serialize.ts

import type {
  ExpressionToken,
  LiqeQuery,
} from './types';

const quote = (value: string, quotes: 'double' | 'single') => {
  if (quotes === 'double') {
    return `"${value}"`;
  }

  if (quotes === 'single') {
    return `'${value}'`;
  }

  return value;
};

const serializeExpression = (expression: ExpressionToken) => {
  if (expression.type === 'LiteralExpression') {
    if (expression.quoted && typeof expression.value === 'string') {
      return quote(expression.value, expression.quotes);
    }

    return String(expression.value);
  }

  if (expression.type === 'RegexExpression') {
    return String(expression.value);
  }

  if (expression.type === 'RangeExpression') {
    const {
      min,
      max,
      minInclusive,
      maxInclusive,
    } = expression.range;

    return `${minInclusive ? '[' : '{'}${min} TO ${max}${maxInclusive ? ']' : '}'}`;
  }

  if (expression.type === 'EmptyExpression') {
    return '';
  }

  throw new Error('Unexpected AST type.');
};

const serializeTag = (ast: LiqeQuery) => {
  if (ast.type !== 'Tag') {
    throw new Error('Expected a tag expression.');
  }

  const {
    field,
    expression,
    operator,
  } = ast;

  if (field.type === 'ImplicitField') {
    return serializeExpression(expression);
  }

  const left = field.quoted ? quote(field.name, field.quotes) : field.name;

  const patEnd = ' '.repeat(expression.location.start - operator.location.end);

  return left + operator.operator + patEnd + serializeExpression(expression);
};

export const serialize = (ast: LiqeQuery): string => {
  if (ast.type === 'ParenthesizedExpression') {
    if (!('location' in ast.expression)) {
      throw new Error('Expected location in expression.');
    }

    if (!ast.location.end) {
      throw new Error('Expected location end.');
    }

    const patStart = ' '.repeat(ast.expression.location.start - (ast.location.start + 1));
    const patEnd = ' '.repeat(ast.location.end - ast.expression.location.end - 1);

    return `(${patStart}${serialize(ast.expression)}${patEnd})`;
  }

  if (ast.type === 'Tag') {
    return serializeTag(ast);
  }

  if (ast.type === 'LogicalExpression') {
    let operator = '';

    if (ast.operator.type === 'BooleanOperator') {
      operator += ' '.repeat(ast.operator.location.start - ast.left.location.end);
      operator += ast.operator.operator;
      operator += ' '.repeat(ast.right.location.start - ast.operator.location.end);
    } else {
      operator = ' '.repeat(ast.right.location.start - ast.left.location.end);
    }

    return `${serialize(ast.left)}${operator}${serialize(ast.right)}`;
  }

  if (ast.type === 'UnaryOperator') {
    return (ast.operator === 'NOT' ? 'NOT ' : ast.operator) + serialize(ast.operand);
  }

  if (ast.type === 'EmptyExpression') {
    return '';
  }

  throw new Error('Unexpected AST type.');
};