dl/lib/dataprovider/FileDataProvider.js

DreamLab Libs

var fs = require('fs');

var Core = require('core'),
    Class = Core.Class,
    Assertions = Core.common.Assertions,
    Types = Core.common.Types;

var AbstractDataProvider = require('./AbstractDataProvider.js').AbstractDataProvider;

var FileDataProvider = function () {
    this.Extends = AbstractDataProvider;

//    this._filePath = null;

    this.initialize = function (filePath) {
        Assertions.isString(filePath, FileDataProvider.Exception.BAD_FILE_NAME);
        this._filePath = filePath;
    };

    this.init = function (callback) {
        var that = this;

        fs.stat(this._filePath, function (error, stats) {
            if (error) {
                if (error.code != "ENOENT") {
                    callback(error, null);
                    return;
                } else {
                    fs.writeFile(that._filePath, '', function (error) {
                        if (error) {
                            callback(error, null);
                            return;
                        }

                        callback(null, true);
                    });
                }
                return;
            }
            callback(null, true);
        });
    };

    this.destroy = function () {
        this.unwatch(null, function () {});
    };

    this.watch = function (key, callback) {
        fs.watchFile(this._filePath, function (current, previous) {
            if (current.size == 0) {
                /*
                 * pomijam event przy czyszczeniu pliku
                 * po CLOSE_WRITE zostanie wygenerowany nowy event
                 */
            } else {
                callback(null, current);
            }
        });
    };

    this.unwatch = function (key, callback) {
        fs.unwatchFile(this._filePath);
        callback();
    };

    this.set = function (key, value, callback) {
        //Assertions.isString(key, FileDataProvider.Exception.KEY_HAS_TO_BE_A_STRING);
        Assertions.guard(value, [Assertions.isString, Assertions.isObject], FileDataProvider.Exception.WRONG_VALUE);

        if (Types.isObject(value)) {
            value = JSON.stringify(value, undefined, 2);
        }

        fs.writeFile(this._filePath, value, function (error) {
            if (error) {
                callback(error, null);
                return; 
            }

            callback(null, true);
        }); 
    };

    this.get = function (key, callback) {
        fs.readFile(this._filePath, 'utf8', function (error, data) {
            if (error) {
                callback(error, null);
                return;
            }

            try {
                data = JSON.parse(data);
            } catch (e) {
                data = {};
            }

            callback(null, data);
        });
    };
};

FileDataProvider = new Class(new FileDataProvider());

FileDataProvider.Exception = {};
FileDataProvider.Exception.BAD_FILE_NAME = "File name has to be a string";
FileDataProvider.Exception.WRONG_KEY = "Key has to be a string";
FileDataProvider.Exception.WRONG_VALUE = "Value has to be a string or an object";

exports.FileDataProvider = FileDataProvider;