import { Injectable, signal, computed, inject, DestroyRef } from '@angular/core';
import { HttpClient, HttpErrorResponse } from '@angular/common/http';
import { firstValueFrom } from 'rxjs';
import {
  readStoredSession,
  writeStoredSession,
  clearStoredSession,
  StoredSession,
} from './auth.session-storage';
import {
  CROSS_TAB_CHANNEL_NAME,
  CROSS_TAB_STORAGE_KEY,
  CROSS_TAB_ROLE_CHANNEL_NAME,
  CROSS_TAB_ROLE_STORAGE_KEY,
  CrossTabInvalidationMessage,
  CrossTabRoleChangeMessage,
  encodeInvalidationMessage,
  encodeRoleChangeMessage,
  isCrossTabInvalidationMessage,
  isCrossTabRoleChangeMessage,
  isStorageInvalidationEvent,
  isStorageRoleChangeEvent,
} from './auth-session-events.pure';

export interface CurrentUser {
  id: string;
  username: string;
  role: 'admin' | 'player';
  rank?: number | null;
  points?: number;
}

interface RefreshResponse {
  accessToken: string;
  expiresIn: number;
  user: CurrentUser;
}

export interface MeResponse {
  id: string;
  username: string;
  role: 'admin' | 'player';
  rank: number | null;
  points: number;
}

export interface LoginSuccess {
  ok: true;
  accessToken: string;
  expiresIn: number;
  user: CurrentUser;
}

export interface LoginFailure {
  ok: false;
  status: number;
  code: string;
  message: string;
}

export type LoginResult = LoginSuccess | LoginFailure;

export interface RegisterSuccess {
  ok: true;
  accessToken: string;
  expiresIn: number;
  user: CurrentUser;
}

export interface RegisterFailure {
  ok: false;
  status: number;
  code: string;
  message: string;
}

export type RegisterResult = RegisterSuccess | RegisterFailure;

export interface ChangePasswordSuccess {
  ok: true;
}

export interface ChangePasswordFailure {
  ok: false;
  status: number;
  code: string;
  message: string;
}

export type ChangePasswordResult = ChangePasswordSuccess | ChangePasswordFailure;

@Injectable({ providedIn: 'root' })
export class AuthService {
  private http: HttpClient;
  private readonly destroyRef = inject(DestroyRef);

  private readonly crossTabOrigin =
    typeof crypto !== 'undefined' && typeof crypto.randomUUID === 'function'
      ? crypto.randomUUID()
      : `tab-${Math.random().toString(36).slice(2)}-${Date.now()}`;
  private channel: BroadcastChannel | null = null;
  private roleChannel: BroadcastChannel | null = null;
  private storageListener: ((ev: StorageEvent) => void) | null = null;
  private suppressBroadcast = false;

  private peerInvalidationListeners = new Set<(reason: 'peer-logout' | 'sse-unauthorized') => void>();
  private peerRoleChangeListeners = new Set<(msg: CrossTabRoleChangeMessage) => void>();

  constructor(http?: HttpClient) {
    this.http = http ?? inject(HttpClient);
    this.installCrossTabListener();
    this.destroyRef.onDestroy(() => this.teardownCrossTabListener());
  }

  private accessToken = signal<string | null>(null);
  private user = signal<CurrentUser | null>(null);
  readonly hydrated = signal<boolean>(false);
  private hydrateWaiters: Array<() => void> = [];

  readonly currentUser = computed(() => this.user());
  readonly isAuthenticated = computed(() => !!this.user());

  async ensureCsrf(): Promise<void> {
    try {
      await firstValueFrom(
        this.http.get('/api/v1/auth/csrf', { withCredentials: true }),
      );
    } catch {
      // middleware will still mint the cookie on the next response
    }
  }

  async login(creds: { username: string; password: string }): Promise<LoginResult> {
    await this.ensureCsrf();
    try {
      const res = await firstValueFrom(
        this.http.post<{ accessToken: string; expiresIn: number; user: CurrentUser }>(
          '/api/v1/auth/login',
          creds,
          { withCredentials: true, observe: 'response' },
        ),
      );
      const success: LoginSuccess = {
        ok: true,
        accessToken: res.body!.accessToken,
        expiresIn: res.body!.expiresIn,
        user: res.body!.user,
      };
      return success;
    } catch (e) {
      return mapAuthError(e as HttpErrorResponse);
    }
  }

  async register(creds: {
    username: string;
    password: string;
    passwordConfirm: string;
  }): Promise<RegisterResult> {
    await this.ensureCsrf();
    try {
      const res = await firstValueFrom(
        this.http.post<{ accessToken: string; expiresIn: number; user: CurrentUser }>(
          '/api/v1/auth/register',
          creds,
          { withCredentials: true, observe: 'response' },
        ),
      );
      const success: RegisterSuccess = {
        ok: true,
        accessToken: res.body!.accessToken,
        expiresIn: res.body!.expiresIn,
        user: res.body!.user,
      };
      return success;
    } catch (e) {
      return mapAuthError(e as HttpErrorResponse) as RegisterFailure;
    }
  }

