import type { z } from 'zod';

/**
 * Validate a heterogeneous candidate (single object, array, or null/undefined) against a
 * Zod schema, keeping only the items that successfully parse. Returns the surviving
 * items in input order. Empty input or all-failing input both yield `[]` — callers
 * decide whether to treat that as fatal.
 *
 * Implements the "Lenient parse" policy described in CONTEXT.md.
 */
export function lenientValidateArray<T>(candidates: unknown, schema: z.ZodType<T>): T[] {
  const arr = Array.isArray(candidates) ? candidates : candidates ? [candidates] : [];
  const valid: T[] = [];
  for (const item of arr) {
    const result = schema.safeParse(item);
    if (result.success) valid.push(result.data);
  }
  return valid;
}