/* CodeQ: an online programming tutor.
   Copyright (C) 2015-2017 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/>. */

/**
 * Creates a hint handler, displaying hints inside the provided jqHints <div>.
 */

(function () {
    "use strict";
    // constants
    var firstCharacterPos = {'line': 0, 'ch': 0},
        sel_no_scroll = {'scroll': false};

    codeq.makeHinter = function (jqHints, jqEditor, editor, trNamespace, problemDef, commonDef, activityHandler) {
        var hintCounter = 0, // for generating unique class-names
            hintCleaners = [],
            popoverHintCleaners = [], // we require separate cleaners for popups, because they are rebuilt when the editor's DOM changes
            popoverCreators = [], // functions that rebuild popover handlers after the editor's DOM changes
            planIdx = 0,
            dictionary = [],
            jqHintsContainer = jqHints.parent(),
            hintProblemDefs = problemDef.hint_type,
            hintCommonDefs = commonDef.hint_type,
            hintProblemTr = problemDef.hint,
            hintCommonTr = commonDef.hint,
            planDef = problemDef.plan,
            templatePath = [problemDef.language, problemDef.group, problemDef.problem],

            clearHints = function () {
                var i;
                for (i = hintCleaners.length - 1; i >= 0; i--) {
                    hintCleaners[i]();
                }
                hintCleaners.length = 0;
                for (i = popoverHintCleaners.length - 1; i >= 0; i--) {
                    popoverHintCleaners[i]();
                }
                popoverHintCleaners.length = 0;
                $('div.hints > div.feedback > button.display-hints').off().remove();
            },

            addMark = function (start, end, style) {
                var posStart = editor.posFromIndex(start),
                    posEnd = editor.posFromIndex(end),
                    doc = editor.getDoc(),
                    mark = doc.markText(posStart, posEnd, {'className': 'editor-mark _emark_' + hintCounter + ' ' + style}),
                    result = {'start': posStart, 'end': posEnd, 'mark': mark, 'className': '_emark_' + hintCounter};
                hintCleaners.push(function () { mark.clear(); mark = null; doc = null; result.mark = null; });
                hintCounter++;
                return result;
            },

