logline/src/protocols/localstorage.js

logging the frontend

import LoggerInterface from './interface';
import * as util from '../lib/util';

/**
 * Localstorage protocol
 * @class LocalStorageLogger
 */
export default class LocalStorageLogger extends LoggerInterface {
    /**
     * Localstorage protocol constructor
     * @constructor
     * @param {String} namespace - namespace to use
     */
    constructor(...args) {
        super(...args);
    }

    /**
     * add a log record
     * @method _reocrd
     * @private
     * @parma {String} level - log level
     * @param {String} descriptor - to speed up search and improve understanding
     * @param {Mixed} [data] - additional data
     */
    _record(level, descriptor, data) {
        var logs;
        try {
            logs = window.localStorage.getItem(LocalStorageLogger._database) ? JSON.parse(window.localStorage.getItem(LocalStorageLogger._database)) : [];
            logs.push([
                Date.now(),
                this._namespace,
                level,
                descriptor,
                data
            ]);
            util.debug(this._namespace, level, descriptor, data);
            window.localStorage.setItem(LocalStorageLogger._database, JSON.stringify(logs));
        } catch (e) {
            window.localStorage.removeItem(LocalStorageLogger._database);
            window.localStorage.setItem(LocalStorageLogger._database, JSON.stringify([]));
            util.throwError('failed to write, may be localStorage is full, ' + e.message);
        }
    }

    /**
     * initialize protocol
     * @method init
     * @static
     * @param {String} database - database name to use
     */
    static init(database) {
        try {
            if (!LocalStorageLogger.support) {
                util.throwError('your platform does not support localstorage protocol.');
            }
            LocalStorageLogger._database = database || 'logline';
            if (!window.localStorage.getItem(LocalStorageLogger._database)) {
                window.localStorage.setItem(LocalStorageLogger._database, JSON.stringify([]));
            }
            LocalStorageLogger.status = super.STATUS.INITED;
        } catch (e) {
            util.throwError('failed to init, ' + e.message);
        }
    }

    /**
     * get logs in range
     * if from and end is not defined, will fetch full log
     * @method get
     * @static
     * @param {String} from - time from, unix time stamp or falsy
     * @param {String} to - time end, unix time stamp or falsy
     * @param {Function} readyFn - function to call back with logs as parameter
     */
    static get(from, to, readyFn) {
        var logs, i;
        try {
            logs = JSON.parse(window.localStorage.getItem(LocalStorageLogger._database));

            from = LoggerInterface.transTimeFormat(from);
            to = LoggerInterface.transTimeFormat(to);

            for (i = 0; i < logs.length; i++) {
                if ((from && logs[i][0] < from) || (to && logs[i][0] > to)) {
                    continue;
                }

                logs[i] = {
                    time: logs[i][0],
                    namespace: logs[i][1],
                    level: logs[i][2],
                    descriptor: logs[i][3],
                    data: logs[i][4]
                };
            }
            readyFn(logs);
        } catch (e) {
            util.throwError('failed to get, ' + e.message);
            readyFn([]);
        }
    }

    /**
     * clean logs = keep limited logs
     * @method keep
     * @static
     * @param {Number} daysToMaintain - keep logs within days
     */
    static keep(daysToMaintain) {
        var logs;
        try {
            logs = !daysToMaintain ? [] : (window.localStorage.getItem(LocalStorageLogger._database) ? JSON.parse(window.localStorage.getItem(LocalStorageLogger._database)) : []).filter(log => {
                return log.time >= (Date.now() - (daysToMaintain || 2) * 24 * 3600 * 1000);
            });
            window.localStorage.setItem(LocalStorageLogger._database, JSON.stringify(logs));
        } catch (e) {
            util.throwError('failed to keep, ' + e.message);
        }
    }

    /**
     * delete log database
     * @method clean
     * @static
     */
    static clean() {
        try {
            delete LocalStorageLogger.status;
            window.localStorage.removeItem(LocalStorageLogger._database);
        } catch (e) {
            util.throwError('failed to clean, ' + e.message);
        }
    }

    /**
     * detect support situation
     * @prop {Boolean} support
     */
    static get support() {
        return 'localStorage' in window;
    }
}