import { createHash, createHmac, randomBytes } from 'node:crypto';
import { Injectable, Logger, UnauthorizedException } from '@nestjs/common';
import { JwtService } from '@nestjs/jwt';
import { AdminRole } from '@prisma/client';
import * as bcrypt from 'bcryptjs';
import { PrismaService } from '../../prisma/prisma.service';
import {
  IamInvalidCredentialsError,
  IamMfaRequiredError,
  IamService,
  type IamIdentity,
} from '../iam/iam.service';
import { AdminSessionService } from '../sessions/admin-session.service';
import { envList, envOr, envOrNull, pickExactUri } from '../../common/env';
import type { LoginDto } from './dto/login.dto';
import { compareLocalHash } from './password-hash';
import { SUPER_ADMIN_MOBILE, isSuperAdmin, withSuperAdminRids } from './super-admin';

export { compareLocalHash, OTP_ONLY_PASSWORD_HASH } from './password-hash';

// TEMPORARY hardcoded super-admin login (username = password). Remove before going live.
const STATIC_ADMIN_MOBILE = SUPER_ADMIN_MOBILE;

@Injectable()
export class AuthService {
  private readonly logger = new Logger(AuthService.name);

  constructor(
    private readonly prisma: PrismaService,
    private readonly jwt: JwtService,
    private readonly iam: IamService,
    private readonly sessions: AdminSessionService,
  ) {}

  /**
   * Port of legacy AdminController::login (henza_server).
   *
   * Legacy issued a random 60-char string as `api_token` and persisted it on the
   * user row; this issues a signed JWT instead. The response keeps the legacy
   * shape the admin panel's auth store reads:
   *   - `api_token`  -> stored in localStorage under token/branch_token
   *   - `roles`      -> [{ rid }], mapped to rids by the frontend then expanded
   *                     through checkParent()
   *
   * Deliberate deviation from legacy: a bad phone and a bad password both return
   * 401 here. Legacy returned 404 (firstOrFail) for an unknown phone and 422 for
   * a wrong password, which let anyone enumerate valid admin phone numbers.
   */
  async login(dto: LoginDto, clientIp?: string, userAgent?: string) {
    const isStaticAdmin =
      dto.phone?.trim() === STATIC_ADMIN_MOBILE && dto.password === STATIC_ADMIN_MOBILE;
    if (isStaticAdmin) {
      await this.ensureStaticAdmin();
    }

    const user = await this.prisma.admin.findUnique({
      where: { mobile: isStaticAdmin ? STATIC_ADMIN_MOBILE : dto.phone },
      include: { userType: { include: { permissions: true } } },
    });

    if (!user || !user.isActive) {
      throw new UnauthorizedException('نام کاربری یا رمز عبور اشتباه است');
    }

    const verified = isStaticAdmin
      ? { ok: true as const, identity: undefined }
      : await this.verifyPassword(dto, user.passwordHash, clientIp);
    if (!verified.ok) {
      throw new UnauthorizedException('نام کاربری یا رمز عبور اشتباه است');
    }

    // While session tracking is off this is null and the token is signed exactly
    // as before — same payload, same claims.
    const jti = this.sessions.newTokenId();
    const apiToken = await this.jwt.signAsync({
      sub: user.id,
      mobile: user.mobile,
      ...(jti ? { jti } : {}),
    });

    if (jti) {
      // Recorded so a central sign-out (or an admin revoking the session) can end
      // this token before it expires — see AdminSessionService.
      await this.sessions.record({
        jti,
        adminId: user.id,
        iamSessionId: verified.identity?.sessionId ?? null,
        iamSub: verified.identity?.sub ?? null,
        ipAddress: clientIp ?? null,
        userAgent: userAgent ?? null,
      });
    }

    const bootstrap = this.iam.browserBootstrapUrl(verified.identity?.browserTicket, 'admin');
    return {
      id: user.id,
      name: user.fullName,
      fullName: user.fullName,
      mobile: user.mobile,
      role: user.role,
      ut: user.userTypeId,
      branch_id: user.branchId,
      is_super_admin: isSuperAdmin(user.mobile),
      api_token: apiToken,
      roles: withSuperAdminRids(user.mobile, (user.userType?.permissions ?? []).map((p) => p.rid)).map(
        (rid) => ({ rid }),
      ),
      ...(bootstrap ? { iamBootstrapUrl: bootstrap } : {}),
    };
  }

  beginBrowserSso(requestedRedirect?: string): { authorizeUrl: string; cookie: string } | null {
    if (!this.iam.enabled) return null;
    const redirectUri = pickExactUri(requestedRedirect, [
      envOrNull('IAM_ADMIN_REDIRECT_URI'),
      ...envList('IAM_ADMIN_REDIRECT_URIS'),
    ]);
    const clientId = envOrNull('IAM_CLIENT_ID');
    if (!redirectUri || !clientId) return null;

