loglevel.js

// The MIT License
//
// Copyright (c) 2013 Tim Perry
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

// Description of import into Moodle:
// Download from https://github.com/pimterry/loglevel/releases
// Copy loglevel.js into lib/amd/src/ in Moodle folder.
// Add the license as a comment to the file and these instructions.

/*
 * loglevel - https://github.com/pimterry/loglevel
 *
 * Copyright (c) 2013 Tim Perry
 * Licensed under the MIT license.
 */
(function (root, definition) {
    "use strict";
    if (typeof define === 'function' && define.amd) {
        define(definition);
    } else if (typeof module === 'object' && module.exports) {
        module.exports = definition();
    } else {
        root.log = definition();
    }
}(this, function () {
    "use strict";

    // Slightly dubious tricks to cut down minimized file size
    var noop = function() {};
    var undefinedType = "undefined";

    // Build the best logging method possible for this env
    // Wherever possible we want to bind, not wrap, to preserve stack traces
    function realMethod(methodName) {
        if (typeof console === undefinedType) {
            return false; // No method possible, for now - fixed later by enableLoggingWhenConsoleArrives
        } else if (console[methodName] !== undefined) {
            return bindMethod(console, methodName);
        } else if (console.log !== undefined) {
            return bindMethod(console, 'log');
        } else {
            return noop;
        }
    }

    // Cross-browser bind equivalent that works at least back to IE6
    function bindMethod(obj, methodName) {
        var method = obj[methodName];
        if (typeof method.bind === 'function') {
            return method.bind(obj);
        } else {
            try {
                return Function.prototype.bind.call(method, obj);
            } catch (e) {
                // Missing bind shim or IE8 + Modernizr, fallback to wrapping
                return function() {
                    return Function.prototype.apply.apply(method, [obj, arguments]);
                };
            }
        }
    }

    // These private functions always need `this` to be set properly

    // In old IE versions, the console isn't present until you first open it.
    // We build realMethod() replacements here that regenerate logging methods
    function enableLoggingWhenConsoleArrives(methodName, level, loggerName) {
        return function () {
            if (typeof console !== undefinedType) {
                replaceLoggingMethods.call(this, level, loggerName);
                this[methodName].apply(this, arguments);
            }
        };
    }

    function replaceLoggingMethods(level, loggerName) {
        /*jshint validthis:true */
        for (var i = 0; i < logMethods.length; i++) {
            var methodName = logMethods[i];
            this[methodName] = (i < level) ?
                noop :
                this.methodFactory(methodName, level, loggerName);
        }
    }

    // By default, we use closely bound real methods wherever possible, and
    // otherwise we wait for a console to appear, and then try again.
    function defaultMethodFactory(methodName, level, loggerName) {
        /*jshint validthis:true */
        return realMethod(methodName) ||
            enableLoggingWhenConsoleArrives.apply(this, arguments);
    }

    var logMethods = [
        "trace",
        "debug",
        "info",
        "warn",
        "error"
    ];

    function Logger(name, defaultLevel, factory) {
        var self = this;
        var currentLevel;
        var storageKey = "loglevel";
        if (name) {
            storageKey += ":" + name;
        }

        function persistLevelIfPossible(levelNum) {
            var levelName = (logMethods[levelNum] || 'silent').toUpperCase();

            // Use localStorage if available
            try {
                window.localStorage[storageKey] = levelName;
                return;
            } catch (ignore) {}

            // Use session cookie as fallback
            try {
                window.document.cookie =
                    encodeURIComponent(storageKey) + "=" + levelName + ";";
            } catch (ignore) {}
        }

        function getPersistedLevel() {
            var storedLevel;

            try {
                storedLevel = window.localStorage[storageKey];
            } catch (ignore) {}

            // Fallback to cookies if local storage gives us nothing
            if (typeof storedLevel === undefinedType) {
                try {
                    var cookie = window.document.cookie;
                    var location = cookie.indexOf(
                        encodeURIComponent(storageKey) + "=");
                    if (location) {
                        storedLevel = /^([^;]+)/.exec(cookie.slice(location))[1];
                    }
                } catch (ignore) {}
            }

            // If the stored level is not valid, treat it as if nothing was stored.
            if (self.levels[storedLevel] === undefined) {
                storedLevel = undefined;
            }

            return storedLevel;
        }

        /*
         *
         * Public logger API - see https://github.com/pimterry/loglevel for details
         *
         */

        self.levels = { "TRACE": 0, "DEBUG": 1, "INFO": 2, "WARN": 3,
            "ERROR": 4, "SILENT": 5};

        self.methodFactory = factory || defaultMethodFactory;

        self.getLevel = function () {
            return currentLevel;
        };

        self.setLevel = function (level, persist) {
            if (typeof level === "string" && self.levels[level.toUpperCase()] !== undefined) {
                level = self.levels[level.toUpperCase()];
            }
            if (typeof level === "number" && level >= 0 && level <= self.levels.SILENT) {
                currentLevel = level;
                if (persist !== false) {  // defaults to true
                    persistLevelIfPossible(level);
                }
                replaceLoggingMethods.call(self, level, name);
                if (typeof console === undefinedType && level < self.levels.SILENT) {
                    return "No console available for logging";
                }
            } else {
                throw "log.setLevel() called with invalid level: " + level;
            }
        };

        self.setDefaultLevel = function (level) {
            if (!getPersistedLevel()) {
                self.setLevel(level, false);
            }
        };

        self.enableAll = function(persist) {
            self.setLevel(self.levels.TRACE, persist);
        };

        self.disableAll = function(persist) {
            self.setLevel(self.levels.SILENT, persist);
        };

        // Initialize with the right level
        var initialLevel = getPersistedLevel();
        if (initialLevel == null) {
            initialLevel = defaultLevel == null ? "WARN" : defaultLevel;
        }
        self.setLevel(initialLevel, false);
    }

    /*
     *
     * Top-level API
     *
     */

    var defaultLogger = new Logger();

    var _loggersByName = {};
    defaultLogger.getLogger = function getLogger(name) {
        if (typeof name !== "string" || name === "") {
            throw new TypeError("You must supply a name when creating a logger.");
        }

        var logger = _loggersByName[name];
        if (!logger) {
            logger = _loggersByName[name] = new Logger(
                name, defaultLogger.getLevel(), defaultLogger.methodFactory);
        }
        return logger;
    };

    // Grab the current global log variable in case of overwrite
    var _log = (typeof window !== undefinedType) ? window.log : undefined;
    defaultLogger.noConflict = function() {
        if (typeof window !== undefinedType &&
            window.log === defaultLogger) {
            window.log = _log;
        }

        return defaultLogger;
    };

    return defaultLogger;
}));