export type MailProfileProtocol = "smtp" | "imap";
export type MailProfileEditSection = MailProfileProtocol;
export type MailProfilePanelMode = "all" | "server" | "credentials";

export type MailProfileEditTarget =
  | {kind: "create";}
  | {kind: "profile";}
  | {kind: "server";protocol: MailProfileProtocol;serverId?: string;}
  | {kind: "credentials";protocol: MailProfileProtocol;serverId?: string;credentialId?: string;};

export type MailProfileTransportLike = {
  host?: string | null;
};

export type MailProfileTreeProfileLike = {
  id: string;
  imap?: MailProfileTransportLike | null;
};

export type MailProfileChildDescriptor = {
  kind: "server" | "credential";
  id: string;
  protocol: MailProfileProtocol;
};

export type MailProfileTransportCredentialsLike = {
  username?: string | null;
  password?: string | null;
};

export type MailProfileTargetedUpdateParts = {
  profile: Record<string, unknown>;
  smtp: Record<string, unknown>;
  imap: Record<string, unknown> | null;
  credentials: {
    smtp: MailProfileTransportCredentialsLike;
    imap: MailProfileTransportCredentialsLike;
  };
  clearImap: boolean;
};

export function mailProfileChildDescriptors(profile: MailProfileTreeProfileLike): MailProfileChildDescriptor[] {
  const children: MailProfileChildDescriptor[] = [
    { kind: "server", id: `server:${profile.id}:smtp`, protocol: "smtp" },
    { kind: "credential", id: `credential:${profile.id}:smtp`, protocol: "smtp" },
    { kind: "server", id: `server:${profile.id}:imap`, protocol: "imap" }
  ];
  if (profile.imap) children.push({ kind: "credential", id: `credential:${profile.id}:imap`, protocol: "imap" });
  return children;
}

export function mailProfileEditTargetInitialSection(target: MailProfileEditTarget): MailProfileEditSection {
  if (target.kind === "server" || target.kind === "credentials") return target.protocol;
  return "smtp";
}

export function mailProfileEditTargetPanelMode(target: MailProfileEditTarget): MailProfilePanelMode | null {
  if (target.kind === "create") return "all";
  if (target.kind === "server") return "server";
  if (target.kind === "credentials") return "credentials";
  return null;
}

export function mailProfileEditTargetVisibleSections(target: MailProfileEditTarget): MailProfileEditSection[] {
  if (target.kind === "server" || target.kind === "credentials") return [target.protocol];
  if (target.kind === "create") return ["smtp", "imap"];
  return [];
}

export function mailProfileEditTargetShowsProfileFields(target: MailProfileEditTarget): boolean {
  return target.kind === "create" || target.kind === "profile";
}

export function mailProfileEditTargetShowsSettingsPanel(target: MailProfileEditTarget): boolean {
  return target.kind !== "profile";
}

/**
 * Keep the PATCH authority surface equal to the focused editor. Profile and
 * server edits must not accidentally replay credential fields merely because
 * the form draft contains their displayed values.
 */
export function mailProfileTargetedUpdatePayload(
  target: MailProfileEditTarget,
  parts: MailProfileTargetedUpdateParts
): Record<string, unknown> {
  if (target.kind === "profile") return parts.profile;
  if (target.kind === "server") {
    if (target.protocol === "smtp") return { smtp: parts.smtp };
    return parts.imap === null
      ? { imap: null, clear_imap: parts.clearImap }
      : { imap: parts.imap };
  }
  if (target.kind === "credentials") {
    return { credentials: { [target.protocol]: parts.credentials[target.protocol] } };
  }
  throw new Error("Create is not an update target");
}

/** Omit blank create credentials so profile-write remains independent. */
export function mailProfileCreateCredentialsPayload(
  smtp: MailProfileTransportCredentialsLike,
  imap: MailProfileTransportCredentialsLike
): {smtp?: MailProfileTransportCredentialsLike;imap?: MailProfileTransportCredentialsLike;} | undefined {
  const populated = (value: MailProfileTransportCredentialsLike): MailProfileTransportCredentialsLike =>
    Object.fromEntries(
      Object.entries(value).filter(([, item]) => item !== null && item !== undefined && item !== "")
    );
  const smtpCredentials = populated(smtp);
  const imapCredentials = populated(imap);
  const result: {smtp?: MailProfileTransportCredentialsLike;imap?: MailProfileTransportCredentialsLike;} = {};
  if (Object.keys(smtpCredentials).length > 0) result.smtp = smtpCredentials;
  if (Object.keys(imapCredentials).length > 0) result.imap = imapCredentials;
  return Object.keys(result).length > 0 ? result : undefined;
}