/* CodeQ: an online programming tutor.
   Copyright (C) 2015 UL FRI

This program is free software: you can redistribute it and/or modify it under
the terms of the GNU Affero General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option) any
later version.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
details.

You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */

(function () {
    window.siteDefinition = {logLevel: 'debug'}; // for debug purposes

    // ================================================================================
    // JSON-ization (stringification) function
    // ================================================================================

    var jsonize = JSON && JSON.stringify || function (obj) {
            var t, buffer, i, isFirst;
            if (null === obj) return 'null';
            t = typeof obj;
            if (t === 'string') {
                return '"' + obj.replace(regexpBackslash, '\\\\').replace(regexpQuote, '\\"') + '"';
            }
            if (t === 'number') {
                if (isFinite(obj)) return obj.toString();
                throw new Error('Cannot jsonize a non-finite number: ' + obj.toString());
            }
            if (t === 'boolean') {
                if (obj) return 'true';
                return 'false';
            }
            if (t === 'object') {
                if (obj instanceof String) return jsonize(obj.valueOf());
                if (obj instanceof Number) return jsonize(obj.valueOf());
                if (obj instanceof Boolean) return jsonize(obj.valueOf());
                if (obj instanceof Array) {
                    buffer = [ '[' ];
                    isFirst = true;
                    for (i = 0; i < obj.length; i++) {
                        if (isFirst) isFirst = false;
                        else buffer.push(',');
                        buffer.push(jsonize(obj[i]));
                    }
                    buffer.push(']');
                    return buffer.join('');
                }
                buffer = [ '{' ];
                isFirst = true;
                for (i in obj) {
                    if (!obj.hasOwnProperty(i)) continue;
                    if (isFirst) isFirst = false;
                    else buffer.push(',');
                    buffer.push(jsonize(i), ':', jsonize(obj[i]));
                }
                buffer.push('}');
                return buffer.join('');
            }
            throw new Error('Cannot jsonize ' + t);
        };

    // ================================================================================
    // The log module: contains methods for logging, sending logs to the server
    // ================================================================================

    var log = (function () {
        var logServiceUrl = window.siteDefinition && (typeof siteDefinition.logService === 'string') && siteDefinition.logService,
            assembleOutput = function (stuff, e) {
                var lines = [ stuff ];
                if (e && e.stack) lines.push(e.stack);
                return lines.join('\n');
            },
            console = window.console || {},
            levelPrefix = {'debug': 'DEBUG: ', 'info': 'INFO: ', 'warn': 'WARN: ', 'error': 'ERROR: '},
            levelSeverity = {'debug': 1, 'info': 2, 'warn': 3, 'error': 4, 'off': 5},
            severityThreshold = window.siteDefinition && levelSeverity[siteDefinition.logLevel] || levelSeverity['off'],
            logToConsole = function (level) {
                var prefix = levelPrefix[level];
                if (levelSeverity[level] < severityThreshold) return function () {}; // level is below threshold, ignore
                if (typeof console[level] === 'function') return function (output) {console[level](output);};
                if (typeof console.log === 'function') return function (output) {console.log(prefix + output);};
                if (typeof dump === 'function') return function (output) {dump(prefix + output);};
                return function () {}; // no way to log in browser
            },
            consoleLogger = {
                'debug': logToConsole('debug'),
                'info': logToConsole('info'),
                'warn': logToConsole('warn'),
                'error': logToConsole('error')
            },
            logger = {},
            level;

