"use strict";

const matchValue = require("match-value");

const { either, oneOrMore, EndOfInput, zeroOrMore, optional } = require("./operations");
const Newline = require("./simple/lines/newline").looseCRLF;
const RestOfLine = require("./simple/lines/rest-of-line").looseCRLF;
const Integer = require("./simple/numeric/integer");
const Decimal = require("./simple/numeric/decimal");
const spacedLine = require("./simple/template/spaced-line").looseCRLF;
const format = require("./simple/template/format");

function* MaybeEmptyLines() {
	yield zeroOrMore(Newline);
}

function* Playlist() {
	return yield either([ MediaPlaylist ]);
}

function* FormatHeader() {
	yield spacedLine`#EXTM3U`;
}

function MetaField(namePrefix, valueParser) {
	// NOTE: prefix must include `:` if required, as this varies between fields
	return function* CommentField() {
		yield format`#${namePrefix}`;
		return yield valueParser;
	};
}

function* MetaLine() {
	let line = yield either([
		MetaField("EXTINF:", function* MetaExtraInfo() {
			// TODO: Support additional property fields in EXTINF, figure out what the correct parsing rules actually are for this
			let [ duration, trackTitle ] = yield spacedLine`${Decimal},${optional(RestOfLine)}`;
			return { type: "track", duration, trackTitle };
		}),
		MetaField("PLAYLIST:", function* MetaPlaylistTitle() {
			return { type: "playlist", playlistTitle: yield RestOfLine };
		}),
		MetaField("EXTGRP:", function* MetaGroup() {
			return { type: "groupStart", name: yield RestOfLine };
		})
	]);

	return line;
}

function* MediaPlaylist() {
	let playlistMeta = {};

	yield FormatHeader;
	let [ targetDuration ] = yield spacedLine`#EXT-X-TARGETDURATION:${Integer}`;

	let items = yield oneOrMore(function* () {
		let trackMeta = {};

		let metaComments = yield zeroOrMore(MetaLine);
		let url = yield RestOfLine;
		yield MaybeEmptyLines;

		for (let { type, ... properties } of metaComments) {
			matchValue(type, {
				track: () => {
					Object.assign(trackMeta, properties);
				},
				playlist: () => {
					Object.assign(playlistMeta, properties);
				},
				groupStart: () => {
					// Ignore for now
				}
			});
		}

		return { url, ... trackMeta };
	});

	return { targetDuration, items, ... playlistMeta };
}

module.exports = { Playlist };