/**
 * Handler for a Python assignment. Works with the corresponding python.html content.
 */

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

    //codeq.makePythonTerminalHandler = function (jqConsole, editor, problem_id, activityHandler) {
    var makePythonTerminalHandler = function (jqConsole, editor, problem_id, activityHandler) {
        var terminal = codeq.makeConsole(jqConsole, {
                'greeting': 'CodeQ Python terminal proxy'
            }),
            tcs = function terminalCommandSuccess (data) {
                if (data.code !== 0) {
                    terminal.append(data.message, 'error');
                }
            },
            tcf = function terminalCommandFailed (error) {
                terminal.append(error + '\n', 'error');
            };

        terminal.onInput = function (text) {
            return codeq.comms.sendPush({
                'text': text + '\n'
            }).then(tcs, tcf);
        };

        codeq.comms.on('terminal_output', function (data) {
            var text = data.text;
            terminal.append(text, 'output');
            lines = text.split('\n');
            terminal.leftmostCol = lines[lines.length-1].length;
        });

        terminal.leftmostCol = 1;

        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.createPythonHandler = 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, mode: 'python' }),
            activityHandler = makeActivityHandler(editor, problem.id),
            terminal = makePythonTerminalHandler(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.join(''))});
            }

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

        $('#btn_code_hint').on('click', function () {
            var doc = editor.getDoc();
            codeq.comms.sendHint({
                'language': 'python',
                'program': editor.getDoc().getValue(),
                'problem_id': problem.id
            }).then(
                function hintSuccess(data) {
                    if (data.code === 0)
                        hinter.handle(data.hints);
                    else
                        terminal.append('error: ' + data.message);
                },
                function hintFailed (error) {
                    terminal.append('exception: ' + error);
                }
            ).done();
        });
        $('#btn_code_test').on('click', function () {
            var doc = editor.getDoc();
            codeq.comms.sendTest({
                'language': 'python',
                'program': editor.getDoc().getValue(),
                'problem_id': problem.id
            }).then(
                function testSuccess(data) {
                    if (data.code === 0)
                        hinter.handle(data.hints);
                    else
                        terminal.append('error: ' + data.message);
                },
                function testFailed (error) {
                    terminal.append('exception: ' + error);
                }
            ).done();
        });

        // TODO first line of interpreter output is buffered without this, why?
        codeq.comms.sendPush({
            'text': ''
        });

        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;
            }
        };
    };
})();