        if (logServiceUrl) {
            // log to the service and to the console
            var logs = []; // buffered logs
            for (level in levelPrefix) {
                if (!levelPrefix.hasOwnProperty(level)) continue;
                logger[level] = (function (levelLogger, level) {
                    if (levelSeverity[level] < severityThreshold) return function () {}; // level is below threshold, ignore
                    return function (stuff, e) {
                        var output = assembleOutput(stuff, e);
                        levelLogger(output);
                        logs.push({
                            't': Date.now(),
                            'l': level,
                            'm': output
                        });
                    };
                })(consoleLogger[level], level);
            }
            setInterval(function () {
                // each second send any logs to the server
                var copyOfLogs;
                if (logs.length < 1) return;
                copyOfLogs = jsonize({'logs': logs});
                logs = [];
                $.ajax({
                    contentType: 'application/json',
                    dataType: 'application/json',
                    type: 'POST',
                    url: logServiceUrl,
                    data: copyOfLogs,
                    error: function (jqXHR, textStatus, errorThrown) {
                        consoleLogger.error(assembleOutput('Posting of logs to ' + logServiceUrl + ' failed: ' + textStatus, errorThrown));
                    },
                    success: function (data, textStatus, jqXHR) {}
                });
            }, 1000);
        }
        else {
            // log only to the console
            for (level in levelPrefix) {
                if (!levelPrefix.hasOwnProperty(level)) continue;
                logger[level] = (function (levelLogger) {
                    if (levelSeverity[level] < severityThreshold) return function () {}; // level is below threshold, ignore
                    return function (stuff, e) { levelLogger(assembleOutput(stuff, e)); };
                })(consoleLogger[level]);
            }
        }

        return logger;
    })();

    // ================================================================================
    // The core CodeQ module
    // ================================================================================

    var jqDisabled = $('#disabled'), // used in codeq.wait()
        waitCssEnter = {'cursor': 'wait', 'display': ''};

    // regular expressions for the templating function, etc.
    var regexpQuote = new RegExp('"', 'g'),
        regexpBackslash = new RegExp('\\\\', 'g'),
        regexpWhiteSpaceStart = new RegExp('^[ \r\n\t]+'),
        regexpWhiteSpaceEnd = new RegExp('[ \r\n\t]+$'),
        regexpWhiteSpaceTrim = new RegExp('^[ \\t\\r\\n]*(.*[^ \\t\\r\\n])[ \\t\\r\\n]*$', 'm'),
        regexpAmp = new RegExp('&', 'g'),
        regexpLt = new RegExp('<', 'g'),
        regexpGt = new RegExp('>', 'g'),
        regexpCR = new RegExp('\\r', 'g'),
        regexpLF = new RegExp('\\n', 'g'),
        regexpTab = new RegExp('\\t', 'g');

    // convert a string into its definition (javascript literal)
    var stringToDef = function (str) {
        return str.replace(regexpBackslash, '\\\\').replace(regexpQuote, '\\"').replace(regexpCR, '\\r').replace(regexpLF, '\\n').replace(regexpTab, '\\t');
    };

    var resources = {}; // resource tree, loaded from data/resources.json in the boot sequence

    // event dispatch
    var eventListeners = {}, // keyed by event name, value is an array of listeners
        asyncTimer = null,
        queuedEvents = [],
        fireEvents = function () {
            if (asyncTimer !== null) return;
            asyncTimer = setTimeout(function () {
                var N = queuedEvents.length,
                    i, event, args, listeners, j;
                asyncTimer = null;
                for (i = 0; i < N; i++) {
                    event = queuedEvents[i];
                    listeners = eventListeners[event.name];
                    if (!listeners) continue;
                    args = event.args;
                    listeners = listeners.slice(); // make a copy of the list, so we're unaffected of any changes
                    for (j = 0; j < listeners.length; j++) {
                        try {
                            listeners[j](args);
                        }
                        catch (e) {
                            codeq.log.error('Error while invoking an event handler for ' + event.name + ': ' + e, e);
                        }
                    }
                }
                queuedEvents.splice(0, N);
                if (queuedEvents.length > 0) fireEvents();
            }, 0);
        };

    var tokenize = function (line) {
        var result = [],
            N = line.length,
            i = 0, // character index into line
            storedAtom = null, // the previous atom, to decide whether to store a string or an object {key:'', value:''}
            atom = [], // currently parsed content
            isKeyValue = false,
            storeAtom = function () {
                if (atom.length == 0) return;
                if (storedAtom === null) storedAtom = atom.join('');
                else if (isKeyValue) {
                    result.push({'key': storedAtom, 'value': atom.join('')});
                    storedAtom = null;
                    isKeyValue = false;
                }
                else {
                    result.push(storedAtom);
                    storedAtom = atom.join('');
                }
                atom.length = 0;
            },
            c, q;

        while (i < N) {
            c = line[i++];
            switch (c) {
                // end-of-atom characters
                case ' ':
                case '\r':
                case '\n':
                case '\t':
                    storeAtom();
                    break;

