--- 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.
-- * In current playlist:
--   * Enter play currently selected song.
--   * Delete remove selected song from 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.
--
-- 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 = "0.0.3"

-- Configuration
let config = {
	-- MPD server
	host = "localhost",
	port = 6600,
	password = "",
	-- Interface
	songDisplay = { "Track", { "Title", "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)()

-- 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("localhost", 6600)
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
]
table.insert(tags, "file")

-- State
let tagCompleting = {
	tag = nil,
	start = nil,
	stop = nil
}

let results, playlist = {}, {}
let state = "stop"

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

							for _, tag in ipairs(tags) do
								if tag:lower() == sel:lower() then
									let r, songs = mpc:list(tag)
									if r then results = songs end

									for _, s in ipairs(results) do
										if s[tag]:lower():match(val:lower()) then -- filter val
											list:insert{tostring(s[tag])}
										end
									end

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

									break
								end
							end
						-- Song search
						else
							-- 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")
								table.insert(query, word)
							end

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

							-- Search
							let r, songs = mpc:search(unpack(query))
							if r then results = songs end

							-- Update widget
							for _, s in ipairs(results) do
								list:insert(songTable(s))
							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,

					onUpdate = :()
						let r, songs = mpc:playlistinfo()
						if r then playlist = songs end

						for i, s in ipairs(playlist) do
							let item = songTable(s)
							if @content[i] then
								if @content[i] ~= item then
									@remove(i)
									@insert(i, item)
								end
							else
								@insert(i, item)
							end
						end

						while #@content > #playlist do
							@remove()
						end
					end,

					onSelect = :(l)
						if #playlist > 0 then
							mpc:playid(playlist[l[1]].Id)
						end
					end,

					onControl = :(control)
						if control == "delete" then
							mpc:deleteid(playlist[@selected].Id)
							@remove(@selected)
						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
}