import {romanize} from "../romanNumeral";
import {WHOLE_DURATION_MAGNITUDE, GRACE_DURATION_FACTOR, FUNCTIONAL_VARIABLE_NAME_PATTERN, MAIN_SCORE_NAME, lcmMulti, lcm} from "./utils";
import {parseRaw, getDurationSubdivider, MusicChunk, constructMusicFromMeasureLayout, StemDirection} from "./lilyTerms";
import LogRecorder from "../logRecorder";
import {StaffContext, PitchContextTable} from "../pitchContext";
import * as idioms from "./idioms";
import LilyDocument from "./lilyDocument";
import * as LilyNotation from "../lilyNotation";

import {
	BaseTerm,
	Root, Block, MusicEvent, Repeat, Relative, TimeSignature, Partial, Times, Tuplet, Grace, AfterGrace, Clef, Scheme, Include, Rest,
	KeySignature, OctaveShift, Duration, Chord, MusicBlock, Assignment, Variable, Command, SimultaneousList, ContextedMusic, Primitive, Version,
	ChordMode, LyricMode, ChordElement, Language, PostEvent, Transposition, ParallelMusic,
} from "./lilyTerms";
import {MeasureLayout, BlockMLayout, SingleMLayout} from "../measureLayout";



interface DurationContextStackStatus {
	factor?: {value: number};
	tickBias?: number;
	tremoloDuration?: Duration;
};


type MusicTransformer = (music: BaseTerm, context: TrackContext) => BaseTerm[];
type MusicListener = (music: BaseTerm, context: TrackContext) => void;


type ContextDict = {[key: string]: string};


export enum TremoloType {
	None,
	Single,
	Pitcher,
	Catcher,
};


interface PitchContextTerm {
	staffName: string;
	track?: number;
	//voiceName?: string;

	tick?: number;
	event: MusicEvent;

	clef?: {
		y: number,
		value: number,
	};
	octaveShift?: number;
	key?: number;
	newMeasure?: boolean;
	pitches?: ChordElement[];
	tickBias?: number;
	rest?: boolean;
	tremoloType?: TremoloType;
};


class LilyStaffContext extends StaffContext {
	staffTrack: number;
	notes: LilyNotation.Note[] = [];

	channelMap: number[] = [];


	executeTerm (term: PitchContextTerm) {
		//console.log("executeTerm:", term);

		if (term.newMeasure)
			this.resetAlters();

		if (term.clef)
			this.setClef(term.clef.y, term.clef.value);
		if (Number.isFinite(term.octaveShift))
			this.setOctaveShift(-term.octaveShift);
		if (Number.isFinite(term.key)) {
			this.resetKeyAlters();

			if (term.key) {
				const step = term.key > 0 ? 1 : -1;
				for (let p = step; p / term.key <= 1; p += step) {
					const index = ((step > 0 ? p - 1 : p) + 70) % 7;
					const note = idioms.PHONETS.indexOf(idioms.FIFTH_PHONETS[index]);

					this.keyAlters[note] = (this.keyAlters[note] || 0) + step;
				}
				this.dirty = true;
			}
		}

		if (term.pitches) {
			// accidental alters
			term.pitches.forEach(pitch => {
				const note = pitch.absoluteNotePosition;
				const alter = this.alterOnNote(note);
				if (pitch.alterValue !== alter) {
					this.alters[note] = pitch.alterValue;
					this.dirty = true;
				}
			});

			const event = term.event;
			const contextIndex = this.snapshot({tick: event._tick});

			const implicitType = event.implicitType || (term.tremoloType ? LilyNotation.ImplicitType.Tremolo : LilyNotation.ImplicitType.None);

			this.notes.push(...term.pitches.map((pitch, index) => ({
				track: term.track,
				channel: this.channelMap[term.track] || 0,
				measure: event._measure,
				start: event._tick,
				duration: event.durationMagnitude,
				division: event.division,
				startTick: event._tick,
				endTick: event._tick + event.durationMagnitude,
				pitch: pitch.absolutePitchValue + (pitch._transposition || 0),
				velocity: 127,
				id: pitch.href,
				ids: [pitch.href],
				tied: !!pitch._tied,
				rest: event.isRest,
				afterGrace: !!term.tickBias,
				implicitType,
				staffTrack: this.staffTrack,
				contextIndex,
				// TODO: consider connected arpeggio & downward arpeggio
				chordPosition: {
					index,
					count: term.pitches.length,
				},
			})));

			term.pitches.forEach(pitch => {
				const tiedParent = pitch.tiedParent;
				if (tiedParent) {
					const note = this.notes.find(note => note.id === tiedParent.href);
					if (note)
						note.ids.push(pitch.href);
				}
			});
		}
		else if (term.rest) {
			const event = term.event;
			const contextIndex = this.snapshot({tick: event._tick});