                // escape character
                case '\\':
                    if (i < N) atom.push(line[i++]);
                    break;

                // key-value delimiter character
                case '=':
                    if (storedAtom) {
                        if (isKeyValue) atom.push(c);
                        else if (atom.length == 0) isKeyValue = true; // must have been a whitespace before "="
                        else {
                            storeAtom();
                            isKeyValue = true;
                        }
                    }
                    else atom.push(c); // "=" is delimiter only before the value, not before the key
                    break;

                // quoted string
                case '"':
                case "'":
                    stringConsume:
                    while (i < N) {
                        q = line[i++];
                        switch (q) {
                            case '\\':
                                if (i < N) atom.push(line[i++]);
                                break;
                            case c:
                                break stringConsume;
                            default:
                                atom.push(q);
                                break;
                        }
                    }
                    break;

                default:
                    atom.push(c);
                    break;
            }
        }
        // purge anything in cache
        storeAtom();
        if (storedAtom !== null) result.push(storedAtom);
        return result;
    };

    var resolveResource = function (resourceName, resourceBranches) {
        var traversedPath = ['data'], // top-level directory
            branch = resources,
            candidate = null,
            i, fragment;
        if (!resourceName) {
            codeq.log.error('No resource name provided; path: "' + resourceBranches.join('/') + '"');
            return null;
        }
        if (branch[resourceName]) candidate = 'data/' + resourceName; // top-level match
        for (i = 0; i < resourceBranches.length; i++) {
            fragment = resourceBranches[i];
            branch = branch[fragment];
            if (!branch) {
                codeq.log.error('Resource sub-branch ' + fragment + ' does not exist; resource: "' + resourceName + '", path: "' + resourceBranches.join('/') + '"');
                break;
            }
            traversedPath.push(fragment);
            if (branch[resourceName]) candidate = traversedPath.join('/') + '/' + resourceName;
        }
        if (candidate) return codeq.ajaxPrefix + candidate;
        codeq.log.error('Resource ' + resourceName + ' was not found; path: "' + resourceBranches.join('/') + '"');
        return null;
    };

    var directiveHandlers = {
        'resource': function (code, tokens, templatePath) {
            code.push('_result.push("', resolveResource(tokens[1], templatePath) || 'data/broken.png', '");\n');
        },

        'img': function (code, tokens, templatePath) {
            var N = tokens.length,
                attrs = [],
                token, i;
            for (i = 1; i < N; i++) {
                token = tokens[i];
                if (!token || typeof token !== 'object') {
                    codeq.log.error('Invalid token at position ' + i + ' in @img');
                    continue;
                }
                switch (token.key) {
                    case 'src':
                        attrs.push('src="' + resolveResource(token.value, templatePath) + '"');
                        break;
                    case 'alt':
                        attrs.push('alt="' + codeq.escapeHtml(token.value) + '"');
                        break;
                    case 'class':
                        attrs.push('class="' + token.value + '"');
                        break;
                }
            }
            code.push('_result.push("<img ', attrs.join(' ').replace(regexpQuote, '\\"'), '>");\n');
        }
    };

    var makeActivityHandler = function (editor, problem_id) {
        var lastActivityMillis = Date.now(),
            deltaActivityMillis = function deltaActivityMillisFunc () {
                var now = Date.now(),
                    dt = now - lastActivityMillis;
                lastActivityMillis = now;
                return dt;
            },
            queue = [],
            ts = null,
            timer = function () {
                var promise;
                ts = null;
                if (queue.length === 0) return Q(true);
                promise = codeq.comms.sendActivity(queue, editor.getDoc().getValue(), problem_id);
                queue.length = 0;
                return promise;
            },
            flush = function () {
                clearTimeout(ts);
                return timer();
            };

