/**
 * This file is part of Satie music engraver <https://github.com/jnetterf/satie>.
 * Copyright (C) Joshua Netterfield <joshua.ca> 2015 - present.
 * 
 * Satie is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * Satie is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with Satie.  If not, see <http://www.gnu.org/licenses/>.
 */

import {Time} from "musicxml-interfaces";
import {IAny} from "musicxml-interfaces/operations";
import * as invariant from "invariant";
import {times, forEach} from "lodash";

import {Document} from "./document";
import {ModelMetreMutationSpec} from "./engine_createPatch";

import {IFactory} from "./private_factory";
import {IAttributesSnapshot} from "./private_attributesSnapshot";

import checkRests from "./private_metre_checkRests";
import getTSString from "./private_metre_getTSString";
import * as D from "./private_metre_metreDurations";
import {barDivisions} from "./private_chordUtil";

export interface IRestSpec {
    readonly song: string;
    readonly models: (ModelMetreMutationSpec | "killed")[];
    readonly modelsToKill: ModelMetreMutationSpec[][];
}

export function voiceToRestSpec(segment: ModelMetreMutationSpec[], attributes: IAttributesSnapshot, factory: IFactory | Document) {
    const emptyRestSpec: IRestSpec = {song: "", models: [], modelsToKill: []};
    let divsToSuppress = 0;
    let killIdx: number;
    let prevIdx: number = 0;
    let spec = segment.reduce((restSpec: IRestSpec, model: ModelMetreMutationSpec) => {
        let divCount = model.newDivisions || 0;
        let oldDivCount = model.previousDivisions || 0;
        const restsAtEnd = model.previousDivisions > divCount ?
            "r" + times(model.previousDivisions - divCount - 1, () => "_").join("") : "";
        const modelsToKill = restSpec.modelsToKill;

        if (divsToSuppress > 0) {
            const extraSong = divCount > divsToSuppress
                ? "r" + times(divCount - divsToSuppress - 1, () => "_").join("")
                : "";

            divsToSuppress = Math.max(0, divsToSuppress - divCount);
            let newModelsToKill = modelsToKill.slice();
            newModelsToKill[killIdx] = newModelsToKill[killIdx] || [];
            newModelsToKill[killIdx].push(model);
            return {
                song: restSpec.song + extraSong,
                models: restSpec.models.concat(times(extraSong.length, () => "killed") as any),
                modelsToKill: newModelsToKill,
            };
        } else if (divCount === 0) {
            let newModelsToKill = modelsToKill.slice();
            newModelsToKill[prevIdx] = newModelsToKill[prevIdx] || [];
            newModelsToKill[prevIdx].push(model);
            return {
                song: restSpec.song,
                models: restSpec.models,
                modelsToKill: newModelsToKill,
            };
        }

        if (divCount) {
            prevIdx = restSpec.models.length + divCount;
        }

        const models = restSpec.models.concat(times(divCount, () => model)).concat(
            restsAtEnd.split("").map(() => null));

        if (divCount > oldDivCount) {
            killIdx = models.length;
            divsToSuppress = divCount - oldDivCount;
        }

        if (model.rest && divCount) {
            return {
                song: restSpec.song + "r" + times(divCount - 1, () => "_").join("") + restsAtEnd,
                models,
                modelsToKill,
            };
        }
        return {
            song: restSpec.song + times(divCount, () => ".").join("") + restsAtEnd,
            models,
            modelsToKill,
        };
    }, emptyRestSpec);

    invariant(spec.models.length === spec.song.length, "Invalid spec");

    const totalDivisions = barDivisions(attributes);
    const restsToAdd = (totalDivisions - (spec.song.length % totalDivisions)) % totalDivisions;

    return {
        song: restsToAdd
            ? spec.song.concat("r" + times(restsToAdd - 1 , () => "_").join(""))
            : spec.song,
        models: spec.models,
        modelsToKill: spec.modelsToKill,
    };
}