			this.notes.push({
				track: term.track,
				channel: this.channelMap[term.track] || 0,
				measure: event._measure,
				start: event._tick,
				duration: event.durationMagnitude,
				startTick: event._tick,
				endTick: event._tick + event.durationMagnitude,
				pitch: null,
				velocity: 0,
				id: event.href,
				ids: [event.href],
				tied: false,
				rest: true,
				afterGrace: !!term.tickBias,
				implicitType: event.implicitType,
				staffTrack: this.staffTrack,
				contextIndex,
			});
		}
	}


	get pitchContextTable (): PitchContextTable {
		const items = this.track.contexts.map(context => ({
			tick: context.tick,
			endTick: null,
			context,
		}));
		items.forEach((item, i) => {
			item.endTick = (i + 1 < items.length ? items[i + 1].tick : Infinity);
		});

		return new PitchContextTable({items});
	}
};



export class MusicTrack {
	block: MusicBlock;
	anchorPitch: ChordElement;
	contextDict?: ContextDict = null;

	name?: string;
	measureHeads: number[];


	static fromBlockAnchor (block: MusicBlock, anchorPitch: ChordElement): MusicTrack {
		const track = new MusicTrack;

		track.block = block;
		track.anchorPitch = anchorPitch;

		const context = new TrackContext(track);
		context.execute(track.music);

		return track;
	}


	get music (): BaseTerm {
		if (!this.block._parent) {
			this.block._parent = new Relative({cmd: "relative", args: this.anchorPitch ? [this.anchorPitch.clone(), this.block] : [this.block]});
			this.block.updateChordAnchors();
		}

		return this.block._parent;
	}


	get noteDurationSubdivider (): number {
		return getDurationSubdivider(this.block);
	}


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


	get isLyricMode (): boolean {
		return (this.music instanceof LyricMode) || !!this.block.findFirst(term => term instanceof LyricMode);
	}


	get isChordMode (): boolean {
		return (this.music instanceof ChordMode) || !!this.block.findFirst(term => term instanceof ChordMode);
	}


	get measureLayoutCode (): string {
		let code = this.block.measureLayout.code;
		if (/^\[.*\]$/.test(code))
			code = code.match(/\[(.*)\]/)[1];

		return code;
	}


	transform (transformer: MusicTransformer) {
		new TrackContext(this, {transformer}).execute(this.music);
	}


	clarifyDurations () {
		this.transform(term => {
			if (term instanceof MusicEvent) {
				if (!term.duration)
					term.duration = term.durationValue;
			}

			return [term];
		});
	}


	splitLongRests () {
		this.clarifyDurations();

		this.transform((term, context) => {
			if (!(term instanceof MusicEvent) || (!term.withMultiplier && !(term instanceof Rest)))
				return [term];

			const timeDenominator = context.time ? context.time.value.denominator : 4;
			const duration = term.durationValue;
			const denominator = Math.max(duration.denominator, timeDenominator);

			const isR = !(term as Rest).isSpacer;

			if (term.withMultiplier) {
				const factor = duration.multipliers.reduce((factor, multiplier) => factor * Number(multiplier), 1);
				if (!Number.isInteger(factor) || factor <= 0) {
					console.warn("invalid multiplier:", factor, duration.multipliers);
					return [term];
				}

				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];
			}
			else {
				const divider = lcm(duration.subdivider, denominator);
				const restCount = term.durationMagnitude * divider / WHOLE_DURATION_MAGNITUDE;
				console.assert(Number.isInteger(restCount), "rest count is not an integer:", restCount);

				if (isR && restCount > 1)
					console.warn("splitLongRests: 'r' was splitted into", restCount, "parts.", term._location);

				const list = Array(restCount).fill(null).map(() =>
					new Rest({name: isR ? "r" : "s", duration: new Duration({number: divider, dots: 0})}));

				if (term.post_events)
					list[list.length - 1].post_events = term.post_events.map(e => e instanceof BaseTerm ? e.clone() : e);

				return list;
			}
		});
	}


	spreadMusicBlocks (): boolean {
		let has = false;

		this.transform((term) => {
			if (term instanceof MusicBlock) {
				has = true;
				return term.body;
			}
			else
				return [term];
		});

		return has;
	}


	spreadRelativeBlocks (): boolean {
		// check if traverse is nessary
		if (!this.block.findFirst(Relative))
			return false;

		this.transform((term, context) => {
			if (term instanceof Relative) {
				if (term.music instanceof MusicBlock)
					term.music.updateChordAnchors();

				const terms = term.shiftBody(context.pitch);

				// initialize anchor pitch for track head chord
				if (!context.event || !context.event.getPreviousT(Chord)) {
					const tempBlock = new MusicBlock({body: []});
					tempBlock.body = terms;
					const head = tempBlock.findFirst(Chord);
					if (head)
						//head._anchorPitch = this.anchorPitch;
						head._anchorPitch = context.pitch;
				}

