import {WHOLE_DURATION_MAGNITUDE, FractionNumber, lcmMulti, gcd, MAIN_SCORE_NAME} from "./utils";
import * as idioms from "./idioms";
import {LILYPOND_VERSION} from "../constants";
import * as measureLayout from "../measureLayout";
import ImplicitType from "../lilyNotation/implicitType";
import pick from "../pick";



interface Location {
	lines: [number, number];
	columns: [number, number];
};


abstract class Locator {
	location: Location;


	constructor (term: BaseTerm) {
		term._location = term._location || {lines: [0, 0], columns: [0, 0]};
		this.location = term._location;
	}

	abstract set (line: number, column: number): void;
};


class OpenLocator extends Locator {
	set (line: number, column: number) {
		this.location.lines[0] = line;
		this.location.columns[0] = column;
	}
};


class CloseLocator extends Locator {
	set (line: number, column: number) {
		this.location.lines[1] = line;
		this.location.columns[1] = column;
	}
};


// concat array of array
const cc = <T>(arrays: T[][]): T[] => [].concat(...arrays);


export class MusicChunk {
	parent: MusicBlock;
	terms: BaseTerm[];


	static join (chunks: MusicChunk[]): BaseTerm[] {
		return cc(chunks.map((chunk, i) => i === chunks.length - 1 ? chunk.terms : [...chunk.terms, new Divide({})]));
	}


	constructor (parent: MusicBlock, terms: BaseTerm[] = []) {
		this.parent = parent;
		this.terms = terms;
	}


	push (term: BaseTerm) {
		this.terms.push(term);
	}


	get size () {
		return this.terms.length;
	}


	get durationMagnitude () {
		return this.terms.reduce((magnitude, term) => magnitude + term.durationMagnitude, 0);
	}
};


interface MusicVoice {
	name?: string;
	body: MusicChunk[];
};


type MusicChunkMap = Map<number, MusicChunk>;


const isNullItem = item => item === "" || item === undefined || item === null || (Array.isArray(item) && !item.length);
const compact = items => cc(items.map((item, index) => isNullItem(item) ? [] : [index > 0 ? "\b" : null, item]));


export const getDurationSubdivider = (term: BaseTerm): number => {
	if (term instanceof MusicEvent) {
		if (!(term instanceof Rest) || !term.isSpacer)
			return term.durationValue.subdivider;
	}
	else if (term instanceof MusicBlock)
		return lcmMulti(...term.body.map(getDurationSubdivider));
	else if (term instanceof MusicChunk)
		return lcmMulti(...term.terms.map(getDurationSubdivider));
	else if ((term instanceof Times) || (term instanceof Tuplet)) {
		const divider = term instanceof Tuplet ? term.divider : term.factor.reciprocal;
		divider.numerator *= getDurationSubdivider(term.music);

		return divider.reduced.numerator;
	}
	else if (term instanceof Repeat)
		return getDurationSubdivider(term.bodyBlock);
	else if (term instanceof Relative)
		return getDurationSubdivider(term.music);
	else if (term.isMusic)
		console.warn("[getDurationSubdivider]	unexpected music term:", term);

	return 1;
};


export const constructMusicFromMeasureLayout = (layout: measureLayout.MeasureLayout, chunks: MusicChunkMap): MusicChunk => {
	const joinMeasureSeq = (seq: measureLayout.MeasureSeq): BaseTerm[] => MusicChunk.join(seq.map(sublayout => constructMusicFromMeasureLayout(sublayout, chunks)));

	if (layout instanceof measureLayout.SingleMLayout) {
		const chunk = chunks.get(layout.measure);
		console.assert(!!chunk, "no chunk for measure:", layout.measure);

		return chunk;
	}
	else if (layout instanceof measureLayout.BlockMLayout) {
		const terms = joinMeasureSeq(layout.seq);

		return new MusicChunk(null, terms);
	}
	else if (layout instanceof measureLayout.VoltaMLayout) {
		const bodyTerms = joinMeasureSeq(layout.body);
		const alternative = layout.alternates && layout.alternates.map(alternate => new MusicBlock({body: joinMeasureSeq(alternate)}));

		const repeat = Repeat.createVolta(layout.times.toString(), new MusicBlock({body: bodyTerms}), alternative);

		return new MusicChunk(null, [repeat]);
	}
	else if (layout instanceof measureLayout.ABAMLayout) {
		const mainList = constructMusicFromMeasureLayout(layout.main, chunks);
		const main = mainList.terms.length === 1 ? mainList.terms[0] : new MusicBlock({body: mainList.terms});
		const restTerms = joinMeasureSeq(layout.rest);

		const block = new MusicBlock({body: [main, ...restTerms]});

		return new MusicChunk(null, [new Variable({name: "lotusRepeatABA"}), block]);
	}
};


export class BaseTerm {
	_location?: Location;
	_measure?: number;
	_tick?: number;
	_previous?: BaseTerm;
	_anchorPitch?: ChordElement;
	_parent?: BaseTerm;

	_headComment: Comment;
	_tailComment: Comment;

	// lotus extensional function modifier
	_functional: string;


	constructor (data: object) {
		//Object.assign(this, data);
		for (const key in data) 
			this[key] = parseRaw(data[key]);
	}


	serialize (): any[] {
		console.warn("unimplemented serilization:", this);
		return [];
	}


	join (): string {
		let words = this.serialize().filter(word => ["string", "number"].includes(typeof word)).map(word => word.toString()) as string[];
		words = words.filter((word, i) => !(i && words[i - 1] === "\n" && word === "\n"));

		let indent = 0;
		const result: string[] = [];

		const pop = char => {
			if (!char || result[result.length - 1] === char) {
				result.pop();
				return true;
			}
		};

		for (const word of words) {
			switch (word) {
			case "\b":
				// remove last space
				pop(" ");
				continue;

			case "\b\n":
				// remove last newline
				while (pop("\t")) {}
				pop("\n");
				continue;

			case "\n":
				// no space at line tail
				pop(" ");
			}

			if (/^(\}|>>)/.test(word))
				pop("\t"); // remove the last tab

			result.push(word);

			if (/\n$/.test(word)) {
				if (/(\{|<<)\n$/.test(word))
					++indent;
				else if (/^(\}|>>)/.test(word)) 
					--indent;

				if (indent)
					result.push(...Array(indent).fill("\t"));
			}
			else
				result.push(" ");
		}

		return result.join("");
	}


	relocate (source: string = this.join()) {
		const words = this.serialize()
			.filter(word => word !== null && word !== undefined
				&& (typeof word !== "string" || (/\S/.test(word) && !word.includes("\b"))))
			.map(word => typeof word === "string" ? word.replace(/\n/g, "") : word);

		const chars = source.split("");
		let line = 1;
		let column = 0;

		let wordIndex = 0;

		for (let i = 0; i < chars.length; ++i) {
			if (wordIndex >= words.length)
				break;

			const char = chars[i];

			switch (char) {
			case "\n":
				++line;
				column = 0;

				break;
			case " ":
			case "\t":
				++column;

				break;
			default:
				let word = words[wordIndex];
				while (word instanceof Locator) {
					word.set(line, column);

					++wordIndex;
					word = words[wordIndex];
				}

				if (wordIndex >= words.length)
					break;

				word = word.toString();
				if (char === word[0]) {
					i += word.length - 1;
					column += word.length;
					++wordIndex;
				}
				else {
					//debugger;
					throw new Error(`unexpected char in source: [${i}]'${char}', expect: ${word}`);
				}
			}
		}
	}


	clone (): this {
		return parseRaw(JSON.parse(JSON.stringify(this)));
	}


	get entries (): BaseTerm[] {
		return null;
	}


	get isMusic (): boolean {
		return false;
	}


	get musicChunks (): MusicChunk[] {
		if (!this.isMusic || !this.entries)
			return [];

		return [].concat(...this.entries.map(entry => entry.musicChunks));
	}


	get measures (): number[] {
		const indices = [this._measure].concat(...(this.entries || []).map(entry => entry.measures)).filter(index => Number.isInteger(index));

		return Array.from(new Set(indices));
	}


	get durationMagnitude (): number {
		return 0;
	}


	get proto () {
		return termProtoMap.get(Object.getPrototypeOf(this));
	}


	get href (): string {
		if (this._location)
			return `${this._location.lines[0]}:${this._location.columns[0]}:${this._location.columns[1]}`;

