// auth.ts - Auth.js v5 configuration
import NextAuth from "next-auth";
import GitHub from "next-auth/providers/github";
import Google from "next-auth/providers/google";
import Credentials from "next-auth/providers/credentials";
import { PrismaAdapter } from "@auth/prisma-adapter";
import { prisma } from "@/lib/prisma";
import { verifyPassword } from "@/lib/password";

export const { handlers, auth, signIn, signOut } = NextAuth({
  adapter: PrismaAdapter(prisma),
  providers: [
    GitHub({
      clientId: process.env.GITHUB_ID!,
      clientSecret: process.env.GITHUB_SECRET!,
    }),
    Google({
      clientId: process.env.GOOGLE_ID!,
      clientSecret: process.env.GOOGLE_SECRET!,
    }),
    Credentials({
      credentials: {
        email: { label: "Email", type: "email" },
        password: { label: "Password", type: "password" },
      },
      async authorize(credentials) {
        if (!credentials?.email || !credentials?.password) return null;

        const user = await prisma.user.findUnique({
          where: { email: credentials.email as string },
        });

        if (!user?.passwordHash) return null;

        const valid = await verifyPassword(
          credentials.password as string,
          user.passwordHash
        );

        if (!valid) return null;

        return { id: user.id, email: user.email, name: user.name };
      },
    }),
  ],
  session: {
    strategy: "database", // Server-side sessions (not JWT)
    maxAge: 30 * 24 * 60 * 60, // 30 days
    updateAge: 24 * 60 * 60, // Refresh session every 24 hours
  },
  callbacks: {
    async session({ session, user }) {
      // Add user role to session
      session.user.id = user.id;
      session.user.role = user.role;
      return session;
    },
    async signIn({ user, account }) {
      // Block sign-in for disabled accounts
      if (user.id) {
        const dbUser = await prisma.user.findUnique({
          where: { id: user.id },
        });
        if (dbUser?.disabled) return false;
      }
      return true;
    },
  },
  pages: {
    signIn: "/login",
    error: "/auth/error",
    verifyRequest: "/auth/verify",
  },
});

// app/api/auth/[...nextauth]/route.ts
import { handlers } from "@/auth";
export const { GET, POST } = handlers;

// Middleware for route protection
// middleware.ts
import { auth } from "@/auth";
import { NextResponse } from "next/server";

export default auth((req) => {
  const isLoggedIn = !!req.auth;
  const isAuthPage = req.nextUrl.pathname.startsWith("/login") ||
                     req.nextUrl.pathname.startsWith("/register");
  const isDashboard = req.nextUrl.pathname.startsWith("/dashboard");

  if (isDashboard && !isLoggedIn) {
    return NextResponse.redirect(new URL("/login", req.url));
  }

  if (isAuthPage && isLoggedIn) {
    return NextResponse.redirect(new URL("/dashboard", req.url));
  }

  return NextResponse.next();
});

export const config = {
  matcher: ["/dashboard/:path*", "/login", "/register"],
};

// Token generation
import jwt from "jsonwebtoken";
import { randomBytes } from "crypto";

interface TokenPayload {
  sub: string; // User ID
  email: string;
  role: string;
}

interface TokenPair {
  accessToken: string;
  refreshToken: string;
  expiresIn: number;
}

const ACCESS_TOKEN_EXPIRY = "15m";
const REFRESH_TOKEN_EXPIRY = "7d";

function generateTokenPair(user: TokenPayload): TokenPair {
  const accessToken = jwt.sign(
    { sub: user.sub, email: user.email, role: user.role },
    process.env.JWT_SECRET!,
    {
      expiresIn: ACCESS_TOKEN_EXPIRY,
      issuer: "myapp",
      audience: "myapp-api",
    }
  );

  // Refresh token is opaque (not JWT) - stored server-side
  const refreshToken = randomBytes(64).toString("hex");

  return {
    accessToken,
    refreshToken,
    expiresIn: 900, // 15 minutes in seconds
  };
}

// Token refresh endpoint
async function refreshTokens(refreshToken: string): Promise<TokenPair> {
  // 1. Look up refresh token in database
  const stored = await db.refreshToken.findUnique({
    where: { token: hashToken(refreshToken) },
    include: { user: true },
  });

  if (!stored || stored.expiresAt < new Date()) {
    throw new UnauthorizedError("Invalid or expired refresh token");
  }

  // 2. Rotate refresh token (invalidate old, create new)
  await db.refreshToken.delete({ where: { id: stored.id } });

  const newPair = generateTokenPair({
    sub: stored.user.id,
    email: stored.user.email,
    role: stored.user.role,
  });

  // 3. Store new refresh token
  await db.refreshToken.create({
    data: {
      token: hashToken(newPair.refreshToken),
      userId: stored.user.id,
      expiresAt: new Date(Date.now() + 7 * 24 * 60 * 60 * 1000),
    },
  });

  return newPair;
}

// Token verification middleware
function verifyAccessToken(token: string): TokenPayload {
  try {
    const decoded = jwt.verify(token, process.env.JWT_SECRET!, {
      issuer: "myapp",
      audience: "myapp-api",
    });
    return decoded as TokenPayload;
  } catch (err) {
    if (err instanceof jwt.TokenExpiredError) {
      throw new UnauthorizedError("Access token expired");
    }
    throw new UnauthorizedError("Invalid access token");
  }
}