            prepareStaticHintContent = function (hintContent, indices, hintId) {
                var content = {},
                    langs = codeq.availableLangs,
                    skippedLangs = [],
                    Nhints = 0, // count hints and remember the count
                    haveIndices = indices instanceof Array,
                    i, lang, j, node, tmpContent;
                langLoop:
                for (j = langs.length - 1; j >= 0; j--) {
                    lang = langs[j];
                    node = hintContent[lang];
                    if (!node) {
                        // no translation for this language, mark for later
                        skippedLangs.push(lang);
                    }
                    else {
                        if (haveIndices) {
                            // traverse node's indices
                            for (i = 0; i < indices.length; i++) {
                                node = node[indices[i]];
                                if (!node) {
                                    // index out of bounds, mark this language for later
                                    codeq.log.error('Cannot reference hint ' + hintId + ' with indices ' + indices);
                                    skippedLangs.push(lang);
                                    continue langLoop;
                                }
                            }
                        }
                        if (typeof node === 'string') {
                            // we have a single string (= a simplex message), put it into an array
                            content[lang] = [node];
                            if (Nhints < 1) Nhints = 1;
                        }
                        else if (node instanceof Array) {
                            // we already have an array
                            if (node.length == 0) {
                                if (haveIndices) codeq.log.error('Hint ' + hintId + ' with indices ' + indices + ' for language ' + lang + ' contains an empty array');
                                else codeq.log.error('Hint ' + hintId + ' for language ' + lang + ' contains an empty array');
                                skippedLangs.push(lang);
                                continue;
                            }
                            // verify that each array element is a string or an object with a message
                            for (i = node.length - 1; i >= 0; i--) {
                                tmpContent = node[i];
                                if (typeof tmpContent === 'string') {
                                    // this is okay
                                }
                                else if (tmpContent && (typeof tmpContent === 'object')) {
                                    if (typeof tmpContent.message !== 'string') {
                                        if (haveIndices) tmpContent.message = 'There is no message defined for hint ' + hintId + 'with indices ' + indices + ' in language ' + lang + ' at index ' + i;
                                        else tmpContent.message = 'There is no message defined for hint ' + hintId + ' in language ' + lang + ' at index ' + i;
                                        codeq.log.error(tmpContent.message);
                                    }
                                }
                                else {
                                    // not a string or an object with a message
                                    if (haveIndices) tmpContent = 'There is no message defined for hint ' + hintId + 'with indices ' + indices + ' in language ' + lang + ' at index ' + i;
                                    else tmpContent = 'There is no message defined for hint ' + hintId + ' in language ' + lang + ' at index ' + i;
                                    node[i] = tmpContent;
                                    codeq.log.error(tmpContent);
                                }
                            }
                            content[lang] = node;
                            if (Nhints < node.length) Nhints = node.length;
                        }
                        else if (node && (typeof node === 'object') && (typeof node.message === 'string')) {
                            // we have a single object with a message (= a complex message), put it into an array
                            content[lang] = [node];
                            if (Nhints < 1) Nhints = 1;
                        }
                        else {
                            if (haveIndices) codeq.log.error('Hint ' + hintId + ' with indices ' + indices + ' did not result in a terminal node for language ' + lang + ', but: ' + node);
                            else codeq.log.error('Hint ' + hintId + ' probably needs indices because it does not have a terminal node for language ' + lang + ', but: ' + node);
                            skippedLangs.push(lang);
                        }
                    }
                }
                if (Nhints === 0) {
                    // provide error feedback on display when there is no hint translation available in any language
                    if (haveIndices) tmpContent = ['No hints found for hint ' + hintId + ' with indices ' + indices];
                    else tmpContent = ['No hints found for hint ' + hintId];
                    codeq.log.error(tmpContent[0]);
                    for (j = langs.length - 1; j >= 0; j--) {
                        content[langs[j]] = tmpContent;
                    }
                    Nhints = 1;
                }
                else if (skippedLangs.length > 0) {
                    // choose a default content and assign it to skipped languages
                    lang = 'en'; // try English first
                    tmpContent = content[lang];
                    if (!tmpContent) {
                        // if no English exists, find one that does
                        for (lang in content) {
                            if (!content.hasOwnProperty(lang)) continue;
                            tmpContent = content[lang];
                            if (tmpContent) break;
                        }
                    }
                    codeq.log.error('Translations in languages ' + skippedLangs.join(', ') + ' are missing or erroneous for hint ' + hintId + ', replacing their content with translation for ' + lang);
                    // assign the default content to skipped languages
                    for (j = skippedLangs.length - 1; j >= 0; j--) {
                        content[skippedLangs[j]] = tmpContent;
                    }
                }
                content.hintLength = Nhints;
                return content;
            },

            ta = function (trObj) { // an object of the form: {'en': 'english content', 'sl': 'slovenska vsebina'}
                var result = ['data-dict="', trNamespace, '" data-tkey="', dictionary.length, '"'].join('');
                dictionary.push(trObj);
                return result;
            },

            typeHandlers = {
                'static': function (template, hint, box) {
		    if (!template) return;
                    var content = prepareStaticHintContent(template, hint.indices, hint.id),
                        args = hint ? hint.args : null,
                        hintIndex = 0,
                        trButton = {},
                        Nhints = content.hintLength,
                        nextJqHint = function () {
                            var trContent = {},
                                langs = codeq.availableLangs,
                                lang, i, msg, jq, deltaHeight;
                            for (i = langs.length - 1; i >= 0; i--) {
                                lang = langs[i];
                                try {
                                    msg = content[lang][hintIndex];
                                    if (typeof msg === 'string') {
                                        trContent[lang] = codeq.template.process(msg, templatePath, args);
                                        trButton[lang] = codeq.tr.translate('btn_more', lang) || 'More...';
                                    }
                                    else {
                                        trContent[lang] = codeq.template.process(msg.message, templatePath, args);
                                        trButton[lang] = msg.linkText;
                                    }
                                }
                                catch (e) {
                                    msg = 'Error processing hint ' + hint.id + ' at index ' + hintIndex + ' for language ' + lang + ': ' + e;
                                    codeq.log.error(msg, e);
                                    trContent[lang] = msg;
                                }
                            }
                            jq = $('<div class="hint-static" ' + ta(trContent) + '></div>');
                            hintIndex++;
                            if (jqButton) {
                                if (hintIndex < Nhints) {
                                    jqButton.before(jq);
                                    codeq.tr.translateDom(jqButton);
                                }
                                else {
                                    jqButton.remove();
                                    jqContainer.append(jq);
                                }
                            }
                            else {
                                jqContainer.append(jq);
                            }
                            codeq.tr.translateDom(jq);
                        },
                        jqContainer, jqButton;

