Interpreter

var script = "";
var hasErrored = false;

function addLineToScript(newLine) {
    script += newLine + "\n";
}

function replaceAll(str, find, replace) {
    return str.replace(new RegExp(find, "g"), replace);
}

function parseConditionalExpression(expression) {
    expression = replaceAll(expression, " е идентично с", " === ");
    expression = replaceAll(expression, " е равно на", " == ");
    expression = replaceAll(expression, " не е равно на ", " != ");
    expression = replaceAll(expression, " и ", " && ");
    expression = replaceAll(expression, " или ", " || ");
    expression = expression.replace(/([a-zA-Z0-9]+) е вътре в ([a-zA-Z0-9]+)/g, "$2.indexOf($1) > -1");
    return expression;
}

function showError(error, parseError) {
    document.getElementById("error").className = "alert alert-danger";
    document.getElementById("error-text").innerHTML += error + "<br>";

    if(parseError) {
        document.getElementById("error-title").innerHTML = "О не! Има грешки в кода ти:<br>";
    } else {
        document.getElementById("error-title").innerHTML = "О не! Получи се грешка, когато се опитахме да пуснем кода ти:<br>";
    }

    hasErrored = true;
}

function hideError() {
    document.getElementById("error").className = "hidden";
    document.getElementById("error-text").innerHTML = "";

    hasErrored = false;
}

function parseFunctionCalls(expression) {
    return expression.replace(/<([^<>]+?) с параметри ([^<>]+?)>/, function(x,y,z) {
        return intoFunctionName(y) + "(" + z + ")";
    });
}

function removeIndent(expression) {
    return expression.replace(/^ +/, "");
}

function intoFunctionName(expression) {
    return replaceAll(expression, " ", "_");
}

function checkForError(matches, lineNumber) {
    if (matches == null) {
        showError("Не разбрах ред номер " + (lineNumber + 1), true);
        return false;
    }
    return true;
}

function execute() {
    var x = document.getElementById("text").value.split("\n");
    script = "";
    hideError();
    for (var i = 0; i < x.length; i++) {

        x[i] = parseFunctionCalls(x[i]);
        x[i] = removeIndent(x[i]);

        var line = x[i].split(" ");
        var matches = "";
        if (line[0] === "") {

            // Do nothing

        } else if (line[0] === "Задай" && line[1] === "стойност" && line[2] === "на") {

            matches = /Задай стойност на (.+) да е (.+)/g.exec(x[i]);

            if(checkForError(matches, i)) {
                addLineToScript(matches[1] + " = " + matches[2]);
            }

        } else if (line[0] === "Покажи") {

            matches = /Покажи (.+)/g.exec(x[i]);

            if(checkForError(matches, i)) {
                addLineToScript("alert(" + matches[1] + ")");
            }

        } else if (line[0] === "Попитай") {

            matches = /Попитай (".+") за (.+)/g.exec(x[i]);

            if(checkForError(matches, i)) {
                addLineToScript("var " + matches[2] + " = prompt(" + matches[1] + ")");
            }

        } else if (line[0] === "Ако") {

            matches = /Ако (.+), тогава направи:/g.exec(x[i]);

            if(checkForError(matches, i)) {
                addLineToScript("if(" + parseConditionalExpression(matches[1]) + ") {");
            }

        } else if (line[0] === "Край") {

            addLineToScript("}");

        } else if (line[0] === "Или") {

            if(line[1] == "в" && line[2] == "противен" && line[3] == "случай:") {
                addLineToScript("} else {");
            } else {
                matches = /Или ако (.+), тогава направи:/g.exec(x[i]);

                if(checkForError(matches, i)) {
                    addLineToScript("} else if(" + parseConditionalExpression(matches[1]) + ") {");
                }
            }

        } else if (line[0] === "Докато") {

            matches = /Докато (.+) прави:/g.exec(x[i]);

            if(checkForError(matches, i)) {
                addLineToScript("while(" + parseConditionalExpression(matches[1]) + ") {");
            }