        return {
            'queueTrace': function (trace) {
                trace['dt'] = deltaActivityMillis();
                queue.push(trace);
                if (ts === null) ts = setTimeout(timer, 10000); // flush every 10 seconds
                return this;
            },
            'flush': flush,
            'addAndPurge': function (trace) {
                var accumulatedTrace = queue;
                queue = [];
                trace['dt'] = deltaActivityMillis();
                accumulatedTrace.push(trace);
                if (ts !== null) {
                    clearTimeout(ts);
                    ts = null;
                }
                return accumulatedTrace;
            }
        };
    };

    window.codeq = {
        'jsonize': jsonize,

        'log': log,

        'samlLogin' : false,//falg if we logged in via saml

        'settings': {
            'gui_lang': 'en', // boot sequence overrides this if the browser uses a supported language
            'gui_layout': 'line-layout'
        },

        'availableLangs': [], // filled at boot from 'supportedLangs'
        'supportedLangs': {
            'en': 'English',
            'sl': 'Slovenščina'
        },
        'supportedLayouts':[
            'line-layout',
            'square-layout'
        ],

        'runningOnPhone': false, // default value, will be changed if detected otherwise
        'browserType': 'unknown',
        'platformType': 'unknown',
        'isWebApp': false, // this is a PhoneGap/Cordova build, will be overridden in cordova.js for webapp

        'setLayout': function(newLayout){
            codeq.settings['gui_layout'] = newLayout;
            codeq.fire('layoutchange');
        },

        'getLayout': function(){
            return codeq.settings['gui_layout'];
        },

        'setLang': function (newLang) {
            codeq.settings['gui_lang'] = newLang;
            codeq.fire('langchange', {'lang': newLang});
        },

        'getLang': function(){
          return codeq.settings['gui_lang'];
        },

        'setResources': function (newResources) {
            resources = newResources;
        },

        'escapeHtml': function (s) {
            return ('' + s).replace(regexpAmp, '&amp;').replace(regexpLt, '&lt;').replace(regexpGt, '&gt;');
        },

        /**
         * Returns the number of Unicode code points in the given string.
         *
         * @param s {string}
         * @returns {number}
         */
        'codePointCount': function (s) {
            var n = 0, i, code;
            if (typeof s !== 'string') {
                code = 'codePointCount(): argument not a string: type = ' + typeof s + ', is null = ' + (s === null);
                if ((typeof s === 'object') && (s !== null) && s.constructor) code += ', constructor = ' + s.constructor.name;
                codeq.log.error(code);
                return 0;
            }
            for (i = 0; i < s.length; i++) {
                try {
                    code = s.charCodeAt(i);
                }
                catch (e) {
                    codeq.log.error('Invocation of charCodeAt() failed at iteration #' + i + ': ' + e, e);
                    return 0;
                }
                if ((code >= 0xd800) && (code < 0xe000)) i++;
                n++;
            }
            return n;
        },

        'makeActivityHandler': makeActivityHandler,

        'wait': function (promise) {
            jqDisabled.css(waitCssEnter);
            return promise.fin(function () {
                jqDisabled.css('display', 'none');
            });
        },

        'templator': function (str, templatePath, templateName) {
            var f, parts, i, subparts, subpart,
                src = [ 'var _result = [], echo = function (s) { _result.push(s); };\n' ],
                atoms, j, atom, debugPrefix, s, r, tokens, handler;

            if (!templateName) templateName = 'unknown template';
            debugPrefix = '[' + templateName + ']';
            if (!templatePath) templatePath = [];

            // remove comments
            parts = str.split('[%--'); // break on start-of-comment
            atoms = [ parts[0] ]; // first part is not a comment
            for (i = 1; i < parts.length; i++) { // iterate over start-of-comments
                atom = parts[i].split('--%]'); // break on end-of-comment
                if (atom.length > 1) { // if end-of-comment was encountered
                    atoms.push(atom[1]); // add whatever is trailing it
                    for (j = 2; j < atom.length; j++) { // re-add even dangling end-of-comments
                        atoms.push('--%]');
                        atoms.push(atom[j]);
                    }
                }
            }