                    if (Nhints > 1) {
                        // hint sequence
                        jqContainer = $('<div class="hint-static-group"></div>');
                        jqButton = $('<a class="hint-static-link" ' + ta(trButton) + '></a>');
                        box.append(jqContainer);
                        jqContainer.append(jqButton);
                        jqButton.on('click', function () {
                            nextJqHint();
                        });
                    }
                    else {
                        // a single hint
                        jqContainer = box;
                        jqButton = null;
                    }
                    nextJqHint();

                    // no hint cleaner here, a static hint remains on the screen
                },

                'popup': function (template, hint, box) {
                    codeq.log.debug('Processing popup hint');
                    var args = hint.args,
                        style = hint.style || 'highlight',
                        langs = codeq.availableLangs,
                        translations = {},
                        lang, i, content, htmlPrefix, instFunc;

		    // highlight given range in the editor
                    var mark = addMark(hint.start, hint.end, style);

                    // execute templates for all languages
                    for (i = langs.length - 1; i >= 0; i--) {
                        lang = langs[i];
                        content = template[lang];
                        if (typeof content === 'string') {
                            translations[lang] = codeq.template.process(content, templatePath, args);
                        }
                        else {
			    // any missing translation → no popup
			    // TODO support highlight-only hints instead
			    return;
                        }
                    }
                    // construct the wrapper element for the translation mechanism
                    htmlPrefix = '<div class="popup-hint" ' + ta(translations) + '>';
                    // create the popover after all the DOM modifications have been made, otherwise only the last made popover can be triggered
                    instFunc = function () {
                        var jqMark = jqEditor.find('.' + mark.className);
                        jqMark.popover({
                            'content': function () {
                                // decide on what to display only after the popup is triggered, so we can choose the correct translation
                                return htmlPrefix + translations[codeq.settings['gui_lang']] + '</div>';
                            },
                            'html': true,
                            'placement': 'auto bottom',
                            'trigger': 'hover focus click',
                            'container': 'body'
                        });
                        // remove the popup on next hint pack
                        popoverHintCleaners.push(function () { if (jqMark) { jqMark.popover('destroy'); jqMark = null; } });
                    };
                    popoverCreators.push(instFunc);
                    return instFunc;
                },

                'dropdown': function (template, hint, box) {
                    codeq.log.debug('Processing dropdown hint');
                    var completion = null, // the completion object, created in showHint()
                        close = function () {
                            if (completion) {
                                completion.close();
                                completion = null;
                            }
                        };

                    if (/*(editor.listSelections().length > 1) ||*/ editor.somethingSelected()) {
                        // showHint() doesn't work if a selection is activeparts
                        editor.setSelection(firstCharacterPos, firstCharacterPos, sel_no_scroll); // deselect anything
                    }

                    editor.showHint({
                        'hint': function () {
                            var hints = {
                                list: hint.choices,
                                from: editor.posFromIndex(hint.start),
                                to: editor.posFromIndex(hint.end)
                            };
                            completion = editor.state.completionActive;
                            return hints;
                        },
                        completeOnSingleClick: true,
                        completeSingle: false
                    });

                    hintCleaners.push(close);
                }
            },

            // process and append [hints] to the element [box]
            appendHints = function (hints, box) {
                var finalizers = [],
                    i, hint, hintDef, hintContent, hintType, t, fn, ret;

		activityHandler.queueTrace({'typ': 'hint', 'feedback': hints, 'shown': true});
                for (i = 0; i < hints.length; i++) {
                    hint = hints[i];
                    hintDef = hintProblemDefs[hint.id] || hintCommonDefs[hint.id];
                    if (!hintDef) {
                        codeq.log.error('Undefined hint: ' + hint.id);
                        continue;
                    }
                    hintContent = hintProblemTr[hint.id] || hintCommonTr[hint.id];

