#!/usr/bin/env node

// requirements
const os = require('os');
const path = require('path');
const fs = require('fs');
const fse = require('fs-extra');
const async = require('async');
const commander = require('commander');
const recursive = require('recursive-readdir');
const metadata = require('musicmetadata');
const progress = require('progress');
const app = require('./package.json');

// generate timestamp
const start = process.hrtime();

printLogo();

// general options
commander
    .version(app.version)
    .usage('[options] <command>')
    .option('-c, --concurrency <n>', 'specify concurrency level', os.cpus().length);

// conversion mode
commander
    .command('convert <input> <output>')
    .description('convert .flac to .mp3 files')
    .option('-b, --bitrate <n>', 'specify conversion bitrate', 320)
    .action(function (input, output, options) {
        console.log('--- CONVERT MODE ---');
        console.log('input: ' + input);
        console.log('output: ' + output);
        console.log('bitrate: ' + commander.options.bitrate);
        console.log('conc: ' + commander.concurrency);
    });

// sort mode
commander
    .command('sort <input> <output>')
    .description('sort audio files by tags')
    .option('-f, --format <type>', 'specify audio format (\'flac\', \'mp3\')', 'flac')
    .action(sort);

// parse command line arguments
commander.parse(process.argv);

// sort files
function sort(input, output, options) {
    const concurrency = commander.concurrency;
    async.waterfall([
        function (asyncCallback) {
            recursive(input, [ignoreFilter], asyncCallback);
        },
        function (files, asyncCallback) {
            console.log(files.length + ' \'' + options.format + '\' files found');
            // display progressbar
            const bar = createProgressBar(files.length);
            // handle each file
            async.eachLimit(files, concurrency, function (file, eachCallback) {
                processFile(output, file, function (err) {
                    bar.tick();
                    if (err) {
                        return eachCallback(err);
                    }
                    eachCallback();
                });
            }, function (err) {
                if (err) {
                    return asyncCallback(err);
                }
                asyncCallback();
            });
        }
    ], function (err, result) {
        exit(err);
    });

    function ignoreFilter(file, stats) {
        return !stats.isDirectory() && path.extname(file).indexOf(options.format) == -1;
    }
}

// move file to location defined by its metadata
function processFile(output, sourceFile, callback) {
    async.waterfall([
        function (asyncCallback) {
            extractMetadata(sourceFile, asyncCallback)
        },
        function (sourceFile, metadata, asyncCallback) {
            pathFromMetadata(sourceFile, output, metadata, asyncCallback);
        },
        function (targetFile, asyncCallback) {
            moveFile(sourceFile, targetFile, asyncCallback);
        }
    ], function (err, results) {
        if (err) {
            return callback(err);
        }
        callback(null, results);
    });
}

// extract metadata for further processing
function extractMetadata(sourceFile, callback) {
    const stream = fs.createReadStream(sourceFile);
    metadata(stream, function (err, metadata) {
        if (err) {
            return callback(err);
        }
        stream.close();
        callback(null, sourceFile, metadata)
    });
}

// create path for target file
function pathFromMetadata(file, output, metadata, callback) {
    // define directory
    let filePath = path.normalize(output);
    if (metadata.albumartist && metadata.albumartist.length > 0) {
        let tmp;
        const artistCount = metadata.albumartist.length;
        for (let counter = 0; counter < artistCount; counter++) {
            if (counter > 0) {
                tmp += ' - ' + metadata.albumartist[counter];
            } else {
                tmp = metadata.albumartist[counter];
            }
        }
        filePath = path.join(filePath, tmp);
    } else {
        filePath = path.join(filePath, metadata.artist[0]);
    }
    if (metadata.album) {
        filePath = path.join(filePath, metadata.album);
    }
    // define filename
    let fileName = '';
    if (metadata.disk.no) {
        fileName += frontFill(metadata.disk.no, '0', 2);
    }
    if (metadata.track.no) {
        if (fileName) {
            fileName += '-' + frontFill(metadata.track.no, '0', 2) + ' ';
        } else {
            fileName += frontFill(metadata.track.no, '0', 2) + ' ';
        }
    }
    if (metadata.artist) {
        fileName += metadata.artist[0] + ' - ';
    }
    if (metadata.title) {
        fileName += metadata.title;
    }
    // append extension
    fileName += path.extname(file);
    // join directory and name
    callback(null, path.join(filePath, fileName));
}

// create a ascii progressbar
function createProgressBar(total) {
    return new progress(':bar | progress: :current/:total (:percent) | elapsed: :elapseds | eta: :etas', {
        total: total,
        width: 32
    });
}

// create target directory and move the file
function moveFile(source, target, callback) {
    async.series([
        function (asyncCallback) {
            fse.mkdirs(path.dirname(target), asyncCallback);
        },
        function (asyncCallback) {
            fse.move(source, target, asyncCallback);
        }
    ], function (err, results) {
        if (err) {
            return callback(err);
        }
        callback();
    });
}

// fill a string beginning from the front
function frontFill(string, fill, length) {
    while (string.toString().length < length) {
        string = fill + string;
    }
    return string;
}

// print logo
function printLogo() {
    console.log('  _             _               _   __  __ ');
    console.log(' | |__  __ _ __| |__ _ ___ _ _ /_\\ |  \\/  |');
    console.log(' | \'_ \\\/ _` \/ _` \/ _` / -_) \'_\/ _ \\| |\\/| |');
    console.log(' |_.__\/\\__,_\\__,_\\__, \\___|_|\/_\/ \\_\\_|  |_|');
    console.log('                 |___/                     ');
}

// shutdown
function exit(err) {
    if (err) {
        console.error(err);
        process.exit(1);
    }
    const diff = process.hrtime(start);
    console.log('exiting after ' + ((diff[0] + (diff[1] / 1000000)) / 1000).toFixed(2) + ' seconds');
    process.exit(0);
}