// runner.js
// Provides a host-agnostic evaluate(source, host) entrypoint that lexes, parses, and interprets.

import { createLexer } from './src/core/lexer.js';
import { createParser } from './src/core/parser.js';
import { createInterpreter } from './src/core/interpreter.js';

/**
 * Evaluate source code in the toy language and return a result object.
 * @param {string} source - The program source code.
 * @param {object} host - Optional host bindings, e.g. { io: { out, in } }.
 * @returns {object} Result object with { ok: boolean, value?: any, error?: string }
 */
export function evaluate(source, host = {}) {
  try {
    const lexer = createLexer(source);
    const tokens = lexer.allTokens();
    const parser = createParser(tokens, false, source);
    const ast = parser.parse();
    const interpreter = createInterpreter(ast, host);
    const result = interpreter.interpret();
    return { ok: true, value: result };
  } catch (error) {
    return { ok: false, error: error.message };
  }
}

/**
 * Create a code frame showing the error location in source code
 * @param {string} source - The source code
 * @param {object} location - Location object with line/column
 * @param {string} message - Error message
 * @returns {string} Formatted code frame
 */
export function makeCodeFrame(source, location, message) {
  if (!location || !location.line) {
    return message;
  }

  const lines = source.split('\n');
  const lineIndex = location.line - 1;
  const line = lines[lineIndex];
  
  if (!line) {
    return message;
  }

  const column = location.column || 1;
  const pointer = ' '.repeat(Math.max(0, column - 1)) + '^';
  
  return `${message}\n  ${location.line} | ${line}\n     | ${pointer}`;
}