		return null;
	}


	get measureLayout (): measureLayout.MeasureLayout {
		return null;
	}


	getField (key): any {
		console.assert(!!this.entries, "[BaseTerm.getField] term's entries is null:", this);

		for (const entry of this.entries) {
			const result = entry.query(key);
			if (result)
				return result;
		}
	}


	query (key: string): any {
		void(key);
		//console.warn("term.query not implemented:", this);
	}


	appendAssignment (key, value) {
		console.assert(!!this.entries, "no entries on this term.");

		const assign = this.getField(key);
		if (assign)
			assign.value = value;
		else {
			this.entries.push(parseRaw({
				proto: "Assignment",
				key,
				value: value,
			}));
		}
	}


	findFirst (condition: Function): BaseTerm {
		if (!this.entries)
			return null;

		if (BaseTerm.isPrototypeOf(condition)) {
			const termClass = condition;
			condition = term => term instanceof termClass;
		}
	
		for (const entry of this.entries) {
			if (condition(entry))
				return entry;
	
			if (entry instanceof BaseTerm) {
				const result = entry.findFirst(condition);
				if (result)
					return result;
			}
		}
	}


	findLast (condition: any): BaseTerm {
		if (!this.entries)
			return null;

		if (BaseTerm.isPrototypeOf(condition)) {
			const termClass = condition;
			condition = term => term instanceof termClass;
		}
	
		const reversedEntries = [...this.entries];
		reversedEntries.reverse();

		for (const entry of reversedEntries) {
			if (condition(entry))
				return entry;
	
			if (entry instanceof BaseTerm) {
				const result = entry.findLast(condition);
				if (result)
					return result;
			}
		}
	}


	findAll (condition: any): any[] {
		if (!this.entries)
			return [];

		if (BaseTerm.isPrototypeOf(condition)) {
			const termClass = condition;
			condition = term => term instanceof termClass;
		}

		const result = [];

		for (const entry of this.entries) {
			if (condition(entry))
				result.push(entry);
	
			if (entry instanceof BaseTerm)
				result.push(...entry.findAll(condition));
		}

		return result;
	}


	forEachTerm (termClass, handle) {
		if (!this.entries)
			return;

		for (const entry of this.entries) {
			if (entry instanceof termClass)
				handle(entry);

			if (entry instanceof BaseTerm)
				entry.forEachTerm(termClass, handle);
		}
	}


	forEachTopTerm (termClass, handle) {
		if (!this.entries)
			return;

		for (const entry of this.entries) {
			if (entry instanceof termClass)
				handle(entry);
			else if (entry instanceof BaseTerm)
				entry.forEachTopTerm(termClass, handle);
		}
	}


	toJSON () {
		// exlude meta fields in JSON
		const fields = Object.keys(this).filter(key => !/^_/.test(key));
		const data = pick(this, fields);

		Object.entries(data).forEach(([key, value]) => {
			if (value && typeof value === "object" && !Array.isArray(value) && !(value instanceof BaseTerm))
				data[key] = {proto: "_PLAIN", ...value};
		});

		return {
			proto: this.proto,
			...data,
		};
	}


	static isTerm (x): boolean {
		return typeof x === "object" && x instanceof BaseTerm;
	}


	static optionalSerialize (item: any): any[] {
		//return BaseTerm.isTerm(item) ? (item as BaseTerm).serialize() : (item === undefined ? [] : [item]);
		if (!BaseTerm.isTerm(item))
			return item === undefined ? [] : [item];

		return [
			...BaseTerm.optionalSerialize(item._headComment),
			...item.serialize(),
			...(item._tailComment ? ["\b\n", "\t"] : []),
			...BaseTerm.optionalSerialize(item._tailComment),
		];
	}


	static serializeScheme (item: any): any[] {
		if (typeof item === "boolean")
			item = item ? "#t" : "#f";

		return BaseTerm.optionalSerialize(item);
	}
}


export class Root extends BaseTerm {
	sections: BaseTerm[];


	serialize () {
		return cc(this.sections.map(section => [...BaseTerm.optionalSerialize(section), "\n\n"]));
	}


	get entries (): BaseTerm[] {
		return this.sections;
	}


	getBlock (head): Block {
		return this.entries.find((entry: any) => entry.head === head || (entry.head === "\\" + head)) as Block;
	}


	get includeFiles (): string[] {
		return this.sections.filter(section => section instanceof Include).map((include: Include) => include.filename);
	}


	static priorityForSection (term: BaseTerm): number {
		if (term instanceof Version)
			return 0;

		if (term instanceof Language)
			return 1;

		if (term instanceof Scheme)
			return 3;

		if (term instanceof Assignment)
			return 7;

		if (term instanceof Block) {
			switch (term.head) {
			case "\\header":
				return 2;

			case "\\paper":
				return 4;

			case "\\layout":
				return 5;

			case "\\score":
				return 10;
			}
		}

		return Infinity;
	}


	reorderSections () {
		this.sections.sort((s1, s2) => Root.priorityForSection(s1) - Root.priorityForSection(s2));
	}
};


export class Primitive extends BaseTerm {
	exp: string | number;


	serialize () {
		return [this.exp];
	}
};


export class LiteralString extends BaseTerm {
	exp: string


	static fromString (content: string): LiteralString {
		return new LiteralString({exp: JSON.stringify(content)});
	}


	serialize () {
		return [this.exp];
	}


	toString () {
		try {
			return eval(this.exp);
		}
		catch (err) {
			console.warn("invalid lilypond string exp:", this.exp);
			return this.exp;
		}
	}
};


export class Command extends BaseTerm {
	cmd: string;
	args: any[];


	static createSet (key: string|BaseTerm, value: BaseTerm): Command {
		return new Command({cmd: "set", args: [new Assignment({key, value})]});
	}


	constructor (data) {
		super(data);

		this.args.forEach(term => {
			if (term instanceof MusicBlock || term instanceof Block)
				term._parent = this;
		});
	}


	serialize () {
		return [
			"\\" + this.cmd,
			...[].concat(...this.args.map(BaseTerm.optionalSerialize)),
			["break", "pageBreak", "overrideProperty"].includes(this.cmd) ? "\n" : null,
		];
	}


	get entries () {
		return this.args.filter(arg => arg instanceof BaseTerm);
	}


	get isMusic (): boolean {
		return this.args.some(arg => arg.isMusic);
	}


	get musicChunks (): MusicChunk[] {
		if (this.cmd === "alternative")
			return [].concat(...this.args[0].body.map(term => term.musicChunks));

		return [].concat(...this.entries.map(entry => entry.musicChunks));
	}


	get isRepeatWithAlternative () {
		return this.cmd === "repeat"
			&& this.args[2] instanceof MusicBlock
			&& this.args[3]
			&& this.args[3].cmd === "alternative";
	}


	get durationMagnitude (): number {
		switch (this.cmd) {
		// TODO: refine this in Times
		case "times": {
			const factor = eval(this.args[0]);
			return this.args[1].durationMagnitude * factor;
		}

		// TODO: refine this in Tuplet
		case "tuplet": {
			const factor = 1 / eval(this.args[0]);
			return this.args[this.args.length - 1].durationMagnitude * factor;
		}

		case "afterGrace":
			return this.args[0].durationMagnitude;

		default:
			if (this instanceof Grace)
				return 0;

			return this.args.filter(arg => arg instanceof BaseTerm).reduce((magnitude, term) => magnitude + term.durationMagnitude, 0);
		}
	}


	get measureLayout (): measureLayout.MeasureLayout {
		const args = [...this.args].reverse();
		for (const arg of args) {
			const layout = arg instanceof BaseTerm && arg.measureLayout;
			if (layout)
				return layout;
		}

		return null;
	}


	getAssignmentPair (): {key: any, value: any} {
		if (this.args[0] instanceof Assignment)
			return {key: this.args[0].key, value: this.args[0].value};

		if (this.args[1] instanceof Assignment)
			return {key: this.args[0], value: this.args[1].value};

		if (typeof this.args[0] === "string")
			return {key: this.args[0], value: ""};

		return null;
	}
};


export class Variable extends Command {
	name: string


	constructor ({name}) {
		super({cmd: name, args: []});

		this.name = name;
	}


	toJSON (): any {
		return {
			proto: this.proto,
			name: this.name,
		};
	}


	queryValue (dict: BaseTerm): any {
		const field = dict.getField(this.name);

		return field && field.value;
	}


	get isMusic (): boolean {
		if ([MAIN_SCORE_NAME].includes(this.name))
			return true;

		return false;
	}
};


export class MarkupCommand extends Command {
	toString () {
		const strs = [];
		this.forEachTerm(LiteralString, term => strs.push(term.toString()));

		return strs.join("\n");
	}
};


export class Repeat extends Command {
	static createVolta (times: string, body: MusicBlock, alternative?: MusicBlock[]): Repeat {
		const args: any[] = [
			"volta",
			times,
			body,
		];

		if (alternative) {
			args.push(new Command({
				cmd: "alternative",
				args: [new MusicBlock({body: alternative})],
			}));
		}

		return new Repeat({cmd: "repeat", args});
	}


	get type (): string {
		return this.args[0];
	}


	get times () {
		return Number(this.args[1]);
	}


	get bodyBlock (): MusicBlock {
		return this.args[2];
	}


	get alternativeBlocks (): MusicBlock[] {
		return this.args[3] && this.args[3].args[0].body;
	}