// Secure cookie-based token delivery (for web apps)
function setAuthCookies(res: Response, tokens: TokenPair): void {
  // Access token in httpOnly cookie
  res.headers.append(
    "Set-Cookie",
    `access_token=${tokens.accessToken}; HttpOnly; Secure; SameSite=Strict; Path=/; Max-Age=${tokens.expiresIn}`
  );

  // Refresh token in httpOnly cookie with restricted path
  res.headers.append(
    "Set-Cookie",
    `refresh_token=${tokens.refreshToken}; HttpOnly; Secure; SameSite=Strict; Path=/api/auth/refresh; Max-Age=${7 * 24 * 60 * 60}`
  );
}

// MFA setup flow
import { authenticator } from "otplib";
import QRCode from "qrcode";

// Step 1: Generate secret and QR code for user
async function setupMFA(userId: string): Promise<{ qrCodeUrl: string; secret: string }> {
  const secret = authenticator.generateSecret();

  const user = await db.user.findUniqueOrThrow({ where: { id: userId } });

  // Store encrypted secret (not yet verified)
  await db.mfaSetup.upsert({
    where: { userId },
    create: { userId, secret: encrypt(secret), verified: false },
    update: { secret: encrypt(secret), verified: false },
  });

  const otpauth = authenticator.keyuri(user.email, "MyApp", secret);
  const qrCodeUrl = await QRCode.toDataURL(otpauth);

  return { qrCodeUrl, secret };
}

// Step 2: Verify code to complete setup
async function verifyMFASetup(userId: string, code: string): Promise<string[]> {
  const setup = await db.mfaSetup.findUniqueOrThrow({
    where: { userId },
  });

  const secret = decrypt(setup.secret);
  const isValid = authenticator.verify({ token: code, secret });

  if (!isValid) {
    throw new ValidationError("Invalid verification code");
  }

  // Generate recovery codes
  const recoveryCodes = Array.from({ length: 10 }, () =>
    randomBytes(4).toString("hex").toUpperCase()
  );

  // Store hashed recovery codes
  await db.$transaction([
    db.mfaSetup.update({
      where: { userId },
      data: { verified: true },
    }),
    db.user.update({
      where: { id: userId },
      data: { mfaEnabled: true },
    }),
    ...recoveryCodes.map((code) =>
      db.recoveryCode.create({
        data: { userId, codeHash: hashCode(code) },
      })
    ),
  ]);

  return recoveryCodes; // Show to user ONCE
}

// Step 3: Verify TOTP during login
async function verifyMFA(userId: string, code: string): Promise<boolean> {
  const setup = await db.mfaSetup.findUniqueOrThrow({
    where: { userId, verified: true },
  });

  const secret = decrypt(setup.secret);

  // Check TOTP code (allows 1 window of drift)
  if (authenticator.verify({ token: code, secret })) {
    return true;
  }

  // Check recovery codes
  const recoveryCodes = await db.recoveryCode.findMany({
    where: { userId, used: false },
  });

  for (const rc of recoveryCodes) {
    if (await verifyHash(code, rc.codeHash)) {
      // Mark recovery code as used (one-time use)
      await db.recoveryCode.update({
        where: { id: rc.id },
        data: { used: true, usedAt: new Date() },
      });
      return true;
    }
  }

  return false;
}

// Permission definitions
const PERMISSIONS = {
  // Projects
  "project:read": "View project details",
  "project:write": "Edit project settings",
  "project:delete": "Delete projects",
  "project:manage_members": "Add/remove project members",

  // Billing
  "billing:read": "View billing information",
  "billing:write": "Manage subscriptions and payments",

  // Admin
  "admin:users": "Manage all users",
  "admin:settings": "Manage organization settings",
} as const;

type Permission = keyof typeof PERMISSIONS;

// Role definitions
const ROLES: Record<string, Permission[]> = {
  viewer: ["project:read"],
  editor: ["project:read", "project:write"],
  admin: [
    "project:read",
    "project:write",
    "project:delete",
    "project:manage_members",
    "billing:read",
    "billing:write",
  ],
  owner: Object.keys(PERMISSIONS) as Permission[],
};

// Permission check middleware
function requirePermission(...requiredPermissions: Permission[]) {
  return async (req: Request, res: Response, next: NextFunction) => {
    const user = req.user;
    if (!user) {
      return res.status(401).json({ error: "Authentication required" });
    }

    const userPermissions = ROLES[user.role] ?? [];
    const hasAllPermissions = requiredPermissions.every((p) =>
      userPermissions.includes(p)
    );

    if (!hasAllPermissions) {
      return res.status(403).json({
        error: "Insufficient permissions",
        required: requiredPermissions,
        current: user.role,
      });
    }

    next();
  };
}

// Usage in routes
app.get("/api/projects/:id", requirePermission("project:read"), getProject);
app.put("/api/projects/:id", requirePermission("project:write"), updateProject);
app.delete("/api/projects/:id", requirePermission("project:delete"), deleteProject);

// Component-level permission checks (React)
function usePermission(permission: Permission): boolean {
  const { data: session } = useSession();
  if (!session?.user?.role) return false;
  const permissions = ROLES[session.user.role] ?? [];
  return permissions.includes(permission);
}

function ProjectSettings({ project }: { project: Project }) {
  const canEdit = usePermission("project:write");
  const canDelete = usePermission("project:delete");

  return (
    <div>
      <h2>Settings</h2>
      {canEdit ? (
        <ProjectForm project={project} />
      ) : (
        <ProjectDetails project={project} />
      )}
      {canDelete && <DeleteProjectButton projectId={project.id} />}
    </div>
  );
}