        } else if (line[0] === "Брой") {

            matches = /Брой докато (.+) стигне (-?\d+):/g.exec(x[i]);

            if(checkForError(matches, i)) {
                var incrementor = "--";
                if (parseInt(matches[2]) > 0) {
                    incrementor = "++";
                }
                addLineToScript("for(" + matches[1] + " = 0; " + matches[1] + " != " + matches[2] + "; " + matches[1] + incrementor + ") {");
            }

        } else if (x[i].charAt(0) === "(" && x[i].charAt(x[i].length - 1) === ")") {

            matches = /\((.+)\)/g.exec(x[i]);
            if(checkForError(matches, i)) {
                addLineToScript("// " + matches[1]);
            }

        } else if (line[0] === "Въведи") {

            matches = /Въведи (.+) в (.+)/g.exec(x[i]);
            if(checkForError(matches, i)) {
                addLineToScript(matches[2] + ".push(" + matches[1] + ");");
            }

        } else if (line[0] === "Изтрий") {

            matches = /Изтрий (.+) от (.+)/g.exec(x[i]);
            if(checkForError(matches, i)) {
                addLineToScript(matches[2] + ".splice((" + matches[2] + ".indexOf(" + matches[1] + ")), 1)");
            }

        } else if (line[0] === "За") {

            matches = /За всеки (.+) в (.+) прави:/g.exec(x[i]);
            if(checkForError(matches, i)) {
                addLineToScript("for (var ___ = 0; ___ < " + matches[2] + ".length; ___++) {");
                addLineToScript("var " + matches[1] + " = " + matches[2] + "[___];");
            }

        } else if (line[0] === "Създай") {

            if(line[1] === "променливата") {

                matches = /Създай променливата (.+)/g.exec(x[i]);

                if(checkForError(matches, i)) {
                    addLineToScript("var " + matches[1] + ";");
                }
            } else {

                matches = /Създай функция (.+) с параметри (.+):/g.exec(x[i]);

                if(checkForError(matches, i)) {
                    matches[1] = intoFunctionName(matches[1]);
                    addLineToScript("function " + matches[1] + "(" + matches[2] + ") {");
                }
            }

        } else if (x[i].slice(-2) === ").") {
            matches = /^([^ ]+?\(.+?\))/g.exec(x[i]);
            if(checkForError(matches, i)) {
                addLineToScript(matches[1]);
            }

        } else if (line[0] === "Върни резултат") {

            matches = /Върни резултат (.+)/g.exec(x[i]);
            console.log(matches)
            if(checkForError(matches, i)) {
                addLineToScript("return " + matches[1]);
            }

        } else {

            showError("Не разбрах ред номер " + (i + 1), true);
            return

        }

    }

    if(!hasErrored) {
        hideError();
        console.log(script);

        try {
            new Function(script)();
        } catch(err) {
            showError(err, false);
        }
    }

}

----

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>Kolev Lang</title>
    <script src="interpreter.js"></script>
    <link rel="stylesheet" type="text/css" href="https://bootswatch.com/3/lumen/bootstrap.min.css">
    <link rel="stylesheet" type="text/css" href="style.css">
</head>

<body>
    <div class="container">
        <div class="row">
            <div class="col-md-6 col-md-offset-3 col-header">
                <h1>Elusive</h1>
                <h3>Programming for everybody.</h3>
            </div>
            <div class="col-md-6 col-md-offset-3">
                <textarea class="block" rows="4" id="text" placeholder="Започи да пишеш кода си и ще се случи чудо!"></textarea>
                <div class="btn btn-success" id="run" onclick="execute();">Компилирай</div>
                <div class="alert alert-danger hidden" role="alert" id="error">
                    <strong id="error-title">О не! Има грешки в кода ти:
                        <br>
                    </strong>
                    <span id="error-text"></span>
                </div>
            </div>
        </div>
    </div>
</body>

</html>

----

@import url('https://fonts.googleapis.com/css?family=Merriweather:400,400i');
* {
    font-family: "Merriweather", Georgia, 'Times New Roman', Times, serif
}

.block {
    min-width: 100%;
    border: none;
    background-color: #eee;
    padding: 10px;
}

.highlight {
    background-color: red;
}

.alert-danger {
    margin-top: 30px;
}

.col-header {
    padding: 50px;
    text-align: center;
}