	// this result length equal to times, if not null
	get completeAlternativeBlocks (): MusicBlock[] {
		if (!this.alternativeBlocks || !this.alternativeBlocks.length)
			return null;

		if (this.alternativeBlocks.length >= this.times)
			return this.alternativeBlocks.slice(0, this.times);

		const list = [];
		for (let i = 0; i < this.times - this.alternativeBlocks.length; ++ i)
			list.push(this.alternativeBlocks[0]);
		list.push(...this.alternativeBlocks);

		return list;
	}


	get measureLayout (): measureLayout.MeasureLayout {
		switch (this.type) {
		case "volta": {
			const layout = new measureLayout.VoltaMLayout();
			layout.times = this.times;
			layout.body = this.bodyBlock.measureLayout.seq;
			layout.alternates = this.alternativeBlocks && this.alternativeBlocks.map(block => block.measureLayout.seq);

			return layout;
		}

		case "tremolo":
			return this.bodyBlock.measureLayout;

		default:
			console.warn("unsupported repeat type:", this.type);
		}

		return null;
	}


	// for tremolo
	get sumDuration (): Duration {
		if (this.bodyBlock instanceof MusicEvent)
			return Duration.fromMagnitude(this.args[2].durationMagnitude * this.times);
		else if (this.bodyBlock instanceof MusicBlock) {
			const events = this.bodyBlock.body.filter(term => term instanceof MusicEvent);
			const magnitude = events.reduce((m, event) => m + event.durationMagnitude, 0) * this.times;

			return Duration.fromMagnitude(magnitude);
		}

		return null;
	}


	get singleTremolo (): boolean {
		if (this.type === "tremolo") {
			if (this.bodyBlock instanceof MusicEvent)
				return true;

			if (this.bodyBlock instanceof MusicBlock) {
				const events = this.bodyBlock.body.filter(term => term instanceof MusicEvent);
				return events.length === 1;
			}
		}

		return false;
	}


	// \repeat {body} \alternative {{alter1} {alter2}}		=> body alter1 body alter2
	getUnfoldTerms (): BaseTerm[] {
		const completeAlternativeBlocks = this.completeAlternativeBlocks;

		const list = [];
		for (let i = 0; i < this.times; ++i) {
			list.push(...this.bodyBlock.clone().body);

			if (completeAlternativeBlocks)
				list.push(...completeAlternativeBlocks[i].clone().body);
		}

		return list;
	}


	// \repeat {body} \alternative {{alter1} {alter2}}		=> body alter1 alter2
	getPlainTerms (): BaseTerm[] {
		const list = [...this.bodyBlock.clone().body];

		const alternativeBlocks = this.alternativeBlocks;
		if (alternativeBlocks)
			alternativeBlocks.forEach(block => list.push(...block.clone().body));

		return list;
	}


	// \repeat {body} \alternative {{alter1} {alter2}}		=> body alter2
	getTailPassTerms (): BaseTerm[] {
		const list = [...this.bodyBlock.clone().body];

		const alternativeBlocks = this.alternativeBlocks;
		if (alternativeBlocks)
			list.push(...alternativeBlocks[alternativeBlocks.length - 1].clone().body);

		return list;
	}
};


export class Relative extends Command {
	static makeBlock (block: MusicBlock, {anchor}: {anchor?: ChordElement} = {}): Relative {
		if (!anchor) {
			const chord = block.findFirst(Chord) as Chord;
			anchor = chord && chord.anchorPitch;
		}

		return new Relative({cmd: "relative", args: [anchor, block].filter(term => term)});
	}


	get anchor (): ChordElement {
		if (this.args[0] instanceof ChordElement)
			return this.args[0];

		return null;
	}


	get music (): BaseTerm {
		return this.args[this.args.length - 1];
	}


	get headChord (): Chord {
		return this.findFirst(Chord) as Chord;
	}


	get tailPitch (): ChordElement {
		const tail = this.findLast(Chord) as Chord;

		return tail && tail.absolutePitch;
	}


	// with side effect
	shiftBody (newAnchor?: ChordElement): BaseTerm[] {
		const headChord = this.headChord;
		if (newAnchor && headChord) {
			headChord.shiftAnchor(newAnchor);
			headChord._anchorPitch = null;
			//console.log("shiftAnchor.post:", headChord.join(), headChord);
		}

		const music = this.music;
		if (music instanceof MusicBlock) {
			//music.clearPitchCache();
			return music.body;
		}

		return [music];
	}
}


export class ParallelMusic extends Command {
	get varNames (): string[] {
		return ((this.args[0].exp as SchemePointer).value as SchemeFunction).asList as string[];
	}


	get body (): MusicBlock {
		return this.args[1];
	}


	get voices (): MusicVoice[] {
		const voiceNames = this.varNames;
		const chunks = this.body.musicChunks;
		const measureCount = Math.ceil(chunks.length / voiceNames.length);

		return voiceNames.map((name, index) => ({
			name: name.toString(),
			body: Array(measureCount).fill(null).map((_, m) => chunks[m * voiceNames.length + index]).filter(Boolean),
		}));
	}
};


export class TimeSignature extends Command {
	get value (): FractionNumber {
		return FractionNumber.fromExpression(this.args[0]);
	}
};


export class Partial extends Command {
	get duration (): Duration {
		return this.args[0];
	}
};


export class Times extends Command {
	get factor (): FractionNumber {
		return FractionNumber.fromExpression(this.args[0]);
	}


	get music (): BaseTerm {
		return this.args[this.args.length - 1];
	}
};


export class Tuplet extends Command {
	get divider (): FractionNumber {
		return FractionNumber.fromExpression(this.args[0]);
	}


	get music (): BaseTerm {
		return this.args[this.args.length - 1];
	}
};


export class Grace extends Command {
	get music (): BaseTerm {
		return this.args[this.args.length - 1];
	}
};


export class AfterGrace extends Command {
	get body (): BaseTerm {
		return this.args[0];
	}

	get grace (): BaseTerm {
		return this.args[1];
	}


	get measureLayout (): measureLayout.MeasureLayout {
		return measureLayout.BlockMLayout.fromSeq([
			this.body.measureLayout,
			this.grace.measureLayout,
		]);
	}
};


export class Clef extends Command {
	get clefName (): string {
		return this.args[0].toString();
	}
};


export class KeySignature extends Command {
	get keyPitch (): ChordElement {
		return new ChordElement({pitch: this.args[0], options: {proto: "_PLAIN"}});
	}


	get key (): number {
		const keyPitch = this.keyPitch;
		const minor = this.args[1] === "\\minor";
		const phonetOrder = idioms.FIFTH_PHONETS.indexOf(keyPitch.phonet);

		return phonetOrder + (minor ? -4 : -1) + keyPitch.alterValue * 7;
	}
};


export class OctaveShift extends Command {
	get value (): number {
		return this.args[0].exp;
	}
};


export class Include extends Command {
	static create (filename: string): Include {
		return new Include({cmd: "include", args: [LiteralString.fromString(filename)]});
	}


	get filename (): string {
		return this.args[0].toString();
	}
};


export class Version extends Command {
	static get default (): Version {
		return new Version({cmd: "version", args: [LiteralString.fromString(LILYPOND_VERSION)]});
	}


	get version (): string {
		return this.args[0].toString();
	}
};


export class Language extends Command {
	static make (language: string): Language {
		return new Language({cmd: "language", args: [LiteralString.fromString(language)]});
	}


	get language (): string {
		return this.args[0].toString();
	}
};


export class LyricMode extends Command {
	get block (): MusicBlock {
		return this.args[0];
	}
};