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

		return true;
	}


	spreadRepeatBlocks ({ignoreRepeat = true, keepTailPass = false} = {}): boolean {
		// check if traverse is nessary
		if (!this.block.findFirst(Repeat))
			return false;

		this.transform(term => {
			if (term instanceof Repeat) {
				if (!ignoreRepeat)
					return term.getUnfoldTerms();
				else if (keepTailPass)
					return term.getTailPassTerms();
				else
					return term.getPlainTerms();
			}
			else if (term instanceof Variable && term.name === "lotusRepeatABA")
				return [];
			else
				return [term];
		});

		return true;
	}


	flatten ({spreadRepeats = false} = {}) {
		this.splitLongRests();
		this.spreadRelativeBlocks();

		if (spreadRepeats) {
			while (this.spreadRepeatBlocks())
				;

			// expand all music blocks
			while (this.spreadMusicBlocks());
		}
	}


	sliceMeasures (start: number, count: number): MusicTrack {
		this.flatten({spreadRepeats: true});

		const context = new TrackContext(this);
		context.pitch = this.anchorPitch;
		this.block.updateChordAnchors();

		for (const term of this.block.body) {
			if (Number.isInteger(term._measure)) {
				if (term._measure < start)
					context.execute(term);
				else
					break;
			}
		}

		const terms = context.declarations.concat(this.block.body.filter(term => term._measure >= start && term._measure < start + count));
		const newBlock = MusicBlock.fromTerms(terms);

		return MusicTrack.fromBlockAnchor(newBlock, context.pitch);
	}


	redivide () {
		this.block.redivide({measureHeads: this.measureHeads});
	}


	applyMeasureLayout (layout: MeasureLayout, {flatten = true} = {}) {
		//console.log("applyMeasureLayout:", this, layout);

		if (flatten)
			this.flatten({spreadRepeats: true});

		const chunks = this.block.measureChunkMap;

		// validate layout value
		const indices = layout.serialize(LilyNotation.LayoutType.Ordinary);
		indices.forEach(index => {
			if (!chunks.get(index))
				throw new Error(`applyMeasureLayout: measure[${index}] missed in chunk map.`);
		});

		// append zero-duration tail chunk, e.g. \bar "|."
		const tailIndex = Math.max(...indices) + 1;
		const tailChunk = chunks.get(tailIndex);
		if (tailChunk && !tailChunk.durationMagnitude && layout instanceof BlockMLayout)
			//layout.seq.push(SingleMLayout.from(tailIndex));
			layout = BlockMLayout.fromSeq([...layout.seq, SingleMLayout.from(tailIndex)]);

		this.block.body = constructMusicFromMeasureLayout(layout, chunks).terms;

		this.redivide();
	}


	generateStaffTracks (): PitchContextTerm[] {
		const pcTerms: PitchContextTerm[] = [];

		let currentTerm = null;
		const commitTerm = () => {
			if (currentTerm) {
				pcTerms.push(currentTerm);
				currentTerm = null;
			}
		};
		const getCurrentTerm = (staffName: string): PitchContextTerm => {
			if (currentTerm && currentTerm.staffName !== staffName)
				commitTerm();

			if (!currentTerm)
				currentTerm = {staffName};

			return currentTerm;
		};

		let measureIndex = 0;

		const listener = (term: BaseTerm, track: TrackContext) => {
			getCurrentTerm(track.staffName).tick = term._tick;

			if (term._measure !== measureIndex) {
				getCurrentTerm(track.staffName).newMeasure = true;
				commitTerm();

				measureIndex = term._measure;
			}

			if (term instanceof Chord) {
				const pcTerm = getCurrentTerm(track.staffName);
				pcTerm.event = term;
				pcTerm.pitches = term.pitchesValue.filter(pitch => pitch instanceof ChordElement) as ChordElement[];
				pcTerm.pitches = [...pcTerm.pitches].sort((p1, p2) => p1.absolutePitchValue - p2.absolutePitchValue);

				if (track.tickBias)
					pcTerm.tickBias = track.tickBias;

				pcTerm.tremoloType = track.tremoloType;

				commitTerm();
			}
			else if (term instanceof Rest && term.name !== "s") {
				const pcTerm = getCurrentTerm(track.staffName);
				pcTerm.event = term;
				pcTerm.rest = true;

				commitTerm();
			}
			else if (term instanceof Clef) {
				//console.log("clef:", term.clefName);
				switch (term.clefName) {
				case "treble":
					// a treble (G4) on the 2nd staff line
					getCurrentTerm(track.staffName).clef = {y: 1, value: 4};

					break;
				case "bass":
					// a bass (F3) on the 4th staff line
					getCurrentTerm(track.staffName).clef = {y: -1, value: -4};

					break;
				case "tenor":
					// a tenor (C4) on the 3rd staff line
					getCurrentTerm(track.staffName).clef = {y: 0, value: 0};

					break;
				}
			}
			else if (term instanceof KeySignature)
				getCurrentTerm(track.staffName).key = term.key;
			else if (term instanceof OctaveShift)
				getCurrentTerm(track.staffName).octaveShift = term.value;
		};
		new TrackContext(this, {listener}).execute(this.music);

		return pcTerms;
	}
};


export class TrackContext {
	track: MusicTrack;
	transformer?: MusicTransformer;
	listener?: MusicListener;

	stack: DurationContextStackStatus[] = [];

