Shaver Parser

function solve(params) {
    var modelLinesCount = parseInt(params[0]),
        currentLine,
        models = {},
        sections = {},
        result = '',
        i, j, k, l;

    for (i = 0; i < modelLinesCount; i += 1) {
        currentLine = params[i + 1].trim();
        var modelName = '',
            modelValue = '',
            isModelName = true;

        for (j = 0; j < currentLine.length; j += 1) {
            if (currentLine[j] === ':') {
                isModelName = false;
                continue;
            }

            if (isModelName) {
                modelName += currentLine[j];
            } else {
                modelValue += currentLine[j];
            }
        }

        models[modelName.trim()] = modelValue.trim();
    }

    var isKeyWord = false,
        inSection = false,
        inRenderSection = false,
        inIf = false,
        inForeach = false,
        isSectionName = false,
        inCondition = false,
        inIfBody = false,
        inForBody = false,
        inEscaped = false,
        inForCondition = false,
        keyWord = '',
        sectionName = '',
        sectionContent = '',
        toBeRendered = '',
        conditionModel = '',
        condition = '',
        forCondition = '',
        forConditionArray = [],
        forBody = '';


    for (i = modelLinesCount + 2; i < params.length; i += 1) {
        currentLine = params[i].trim();

        if (currentLine === '') {
            result += '\n';
            continue;
        }

        for (j = 0; j < currentLine.length; j += 1) {
            if (currentLine[j] === '@' && currentLine[j + 1] === '@') {
                inEscaped = true;
                continue;
            }

            if (inEscaped) {
                if (currentLine[j] === ' ' || currentLine[j] === '<') {
                    inEscaped = false;
                }

                result += currentLine[j];
                if (j === currentLine.length - 1) {
                    result += '\n';
                }

                continue;
            }

            if (currentLine[j] === '@' && !inEscaped) {
                isKeyWord = true;
                keyWord = '@';
                continue;
            }

            if (isKeyWord) {
                if (currentLine[j] === ' ' || currentLine[j] === '(' || currentLine[j] === '<' || j === currentLine.length - 1) {
                    isKeyWord = false;

                    switch (keyWord) {
                        case '@section':    // TODO: same as if
                            inSection = true;
                            isSectionName = true;
                            break;
                        case '@renderSection':
                            inRenderSection = true;
                            break;
                        case '@if':
                            if (currentLine[currentLine.length - 1] === '{') {
                                inIf = true;
                                break;
                            }
                        case '@foreach':
                            if (currentLine[currentLine.length - 1] === '{') {
                                inForeach = true;
                                break;
                            }
                        default:
                            keyWord = keyWord.slice(1);
                            if (inIf && condition === 'false') {
                                continue;
                            }

                            if (inForBody) {
                                if (j === currentLine.length - 1) {
                                    if (models[keyWord]) {
                                        forBody += models[keyWord] + '\n';
                                    } else {
                                        forBody += '##' + keyWord + '##' + '\n';
                                    }
                                } else {
                                    if (models[keyWord]) {
                                        forBody += models[keyWord] + currentLine[j];
                                    } else {
                                        forBody += '##' + keyWord + '##' + currentLine[j];
                                    }
                                }

                                continue;
                            }

                            if (j === currentLine.length - 1) {
                                keyWord += currentLine[j];
                                result += models[keyWord] + '\n';
                            } else {
                                result += models[keyWord] + currentLine[j];
                            }
                            break;
                    }

                    continue;
                }

                keyWord += currentLine[j];
                continue;
            }

            if (inSection) {
                if (currentLine[j] === '}') {
                    inSection = false;
                    sections[sectionName] = sectionContent;
                    sectionName = '';
                    sectionContent = '';
                    continue;
                }

                if (isSectionName && (currentLine[j] === ' ' || currentLine[j] === '{')) {
                    isSectionName = false;
                    continue;
                }

                if (isSectionName) {
                    sectionName += currentLine[j];
                } else {
                    if (currentLine[j] === '{') {
                        continue;
                    }

                    sectionContent += currentLine[j];
                    if (j === currentLine.length - 1) {
                        sectionContent += '\n';
                    }
                }

                continue;
            }

            if (inRenderSection) {
                if (currentLine[j] === ')') {
                    inRenderSection = false;
                    result += sections[toBeRendered];
                    toBeRendered = '';
                    continue;
                }
                if (currentLine[j] === '(' || currentLine[j] === '"' || currentLine[j] === "'") {
                    continue;
                }

                toBeRendered += currentLine[j];
                continue;
            }

            if (inIf) {
                if (currentLine[j] === '}') {
                    inIf = false;
                    inIfBody = false;
                    condition = '';
                    continue;
                }

                if (currentLine[j] === '{') {
                    inIfBody = true;
                    continue;
                }

                if (currentLine[j] === '(' && !inIfBody) {
                    inCondition = true;
                    continue;
                }

                if (currentLine[j] === ')' && !inIfBody) {
                    inCondition = false;
                    condition = models[conditionModel];
                    conditionModel = '';
                    continue;
                }

                if (inCondition) {
                    conditionModel += currentLine[j];
                    continue;
                }

                if (condition === 'true' && inIfBody) {
                    result += currentLine[j];
                    if (j === currentLine.length - 1) {
                        result += '\n';
                    }
                    continue;
                } else {
                    continue;
                }
            }

            if (inForeach) {
                if (currentLine[j] === '}') {
                    inForeach = false;

                    for (k = 0; k < models[forConditionArray[3]].length; k += 1) {
                        var arr = forBody.split('##');
                        var prop = arr[1];
                        for (l in arr) {
                            if (arr[l] === prop) {
                                arr[l] = models[forConditionArray[3]][k];
                            }
                        }

                        var resultBody = arr.join('');
                        result += resultBody;
                    }

                    inForBody = false;
                    forBody = '';
                    forCondition = '';
                    continue;
                }

                if (currentLine[j] === '(' && !inForBody) {
                    inForCondition = true;
                    continue;
                }

                if (currentLine[j] === ')' && !inForBody) {
                    inForCondition = false;
                    forConditionArray = forCondition.split(' '); // var, prop, in, model
                    models[forConditionArray[3]] = models[forConditionArray[3]].split(',');
                    continue;
                }

                if (inForCondition) {
                    forCondition += currentLine[j];
                    continue;
                }

                if (currentLine[j] === '{') {
                    inForBody = true;
                    continue;
                }

                if (inForBody) {
                    forBody += currentLine[j];
                    if (j === currentLine.length - 1) {
                        forBody += '\n';
                    }
                    continue;
                }
            }

            result += currentLine[j];

            if (j === currentLine.length - 1) {
                result += '\n';
            }
        }
    }
    // console.log(models);
    return result.trim();
}