export class ChordMode extends Command {
	get block (): MusicBlock {
		return this.args[0];
	}
};


export class Transposition extends Command {
	get transposition (): number {
		return this.args[0].pitchValue - 60;
	}
};


export class StemDirection extends Command {
	get direction (): string {
		return this.cmd.substr(4);
	}
};


export class Change extends Command {
	get key (): string {
		return this.args[0].toString();
	}


	get value (): string {
		return this.args[1].toString();
	}
};


export class Block extends BaseTerm {
	block: string;
	head: (string|string[]);
	body: BaseTerm[];


	constructor (data) {
		super(data);

		this.body = this.body.map(parseRawEnforce);
	}


	serialize () {
		const heads = Array.isArray(this.head) ? this.head : (this.head ? [this.head] : []);

		return [
			...heads,
			"{\n",
			...cc(this.body.map(section => [...BaseTerm.optionalSerialize(section), "\n"])),
			"}\n",
		];
	}


	get entries () {
		return this.body;
	}


	get isMIDIDedicated () {
		const subBlocks = this.body.filter(term => term instanceof Block) as Block[];

		return subBlocks.some(term => term.head === "\\midi")
			&& !subBlocks.some(term => term.head === "\\layout");
	}


	get assignmentDict (): {[key: string]: string} {
		const assignments = this.body.filter(term => term instanceof Assignment) as Assignment[];

		return assignments.reduce((dict, assignment) => ((dict[assignment.key.toString()] = assignment.value.toString()), dict), {});
	}
};


export class InlineBlock extends Block {
	serialize () {
		return [
			"{",
			...cc(this.body.map(BaseTerm.optionalSerialize)),
			"}",
		];
	}
};


export class MusicBlock extends BaseTerm {
	body: BaseTerm[];


	static fromTerms (terms: BaseTerm[]): MusicBlock {
		const block = new MusicBlock({body: [...terms]});
		block.clarifyHead();

		return block;
	}


	constructor (data) {
		super(data);

		this.body = this.body.map(parseRawEnforce);
	}


	serialize () {
		return [
			"{\n",
			...cc(this.body.map(BaseTerm.optionalSerialize)),
			"\n",
			"}\n",
		];
	}


	clone (): this {
		if (this._parent) {
			const parent = this._parent.clone();
			const block = parent.findFirst(MusicBlock);
			console.assert(block && block._parent === parent, "invalid block-parent relation", parent, block);

			return block as this;
		}

		return BaseTerm.prototype.clone.call(this) as this;
	}


	get entries () {
		return this.body;
	}


	get isMusic (): boolean {
		return true;
	}


	get musicChunks (): MusicChunk[] {
		const chunks = [];
		let currentChunk = new MusicChunk(this);

		const dumpChunk = () => {
			if (currentChunk.size)
				chunks.push(currentChunk);

			currentChunk = new MusicChunk(this);
		};

		for (const term of this.entries) {
			if (term instanceof Repeat) {
				dumpChunk();
				chunks.push(...term.musicChunks);
			}
			else if (term instanceof Divide)
				dumpChunk();
			else
				currentChunk.push(term);
		}

		dumpChunk();

		return chunks;
	}


	// [deprecated]
	// for parallelMusic only
	get voiceNames () {
		const header = this._parent as Command;
		if (header && header.cmd === "parallelMusic") {
			if (header.args[0] instanceof Scheme && header.args[0].exp instanceof SchemePointer && header.args[0].exp.value instanceof SchemeFunction) {
				const voices = header.args[0].exp.value.asList;
				return voices;
			}
		}

		return null;
	}


	// [deprecated]
	get voices (): MusicVoice[] {
		const voiceNames = this.voiceNames;
		if (!voiceNames)
			return [{body: this.musicChunks}];

		const chunks = this.musicChunks;
		const measureCount = Math.ceil(chunks.length / voiceNames.length);

		return voiceNames.map((name, index) => ({
			name: name.toString(),
			body: Array(measureCount).fill(null).map((_, m) => chunks[m * voiceNames.length + index]).filter(chunk => chunk),
		}));
	}


	get durationMagnitude (): number {
		return this.body.reduce((magnitude, term) => magnitude + term.durationMagnitude, 0);
	}


	get isRelative (): boolean {
		return this._parent instanceof Relative;
	}


	get anchorPitch (): ChordElement {
		if (this.isRelative) 
			return (this._parent as Relative).anchor;

		return null;
	}


	get measures (): number[] {
		// make a continouse indices list
		const subterms = this.findAll(term => term.isMusic);
		const subIndices = [].concat(...subterms.map(term => term.measures)).filter(index => Number.isInteger(index));
		if (!subIndices.length)
			return [];

		const min = Math.min(...subIndices);
		const max = Math.max(...subIndices);

		return Array(max + 1 - min).fill(null).map((_, i) => i + min);
	}


	get notes (): Chord[] {
		const notes = this.body.filter(term => term instanceof Chord && !term.isRest) as Chord[];
		this.forEachTopTerm(MusicBlock, block => notes.push(...block.notes));

		return notes;
	}


	get sonicNotes (): Chord[] {
		return this.notes.filter(note => !note.completeTied);
	}


	get noteTicks (): number[] {
		const ticks = this.sonicNotes.map(note => note._tick);
		return Array.from(new Set(ticks)).sort((t1, t2) => t1 - t2);
	}


	get measureTicks (): [number, number][] {
		const tickTable: {[key: string]: number} = {};

		this.body.forEach(term => {
			if (Number.isFinite(term._measure) && Number.isFinite(term._tick)) {
				if (!Number.isFinite(tickTable[term._measure]))
					tickTable[term._measure] = term._tick;
			}
		});

		return Object.entries(tickTable).map(([measure, tick]) => [Number(measure), tick]);
	}


	get measureLayout (): measureLayout.MeasureLayout {
		const seq = this.body.filter(term => term.isMusic).map(term => term.measureLayout).filter(Boolean);

		if (this._functional === "lotusRepeatABA") {
			const [main, ...rest] = seq;

			const layout = new measureLayout.ABAMLayout();
			layout.main = main;
			layout.rest = measureLayout.BlockMLayout.trimSeq(rest);

			return layout;
		}

		return measureLayout.BlockMLayout.fromSeq(seq);
	}


	get measureChunkMap (): MusicChunkMap {
		const map = new Map<number, MusicChunk>();
		this.body.forEach(term => {
			if (Number.isInteger(term._measure) && !(term instanceof Divide)) {
				if (!map.get(term._measure))
					map.set(term._measure, new MusicChunk(this));

				const chunk = map.get(term._measure);
				chunk.terms.push(term);
			}
		});

		return map;
	}


	clearPitchCache () {
		this.forEachTerm(ChordElement, pitch => {
			pitch._absolutePitch = null;
			//pitch._previous = null;
		});
	}


	updateChordAnchors () {
		const chord = this.findFirst(Chord) as Chord;
		if (chord)
			chord._anchorPitch = chord._anchorPitch || this.anchorPitch;

		this.clearPitchCache();
	}


	// deprecated
	updateChordChains () {
		let previous: MusicEvent = null;

		this.updateChordAnchors();

		this.forEachTerm(MusicBlock, block => block.updateChordAnchors());

		this.forEachTerm(MusicEvent, event => {
			event._previous = previous;

			previous = event;
		});
	}


	// with side effect
	spreadRepeatBlocks ({ignoreRepeat = true, keepTailPass = false} = {}): this {
		this.forEachTerm(MusicBlock, block => block.spreadRepeatBlocks());

		this.body = cc(this.body.map(term => {
			if (term instanceof Repeat) {
				if (!ignoreRepeat)
					return term.getUnfoldTerms();
				else if (keepTailPass)
					return term.getTailPassTerms();
				else
					return term.getPlainTerms();
			}
			else
				return [term];
		}));

		return this;
	}


	/*// with side effect
	spreadRelativeBlocks (): this {
		this.forEachTerm(MusicBlock, block => block.spreadRelativeBlocks());

		let anchorPitch = null;

		this.body = cc(this.body.map(term => {
			if (term instanceof Relative) {
				const list = term.shiftBody(anchorPitch);

				anchorPitch = term.tailPitch || anchorPitch;

				return list;
			}
			else
				return [term];
		}));

		return this;
	}*/


	// with side effect
	unfoldDurationMultipliers (): this {
		let timeDenominator = 4;

		const unfoldMultipliers = (term): BaseTerm[] => {
			if (term instanceof TimeSignature)
				timeDenominator = term.value.denominator;

			if (!(term instanceof MusicEvent) || !term.duration || !term.duration.multipliers || !term.duration.multipliers.length)
				return [term];

			const factor = term.duration.multipliers.reduce((factor, multiplier) => factor * Number(multiplier), 1);
			if (!Number.isInteger(factor) || factor <= 0)
				return [term];

			const denominator = Math.max(term.duration.denominator, timeDenominator);

			const event = term.clone() as MusicEvent;
			event.duration.multipliers = [];

