import { SqlEvaluationError } from './errors.js';

/**
 * Builtin functions callable from expressions, keyed by uppercase name.
 * Extend/override at call time via `evaluate(ast, ctx, { functions })`.
 * @type {Record<string, (...args: any[]) => any>}
 */
export const builtins = {
  LOWER: (v) => (v === null || v === undefined ? null : String(v).toLowerCase()),
  UPPER: (v) => (v === null || v === undefined ? null : String(v).toUpperCase()),
  LENGTH: (v) => {
    if (v === null || v === undefined) return null;
    if (typeof v === 'string' || Array.isArray(v)) return v.length;
    throw new SqlEvaluationError('LENGTH requires a string or array');
  },
  ABS: (v) => {
    if (v === null || v === undefined) return null;
    if (typeof v !== 'number') throw new SqlEvaluationError('ABS requires a number');
    return Math.abs(v);
  },
  COALESCE: (...args) => {
    for (const a of args) {
      if (a !== null && a !== undefined) return a;
    }
    return null;
  },
};