/**
 * Federation Configuration
 *
 * Validates federation-related environment variables at startup.
 * Issue #338: Validate DEFAULT_WORKSPACE_ID is a valid UUID
 */

/**
 * UUID v4 regex pattern
 * Matches standard UUID format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
 * where y is 8, 9, a, or b
 */
const UUID_V4_REGEX = /^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i;

/**
 * Check if a string is a valid UUID v4
 */
export function isValidUuidV4(value: string): boolean {
  return UUID_V4_REGEX.test(value);
}

/**
 * Get the configured default workspace ID for federation
 * @throws Error if DEFAULT_WORKSPACE_ID is not set or is not a valid UUID
 */
export function getDefaultWorkspaceId(): string {
  const workspaceId = process.env.DEFAULT_WORKSPACE_ID;

  if (!workspaceId || workspaceId.trim() === "") {
    throw new Error(
      "DEFAULT_WORKSPACE_ID environment variable is required for federation but is not set. " +
        "Please configure a valid UUID v4 workspace ID for handling incoming federation connections."
    );
  }

  const trimmedId = workspaceId.trim();

  if (!isValidUuidV4(trimmedId)) {
    throw new Error(
      `DEFAULT_WORKSPACE_ID must be a valid UUID v4. ` +
        `Current value "${trimmedId}" is not a valid UUID format. ` +
        `Expected format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx (where y is 8, 9, a, or b)`
    );
  }

  return trimmedId;
}

/**
 * Validates federation configuration at startup.
 * Call this during module initialization to fail fast if misconfigured.
 *
 * @throws Error if DEFAULT_WORKSPACE_ID is not set or is not a valid UUID
 */
export function validateFederationConfig(): void {
  // Validate DEFAULT_WORKSPACE_ID - this will throw if invalid
  getDefaultWorkspaceId();
}