			// break duration into multiple rest events
			const restCount = (event.duration.magnitude / WHOLE_DURATION_MAGNITUDE) * (factor - 1) * denominator;
			if (!Number.isInteger(restCount))
				console.warn("Rest count is not integear:", restCount, denominator, event.duration.magnitude, factor);

			const rests = Array(Math.floor(restCount)).fill(null).map(() => 
				new Rest({name: "s", duration: new Duration({number: denominator, dots: 0})}));

			return [event, ...rests];
		};

		this.body = cc(this.body.map(unfoldMultipliers));

		return this;
	}


	/*// pure
	flatten ({spreadRepeats = false} = {}): Relative {
		this.updateChordChains();

		const chord = this.findFirst(Chord) as Chord;
		const anchor = this.anchorPitch || (chord && chord.anchorPitch);

		const block = this.clone();
		if (spreadRepeats)
			block.spreadRepeatBlocks();
		block.spreadRelativeBlocks();
		block.unfoldDurationMultipliers();

		return Relative.makeBlock(block, {anchor: anchor && anchor.clone()});
	}*/


	// with side effect
	expandVariables (dict: BaseTerm): this {
		this.body = this.body.map(term => {
			if (term instanceof Variable) {
				const value = term.queryValue(dict);
				const clonedValue = value instanceof BaseTerm ? value.clone() : value;

				if (clonedValue instanceof BaseTerm) {
					clonedValue.forEachTerm(MusicBlock, block => block.expandVariables(dict));

					if (clonedValue instanceof MusicBlock)
						clonedValue.expandVariables(dict);
				}

				return clonedValue;
			}

			return term;
		});

		return this;
	}


	// with side effects
	redivide ({recursive = true, measureHeads = null}: {recursive?: boolean, measureHeads?: number[]} = {}) {
		if (recursive) {
			this.forEachTerm(MusicBlock, block => {
				if (!block._parent || block._parent.cmd !== "alternative")
					block.redivide({recursive, measureHeads});
			});
		}

		// split rests
		if (measureHeads) {
			this.body = [].concat(...this.body.map(term => {
				if (!(term instanceof Rest) || term.name !== "s" || !Number.isInteger(term._measure))
					return [term];

				const nextHead = measureHeads[term._measure];
				const endTick = term._tick + term.durationMagnitude;
				if (nextHead > 0 && endTick > nextHead) {
					const post_events = term.post_events;

					let startTick = term._tick;
					const rests = [];
					let nextMeasure;
					for (nextMeasure = term._measure; nextMeasure < measureHeads.length && endTick > measureHeads[nextMeasure]; ++nextMeasure) {
						const duration = Duration.fromMagnitude(measureHeads[nextMeasure] - startTick);
						if (!duration) {
							console.warn("invalid middle rest duration, splitting gave up:", measureHeads[nextMeasure] - startTick, term);
							return [term];
						}
	
						const rest = new Rest({name: "s", duration, post_events: []});
						rest._measure = nextMeasure;
						rest._lastMeasure = nextMeasure;
						rests.push(rest);

						console.assert(!!rest.duration, "middle splitted rest duration invalid:", measureHeads[nextMeasure] - startTick);

						startTick = measureHeads[nextMeasure];
					}

					const duration = Duration.fromMagnitude(endTick - startTick);
					if (!duration) {
						console.warn("invalid tail rest duration, splitting gave up:", endTick - startTick, term);
						return [term];
					}

					const rest = new Rest({name: "s", duration, post_events: post_events && [...post_events]});
					rest._measure = nextMeasure;
					rest._lastMeasure = nextMeasure;
					rests.push(rest);

					console.assert(rests.reduce((sum, rest) => sum + rest.durationMagnitude, 0) === term.durationMagnitude, "duration splitting error:", rests, term);
					//if (rests.reduce((sum, rest) => sum + rest.durationMagnitude, 0) !== term.durationMagnitude)
					//	debugger;

					return rests;
				}

				return [term];
			}));
		}

		const isPostTerm = term => !term
			|| term instanceof PostEvent
			|| (term as Primitive).exp === "~"
			|| ["bar", "arpeggio", "glissando", "sustainOff", "sustainOn"].includes((term as Command).cmd)
			;

		const list = this.body.filter(term => !(term instanceof Divide));
		let measure = null;
		for (const term of list) {
			if (Number.isInteger(measure) && isPostTerm(term))
				term._measure = measure;
			else
				measure = term._measure;
		}

		const body: BaseTerm[] = [];
		const measures = new Set();

		list.reverse().forEach(term => {
			if (term instanceof BaseTerm) {
				const newMeasures = term.measures.filter(m => !measures.has(m));
				if (newMeasures.length) {
					const comment = " " + newMeasures[0] + (newMeasures.length > 1 ? "-" + Math.max(...newMeasures) : "");

					if (body.length)
						body.push(new Divide({_tailComment: Comment.createSingle(comment)}));

					newMeasures.forEach(m => measures.add(m));
				}
			}

			body.push(term);
		});

		this.body = body.reverse();
	}


	clarifyHead () {
		const terms = this.body;

		const head = terms.find(term => term.isMusic);
		if (head instanceof MusicEvent) {
			// clarify the first music event content
			const firstEventIndex = terms.indexOf(head);
			if (firstEventIndex >= 0) {
				const firstEvent = terms[firstEventIndex] as MusicEvent;
				//console.log("firstEvent:", firstEvent);
				if (firstEvent._previous) {
					const clarified = firstEvent.clarified;
	
					terms.splice(firstEventIndex, 1, clarified);
					//console.log("terms:", firstEventIndex, terms, clarified);
				}
			}
		}
		else if (head) {
			const block = head.findFirst(MusicBlock) as MusicBlock;
			if (block)
				block.clarifyHead();
			else
				console.warn("[MusicBlock.clarifyHead] unexpected music head:", head);
		}
	}


	absoluteToRelative (): Relative {
		const anchor = this.findFirst(Chord) as Chord;
		if (!anchor)
			return null;

		const anchorPitch = anchor.absolutePitch;
		let pitch = anchorPitch;

		const newBody = this.clone();
		newBody.forEachTerm(Chord, chord => {
			const newPitch = chord.absolutePitch;
			chord.makeRelativeTo(pitch);

			pitch = newPitch;
		});

		return Relative.makeBlock(newBody, {anchor: anchorPitch});
	}
};


export class SimultaneousList extends BaseTerm {
	list: BaseTerm[];


	serialize () {
		return [
			"<<\n",
			...cc(this.list.map(item => [...BaseTerm.optionalSerialize(item), "\n"])),
			">>\n",
		];
	}


	removeStaffGroup () {
		for (let i = 0; i < this.list.length; ++i) {
			const item: any = this.list[i];
			if (item.head instanceof Command && item.head.args && item.head.args[0] === "StaffGroup")
				this.list[i] = item.body;
		}

		this.list.forEach(item => {
			if (item instanceof SimultaneousList)
				item.removeStaffGroup();
		});
	}


	get isMusic (): boolean {
		return true;
	}


	get entries () {
		return this.list;
	}


	get durationMagnitude (): number {
		return Math.max(...this.list.filter(term => term instanceof BaseTerm).map(term => term.durationMagnitude));
	}


	get measureLayout (): measureLayout.MeasureLayout {
		const track = this.list.find(term => term instanceof BaseTerm && term.measureLayout);
		return track && track.measureLayout;
	}
};


export class ContextedMusic extends BaseTerm {
	head: Command;
	body: BaseTerm;
	lyrics?: BaseTerm;


	serialize () {
		return [
			...BaseTerm.optionalSerialize(this.head),
			...BaseTerm.optionalSerialize(this.body),
			...BaseTerm.optionalSerialize(this.lyrics),
		];
	}


