type SignUpVerificationResult = {
  status: string | null;
  createdSessionId: string | null;
};

type SignUpForEmailVerify = {
  missingFields?: readonly string[] | null;
  unverifiedFields?: readonly string[] | null;
  update: (params: Record<string, never>) => Promise<SignUpVerificationResult>;
};

export type EmailSignUpCompletion =
  | { status: "complete"; sessionId: string }
  | { status: "incomplete"; message: string };

export async function completeEmailSignUpAfterVerify(
  signUp: SignUpForEmailVerify,
  result: SignUpVerificationResult,
): Promise<EmailSignUpCompletion> {
  if (result.status === "complete" && result.createdSessionId) {
    return { status: "complete", sessionId: result.createdSessionId };
  }

  if (result.status === "missing_requirements") {
    const missingFields = signUp.missingFields ?? [];
    const unverifiedFields = signUp.unverifiedFields ?? [];
    const onlyPhoneMissing =
      missingFields.length === 1 &&
      missingFields[0] === "phone_number" &&
      unverifiedFields.length === 0;

    if (onlyPhoneMissing) {
      try {
        const updated = await signUp.update({});
        if (updated.status === "complete" && updated.createdSessionId) {
          return { status: "complete", sessionId: updated.createdSessionId };
        }
      } catch {
        // Fall through to generic incomplete message.
      }
    }

    return {
      status: "incomplete",
      message: "One more step required. Please complete your profile to continue.",
    };
  }

  return { status: "incomplete", message: "Verification incomplete. Please try again." };
}