) do
											table.insert(results, s)
											list:insert{tostring(s.file)}
										end
									end
								end)

								tagCompleting.tag = "file"
								tagCompleting.start = start
								tagCompleting.stop = stop
							end
						-- Song search
						else
							results = {
								_filenameSearchOffset = 0, -- where the filename search begin in the result list
								_filenameSearchStart = 0 -- where the search window should start in the filename search
							}

							-- Build query
							let query = {}

							-- Any selectors
							let withoutSel = @content:gsub("[A-Za-z_]+=[^\" ]+", ""):gsub("[A-Za-z_]+=\"[^\"]*\"", "")
							for word in withoutSel:gmatch("[^%s]+") do
								table.insert(query, "(any == %q)":format(word))
							end

							-- Tag selectors
							for tag, val in @content:gmatch("([A-Za-z_]+)=([^\" ]+)") do
								table.insert(query, "(%s == %q)":format(tag, val))
							end
							for tag, val in @content:gmatch("([A-Za-z_]+)=\"([^\"]*)\"") do
								table.insert(query, "(%s == %q)":format(tag, val))
							end

							-- Limit
							table.insert(query, "window")
							table.insert(query, "0:0")

							-- And they pumped...
							list:setPump(10, :(start, stop)
								let filenameSearchStop -- where the filename search window should end

								-- only search if didn't reache filename search
								if results._filenameSearchStart == 0 then
									-- Update limit
									query[#query] = "%s:%s":format(start-1, stop)

									-- Search
									let r, songs = mpc:search(unpack(query))
									if r then
										-- Update widget
										for _, s in ipairs(songs) do
											table.insert(results, songs)
											@insert(songTable(s))
										end

										-- Fill what's left with filename search
										if config.filenameSearch and #results < stop then
											results._filenameSearchOffset = #results
											filenameSearchStop = stop-results._filenameSearchOffset+results._filenameSearchStart
										end
									end
								else
									filenameSearchStop = stop-results._filenameSearchOffset+results._filenameSearchStart
								end

								-- Filename search
								if filenameSearchStop then
									for i=1, #query-2, 1 do
										query[i] = query[i]:gsub("^%(any", "(file")
									end

									-- Loop to fill as much as possible (since we skip tracks with a title)
									repeat
										query[#query] = "%s:%s":format(results._filenameSearchStart, filenameSearchStop)
										results._filenameSearchStart = filenameSearchStop

										let r, songs = mpc:search(unpack(query))
										if r then
											for _, newSong in ipairs(songs) do
												if not newSong.Title then
													table.insert(results, newSong)
													@insert(songTable(newSong))
												end
											end
										end

										filenameSearchStop = stop-results._filenameSearchOffset+results._filenameSearchStart
									until filenameSearchStop == results._filenameSearchStart or #songs == 0
								end
							end)
						end
					end
				},
				{
					type = "fill",

					width = "extend",
					height = "1em",

					fill = "ACS_HLINE"
				},
				{
					id = "list",

					type = "list",
					focused = true,

					width = "extend",
					height = "extend",

					onSelect = :(l)
						-- Tag complete
						if tagCompleting.tag then
							let prompt = @byId("prompt")
							if results[l[1]][tagCompleting.tag]:match(" ") then
								prompt:replace(tagCompleting.start, tagCompleting.stop, tagCompleting.tag.."=\""..results[l[1]][tagCompleting.tag].."\"")
							else
								prompt:replace(tagCompleting.start, tagCompleting.stop, tagCompleting.tag.."="..results[l[1]][tagCompleting.tag])
							end
						-- Song search
						else
							for _, i in ipairs(l) do
								if results[i] then
									mpc:add(results[i].file)
								end
							end
							@byId("playlist"):updateAfter(1)

							let status = @byId("status")
							status:set("Added "..#l.." songs to the current playlist") -- FIXME
						end
					end
				}
			},

			-- Playlist
			{
				{
					id = "playlist",

					type = "list",
					focused = true,

					width = "extend",
					height = "extend",

					updateInterval = 5,

					pump = :(start, stop)
						let r, songs = mpc:playlistinfo("%s:%s":format(start-1, stop))
						if r then
							for i=1, stop-start+1, 1 do
								if songs[i] then
									playlist[start+i-1] = songs[i]
									let item = songTable(songs[i])
									if @content[start+i-1] then
										@replace(start+i-1, item)
									else
										@insert(start+i-1, item)
									end
								else
									playlist[start+i-1] = 0
									@remove(start+i-1)
									start -= 1
								end
							end
						end
					end,

					onUpdate = :()
						@repump()
					end,

					onSelect = :(l)
						if playlist[l[1]] then
							mpc:playid(playlist[l[1]].Id)
						end
					end,

					onControl = :(control)
						if control == "delete" then
							mpc:deleteid(playlist[@selected].Id)
							@remove(@selected)
						elseif control == "clear" then
							mpc:clear()
							@clear()
						end
					end
				}
			}
		},
		-- Status bar
		{
			id = "play-position",
			type = "slider",

			width = "extend",
			height = "1em"
		},
		{
			id = "status",
			type = "label",
			focused = true,

			width = "extend",
			height = "1em",

			content = "No current song",

			updateInterval = 1,

			onUpdate = :()
				let r, s = mpc:currentsong()
				if r then
					if s.file then
						@set(table.concat(songTable(s), " - "))
					else
						@set("daccord v"..VERSION.." - nothing playing")
					end
				end

				let r, s = mpc:status()
				if r then
					state = s.state
					pos = @byId("play-position")
					pos:setHead(state == "play" and "▶️" or "⏸")
					pos:setMax(s.duration)
					pos:set(s.elapsed)
				end
			end,

			onControl = :(control)
				if control == "space" then
					if state == "play" then
						mpc:pause()
					else
						mpc:play()
					end
				end
				@onUpdate()
			end
		},

		onClose = :() @exit() end
}