	get isMusic (): boolean {
		return true;
	}


	get entries () {
		return [this.head, this.body];
	}


	get type (): string {
		return this.head.args[0];
	}


	get durationMagnitude (): number {
		return this.body.durationMagnitude;
	}


	get withClause (): Command {
		if (this.head.args[2] && this.head.args[2] instanceof Command && this.head.args[2].cmd === "with")
			return this.head.args[2];
	}


	get contextDict (): {[key: string]: string} {
		const withEntries = this.withClause ? Object.entries((this.withClause.args[0] as Block).assignmentDict) : [];
		const entries = withEntries.map(([key, value]) => [`${this.type}.${key}`, value]);

		const pair = this.head.getAssignmentPair();
		if (pair)
			entries.push([pair.key.toString(), pair.value.toString()]);

		return entries.reduce((dict, [key, value]) => ((dict[key] = value), dict), {});
	}


	get list (): BaseTerm[] {
		if (this.body instanceof SimultaneousList)
			return this.body.list;

		return null;
	}


	set list (value: BaseTerm[]) {
		if (this.body instanceof SimultaneousList)
			this.body.list = value;
	}


	get measureLayout (): measureLayout.MeasureLayout {
		return this.body.measureLayout;
	}
};


export class Divide extends BaseTerm {
	serialize () {
		return ["|", "\n"];
	}
}


export class Scheme extends BaseTerm {
	exp: (boolean|BaseTerm);


	serialize () {
		if (BaseTerm.isTerm(this.exp))
			return ["#", "\b", ...(this.exp as BaseTerm).serialize()];
		else if (typeof this.exp === "boolean")
			return ["#", "\b", this.exp ? "#t" : "#f"];
		// TODO: enhance grammar to parse empty scheme list
		//else if (this.exp === null)
		//	return ["#", "\b", "'()"];
		else
			return ["#", "\b", this.exp];
	}


	query (key: string): any {
		if (this.exp instanceof SchemeFunction)
			return this.exp.query(key);
	}


	get entries () {
		if (this.exp instanceof BaseTerm)
			return [this.exp];

		return [];
	}
};


export class SchemeFunction extends BaseTerm {
	func: (string | BaseTerm);
	args: (boolean | string | BaseTerm)[];


	serialize () {
		return [
			"(", "\b",
			...BaseTerm.optionalSerialize(this.func),
			...cc(this.args.map(BaseTerm.serializeScheme)),
			"\b", ")",
		];
	}


	query (key: string): any {
		if (key === this.func) {
			const term = this;

			return {
				get value () {
					return term.args.length === 1 ? term.args[0] : term.args;
				},

				set value (value) {
					if (term.args.length === 1)
						term.args[0] = value as string|BaseTerm;
					else
						term.args = value as (string|BaseTerm)[];
				},
			};
		}
	}


	get asList (): (boolean | string | BaseTerm)[] {
		return [this.func, ...this.args];
	}


	get entries () {
		return this.asList.filter(term => term instanceof BaseTerm) as BaseTerm[];
	}
};


export class SchemePair extends BaseTerm {
	left: any;
	right: any;


	serialize () {
		return [
			"(", "\b",
			...BaseTerm.optionalSerialize(this.left), ".", ...BaseTerm.optionalSerialize(this.right),
			"\b", ")",
		];
	}
};


export class SchemePointer extends BaseTerm {
	value: any;


	serialize () {
		const content = this.value === null ? ["()"] : BaseTerm.optionalSerialize(this.value);

		return [
			"'", "\b", ...content,
		];
	}


	get entries () {
		if (this.value instanceof BaseTerm)
			return [this.value];

		return [];
	}
};


export class SchemeEmbed extends BaseTerm {
	value: Root;


	serialize () {
		return [
			"#{",
			...BaseTerm.optionalSerialize(this.value),
			"#}",
		];
	}
};


export class Assignment extends BaseTerm {
	key: (string|any[]);
	value: any;


	constructor (data) {
		super(data);

		if (this.value instanceof BaseTerm)
			this.value._parent = this;
	}


	serialize () {
		const keys = (Array.isArray(this.key) ? this.key : [this.key]).map(BaseTerm.optionalSerialize);
		const values = (Array.isArray(this.value) ? this.value : [this.value]).map(BaseTerm.optionalSerialize);

		return [
			...cc(keys),
			"=",
			...cc(values),
		];
	}


	get entries () {
		if (this.value instanceof BaseTerm)
			return [this.value];

		return null;
	}


	query (key) {
		if (this.key === key) {
			const term = this;

			return {
				get value () {
					return term.value;
				},

				set value (value) {
					term.value = value;
				},
			};
		}
	}
};


export class MusicEvent extends BaseTerm {
	duration?: Duration;
	post_events?: (string | PostEvent)[];

	declare _previous?: MusicEvent;
	//_anchorPitch?: ChordElement;
	_lastMeasure?: number;


	constructor (data: object) {
		super(data);

		if (this.post_events)
			this.post_events = this.post_events.map(parseRaw);
	}


	getPreviousT (T) {
		if (this._previous instanceof T)
			return this._previous;

		if (this._previous)
			return this._previous.getPreviousT(T);
	}


	get durationValue (): Duration {
		return this.duration || (this._previous ? this._previous.durationValue : Duration.default);
	}


	get durationMagnitude (): number {
		return this.durationValue.magnitude;
	}


	get division (): number {
		return this.durationValue.division;
	}


	get withMultiplier () {
		return this.duration && this.duration.withMultiplier;
	}


	get isMusic (): boolean {
		return true;
	}


	get isTying (): boolean {
		return this.post_events && this.post_events.some(event => event instanceof PostEvent && event.isTying);
	}


	get isStaccato (): boolean {
		return this.post_events && this.post_events.some(event => event instanceof PostEvent && event.isStaccato);
	}


	// to be implement in derived classes
	get isRest (): boolean {
		return null;
	}


	get beamOn (): boolean {
		return this.post_events && this.post_events.includes("[");
	}


	get beamOff (): boolean {
		return this.post_events && this.post_events.includes("]");
	}


	get measures (): number[] {
		if (!Number.isFinite(this._measure) || !Number.isFinite(this._lastMeasure))
			return [];

		return Array(this._lastMeasure + 1 - this._measure).fill(null).map((_, i) => this._measure + i);
	}


	get measureLayout (): measureLayout.MeasureLayout {
		if (this.measures.length > 1)
			return measureLayout.BlockMLayout.fromSeq(this.measures.map(measure => measureLayout.SingleMLayout.from(measure)));

		if (this.measures.length === 1)
			return measureLayout.SingleMLayout.from(this._measure);

		return null;
	}


	get implicitType (): ImplicitType {
		if (this.post_events) {
			for (const event of this.post_events) {
				if (event instanceof PostEvent && event.arg instanceof Command) {
					switch (event.arg.cmd) {
					case "startTrillSpan":
					case "trill":
						return ImplicitType.Trill;

					case "turn":
						return ImplicitType.Turn;

					case "mordent":
						return ImplicitType.Mordent;

					case "prall":
						return ImplicitType.Prall;

					// Arpeggio is not implemented in 'articulate.ly' yet
					case "arpeggio":
						return ImplicitType.Arpeggio;
					}
				}
			}
		}

		return ImplicitType.None;
	}


	get clarified (): MusicEvent {
		const clarified = this instanceof Chord ? this.clarifiedChord : this.clone();
		clarified.duration = this.durationValue && this.durationValue.clone();

		return clarified;
	}
};


export class Chord extends MusicEvent {
	pitches: (ChordElement | Command)[];
	options: {
		exclamations?: string[],
		questions?: string[],
		rest?: string,
		withAngle?: boolean,
	};


	constructor (data) {
		super(data);

		this.connectPitches();
	}


	connectPitches () {
		if (this.basePitch)
			this.basePitch._parent = this;
		for (let i = 1; i < this.pitchElements.length; ++i)
			this.pitchElements[i]._previous = this.pitchElements[i - 1];
	}


	get single (): boolean {
		return this.pitches.length === 1;
	}


	get entries () {
		const list: any[] = [...this.pitches];
		if (Array.isArray(this.post_events))
			list.push(...this.post_events);

		return list;
	}


	serialize () {
		const innerPitches = this.pitches.map(BaseTerm.optionalSerialize);
		const pitches = (this.single && !this.options.withAngle) ? cc(innerPitches) : [
			"<", "\b", ...cc(innerPitches), "\b", ">",
		];

