/**
 * Handler for a Prolog assignment. Works with the corresponding prolog.html content.
 */

(function () {
    // a constant
    var firstCharacterPos = {'line': 0, 'ch': 0};

    var makePrologTerminalHandler = function (jqConsole, editor, problem_group, problem) {
        var promptMode = true, // default: query composition; alternative: query result browsing
            tcs = function terminalCommandSuccess (data) {
                var t, lines, i;
                terminal.resume();
                if (data.code === 0) {
                    t = data.terminal;
                    lines = t.messages;
                    for (i = 0; i < lines.length; i++) {
                        terminal.echo(lines[i]);
                    }
                    promptMode = !t.have_more;
                }
                else {
                    terminal.error(data.message);
                    promptMode = true;
                }
            },
            tcf = function terminalCommandFailed (error) {
                terminal.resume();
                terminal.exception(error);
                promptMode = true;
            },
            terminal = jqConsole.terminal(function (command, terminal) {
                if (promptMode) {
                    terminal.pause();
                    codeq.comms.sendQuery({
                        'step': 'run',
                        'program': editor.getDoc().getValue(),
                        'query': command,
                        'language': 'prolog',
                        'problem_group': problem_group,
                        'problem': problem
                    }).then(tcs, tcf).done();
                }
                else {
                    // not in prompt mode -- we should never land here, but handle it anyway
                    codeq.comms.sendQuery({
                        'step': 'end'
                    }).then(tcs, tcf).done();
                }
            }, {
                'history': true,
                'prompt': '?- ',
                'greetings': 'CodeQ prolog terminal proxy',
                'exit': false,
                'clear': false,
                'keypress': function (event, terminal) {
                    if (promptMode) return true;
                    setTimeout(function () {
                        terminal.echo(''); // send newline after semicolon or full-stop
                        terminal.pause();
                    }, 0);
                    if ((event.which == 32) || (event.which == 59)) {
                        // space or semicolon -> show next answer
                        event.which = 59; // semicolon
                        codeq.comms.sendQuery({
                            'step': 'next'
                        }).then(tcs, tcf).done();
                    }
                    else {
                        // everything else: stop searching for answers
                        event.which = 46; // full stop
                        codeq.comms.sendQuery({
                            'step': 'end'
                        }).then(tcs, tcf).done();
                    }
                }
            });

        return {};
    };

    /**
     * Creates a new handler for the given Prolog assignment definition.
     *
     * @param {PrologTaskDef} info
     * @returns {{destroy: Function, processServerHints: Function}}
     */
    codeq.createPrologHandler = function (info, problem_group, problem) {
        var jqDescription = $('#description'),
            jqEditor = $('#code_editor'),
            jqConsole = $('#console'),
            jqHints = $('#info'),
            editor = CodeMirror(jqEditor[0], { cursorHeight: 0.85, lineNumbers: true, matchBrackets: true }),
/*            controller = jqConsole.console({
                promptLabel: '?- ',
                commandValidate: function (line) {
                    return !!line;
                },
                commandHandle: function (line) {
                    return [{msg:'Not implemented.', className:'console-response'}];
                },
                autofocus: false,
                animateScroll: false,
                promptHistory: false,
                welcomeMessage: 'Prolog REPL.'
            }),*/
            terminal = makePrologTerminalHandler(jqConsole, editor, problem_group, problem),
            /** Object.<string, HintDefinition> */
            hintDefs = info.hint,
            hintCounter = 0, // for generating unique class-names
            hintCleaners = [],
            clearHints = function () {
                var i;
                for (i = hintCleaners.length - 1; i >= 0; i--) {
                    hintCleaners[i]();
                }
                hintCleaners.length = 0;
                hintCounter = 0;
            },
            addMark = function (start, end) {
                var posStart = editor.posFromIndex(start),
                    posEnd = editor.posFromIndex(end),
                    doc = editor.getDoc(),
                    mark = doc.markText(posStart, posEnd, {className: 'editor-mark _emark_' + hintCounter}),
                    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;
            },
            hintHandlers = {
                'static': function (type, template, serverHint) {
                    codeq.log.debug('Processing static hint');
                    jqHints.append('<div class="hint-static">' + template + '</div>'); // TODO: incorporate any serverHint.args
                    // no hint cleaner here, a static hint remains on the screen
                },
                'popup': function (type, template, serverHint) {
                    codeq.log.debug('Processing popup hint');
                    var mark = addMark(serverHint.start, serverHint.end), // add the mark
                        jqMark = jqEditor.find('.' + mark.className);
/*                        jqPopup = null,
                        onBlur = function () {
                            codeq.log.debug('Removing popup');
                            if (jqPopup) {
                                jqPopup.off('blur', onBlur);
                                jqPopup.remove();
                                jqPopup = null;
                            }
                        };

