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

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

    //codeq.makePrologTerminalHandler = function (jqConsole, editor, problem_id, activityHandler) {
    var makePrologTerminalHandler = function (jqConsole, editor, problem_id, activityHandler) {
        var promptMode = true, // default: query composition; alternative: query result browsing
            manualStop = false, // if the user stopped showing next answers (false) or if there are no more answers (true)
            terminal = codeq.makeConsole(jqConsole, {
                'greeting': 'CodeQ Prolog terminal proxy'
            }),
            tcs = function terminalCommandSuccess (data) {
                var t, lines, i;
                if (data.code === 0) {
                    t = data.terminal;
                    terminal.append(t.messages.join('\n'), 'output');
                    promptMode = !t.have_more;
                }
                else {
                    terminal.append(data.message, 'error');
                    promptMode = true;
                }
                if (promptMode) {
                    terminal.setLineBuffered();
                    terminal.append(manualStop ? '?- ' : '.\n?- ', 'output');
                }
            },
            tcf = function terminalCommandFailed (error) {
                promptMode = true;
                terminal.setLineBuffered();
                terminal.append(error + '\n', 'error');
                terminal.append('?- ', 'output');
            };

        terminal.onKeypress = function (c) {
            if (promptMode) return c; // query composition: return the character unchanged
            switch (c) {
                case ' ':
                case ';':
                case '\n':
                    return ';'; // show next answer on space, semicolon or enter
                default:
                    return '.'; // everything else: stop searching for answers
            }
        };

        terminal.onInput = function (command) {
            if (promptMode) {
                promptMode = false;
                manualStop = false;
                terminal.setNotBuffered();
                return codeq.comms.sendQuery({
                    'problem_id': problem_id,
                    'step': 'run',
                    'program': editor.getDoc().getValue(),
                    'query': command,
                    'trace': activityHandler.addAndPurge({'typ': 'slv', 'qry': command})
                }, problem_id).then(tcs, tcf);
            }
            else {
                terminal.append('\n', 'input');
                if (command == ';') {
                    // show next answer
                    return codeq.comms.sendQuery({
                        'problem_id': problem_id,
                        'step': 'next',
                        'trace': activityHandler.addAndPurge({'typ': 'nxt'})
                    }, problem_id).then(tcs, tcf);
                }
                else {
                    // stop searching for answers
                    manualStop = true;
                    return codeq.comms.sendQuery({
                        'problem_id': problem_id,
                        'step': 'end',
                        'trace': activityHandler.addAndPurge({'typ': 'stp'})
                    }, problem_id).then(tcs, tcf);
                }

            }
        };

        terminal.leftmostCol = 3;
        terminal.append('?- ', 'output');

        return terminal;
    };

    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;
            }
        };
    };

    /**
     * Creates a new handler for the given Prolog assignment definition.
     *
     * @param {PrologTaskDef} info
     * @returns {{destroy: Function, processServerHints: Function}}
     */
    codeq.createPrologHandler = function (info) {
        var problem = info.problem,
            jqDescription = $('#description'),
            jqEditor = $('#code_editor'),
            jqConsole = $('#console'),
            jqHints = $('#info'),
            editor = CodeMirror(jqEditor[0], { cursorHeight: 0.85, lineNumbers: true, matchBrackets: true }),
            activityHandler = codeq.makeActivityHandler(editor, problem.id),
            terminal = makePrologTerminalHandler(jqConsole, editor, problem.id, activityHandler),
            hinter = codeq.makeHinter(jqHints, jqEditor, editor, problem.hint);

        editor.setValue(info.solution);
        $('#title').text(problem.slug);
        jqDescription.html(problem.description);

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

            if (changeObj.removed) {
                activityHandler.queueTrace({'typ': 'rm', 'off': pos, 'len': codeq.codePointCount(changeObj.removed)});
            }

            if (changeObj.text) {
                activityHandler.queueTrace({'typ': 'ins', 'off': pos, 'txt': changeObj.text});
            }
        });

        $('#btn_code_hint').on('click', function () {
            terminal.append('hint.\n', 'input');
            terminal.inputDisable();
            var doc = editor.getDoc();
            codeq.comms.sendHint({
                    'language': 'prolog',
                    'program': editor.getDoc().getValue(),
                    'problem_id': problem.id
                })
                .then(
                    function hintSuccess(data) {
                        if (data.code === 0)
                            hinter.handle(data.hints);
                        else
                            terminal.append(data.message + '\n', 'error');
                    },
                    function hintFailed (error) {
                        terminal.append(error + '\n', 'error');
                    }
                )
                .fin(function () {
                    terminal.inputEnable();
                    terminal.append('?- ', 'output');
                })
                .done();
        });
        $('#btn_code_test').on('click', function () {
            terminal.append('test.\n', 'input');
            terminal.inputDisable();
            var doc = editor.getDoc();
            codeq.comms.sendTest({
                    'language': 'prolog',
                    'program': editor.getDoc().getValue(),
                    'problem_id': problem.id
                })
                .then(
                    function testSuccess(data) {
                        if (data.code === 0)
                            hinter.handle(data.hints);
                        else
                            terminal.append(data.message + '\n', 'error');
                    },
                    function testFailed (error) {
                        terminal.append(error + '\n', 'error');
                    }
                )
                .fin(function () {
                    terminal.inputEnable();
                    terminal.append('?- ', 'output');
                })
                .done();
        });

        return {
            destroy: function () {
                hinter.destroy();
                terminal.destroy();
                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
                jqDescription = null;
                jqEditor = null;
                jqConsole = null;
                jqHints = null;
            }
        };
    };
})();