		const {exclamations, questions, rest} = this.options;
		const postfix = cc([...(exclamations || []), ...(questions || []), ...BaseTerm.optionalSerialize(this.duration), rest]
			.filter(item => item)
			.map(item => ["\b", item]),
		).concat(...(this.post_events || []).map(BaseTerm.optionalSerialize));

		return [
			new OpenLocator(this),
			...pitches,
			...postfix,
			new CloseLocator(this),
		];
	}


	get pitchElements (): ChordElement[] {
		return this.pitches.filter(pitch => pitch instanceof ChordElement) as ChordElement[];
	}


	get pitchNames (): string[] {
		return this.pitchElements.map((elem: ChordElement) => elem.pitch.replace(/'|,/g, ""));
	}


	get basePitch (): ChordElement {
		return this.pitchElements[0];
	}


	get absolutePitch (): ChordElement {
		console.assert(!!this.basePitch, "absolutePitch on non pitch:", this.join());
		return this.basePitch.absolutePitch;
	}


	get anchorPitch (): ChordElement {
		if (this._anchorPitch)
			return this._anchorPitch;

		const previous = this.getPreviousT(Chord);
		if (previous)
			return previous.absolutePitch;

		return this.basePitch;
	}


	get isRest (): boolean {
		return !!this.options.rest;
	}


	get completeTied (): boolean {
		return this.pitchElements.filter(pitch => !pitch._tied).length === 0;
	}


	get pitchesValue (): (ChordElement | Command)[] {
		if (this._previous instanceof Chord && this.basePitch.pitch === "q") {
			const pitches = this._previous.pitchesValue.map(pitch => {
				const newPitch = pitch.clone();
				if (newPitch instanceof ChordElement) {
					newPitch._location = this.basePitch._location;
					newPitch._tied = this.basePitch._tied;
					newPitch._parent = (pitch as ChordElement)._parent && this;
					newPitch._previous = (pitch as ChordElement)._previous;
				}

				return newPitch;
			});
			const base = pitches.find(pitch => pitch instanceof ChordElement) as ChordElement;
			if (base)
				base.pitch = base.pitch.replace(/[,']/g, "");

			return pitches;
		}

		return this.pitches;
	}


	get clarifiedChord (): MusicEvent {
		const clarified = this.clone();
		clarified.pitches = this.pitchesValue.filter(pitch => !(pitch as ChordElement)._tied).map(pitch => pitch.clone());
		clarified.connectPitches();

		// replace by rest if all pitches tied
		if (!clarified.pitches.length)
			return new Rest({name: "r", duration: this.duration});

		return clarified;
	}


	shiftAnchor (newAnchor: ChordElement) {
		//console.warn("shiftAnchor:", this.join(), newAnchor.join(), this.absolutePitch.pitchValue, newAnchor.pitchValue, this.anchorPitch.pitchValue);
		const _location = this.basePitch._location;
		const shift = idioms.phonetDifferToShift(this.basePitch.phonetStep - newAnchor.phonetStep);
		const relativeOctave = this.basePitch.absoluteOctave(this.anchorPitch) - newAnchor.octave - shift;
		//console.log("_location:", _location);

		this.pitches[0] = ChordElement.from({
			phonet: this.basePitch.phonet,
			alters: this.basePitch.alters,
			octave: relativeOctave,
		});

		this.pitches[0]._location = _location;
		this.pitches[0]._parent = this;

		this.connectPitches();

		//console.log("shiftAnchor.1:", this.join(), this.absolutePitch.pitchValue, {relativeOctave, shift, "newAnchor.octave": newAnchor.octave});
	}


	makeRelativeTo (from: ChordElement) {
		const _location = this.basePitch._location;

		const octave = this.basePitch.relativeOctave(from);
		this.pitches[0] = ChordElement.from({
			phonet: this.basePitch.phonet,
			alters: this.basePitch.alters,
			octave,
		});

		this.pitches[0]._location = _location;
		this.pitches[0]._parent = this;
	}
};


export class Rest extends MusicEvent {
	name: string;


	serialize () {
		return [
			new OpenLocator(this),
			...compact([
				this.name,
				...BaseTerm.optionalSerialize(this.duration),
			]),
			...cc((this.post_events || []).map(BaseTerm.optionalSerialize)),
			new CloseLocator(this),
		];
	}


	get isSpacer () {
		return this.name === "s";
	}


	get isRest (): boolean {
		return true;
	}
};


export class ChordElement extends BaseTerm {
	pitch: string;
	options: {
		exclamations?: string[],
		questions?: string[],
		post_events?: PostEvent[],
	};

	declare _parent?: Chord;
	declare _previous?: ChordElement;
	_tied?: MusicEvent;
	_transposition?: number;

	// cache for property of absolutePitch
	_absolutePitch?: ChordElement;


	static from ({phonet, alters = "", octave, options = {}}): ChordElement {
		const octaveString = octave ? Array(Math.abs(octave)).fill(octave > 0 ? "'" : ",").join("") : "";
		const pitch = phonet + (alters || "") + octaveString;

		return new ChordElement({pitch, options: {...options, proto: "_PLAIN"}});
	}


	static get default (): ChordElement {
		return ChordElement.from({phonet: "c", octave: 0});
	}


	constructor (data: object) {
		super(data);

		if (this.options.post_events)
			this.options.post_events = this.options.post_events.map(parseRaw);

		if (!this.pitch)
			console.log("null pitch:", this);
	}


	serialize () {
		const {exclamations, questions, post_events} = this.options;
		const postfix = [].concat(...[...(exclamations || []), ...(questions || [])]
			.filter(item => item)
			.map(item => ["\b", item]),
		).concat(...(post_events || []).map(item => ["\b", ...BaseTerm.optionalSerialize(item)]));

		return [
			new OpenLocator(this),
			this.pitch,
			...postfix,
			new CloseLocator(this),
		];
	}


	get octave (): number {
		const positive = (this.pitch.match(/'/g) || []).length;
		const negative = (this.pitch.match(/,/g) || []).length;

		return positive - negative;
	}


	get phonet (): string {
		const ph = this.pitch.substr(0, 1);

		return idioms.PHONETS_ALIAS[ph] || ph;
	}


	get phonetStep (): number {
		return idioms.PHONETS.indexOf(this.phonet);
	}


	get alters (): string {
		const captures = this.pitch.substr(1).match(/^\w+/);
		return captures && captures[0];
	}


	get alteredPhonet (): string {
		const captures = this.pitch.match(/^\w+/);
		return captures && captures[0];
	}


	get anchorPitch (): ChordElement {
		if (this._previous)
			return this._previous.absolutePitch;

		if (this._parent)
			return this._parent.anchorPitch;

		return ChordElement.from({phonet: this.phonet, octave: 0});
	}


	getAbsolutePitch (): ChordElement {
		if (this.phonet === "q")
			return this.anchorPitch;

		if (this.anchorPitch === this)
			return this;

		const octave = this.absoluteOctave(this.anchorPitch);

		return ChordElement.from({phonet: this.phonet, alters: this.alters, octave});
	}


	get absolutePitch (): ChordElement {
		if (!this._absolutePitch)
			this._absolutePitch = this.getAbsolutePitch();

		return this._absolutePitch;
	}


	absoluteOctave (anchor: ChordElement): number {
		if (this.phonet === "q")
			return anchor.octave;

		const phonetDiffer = this.phonetStep - anchor.phonetStep;
		const shift = idioms.phonetDifferToShift(phonetDiffer);

		return anchor.octave + shift + this.octave;
	}


	relativeOctave (from: ChordElement): number {
		if (this.phonet === "q") {
			if (this.anchorPitch)
				return this.anchorPitch.relativeOctave(from);
			else
				return 0;
		}

		const phonetDiffer = this.phonetStep - from.phonetStep;
		const shift = idioms.phonetDifferToShift(phonetDiffer);

		return this.octave - shift - from.octave;
	}


	get alterValue (): number {
		return idioms.ALTER_VALUES[this.alters] || 0;
	}


	get pitchValue (): number {
		const phonetValue = idioms.PHONET_VALUES[this.phonet];
		console.assert(Number.isInteger(phonetValue), "invalid phonet:", this.phonet);
		console.assert(!this.alters || idioms.ALTER_VALUES[this.alters], "invalid alters:", this.alters);

		return 48 + this.octave * 12 + phonetValue + this.alterValue;
	}


	get absolutePitchValue (): number {
		return this.absolutePitch.pitchValue;
	}


	// middle C is zero
	get notePosition (): number {
		const phonet = idioms.PHONETS.indexOf(this.phonet);

