const fs = require('fs');
const path = require('path');

let Converter = {
	sourcePath: __dirname + '/' + process.argv[2],
	destPath: __dirname + '/' + process.argv[3],
	
	start() {
		this.traversalDir(this.sourcePath, this.destPath);
	},

	// 遍历文件夹找到
	traversalDir: function(srcDir, destDir) {
		let files = [];
		if ( fs.existsSync(srcDir) ) {    //判断给定的路径是否存在
			files = fs.readdirSync(srcDir);    //返回文件和子目录的数组
			for (let i = 0, len = files.length; i < len; i++) {
				let file = files[i];
				let srcFile = path.join(srcDir, file);
				let destFile = path.join(destDir, file);

				let baseName = path.basename(srcFile, '.json');
				let names = baseName.split('_');
				if (names[0] !== 'track') {
					continue;
				}
			
				fs.readFile(srcFile, (err, data) => {
					if (err) {
						console.error(err);
						return;
					}

					console.log('Success to read file: ' +srcFile);

					let strTrack = this.convertTrack(data);
					if (!strTrack || strTrack.length <= 0) {
						console.log('track is invalid: ' +srcFile);
						return;
					}

					fs.writeFile(destFile, strTrack, (err) => {
						if (err) {
							console.error(err);
							return;
						}
						console.log('Success to write file: ' +destFile);
					});
				});

			}
		}
		return files;
	},

	convertTrack(data) {
		let str = '';
        try {
			let track = JSON.parse(data);
			track.sort(function(a, b) {
				return b.enterTime - a.enterTime;
			});
            str = JSON.stringify(track);
        } catch(e) {
            console.error('convertTrack: error to sort track');
        }

        return str;
	},

};

module.exports = Converter;

Converter.start();