/**
 * Resolves a TypeScript literal string to use as a mock value for a single schema property.
 *
 * Priority chain:
 *   $ref mock call → array $ref mock call → enum[0] → example → format fallback → type default
 *
 * @param propName  Property name (used for format heuristics such as "email").
 * @param prop      Raw OpenAPI property definition.
 * @param context   'dto' generates `mockFooDto()`, 'model' generates `mockFooModel()`.
 */
export function resolveMockValue(
  propName: string,
  prop: {
    type?: string;
    format?: string;
    example?: unknown;
    enum?: unknown[];
    $ref?: string;
    items?: { $ref?: string; type?: string };
  },
  context: 'dto' | 'model' = 'dto'
): string {
  const suffix = context === 'dto' ? 'Dto' : 'Model';

  // 1. Direct $ref → call the referenced mock factory
  if (prop.$ref) {
    const refName = prop.$ref.split('/').pop()!;
    return `mock${refName}${suffix}()`;
  }

  // 2. Array of $ref → wrap referenced mock in an array
  if (prop.type === 'array' && prop.items?.$ref) {
    const refName = prop.items.$ref.split('/').pop()!;
    return `[mock${refName}${suffix}()]`;
  }

  // 3. Array of primitives
  if (prop.type === 'array') return '[]';

  // 4. Enum → first declared value
  if (prop.enum?.length) {
    const first = prop.enum[0];
    return typeof first === 'string' ? `'${first}'` : String(first);
  }

  // 5. Example value from the swagger spec (highest fidelity)
  if (prop.example !== undefined) return formatLiteral(prop.example);

  // 6. Format-aware fallbacks (when no example is provided)
  if (prop.format === 'date-time') return `'2024-01-01T00:00:00.000Z'`;
  if (prop.format === 'date') return `'2024-01-01'`;
  if (prop.format === 'uuid') return `'00000000-0000-0000-0000-000000000000'`;
  if (prop.format === 'uri') return `'https://example.com'`;
  if (prop.format === 'email' || propName.toLowerCase().includes('email'))
    return `'user@example.com'`;

  // 7. Type defaults
  if (prop.type === 'string') return `'value'`;
  if (prop.type === 'integer' || prop.type === 'number') return `0`;
  if (prop.type === 'boolean') return `false`;

  return 'undefined';
}

function formatLiteral(value: unknown): string {
  if (typeof value === 'string') return `'${value}'`;
  if (typeof value === 'number') return `${value}`;
  if (typeof value === 'boolean') return `${value}`;
  return `'${String(value)}'`;
}