                    window.jqMark = jqMark; // TODO: DEBUG

                    jqMark.on('click', function () {
                        if (jqPopup) return;
                        codeq.log.debug('Showing popup');
                        var pos = mark.mark.find(), // results in {from: {line: number, ch: number}, to: {line: number, ch: number}}
                            left = pos.from.ch < pos.to.ch ? pos.from.ch : pos.to.ch,
                            down = pos.from.line < pos.to.line ? pos.to.line : pos.from.line;
                        jqPopup = $('<div style="position: absolute;" class="editor-popup ' + mark.className + '"></div>').html(template);
                        editor.addWidget({line: down, ch: left}, jqPopup[0], true);
                        jqPopup = jqEditor.find('.editor-popup.' + mark.className);
                        setTimeout(function () {jqPopup.trigger('focus'); jqPopup.on('click', onBlur);}, 50); // event handlers can be registered only when the DOM elements is part of the document
                        window.jqPopup = jqPopup; // TODO: DEBUG
                    });

                    hintCleaners.push(function () {
                        if (jqPopup) {
                            jqPopup.off('blur', onBlur);
                            jqPopup.remove();
                            jqPopup = null;
                        }
                        if (jqMark) {
                            jqMark = null;
                        }
                        mark = null;
                    });*/

                    jqMark.popover({content: template, html: true, placement: 'auto bottom', trigger: 'hover focus click', container: 'body'});
                    hintCleaners.push(function () { if (jqMark) { jqMark.popover('destroy'); jqMark = null; } });

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

                    hintCleaners.push(close);
                }
            },
            lastActivityMillis = Date.now(),
            deltaActivityMillis = function deltaActivityMillisFunc () {
                var now = Date.now(),
                    dt = Math.max(0, Math.min(30000, now - lastActivityMillis)); // 0 sec <= dt <= 30 sec
                lastActivityMillis = now;
                return dt;
            };

        editor.setValue('sister(X, Y) :-\n    female(X),\n    parent(Z, X),\n    parent(Z, Y),\n    X \\== Y.'); // demo
        jqDescription.html(info.description);

        editor.on('change', function (instance, changeObj) {
            var doc = editor.getDoc(),
                pos = codeq.codePointCount(doc.getRange(firstCharacterPos, changeObj.from)),
                dt = deltaActivityMillis();

            if (changeObj.removed) {
//                codeq.comms.sendActivity({'typ': 'rm', 'dt': dt, 'off': pos, 'len': codeq.codePointCount(changeObj.removed)});
            }

            if (changeObj.text) {
//                codeq.comms.sendActivity({'typ': 'ins', 'dt': dt, 'off': pos, 'txt': changeObj.text});
            }
        });

        var handler = {
            destroy: function () {
                jqDescription.empty();
                jqEditor.empty(); // TODO: perhaps you do not want to "free" the editor, just empty it
                jqConsole.empty(); // TODO: the same with the console
                jqHints.empty(); // TODO: just make static references to these
                jqDescription = null;
                jqEditor = null;
                jqConsole = null;
                jqHints = null;
            },

            /**
             * 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[]} serverHints an array of hints from the server
             */
            processServerHints: function (serverHints) {
                var n = serverHints.length,
                    /** number */ i,
                    /** ServerHint */ serverHint,
                    /** HintDefinition */ hintDef,
                    hintType, hintTemplate, t, fn;
                clearHints();
                for (i = 0; i < n; i++) {
                    serverHint = serverHints[i];
                    hintDef = hintDefs[serverHint.id];
                    if (!hintDef) {
                        codeq.log.error('Undefined hint: ' + serverHint.id);
                        continue;
                    }
                    t = typeof hintDef;
                    if (t === 'object') {
                        hintType = hintDef.type;
                        hintTemplate = hintDef.message;
                    }
                    else if (t === 'string') {
                        hintType = 'static';
                        hintTemplate = hintDef;
                    }
                    else {
                        codeq.log.error('Unsupported hint definition: ' + t);
                        continue;
                    }

                    fn = hintHandlers[hintType];
                    if (!fn) codeq.log.error('Unsupported hint type: ' + hintType);
                    else fn(hintType, hintTemplate, serverHint);
                }
            }
        };

        var jqButtons = $('#block-toolbar button');
//        $(jqButtons.get(0)).on('click', function () { handler.processServerHints([{id:'x_must_be_female'}]); });
//        $(jqButtons.get(1)).on('click', function () { handler.processServerHints([{id:'popup_unknown', start: 20, end: 26}]); });
//        $(jqButtons.get(2)).on('click', function () { handler.processServerHints([{id:'drop_down', start: 20, end: 26, choices:['ena', 'dva', 'tri']}]); });

        $('#btn_code_run').on('click', function () {
            var doc = editor.getDoc(),
                dt = deltaActivityMillis();
//            codeq.comms.sendActivity({'typ': 'slv', 'dt': dt, 'qry': });
            handler.processServerHints([{id:'list_empty'}]);
        });
        $('#btn_code_break').on('click', function () {
            handler.processServerHints([{id:'popup_unknown', start: 20, end: 26}]);
        });
        $('#btn_code_hint').on('click', function () {
            handler.processServerHints([{id:'drop_down', start: 20, end: 26, choices:['ena', 'dva', 'tri']}]);
        });

        return handler;
    };
})();