	// declarations
	staff: Command = null;
	clef: Clef = null;
	key: KeySignature = null;
	time: TimeSignature = null;
	octave: OctaveShift = null;

	pitch: ChordElement = null;

	staffName: string = null;
	voiceName: string = null;
	transposition: number = 0;

	// time status
	tick: number = 0;
	tickInMeasure: number = 0;
	measureSpan: number = WHOLE_DURATION_MAGNITUDE;
	measureIndex: number = 1;
	partialDuration: Duration = null;
	measureHeads: number[] = [0];

	event: MusicEvent = null;
	tying: MusicEvent = null;
	staccato: boolean = false;
	inGrace: boolean = false;
	stemDirection: string = null;
	beamOn: boolean = false;

	tremoloType: TremoloType = TremoloType.None;


	constructor (track = new MusicTrack, {transformer = null, listener = null, contextDict = null}:
		{
			transformer?: MusicTransformer,
			listener?: MusicListener,
			contextDict?: ContextDict,
		} = {}) {
		this.track = track;
		this.track.contextDict = contextDict || this.track.contextDict;
		this.track.measureHeads = this.measureHeads;

		this.transformer = transformer;
		this.listener = listener;

		if (this.track.contextDict) {
			this.staffName = this.track.contextDict.Staff;
			this.voiceName = this.track.contextDict.Voice;
		}
		//console.debug("contextDict:", contextDict);
	}


	clone (): this {
		const ctx = {...this};
		Object.setPrototypeOf(ctx, Object.getPrototypeOf(this));

		return ctx;
	}


	mergeParallelClones (contexts: TrackContext[]) {
		const frontContext = contexts.reduce((front, context) => {
			const next = !front || context.tick > front.tick ? context : front;
			next.tying = next.tying || context.tying;
			next.staccato = next.staccato || context.staccato;

			return next;
		}, null);
		const lastContext = contexts[contexts.length - 1];

		this.tick = frontContext.tick;
		this.tickInMeasure = frontContext.tickInMeasure;
		this.measureIndex = frontContext.measureIndex;
		this.partialDuration = frontContext.partialDuration;
		this.tying = frontContext.tying;
		this.staccato = frontContext.staccato;

		this.pitch = lastContext.pitch;
		this.event = lastContext.event;
	}


	get factor (): {value: number} {
		for (let i = this.stack.length - 1; i >= 0; i--) {
			const status = this.stack[i];
			if (status.factor)
				return status.factor;
		}

		return null;
	}


	get tremoloDuration (): Duration {
		for (let i = this.stack.length - 1; i >= 0; i--) {
			const status = this.stack[i];
			if (status.tremoloDuration)
				return status.tremoloDuration;
		}

		return null;
	}


	get tickBias (): number {
		for (let i = this.stack.length - 1; i >= 0; i--) {
			const status = this.stack[i];
			if (status.tickBias)
				return status.tickBias;
		}

		return 0;
	}


	get measureIndexBias (): number {
		if (this.tickInMeasure + this.tickBias < -1)
			return -1;

		return 0;
	}


	get factorValue (): number {
		return this.factor && Number.isFinite(this.factor.value) ? this.factor.value : 1;
	}


	get currentMeasureSpan (): number {
		return Math.round(this.partialDuration ? this.partialDuration.magnitude : this.measureSpan);
	}


	setPitch (pitch: ChordElement) {
		if (!this.track.anchorPitch)
			this.track.anchorPitch = pitch;

		this.pitch = pitch;
	}


	newMeasure (measureSpan: number) {
		console.assert(Number.isFinite(this.measureHeads[this.measureIndex - 1]), "invalid measureHeads at", this.measureIndex - 1, this.measureHeads);
		this.measureHeads[this.measureIndex] = this.measureHeads[this.measureIndex - 1] + measureSpan;

		++this.measureIndex;
		this.tickInMeasure -= measureSpan;

		this.partialDuration = null;
	}


	checkIncompleteMeasure () {
		if (this.tickInMeasure) {
			console.warn("incomplete measure trunated:", this.measureIndex, `${this.tickInMeasure}/${this.currentMeasureSpan}`);
			this.newMeasure(this.tickInMeasure);
		}
	}


	elapse (duration: number) {
		const increment = duration * this.factorValue;

		this.tick += increment;

		this.tickInMeasure += increment;
		while (Math.round(this.tickInMeasure) >= this.currentMeasureSpan)
			this.newMeasure(this.currentMeasureSpan);
	}


	push (status: DurationContextStackStatus) {
		this.stack.push(status);
	}

	
	pop () {
		this.stack.pop();
	}


	processGrace (music: BaseTerm, factor = GRACE_DURATION_FACTOR) {
		// pull back grace notes' ticks
		let events = [music];
		if (!(music instanceof MusicEvent))
			events = music.findAll(MusicEvent);

		let tick = this.tick;
		events.reverse().forEach(event => {
			tick -= Math.round(event.durationMagnitude * factor * this.factorValue);
			event._tick = tick;

			event.findAll(ChordElement).forEach(note => note._tick = tick);
		});
	}


	execute (term: BaseTerm) {
		if (!term) {
			console.warn("null term:", term);
			return;
		}

		if (!(term instanceof BaseTerm))
			return;

		term._measure = this.measureIndex + this.measureIndexBias;
		term._tick = this.tick;

		if (term instanceof MusicEvent) {
			term._previous = this.event;

			if (term instanceof Chord) {
				if (!this.track.anchorPitch)
					this.track.anchorPitch = ChordElement.default.clone();

				this.setPitch(term.absolutePitch);

				term.pitches.forEach(pitch => {
					this.execute(pitch);

					if (pitch instanceof ChordElement)
						pitch._transposition = this.transposition;
				});