                    t = typeof hintDef;
                    if (t === 'string') hintType = hintDef; // currently a hint type is a string
                    else if ((t === 'object') && (hintDef !== null)) hintType = hintDef.type; // but in future we may use an object, if a definition becomes more complex
                    else {
                        codeq.log.error('Cannot determine the type of hint ' + hint.id + ' from: ' + hintDef);
                        continue;
                    }

                    fn = typeHandlers[hintType];
                    if (!fn) codeq.log.error('Unsupported hint type: ' + hintType);
                    else {
                        ret = fn(hintContent, hint, box);
                        if (typeof ret === 'function') finalizers.push(ret);
                    }
                }
                // invoke any finalizers
                for (i = 0; i < finalizers.length; i++) {
                    finalizers[i]();
                }
            },

            /**
             * When the editor updates its DOM, we have to re-register any popup hints.
             */
            onEditorUpdate = function () {
                var i;
                for (i = 0; i < popoverHintCleaners.length; i++) popoverHintCleaners[i]();
                for (i = 0; i < popoverCreators.length; i++) popoverCreators[i]();
            };

        codeq.tr.registerDictionary(trNamespace, dictionary);
        editor.on('update', onEditorUpdate);

        return {
            /**
             * Display the next "planning" hint and return whether there are
             * any more available.
             */
            'planNext': function () {
                if (planIdx < planDef.length) {
                    var jqHintBox = $('<div class="feedback"></div>');
                    activityHandler.queueTrace({'typ': 'plan', 'index': planIdx});
                    typeHandlers['static'](planDef[planIdx], {'id': 'plan'}, jqHintBox);
                    jqHints.prepend(jqHintBox);
                    jqHintsContainer.scrollTop(0);
                    planIdx++;
                }
                return planIdx < planDef.length;
            },

            'hasNextPlan': function () {
                return planIdx < planDef.length;
            },

            /**
             * Processes and display appropriately the server hints.
             * TODO: sort hints so static and popup hints come first, and a (single) drop-down hint last
             *
             * @param {ServerHint[]} hints an array of hints from the server
             */
            'handle': function (hints) {
                var i, hint, hintDef, hintContent,
                    n_correct = 0, n_all = 0,
                    jqHintBox = $('<div class="feedback"></div>'),
                    jqHintBtn,
		    fn;

                // display the test_results hint first if found
                for (i = 0; i < hints.length; i++) {
                    hint = hints[i];
                    if (hint.id === 'test_results') {
                        activityHandler.queueTrace({'typ': 'test', 'feedback': hint});
                        n_correct = hint.args.passed
                        n_all = hint.args.total
                        hintContent = hintProblemTr[hint.id] || hintCommonTr[hint.id];
                        typeHandlers['static'](hintContent, hint, jqHintBox);
                        hints.splice(i, 1);
                        break;
                    }
                }

                // display remaining hints
                if (hints.length > 0) {
                    if (n_all == 0 || n_correct == n_all) {
                        // no test_results or program correct: show all hints immediately
                        appendHints(hints, jqHintBox);
                    }
                    else {
                        // otherwise, hide hints behind a button
                        activityHandler.queueTrace({'typ': 'hint', 'feedback': hints, 'shown': false});
                        jqHintBtn = $('<button class="display-hints" data-tkey="btn_hint">Hint</button>');
                        codeq.tr.translateDom(jqHintBtn);
                        jqHintBtn.on('click', function (e) {
                            jqHintBtn.off().remove();
                            appendHints(hints, jqHintBox);
                        });

			// hide the hint button if code changes
			fn = function (instance, changeObj) {
			    jqHintBtn.off().remove();
			    editor.off('change', fn);
			};
			editor.on('change', fn);

                        jqHintBox.append(jqHintBtn);
                    }
                }
                jqHints.prepend(jqHintBox);
                jqHintsContainer.scrollTop(0);
            },

            'clear': clearHints,

            'destroy': function () {
                editor.off('update', onEditorUpdate);
                clearHints();
                codeq.tr.unregisterDictionary(trNamespace);
                jqHints.empty();
                jqHints = null;
                jqEditor = null;
                jqHintsContainer = null;
                editor = null;
            }
        };
    };
})();