const SESSION_KEY = "geo.ops-web.session";
const PREFERENCE_KEY = "geo.ops-web.login-preference";

export interface OperatorView {
  id: number;
  username: string;
  display_name: string;
  email: string | null;
  role: string;
  status: string;
}

export interface OpsSession {
  accessToken: string | null;
  expiresAt: number | null;
  operator: OperatorView | null;
}

export interface LoginPreference {
  remember: boolean;
  lastUsername: string;
}

export interface StoredSession {
  session: OpsSession;
  persistent: boolean;
}

function emptySession(): OpsSession {
  return { accessToken: null, expiresAt: null, operator: null };
}

function emptyPreference(): LoginPreference {
  return { remember: false, lastUsername: "" };
}

function hasWindow(): boolean {
  return typeof window !== "undefined";
}

function readFrom(storage: Storage): OpsSession | null {
  try {
    const raw = storage.getItem(SESSION_KEY);
    if (!raw) return null;
    const parsed = JSON.parse(raw) as Partial<OpsSession>;
    if (typeof parsed.accessToken !== "string" || !parsed.accessToken) return null;
    return {
      accessToken: parsed.accessToken,
      expiresAt: typeof parsed.expiresAt === "number" ? parsed.expiresAt : null,
      operator:
        parsed.operator && typeof parsed.operator === "object"
          ? (parsed.operator as OperatorView)
          : null,
    };
  } catch {
    return null;
  }
}

export function readStoredSession(): StoredSession {
  if (!hasWindow()) return { session: emptySession(), persistent: false };
  const persistent = readFrom(window.localStorage);
  if (persistent) return { session: persistent, persistent: true };
  const ephemeral = readFrom(window.sessionStorage);
  if (ephemeral) return { session: ephemeral, persistent: false };
  return { session: emptySession(), persistent: false };
}

export function writeStoredSession(session: OpsSession, persistent: boolean): void {
  if (!hasWindow()) return;
  const target = persistent ? window.localStorage : window.sessionStorage;
  const other = persistent ? window.sessionStorage : window.localStorage;
  try {
    target.setItem(SESSION_KEY, JSON.stringify(session));
  } catch {
    // ignore quota / serialization errors
  }
  try {
    other.removeItem(SESSION_KEY);
  } catch {
    // noop
  }
}

export function clearStoredSession(): void {
  if (!hasWindow()) return;
  try {
    window.localStorage.removeItem(SESSION_KEY);
  } catch {
    // noop
  }
  try {
    window.sessionStorage.removeItem(SESSION_KEY);
  } catch {
    // noop
  }
}

export function readLoginPreference(): LoginPreference {
  if (!hasWindow()) return emptyPreference();
  try {
    const raw = window.localStorage.getItem(PREFERENCE_KEY);
    if (!raw) return emptyPreference();
    const parsed = JSON.parse(raw) as Partial<LoginPreference>;
    return {
      remember: parsed.remember === true,
      lastUsername: typeof parsed.lastUsername === "string" ? parsed.lastUsername : "",
    };
  } catch {
    return emptyPreference();
  }
}

export function writeLoginPreference(pref: LoginPreference): void {
  if (!hasWindow()) return;
  try {
    window.localStorage.setItem(PREFERENCE_KEY, JSON.stringify(pref));
  } catch {
    // noop
  }
}