				// update tied for ChordElement
				// TODO: staccato trigger condition?
				if (this.tying /*&& !this.staccato*/ && this.event && this.event instanceof Chord) {
					const pitches = new Set(this.event.pitchElements.map(pitch => pitch.absolutePitch.pitch));
					term.pitchElements.forEach(pitch => {
						if (pitches.has(pitch.absolutePitch.pitch))
							pitch._tied = this.tying;
						//else
						//	console.log("missed tie:", `${pitch._location.lines[0]}:${pitch._location.columns[0]}`, pitch.absolutePitch.pitch, pitches);
					});

					if (this.staccato)
						console.warn("tie on staccato note:", term.href);
				}
				//console.log("chord:", term.pitches[0]);
			}

			if (term.beamOn)
				this.beamOn = true;
			else if (term.beamOff)
				this.beamOn = false;

			this.event = term;

			this.elapse(term.durationMagnitude);

			term._lastMeasure = this.tickInMeasure > 0 ? this.measureIndex : this.measureIndex - 1;

			this.tying = null;
			this.staccato = false;

			if (term.isTying)
				this.tying = term;
			if (term.isStaccato)
				this.staccato = true;
		}
		else if (term instanceof ChordElement) {
			// ignore
		}
		else if (term instanceof MusicBlock) {
			if (!this.track.block)
				this.track.block = term;

			term.updateChordAnchors();

			if (this.transformer) {
				const body = [];
				for (const subterm of term.body) {
					const terms = this.transformer(subterm, this);
					terms.forEach(t => this.execute(t));

					body.push(...terms);
				}
	
				term.body = body;
			}
			else {
				for (const subterm of term.body)
					this.execute(subterm);
			}
		}
		else if (term instanceof Command && term.cmd === "numericTimeSignature")
			this.execute(term.args[0]);
		else if (term instanceof TimeSignature) {
			this.time = term;
			this.measureSpan = term.value.value * WHOLE_DURATION_MAGNITUDE;
		}
		else if (term instanceof Partial)
			this.partialDuration = term.duration;
		else if (term instanceof Repeat) {
			switch (term.type) {
			case "volta":
				this.checkIncompleteMeasure();

				this.execute(term.bodyBlock);

				this.checkIncompleteMeasure();

				if (term.alternativeBlocks) {
					for (const block of term.alternativeBlocks) {
						this.execute(block);

						this.checkIncompleteMeasure();
					}
				}

				break;
			case "tremolo":
				this.push({factor: {value: term.times}, tremoloDuration: term.sumDuration});
				this.tremoloType = term.singleTremolo ? TremoloType.Single : TremoloType.Pitcher;
				this.execute(term.bodyBlock);
				this.tremoloType = TremoloType.None;
				this.pop();

				break;
			default:
				console.warn("unsupported repeat type:", term.type);
			}
		}
		else if (term instanceof Relative) {
			if (term.anchor)
				this.setPitch(term.anchor);

			this.execute(term.music);
		}
		else if (term instanceof LyricMode) {
			// ignore lyric mode
		}
		else if (term instanceof Command && term.cmd === "lyricsto") {
			// ignore lyric mode
		}
		else if (term instanceof ChordMode) {
			// ignore chord mode
		}
		else if (term instanceof Transposition)
			this.transposition = term.transposition;
		else if (term instanceof Times) {
			this.push({factor: term.factor});
			this.execute(term.music);
			this.pop();
		}
		else if (term instanceof Tuplet) {
			this.push({factor: term.divider.reciprocal});
			this.execute(term.music);
			this.pop();
		}
		else if (term instanceof Grace) {
			this.inGrace = true;
			this.push({factor: {value: 0}});
			this.execute(term.music);
			this.pop();
			this.inGrace = false;

			this.processGrace(term.music);
		}
		else if (term instanceof AfterGrace) {
			this.execute(term.body);

			this.inGrace = true;
			this.push({factor: {value: 0}, tickBias: -term.body.durationMagnitude});
			this.execute(term.grace);
			this.pop();
			this.inGrace = false;

			this.processGrace(term.grace);
		}
		else if (term instanceof Clef)
			this.clef = term;
		else if (term instanceof KeySignature)
			this.key = term;
		else if (term instanceof OctaveShift)
			this.octave = term;
		else if (term instanceof Command && term.cmd === "change") {
			const pair = term.getAssignmentPair();
			if (pair) {
				switch (pair.key) {
				case "Staff":
					this.staffName = pair.value.toString();
					this.staff = term;