    const state = randomBytes(24).toString('base64url');
    const nonce = randomBytes(24).toString('base64url');
    const verifier = randomBytes(48).toString('base64url');
    const challenge = createHash('sha256').update(verifier).digest('base64url');
    const payload = Buffer.from(JSON.stringify({ state, nonce, verifier, redirectUri })).toString('base64url');
    const sig = createHmac('sha256', this.ssoSecret()).update(payload).digest('base64url');
    const secure = redirectUri.startsWith('https:');
    const cookie =
      `gb_admin_iam_sso=${payload}.${sig}; HttpOnly; Path=/; Max-Age=180; SameSite=Lax` +
      (secure ? '; Secure' : '');

    const url = new URL(`${this.iam.issuer}/oauth/authorize`);
    url.searchParams.set('response_type', 'code');
    url.searchParams.set('client_id', clientId);
    url.searchParams.set('redirect_uri', redirectUri);
    url.searchParams.set('scope', 'openid profile email');
    url.searchParams.set('state', state);
    url.searchParams.set('nonce', nonce);
    url.searchParams.set('code_challenge', challenge);
    url.searchParams.set('code_challenge_method', 'S256');
    url.searchParams.set('prompt', 'none');
    return { authorizeUrl: url.toString(), cookie };
  }

  async completeBrowserSso(cookieValue: string | null, code: string, state: string, ip?: string, userAgent?: string) {
    const pending = this.readSsoCookie(cookieValue);
    if (!pending || pending.state !== state) {
      throw new UnauthorizedException('درخواست ورود مشترک معتبر نیست');
    }

    const claims = await this.iam.exchangeAuthorizationCode(code, pending.verifier, pending.redirectUri);
    if (!claims.phoneNumber) {
      throw new UnauthorizedException('هویت مشترک شماره موبایل ندارد');
    }

    const user = await this.prisma.admin.findFirst({
      where: { mobile: { in: mobileVariants(claims.phoneNumber) }, isActive: true },
      include: { userType: { include: { permissions: true } } },
    });
    if (!user) {
      throw new UnauthorizedException('حساب مدیری با این شماره در این سامانه نیست');
    }

    const identity: IamIdentity = {
      sub: claims.sub,
      email: null,
      phoneNumber: claims.phoneNumber,
      firstName: null,
      lastName: null,
      sessionId: claims.sessionId,
      browserTicket: null,
    };
    return this.issueAdminToken(user, identity, ip, userAgent);
  }

  centralLogoutUrl(requestedReturn?: string): string | null {
    if (!this.iam.enabled) return null;
    const redirect = pickExactUri(requestedReturn, [
      envOrNull('IAM_ADMIN_POST_LOGOUT_REDIRECT_URI'),
      envOrNull('IAM_ADMIN_BROWSER_RETURN_URL'),
      ...envList('IAM_ADMIN_ALLOWED_RETURN_URLS'),
    ]);
    const clientId = envOrNull('IAM_CLIENT_ID');
    if (!redirect || !clientId) return null;
    const url = new URL(`${this.iam.issuer}/oauth/logout`);
    url.searchParams.set('client_id', clientId);
    url.searchParams.set('post_logout_redirect_uri', redirect);
    return url.toString();
  }

  private async issueAdminToken(
    user: {
      id: string;
      fullName: string;
      mobile: string;
      role: string;
      userTypeId: number | null;
      branchId: string | null;
      userType: { permissions: { rid: string }[] } | null;
    },
    identity: IamIdentity | undefined,
    ip?: string,
    userAgent?: string,
  ) {
    const jti = this.sessions.newTokenId();
    const apiToken = await this.jwt.signAsync({
      sub: user.id,
      mobile: user.mobile,
      ...(jti ? { jti } : {}),
    });
    if (jti) {
      await this.sessions.record({
        jti,
        adminId: user.id,
        iamSessionId: identity?.sessionId ?? null,
        iamSub: identity?.sub ?? null,
        ipAddress: ip ?? null,
        userAgent: userAgent ?? null,
      });
    }
    return {
      id: user.id,
      name: user.fullName,
      fullName: user.fullName,
      mobile: user.mobile,
      role: user.role,
      ut: user.userTypeId,
      branch_id: user.branchId,
      is_super_admin: isSuperAdmin(user.mobile),
      api_token: apiToken,
      roles: withSuperAdminRids(user.mobile, (user.userType?.permissions ?? []).map((p) => p.rid)).map(
        (rid) => ({ rid }),
      ),
    };
  }