            // start processing
            parts = atoms.join('').split('[%');

            if (parts[0].length > 0) src.push('_result.push("', stringToDef(parts[0]), '");\n'); // the first part that doesn't begin with '[%'
            for (i = 1; i < parts.length; i++) { // for every part that begins with '[%'
                if (parts[i].slice(0, 2) === '--') { // a comment start
                    subparts = parts[i].split('--%]'); // split at comment end
                }
                else { // a start of a statement or of a value reference
                    subparts = parts[i].split('%]'); // there should be only one terminating '%]', find it
                    subpart = subparts[0].replace(regexpWhiteSpaceStart, '').replace(regexpWhiteSpaceEnd, ''); // trim the white space
                    if (subpart.length > 0) {
                        if (subpart[0] === '=') { // a value reference
                            s = subpart.slice(1);
                            r = regexpWhiteSpaceTrim.exec(s);
                            r = r && r[1] || s;
                            src.push('_result.push(typeof this.', r, ' === \'undefined\' ? \'', r, ' missing\' : this.', r, ');\n');
                        }
                        else if (subpart[0] === '@') { // a directive
                            tokens = tokenize(subpart.slice(1));
                            if (tokens.length === 0) {
                                codeq.log.error('An empty directive in ' + templateName);
                            }
                            else {
                                handler = directiveHandlers[tokens[0]];
                                if (!handler) {
                                    codeq.log.error('An unknown directive in ' + templateName + ': ' + tokens[0]);
                                }
                                else {
                                    handler(src, tokens, templatePath);
                                }
                            }
                        }
                        else { // javascript statement(s)
                            src.push(subpart, '\n');
                        }
                    }
                }
                if ((subparts.length > 1) && (subparts[1].length > 0)) { // there's a trailing text
                    src.push('_result.push("', stringToDef(subparts[1]), '");\n');
                }
            }
            src.push('return _result.join("");');
//            if (_internalDoLog_) codeq.log.debug('createTemplate(): ' + debugPrefix + ' creating templating function:\nfunction(_components_) {\n' + src.join('') + '\n}\n=== Created from template: ===\n' + str);
            try {
                f = new Function(src.join('')); // create a function based on the given template
            }
            catch (e) {
                codeq.log.error('createTemplate(): ' + debugPrefix + ' Failed to instantiate template function: ' + e + '\nfunction() {\n' + src.join('') + '\n}\n=== Created from template: ===\n' + str, e);
                throw e;
            }

            return function (args) {
                var esc = codeq.escapeHtml,
                    escArgs = {},
                    key;
                if ((typeof args === 'object') && (args !== null)) {
                    for (key in args) {
                        if (!args.hasOwnProperty(key)) continue;
                        escArgs[key] = esc(args[key]);
                    }
                }
                try {
                    return f.apply(escArgs);
                }
                catch (e) {
                    codeq.log.error('Error evaluating template ' + templateName + ' function: ' + e + '\nfunction() {\n' + src.join('') + '\nCreated from template:\n' + str, e);
                    throw e;
                }
            };
        },

        // codeq event handling

        'fire': function (eventName, args) {
            queuedEvents.push({'name': eventName, 'args': args});
            fireEvents();
        },

        'on': function (eventName, callback) {
            var listeners = eventListeners[eventName],
                i;
            if (listeners) {
                for (i = listeners.length - 1; i >= 0; i--) {
                    if (listeners[i] === callback) return; // already registered
                }
            }
            else {
                listeners = [];
                eventListeners[eventName] = listeners;
            }
            listeners.push(callback);
        },

        'off': function (eventName, callback) {
            var listeners = eventListeners[eventName],
                i;
            if (listeners) {
                for (i = listeners.length - 1; i >= 0; i--) {
                    if (listeners[i] === callback) listeners.splice(i, 1);
                }
            }
        },

        // reset the app
        'reset': function (reason) {
            codeq.log.info('App reset: ' + (reason || 'no reason given'));
            codeq.globalStateMachine.transition('login');
            codeq.wait(
                    codeq.comms.getSid() == null ? Q() : codeq.comms.logout()
                            .finally(
                                codeq.comms.disconnect
                            )
                            .fail(function (e) {
                                codeq.log.debug(e)
                            }) // ignore errors
                )
                .then(function () {
                    if (reason) {
                        alert(reason);
                    }
                })
                .done();
        }
    };
})();