function _cleanupRests(pattern: string, time: Time) {
    // Now, call "checkRests" and apply the 
    const ts = getTSString(time);
    const next = () => checkRests(ts, pattern.length, pattern, {dotsAllowed: true});
    let operationsRemaining = 15;
    for (let status = next(); status !== "GOOD"; status = next()) {
        if (!--operationsRemaining) {
            throw new Error("Rest cleanup timeout");
        }
        // Apply patches until we're in a good state.
        const cmd = status.split(" ");
        invariant(cmd[0] === "apply", "Unexpected instruction '%s'", status);
        invariant(parseInt(cmd[1], 10) === pattern.length,
            "Unexpected length change from %s to %s", cmd[1], pattern.length);
        const patch = cmd[2];
        let nextPattern = "";
        for (let i = 0; i < pattern.length; ++i) {
            if (patch[i] === ".") {
                if (nextPattern[i] !== "." && i && patch[i - 1] !== ".") {
                    nextPattern += "r";
                } else {
                    nextPattern += pattern[i];
                }
            } else {
                nextPattern += patch[i];
            }
        }
        pattern = nextPattern;
    }
    return pattern;
}

export function simplifyRests(
        segment: (ModelMetreMutationSpec)[],
        factory: IFactory | Document,
        attributes: IAttributesSnapshot): IAny[] {
    const originalSpec = voiceToRestSpec(segment, attributes, factory);

    // Correct the rests.
    const totalDivisions = barDivisions(attributes);
    let cleanRestPattern = "";
    for (let i = 0; i < originalSpec.song.length; i += totalDivisions) {
        cleanRestPattern += _cleanupRests(originalSpec.song.slice(i, i + totalDivisions), attributes.time);
    }

    // We now need to make patches to turn originalSpec.song into cleanRestPattern.
    let patches: IAny[] = [];
    let currIdx = -1;
    function killModel(model: ModelMetreMutationSpec) {
        if (!model.newDivisions) {
            ++currIdx;
        } else {
            invariant(segment.indexOf(model) > -1, "Model must be present in segment");
            patches.push({
                ld: model.toSpec(),
                p: [currIdx + 1],
            } as any);
            --currIdx;
        }
    }
    for (let i = 0; i < cleanRestPattern.length; ++i) {
        const originalModel = originalSpec.models[i];
        forEach(originalSpec.modelsToKill[i], killModel);
        if (originalModel && originalModel !== originalSpec.models[i - 1]) {
            ++currIdx;
        }

        if (cleanRestPattern[i] === "r") {
            let cleanRestEnd = i + 1;
            while (cleanRestPattern[cleanRestEnd] === "_") { ++cleanRestEnd; }

            const newDuration = D.makeDuration(
                totalDivisions / parseInt(attributes.time.beats[0], 10) * (4 / attributes.time.beatTypes[0]),
                attributes.time,
                cleanRestEnd - i
            );

            if (originalSpec.song[i] === "r" || originalModel === "killed" || !originalModel) {
                // Check if the length of the rest needs to be changed
                let originalRestEnd = i + 1;
                while (originalSpec.song[originalRestEnd] === "_") { ++originalRestEnd; }

                if (!originalModel || originalModel === "killed") {
                    ++currIdx;
                    newDuration[0].rest = newDuration[0].rest || {};
                    newDuration._class = "Chord";
                    patches.push({
                        li: newDuration,
                        p: [currIdx],
                    });
                } else if (cleanRestEnd !== originalRestEnd) {
                    if (!originalModel.rest) {
                        throw new Error("Expected rest");
                    }
                    const newDots = times(originalModel.newDots, () => ({}));
                    if (JSON.stringify(newDots) !== JSON.stringify(newDuration[0].dots)) {
                        patches.push({
                            od: newDots,
                            oi: newDuration[0].dots,
                            p: [currIdx, "notes", 0, "dots"],
                        });
                    }

                    if (originalModel.newCount !== newDuration[0].noteType.duration) {
                        patches.push({
                            od: originalModel.newCount,
                            oi: newDuration[0].noteType.duration,
                            p: [currIdx, "notes", 0, "noteType", "duration"],
                        });
                    }
                }
            } else {
                // New rest
                ++currIdx;
                newDuration[0].rest = newDuration[0].rest || {};
                newDuration._class = "Chord";
                patches.push({
                    li: newDuration,
                    p: [currIdx],
                });
            }
        } else if (cleanRestPattern[i] === "_" || cleanRestPattern[i] === ".") {
            if (originalSpec.song[i] === "r") {
                const model = originalSpec.models[i];
                if (model === "killed") {
                    throw new Error("Not reached");
                }
                invariant(!!model, "Cannot remove undefined model");
                invariant(segment.indexOf(model) > -1, "Model must be present in segment");
                patches.push({
                    ld: model.toSpec(),
                    p: [currIdx],
                } as any);
                --currIdx;
            }
        }
    }
    forEach(originalSpec.modelsToKill[originalSpec.models.length], killModel);

    return patches;
}