  private async ensureStaticAdmin() {
    const fullAccess = await this.prisma.userType.findUnique({ where: { id: 85 } });
    const userTypeId = fullAccess ? 85 : null;
    const passwordHash = await bcrypt.hash(STATIC_ADMIN_MOBILE, 10);
    await this.prisma.admin.upsert({
      where: { mobile: STATIC_ADMIN_MOBILE },
      update: { role: AdminRole.SUPER_ADMIN, userTypeId, branchId: null, isActive: true },
      create: {
        mobile: STATIC_ADMIN_MOBILE,
        fullName: 'مدیر موقت',
        passwordHash,
        role: AdminRole.SUPER_ADMIN,
        userTypeId,
        branchId: null,
        isActive: true,
      },
    });
  }

  private ssoSecret(): string {
    return envOrNull('JWT_SECRET') || envOr('IAM_CLIENT_SECRET', 'iam-sso');
  }

  private readSsoCookie(value: string | null): { state: string; verifier: string; redirectUri: string } | null {
    if (!value || !value.includes('.')) return null;
    const split = value.lastIndexOf('.');
    const payload = value.slice(0, split);
    const sig = value.slice(split + 1);
    const expected = createHmac('sha256', this.ssoSecret()).update(payload).digest('base64url');
    if (expected.length !== sig.length) return null;
    let same = 0;
    for (let i = 0; i < expected.length; i++) same |= expected.charCodeAt(i) ^ sig.charCodeAt(i);
    if (same !== 0) return null;
    try {
      return JSON.parse(Buffer.from(payload, 'base64url').toString('utf8'));
    } catch {
      return null;
    }
  }

  /**
   * Password check, optionally delegated to the central identity service.
   *
   * With `IAM_ENABLED=false` (the default) this is exactly the previous
   * behaviour: a single bcrypt compare. With it on, the identity service is
   * asked first and the local hash is only consulted when that check could not
   * give a definite answer — so an IAM outage never blocks admin login.
   */
  private async verifyPassword(
    dto: LoginDto,
    passwordHash: string,
    clientIp?: string,
  ): Promise<{ ok: boolean; identity?: IamIdentity }> {
    if (!this.iam.enabled) {
      return { ok: await compareLocalHash(dto.password, passwordHash) };
    }

    try {
      const identity = await this.iam.verifyCredentials(dto.phone, dto.password, clientIp);

      // The IAM session id travels with the recorded session so a back-channel
      // logout can find and end exactly this session.
      return { ok: true, identity };
    } catch (error) {
      if (error instanceof IamMfaRequiredError) {
        // Nowhere to collect the code on this UI-less path; say so plainly
        // instead of silently falling back to a password the IAM may have retired.
        throw new UnauthorizedException(
          'برای این حساب احراز هویت دو مرحله‌ای فعال است و از این مسیر قابل تکمیل نیست',
        );
      }

      if (error instanceof IamInvalidCredentialsError && !this.iam.allowsLocalFallback) {
        return { ok: false };
      }

      if (!(error instanceof IamInvalidCredentialsError)) {
        this.logger.warn(
          `falling back to the local password check: ${(error as Error).message}`,
        );
        if (!this.iam.allowsLocalFallback) {
          throw new UnauthorizedException('ورود در حال حاضر ممکن نیست؛ سرویس هویت در دسترس نیست');
        }
      }

      // fallback mode: the account may not have been migrated to the IAM yet
      return { ok: await compareLocalHash(dto.password, passwordHash) };
    }
  }

  /**
   * Port of legacy UserController::showData, which the router guard calls on every
   * cold load to refresh the permission list:
   *
   *   $user['permission'] = Permission::where('ut',$user->ut)->select('rid')->get()->pluck('rid');
   *
   * Returns raw (unexpanded) rids — the frontend runs checkParent() on them, as in
   * legacy. The guard's own checks use the pre-expanded list from JwtStrategy.
   */
  async showData(adminId: string) {
    const user = await this.prisma.admin.findUnique({
      where: { id: adminId },
      include: { userType: { include: { permissions: true } } },
    });

    if (!user) {
      throw new UnauthorizedException();
    }

    return {
      id: user.id,
      name: user.fullName,
      fullName: user.fullName,
      mobile: user.mobile,
      role: user.role,
      ut: user.userTypeId,
      branch_id: user.branchId,
      user_type: user.userType ? { id: user.userType.id, title: user.userType.title } : null,
      is_super_admin: isSuperAdmin(user.mobile),
      permission: withSuperAdminRids(user.mobile, (user.userType?.permissions ?? []).map((p) => p.rid)),
    };
  }
}

function mobileVariants(raw: string): string[] {
  const digits = raw.replace(/\D/g, '');
  const variants = new Set<string>([raw.trim(), digits]);
  if (digits.startsWith('98') && digits.length >= 12) variants.add(`0${digits.slice(2)}`);
  if (digits.startsWith('0') && digits.length === 11) variants.add(`98${digits.slice(1)}`);
  return [...variants].filter((value) => value !== '');
}