					break;
				case "Voice":
					this.voiceName = pair.value.toString();

					break;
				}
			}
		}
		else if (term instanceof Primitive) {
			if (term.exp === "~")
				this.tying = this.event;
		}
		else if (term instanceof PostEvent) {
			if (term.isStaccato)
				this.staccato = true;
		}
		else if (term instanceof SimultaneousList) {
			const contexts: TrackContext[] = [];
			let lastContext = this;
			for (const subterm of term.list) {
				const context = this.clone();
				context.pitch = lastContext.pitch;
				context.event = lastContext.event;

				context.execute(subterm);
				contexts.push(context);
				lastContext = context;
			}

			this.mergeParallelClones(contexts);
		}
		else if (term instanceof ContextedMusic) {
			// TODO: process contextDict

			this.execute(term.body);
		}
		else if (term instanceof StemDirection)
			this.stemDirection = term.direction;
		else {
			if (term.isMusic)
				console.warn("[TrackContext]	unexpected music term:", term);
		}

		if (this.listener)
			this.listener(term, this);

		if (term instanceof MusicEvent && this.tremoloType === TremoloType.Pitcher)
			this.tremoloType = TremoloType.Catcher;
	}


	get declarations (): BaseTerm[] {
		return [this.staff, this.clef, this.key, this.time, this.octave].filter(term => term);
	}
};


class MusicPerformance {
	staffNames: string[] = [];
	musicTracks: MusicTrack[] = [];


	get mainTrack (): MusicTrack {
		// find the longest track
		const trackPrior = (track: MusicTrack, index: number): number => -track.block.durationMagnitude + index * 1e-3;
		const priorTracks = this.musicTracks
			.filter(track => track.block._parent && !track.isChordMode && !track.isLyricMode)
			.map((track, index) => ({track, index}))
			.sort((t1, t2) => trackPrior(t1.track, t1.index) - trackPrior(t2.track, t2.index));

		return priorTracks[0] ? priorTracks[0].track : null;
	}


	get trackNames (): string[] {
		return this.musicTracks.map(track => `${track.contextDict.Staff}:${track.contextDict.Voice}`);
	}


	get trackContextDicts (): ContextDict[] {
		const dicts = this.musicTracks.map(track => track.contextDict);
		dicts.unshift(undefined);	// zero placeholder for track index from 1 in notation & SheetDocument

		return dicts;
	}


	get trackInstruments (): string[] {
		return this.musicTracks.map(track => {
			const instrumentKey = Object.keys(track.contextDict).find(key => /\.instrumentName/.test(key));
			if (instrumentKey)
				return track.contextDict[instrumentKey];

			return null;
		});
	}


	get instrumentList (): string[] {
		return Array.from(new Set(this.trackInstruments));
	}


	get channelMap (): number[] {
		const instrumentList = this.instrumentList;
		const channels = this.trackInstruments.map(instrument => instrumentList.indexOf(instrument) + 1);
		channels.unshift(0);

		return channels;
	}


	get measureLayoutCode (): string {
		return this.mainTrack && this.mainTrack.measureLayoutCode;
	}


	applyMeasureLayout (layout: MeasureLayout) {
		this.musicTracks.forEach(track => track.applyMeasureLayout(layout));
	}


	getNotation ({logger = new LogRecorder()} = {}): LilyNotation.Notation {
		const pcTerms: PitchContextTerm[] = [].concat(...this.musicTracks.map((track, i) =>
			track.generateStaffTracks().map(term => ({track: i + 1, ...term}))));
		//console.log("pcTerms:", pcTerms);

		const termsToContexts = (staffTerms: PitchContextTerm[], trackIndex: number): LilyStaffContext => {
			staffTerms.forEach(term => {
				if (term.event)
					term.tick = term.event._tick;
			});
			staffTerms.sort((t1, t2) => t1.tick - t2.tick);

			const context = new LilyStaffContext({logger});
			context.staffTrack = trackIndex;
			context.channelMap = this.channelMap;

			logger.append("staffTerms", staffTerms);
			//console.debug("staffTerms:", staffTerms);
			staffTerms.forEach(term => context.executeTerm(term));

			return context;
		};

		const staffContexts: LilyStaffContext[] = [];
		if (this.staffNames.length) {
			this.staffNames.forEach((name, trackIndex) => {
				const staffTerms = pcTerms.filter(term => term.staffName === name);
				staffContexts.push(termsToContexts(staffTerms, trackIndex));
			});
		}
		else
			staffContexts.push(termsToContexts(pcTerms, 0));

		const notes = []
			.concat(...staffContexts.map(context => context.notes))
			.sort((n1, n2) => n1.startTick - n2.startTick);