		return (this.octave - 1) * 7 + phonet;
	}


	get absoluteNotePosition (): number {
		return this.absolutePitch.notePosition;
	}


	get tiedParent (): ChordElement {
		if (!this._tied || !(this._tied instanceof Chord))
			return null;

		const pitch = this._tied.pitchElements.find(p => p.absolutePitchValue === this.absolutePitchValue);
		if (!pitch)
			return null;

		if (pitch._tied)
			return pitch.tiedParent;

		return pitch;
	}
};


export class Duration extends BaseTerm {
	number: string;
	dots: number;
	multipliers?: string[];


	static _default: Duration;
	static get default (): Duration {
		if (!Duration._default)
			Duration._default = new Duration({number: 4, dots: 0});

		return Duration._default;
	}


	static fromMagnitude (magnitude: number): Duration {
		const MULTI = 1024;
		const MULTI_DURATION_MAGNITUDE = WHOLE_DURATION_MAGNITUDE * MULTI;
		const multiMag = magnitude * MULTI;
		if (!Number.isInteger(multiMag)) {
			console.warn("magnitude must be integer:", magnitude);
			return null;
		}

		const di = gcd(multiMag, MULTI_DURATION_MAGNITUDE);
		const denominator = MULTI_DURATION_MAGNITUDE / di;
		const numerator = multiMag / di;
		if (!Number.isInteger(Math.log2(denominator)))
			return new Duration({number: 1, dots: 0, multipliers: [`${numerator}/${denominator}`]});

		switch (numerator) {
		case 1:
			return new Duration({number: denominator, dots: 0});

		case 3:
			return new Duration({number: denominator / 2, dots: 1});

		case 7:
			return new Duration({number: denominator / 4, dots: 2});

		default:
			return new Duration({number: denominator, dots: 0, multipliers: [numerator.toString()]});
		}
	}


	serialize () {
		const dots = Array(this.dots).fill(".").join("");
		const multipliers = this.multipliers && this.multipliers.map(multiplier => `*${multiplier}`).join("");

		return compact([
			this.number, dots, multipliers,
		]);
	}


	get withMultiplier () {
		return this.multipliers && this.multipliers.length > 0;
	}


	get denominator (): number {
		switch (this.number) {
		case "\\breve":
			return 0.5;

		case "\\longa":
			return 0.25;
		}

		return Number(this.number);
	}


	get division (): number {
		return Math.log2(this.denominator);
	}


	// how many smallest rhythm unit in a whole note
	get subdivider (): number {
		return this.denominator * (2 ** this.dots);
	}


	get magnitude (): number {
		let value = WHOLE_DURATION_MAGNITUDE / this.denominator;

		if (this.dots)
			value *= 2 - 0.5 ** this.dots;

		if (this.multipliers)
			this.multipliers.forEach(multiplier => value *= eval(multiplier));

		return value;
	}
};


interface BriefChordBody {
	pitch: string;
	duration: Duration;
	separator: string;
	items: string[];
};


export class BriefChord extends BaseTerm {
	body: BriefChordBody;
	post_events: any[];


	constructor (data: object) {
		super(data);

		if (this.body)
			this.body.duration = parseRaw(this.body.duration);
	}


	serialize () {
		const {pitch, duration, separator, items} = this.body;

		return [
			...compact(cc([pitch, duration, separator, ...(items || [])].map(BaseTerm.optionalSerialize))),
			...cc((this.post_events || []).map(BaseTerm.optionalSerialize)),
		];
	}


	get isMusic (): boolean {
		return true;
	}


	get durationMagnitude (): number {
		if (this.body.duration)
			return this.body.duration.magnitude;

		return 0;
	}
};


export class NumberUnit extends BaseTerm {
	number: number;
	unit: string;


	serialize () {
		return [this.number, "\b", this.unit];
	}


	set ({number, unit}) {
		this.number = Number(number.toFixed(2));

		if (unit !== undefined)
			this.unit = unit;
	}
}


export class Tempo extends BaseTerm {
	beatsPerMinute?: number;
	unit?: Duration;
	text?: string;


	static fromNoteBpm (note: number, bpm: number): Tempo {
		return new Tempo ({
			unit: new Duration({number: note.toString(), dots: 0}),
			beatsPerMinute: bpm,
		});
	}


	serialize () {
		const assignment = Number.isFinite(this.beatsPerMinute) ? [...BaseTerm.optionalSerialize(this.unit), "=", this.beatsPerMinute] : [];

		return [
			"\\tempo",
			...BaseTerm.optionalSerialize(this.text),
			...assignment,
		];
	}
}


const DIRECTION_CHAR = {
	up: "^",
	down: "_",
	middle: "-",
};


export class PostEvent extends BaseTerm {
	direction: string;
	arg: string | BaseTerm;


	serialize () {
		const dir = DIRECTION_CHAR[this.direction];
		const prefix = dir ? [dir, "\b"] : [];

		return prefix.concat(BaseTerm.optionalSerialize(this.arg));
	}


	get entries () {
		if (this.arg instanceof BaseTerm)
			return [this.arg];

		return null;
	}


	get isTying (): boolean {
		return this.arg === "~";
	}


	get isStaccato (): boolean {
		if (this.arg instanceof Command)
			return ["staccato", "staccatissimo", "portato"].includes(this.arg.cmd);

		if ([".", "!"].includes(this.arg as string))
			return true;

		return false;
	}
};


export class Fingering extends BaseTerm {
	value: number;


	serialize () {
		return [this.value];
	}
};


export class Markup extends BaseTerm {
	head: any[];
	body: (string|BaseTerm);


	serialize () {
		return [
			...cc(this.head.map(BaseTerm.optionalSerialize)),
			...BaseTerm.optionalSerialize(this.body),
		];
	}
};


export class Lyric extends MusicEvent {
	content: string | LiteralString;


	serialize () {
		return [
			...BaseTerm.optionalSerialize(this.content),
			...BaseTerm.optionalSerialize(this.duration),
			...cc((this.post_events || []).map(BaseTerm.optionalSerialize)),
		];
	}
};


export class Comment extends BaseTerm {
	text: string;
	scoped: boolean;


	serialize () {
		return [
			this.text,
			"\n",
		];
	}


	static createSingle (text): Comment {
		return new Comment({text: "%" + text});
	}


	static createScoped (text): Comment {
		console.assert(!/%\}/.test(text), "invalid scoped comment text:", text);

		return new Comment({text: `%{${text}%}`, scoped: true});
	}
};


export class Unexpect extends BaseTerm {
	constructor (data) {
		super(data);

		console.warn("unexpected term", data);
	}
};


export const termDictionary = {
	Root,
	LiteralString,
	Command,
	Variable,
	MarkupCommand,
	Repeat,
	Relative,
	ParallelMusic,
	TimeSignature,
	Partial,
	Times,
	Tuplet,
	Grace,
	AfterGrace,
	Clef,
	KeySignature,
	OctaveShift,
	Include,
	Version,
	Language,
	LyricMode,
	ChordMode,
	Transposition,
	StemDirection,
	Change,
	Block,
	InlineBlock,
	Scheme,
	SchemeFunction,
	SchemePair,
	SchemePointer,
	SchemeEmbed,
	Assignment,
	Duration,
	ChordElement,
	Chord,
	Rest,
	BriefChord,
	NumberUnit,
	MusicBlock,
	SimultaneousList,
	ContextedMusic,
	Divide,
	Tempo,
	PostEvent,
	Fingering,
	Markup,
	Lyric,
	Primitive,
	Comment,
};


const termProtoMap: Map<object, string> = Object.entries(termDictionary)
	.reduce((map, [name, cls]: [string, {prototype: object}]) => (map.set(cls.prototype, name), map), new Map());


const parseRawEnforce = data => {
	switch (typeof data) {
	case "string":
	case "number":
		return new Primitive({exp: data});

	default:
		return parseRaw(data);
	}
};


export const parseRaw = data => {
	if (data instanceof BaseTerm)
		return data;

	if (!data)
		return data;

	switch (typeof data) {
	case "object":
		if (Array.isArray(data))
			return data.map(item => parseRaw(item));

		const {proto, ...fields} = data;
		if (proto) {
			if (proto === "_PLAIN")
				return fields;

			const termClass = termDictionary[proto];
			if (!termClass)
				throw new Error(`Unexpected term class: ${data.proto}`);

			return new termClass(fields);
		}

		return new Unexpect(data); 
	}

	return data;
};