  async logout(): Promise<void> {
    await this.ensureCsrf();
    try {
      await firstValueFrom(
        this.http.post('/api/v1/auth/logout', {}, { withCredentials: true, observe: 'response' }),
      );
    } catch {
      // ignore network/auth errors; we still clear local state
    }
    this.clearAndBroadcast();
  }

  async me(): Promise<MeResponse> {
    const res = await firstValueFrom(
      this.http.get<MeResponse>('/api/v1/auth/me', { withCredentials: true }),
    );
    const current = this.user();
    if (current && current.id === res.id) {
      this.user.set({ ...current, rank: res.rank, points: res.points });
    }
    return res;
  }

  async changePassword(dto: {
    oldPassword: string;
    newPassword: string;
    confirmNewPassword: string;
  }): Promise<ChangePasswordResult> {
    await this.ensureCsrf();
    try {
      await firstValueFrom(
        this.http.post(
          '/api/v1/auth/change-password',
          dto,
          { withCredentials: true, observe: 'response' },
        ),
      );
      return { ok: true };
    } catch (e) {
      return mapAuthError(e as HttpErrorResponse);
    }
  }

  setSession(token: string, user: CurrentUser): void {
    this.accessToken.set(token);
    this.user.set(user);
    writeStoredSession(this.sessionStorage(), { token, user });
  }

  clear(): void {
    this.accessToken.set(null);
    this.user.set(null);
    clearStoredSession(this.sessionStorage());
  }

  clearAndBroadcast(): void {
    this.clear();
    if (this.suppressBroadcast) return;
    const message = encodeInvalidationMessage(this.crossTabOrigin);
    this.publishInvalidation(message);
  }

  /**
   * Forcibly invalidate the local session (and broadcast peer
   * invalidation) — used after a destructive server-initiated action such
   * as a successful restore that revokes access. Same as a normal logout
   * from the client's perspective.
   */
  forceServerInvalidation(): void {
    this.suppressBroadcast = false;
    this.clearAndBroadcast();
  }

  handleSseUnauthorized(): void {
    this.clearAndBroadcast();
    this.notifyPeerInvalidation('sse-unauthorized');
  }

  onPeerInvalidation(cb: (reason: 'peer-logout' | 'sse-unauthorized') => void): () => void {
    this.peerInvalidationListeners.add(cb);
    return () => this.peerInvalidationListeners.delete(cb);
  }

  onPeerRoleChange(cb: (msg: CrossTabRoleChangeMessage) => void): () => void {
    this.peerRoleChangeListeners.add(cb);
    return () => this.peerRoleChangeListeners.delete(cb);
  }

  applyPeerRoleChange(newRole: 'admin' | 'player'): void {
    const current = this.user();
    if (!current) return;
    if (current.role === newRole) return;
    const updated = { ...current, role: newRole };
    this.user.set(updated);
    if (typeof window !== 'undefined') {
      try {
        writeStoredSession(this.sessionStorage(), { token: this.accessToken() ?? '', user: updated });
      } catch {
        // ignore storage failures
      }
    }
  }

  publishRoleChange(userId: string, newRole: 'admin' | 'player'): void {
    const message = encodeRoleChangeMessage(this.crossTabOrigin, userId, newRole);
    if (this.roleChannel) {
      try {
        this.roleChannel.postMessage(message);
      } catch {
        // ignore serialization failures; storage fallback still fires
      }
    }
    if (typeof window !== 'undefined' && window.localStorage) {
      try {
        window.localStorage.setItem(CROSS_TAB_ROLE_STORAGE_KEY, JSON.stringify(message));
      } catch {
        // ignore quota / serialization errors
      }
    }
  }

  getAccessToken(): string | null {
    return this.accessToken();
  }

  private publishInvalidation(message: CrossTabInvalidationMessage): void {
    if (this.channel) {
      try {
        this.channel.postMessage(message);
      } catch {
        // ignore serialization failures; the storage fallback will still fire
      }
    }
    if (typeof window !== 'undefined' && window.localStorage) {
      try {
        window.localStorage.setItem(CROSS_TAB_STORAGE_KEY, JSON.stringify(message));
      } catch {
        // ignore quota / serialization errors
      }
    }
  }

  private installCrossTabListener(): void {
    if (typeof window === 'undefined') return;
    if (typeof BroadcastChannel !== 'undefined') {
      try {
        this.channel = new BroadcastChannel(CROSS_TAB_CHANNEL_NAME);
        this.channel.addEventListener('message', this.onBroadcastMessage);
      } catch {
        this.channel = null;
      }
      try {
        this.roleChannel = new BroadcastChannel(CROSS_TAB_ROLE_CHANNEL_NAME);
        this.roleChannel.addEventListener('message', this.onRoleBroadcastMessage);
      } catch {
        this.roleChannel = null;
      }
    }
    this.storageListener = (ev: StorageEvent) => {
      if (isStorageInvalidationEvent(ev)) {
        this.handlePeerInvalidation(ev.newValue, 'peer-logout');
        return;
      }
      if (isStorageRoleChangeEvent(ev)) {
        this.handlePeerRoleChange(ev.newValue);
      }
    };
    window.addEventListener('storage', this.storageListener);
  }