		// append duration of tied notes to root note
		const pitchMap = {};
		notes.forEach(note => {
			if (note.tied) {
				const root = pitchMap[note.pitch];
				if (root) {
					root.endTick = Math.max(root.endTick, note.endTick);
					root.duration = root.endTick - root.startTick;
				}
			}
			else
				pitchMap[note.pitch] = note;
		});

		const pitchContextGroup = staffContexts.map(context => context.pitchContextTable);

		const mainTrack = this.mainTrack;

		const measureHeads = mainTrack && mainTrack.measureHeads;
		const measureLayout = mainTrack && mainTrack.block.measureLayout;

		return LilyNotation.Notation.fromAbsoluteNotes(notes, measureHeads, {pitchContextGroup, measureLayout, trackNames: this.trackNames});
	}


	getNoteDurationSubdivider (): number {
		const subdivider = lcmMulti(...this.musicTracks.map(track => track.noteDurationSubdivider));

		return subdivider;
	}


	sliceMeasures (start: number, count: number) {
		this.musicTracks = this.musicTracks.map(track => {
			const newTrack = track.sliceMeasures(start, count);
			newTrack.name = track.name;	// inherit name

			return newTrack;
		});
	}
};



export default class LilyInterpreter {
	variableTable: Map<string, BaseTerm> = new Map();

	// temporary status
	musicTracks: MusicTrack[] = [];
	staffNames: string[] = [];
	musicTrackIndex: number = 0;
	musicPerformance: MusicPerformance;
	mainPerformance: MusicPerformance;

	version: Version = null;
	language: Language = null;
	header: Block = null;
	includeFiles: Set<string> = new Set;
	statements: BaseTerm[] = [];
	paper: Block = null;
	layout: Block = null;
	scores: Block[] = [];

	layoutMusic: MusicPerformance;
	midiMusic: MusicPerformance;

	functionalCommand?: Variable;

	reservedVariables: Set<string> = new Set();


	static trackName (index: number): string {
		return `Voice_${romanize(index)}`;
	};


	/*eval (term: BaseTerm): BaseTerm {
		return this.execute(term.clone());
	}*/


	get mainScore (): BaseTerm {
		return this.variableTable.get(MAIN_SCORE_NAME);
	};


	interpretMusic (music: BaseTerm, contextDict: ContextDict): Variable {
		//console.log("interpretMusic:", music);
		const context = new TrackContext(undefined, {contextDict});
		//context.execute(music.clone());
		context.execute(music);

		context.track.spreadRelativeBlocks();
		this.musicTracks.push(context.track);

		const varName = LilyInterpreter.trackName(++this.musicTrackIndex);

		context.track.name = varName;

		return new Variable({name: varName});
	}


	interpretDocument (doc: LilyDocument): this {
		if (doc.reservedVariables)
			this.appendReservedVariables(doc.reservedVariables);

		this.execute(doc.root);

		return this;
	}


	createMusicPerformance () {
		if (this.musicTracks.length) {
			if (!this.musicPerformance)
				this.musicPerformance = new MusicPerformance();

			this.staffNames.forEach(name => {
				if (!this.musicPerformance.staffNames.some(sn => sn === name))
					this.musicPerformance.staffNames.push(name);
				else if (!name)
					console.warn("[LilyInterpreter]	Multiple empty context staff name may cause error pitchContextTable:", this.musicPerformance.staffNames);
			});
			this.musicTracks.forEach(track => this.musicPerformance.musicTracks.push(track));

			this.staffNames = [];
			this.musicTracks = [];
		}
	}


	execute (term: BaseTerm, {execMusic = false, contextDict = {}}: {execMusic?: boolean, contextDict?: ContextDict} = {}): BaseTerm {
		if (!term)
			return term;

		if (this.functionalCommand && term.isMusic) {
			term._functional = this.functionalCommand.name;
			this.functionalCommand = null;
		}

		if (term instanceof Root) {
			for (const section of term.sections) {
				const sec = this.execute(section, {execMusic: true});
				if (sec instanceof Version)
					this.version = sec;
				else if (sec instanceof Language)
					this.language = sec;
				else if (sec instanceof Scheme)
					this.statements.push(sec);
				else if (sec instanceof Block) {
					switch (sec.head) {
					case "\\header":
						this.header = sec;

						break;
					case "\\paper":
						this.paper = sec;

						break;
					case "\\layout":
						this.layout = sec;

						break;
					case "\\score":
						this.scores.push(sec);

						break;
					}
				}
			}

			this.createMusicPerformance();

			if (this.musicPerformance) {
				this.layoutMusic = this.musicPerformance;
				this.midiMusic = this.musicPerformance;

				this.musicPerformance = null;
			}
		}
		else if (term instanceof Assignment) {
			if (term.key) {
				const name = term.key as string;
				const isMainScore = name === MAIN_SCORE_NAME;
				if (isMainScore)
					this.musicPerformance = null;

				const value = this.execute(term.value, {execMusic: isMainScore});

				this.variableTable.set(name, value);

				if (isMainScore)
					this.mainPerformance = this.musicPerformance;
			}
		}
		else if (term instanceof Block) {
			switch (term.head) {
			case "\\score":
				const body = term.body.map(subterm => this.execute(subterm, {execMusic: true}));

				this.musicPerformance = null;

				return new Block({
					block: term.block,
					head: term.head,
					body,
				});
			case "\\layout":
				this.layoutMusic = this.musicPerformance;

				break;
			case "\\midi":
				this.midiMusic = this.musicPerformance;

				break;
			}
		}
		else if (term instanceof Variable) {
			const result = this.variableTable.get(term.name);
			if (!result) {
				if (FUNCTIONAL_VARIABLE_NAME_PATTERN.test(term.name)) {
					this.functionalCommand = term;

					return term;
				}
				else if (this.reservedVariables.has(term.name)) {
					// ignore reserved variables
				}
				else
					console.warn("uninitialized variable is referred:", term);
			}

			if (term.name === MAIN_SCORE_NAME) {
				this.musicPerformance = this.mainPerformance;

				return term;
			}

			return this.execute(result, {execMusic, contextDict});
		}
		else if (term instanceof MusicBlock) {
			const result = new MusicBlock({
				_parent: term._parent,
				_functional: term._functional,
				body: term.body.map(subterm => this.execute(subterm)).filter(Boolean),
			});

			this.functionalCommand = null;

			if (execMusic) {
				const variable = this.interpretMusic(result, contextDict);
				return new MusicBlock({body: [variable]});
			}

			return result;
		}
		else if (term instanceof SimultaneousList) {
			const list = term.list.map(subterm => this.execute(subterm, {execMusic, contextDict})).filter(term => term);
			this.createMusicPerformance();

			return new SimultaneousList({list});
		}
		else if (term instanceof ContextedMusic) {
			if (term.contextDict && typeof term.contextDict.Staff === "string")
				this.staffNames.push(term.contextDict.Staff);

			return new ContextedMusic({
				head: this.execute(term.head),
				lyrics: this.execute(term.lyrics),
				body: this.execute(term.body, {execMusic, contextDict: {...contextDict, ...term.contextDict}}),
			});
		}
		else if (term instanceof ParallelMusic) {
			term.voices.forEach(voice => {
				const block = new MusicBlock({
					body: MusicChunk.join(voice.body),
				});

				const value = this.execute(block);
				this.variableTable.set(voice.name, value);
			});
		}
		else if (term instanceof Include)
			this.includeFiles.add(term.filename);
		else if (term instanceof Command) {
			switch (term.cmd) {
			case "set":
				if (term.args[0] instanceof Assignment) {
					const assign = term.args[0];
					contextDict[assign.key.toString()] = assign.value.toString();
				}

				break;
			}

			return parseRaw({proto: term.proto, cmd: term.cmd, args: term.args.map(arg => this.execute(arg, {execMusic, contextDict}))});
		}

		return term;
	}


	updateTrackAssignments () {
		if (this.layoutMusic)
			this.layoutMusic.musicTracks.forEach(track => this.variableTable.set(track.name, track.music));

		if (this.midiMusic && this.midiMusic !== this.layoutMusic)
			this.midiMusic.musicTracks.forEach(track => this.variableTable.set(track.name, track.music));

		// update main score variable order in table
		const mainScore = this.mainScore;
		if (mainScore) {
			this.variableTable.delete(MAIN_SCORE_NAME);
			this.variableTable.set(MAIN_SCORE_NAME, mainScore);
		}
	}


	toDocument (): LilyDocument {
		this.updateTrackAssignments();

		const variables = [].concat(...[this.paper, this.layout, ...this.scores, this.mainScore].filter(block => block).map(block => block.findAll(Variable).map(variable => variable.name)));
		const variablesUnique = Array.from(new Set(variables));

		// sort variables by order in variable table
		const vars = [...this.variableTable.keys()];
		variablesUnique.sort((v1, v2) => vars.indexOf(v1) - vars.indexOf(v2));

		const assignments = variablesUnique.filter(name => this.variableTable.get(name)).map(name => new Assignment({key: name, value: this.variableTable.get(name)}));
		const includes = Array.from(this.includeFiles).map(filename => Include.create(filename));

		const root = new Root({sections: [
			this.version,
			this.language,
			this.header,
			...includes,
			...this.statements,
			this.paper,
			this.layout,
			...assignments,
			...this.scores,
		].filter(section => section)});

		const doc = new LilyDocument(root);
		doc.reservedVariables = this.reservedVariables;

		return doc;
	}


	sliceMeasures (start: number, count: number) {
		if (this.layoutMusic)
			this.layoutMusic.sliceMeasures(start, count);

		if (this.midiMusic && this.midiMusic !== this.layoutMusic)
			this.midiMusic.sliceMeasures(start, count);
	}


	addIncludeFile (filename: string) {
		this.includeFiles.add(filename);
	}


	appendReservedVariables (names: Iterable<string>) {
		for (const name of names)
			this.reservedVariables.add(name);
	}


	getNotation ({logger = new LogRecorder()} = {}): LilyNotation.Notation {
		if (this.midiMusic)
			return this.midiMusic.getNotation({logger});

		return null;
	}
};