  private teardownCrossTabListener(): void {
    if (this.channel) {
      try {
        this.channel.removeEventListener('message', this.onBroadcastMessage);
        this.channel.close();
      } catch {
        // ignore
      }
      this.channel = null;
    }
    if (this.roleChannel) {
      try {
        this.roleChannel.removeEventListener('message', this.onRoleBroadcastMessage);
        this.roleChannel.close();
      } catch {
        // ignore
      }
      this.roleChannel = null;
    }
    if (this.storageListener && typeof window !== 'undefined') {
      try {
        window.removeEventListener('storage', this.storageListener);
      } catch {
        // ignore
      }
      this.storageListener = null;
    }
    this.peerInvalidationListeners.clear();
    this.peerRoleChangeListeners.clear();
  }

  private readonly onBroadcastMessage = (ev: MessageEvent<unknown>) => {
    if (!isCrossTabInvalidationMessage(ev.data)) return;
    if (ev.data.origin === this.crossTabOrigin) return;
    this.handlePeerInvalidation(JSON.stringify(ev.data), 'peer-logout');
  };

  private readonly onRoleBroadcastMessage = (ev: MessageEvent<unknown>) => {
    if (!isCrossTabRoleChangeMessage(ev.data)) return;
    if (ev.data.origin === this.crossTabOrigin) return;
    this.handlePeerRoleChange(JSON.stringify(ev.data));
  };

  private handlePeerInvalidation(
    raw: string | null,
    reason: 'peer-logout' | 'sse-unauthorized',
  ): void {
    if (raw) {
      try {
        const parsed = JSON.parse(raw) as unknown;
        if (!isCrossTabInvalidationMessage(parsed)) return;
        if (parsed.origin === this.crossTabOrigin) return;
      } catch {
        return;
      }
    }
    if (!this.isAuthenticated()) return;
    this.suppressBroadcast = true;
    this.clear();
    this.suppressBroadcast = false;
    this.notifyPeerInvalidation(reason);
  }

  private notifyPeerInvalidation(reason: 'peer-logout' | 'sse-unauthorized'): void {
    for (const cb of this.peerInvalidationListeners) {
      try {
        cb(reason);
      } catch {
        // ignore listener errors
      }
    }
  }

  private handlePeerRoleChange(raw: string | null): void {
    if (!raw) return;
    let parsed: CrossTabRoleChangeMessage | null = null;
    try {
      const candidate = JSON.parse(raw) as unknown;
      if (!isCrossTabRoleChangeMessage(candidate)) return;
      if (candidate.origin === this.crossTabOrigin) return;
      parsed = candidate;
    } catch {
      return;
    }
    if (!parsed) return;
    const me = this.user();
    if (!me) return;
    if (me.id !== parsed.userId) return;
    this.applyPeerRoleChange(parsed.newRole);
    for (const cb of this.peerRoleChangeListeners) {
      try {
        cb(parsed);
      } catch {
        // ignore listener errors
      }
    }
  }

  private sessionStorage(): Storage {
    return typeof window !== 'undefined' ? window.sessionStorage : (undefined as unknown as Storage);
  }

  private restoreFromStorage(): void {
    const stored = readStoredSession(this.sessionStorage());
    if (stored) {
      this.accessToken.set(stored.token);
      this.user.set(stored.user as CurrentUser);
    }
  }

  private markHydrated(): void {
    if (this.hydrated()) return;
    this.hydrated.set(true);
    const waiters = this.hydrateWaiters;
    this.hydrateWaiters = [];
    for (const resolve of waiters) resolve();
  }

  waitUntilHydrated(): Promise<void> {
    if (this.hydrated()) return Promise.resolve();
    return new Promise<void>((resolve) => {
      this.hydrateWaiters.push(resolve);
    });
  }

  async restoreSession(): Promise<boolean> {
    this.restoreFromStorage();

    try {
      const res = await firstValueFrom(
        this.http.post<RefreshResponse>(
          '/api/v1/auth/refresh',
          {},
          { withCredentials: true },
        ),
      );
      if (res && res.accessToken && res.user) {
        this.setSession(res.accessToken, res.user);
        this.markHydrated();
        return true;
      }
      this.clear();
      this.markHydrated();
      return false;
    } catch {
      this.clear();
      this.markHydrated();
      return false;
    }
  }
}

function mapAuthError(err: HttpErrorResponse): LoginFailure {
  const body = err.error as { code?: string; message?: string } | null;
  return {
    ok: false,
    status: err.status ?? 0,
    code: body?.code ?? 'INTERNAL',
    message: body?.message ?? err.message ?? 'Authentication failed',
  };
}