import crypto from 'node:crypto';
import type { FastifyInstance } from 'fastify';
import { z } from 'zod';
import { and, eq, gte, isNull, sql } from 'drizzle-orm';
import {
  getDb,
  users,
  firms,
  loginAttempts,
  passwordResets,
  emailVerifications,
  sessions as sessionsTable,
} from '@lawdesk/db';
import { hashPassword, verifyPassword } from '../auth/password';
import { SESSION_COOKIE, createSession, destroySession } from '../auth/sessions';
import { ensureSuperadminFlag } from '../auth/superadmin';
import { generateCsrfToken } from '../auth/csrf';
import {
  sendEmail,
  passwordResetEmail,
  passwordChangedEmail,
  welcomeEmail,
  verifyEmailEmail,
} from '../lib/email';
import { env } from '../env';

const signupBody = z.object({
  email: z.string().email().max(254).toLowerCase().trim(),
  password: z.string().min(10).max(200),
  fullName: z.string().min(1).max(120).trim(),
  firmName: z.string().min(1).max(160).trim(),
});

const loginBody = z.object({
  email: z.string().email().max(254).toLowerCase().trim(),
  password: z.string().min(1).max(200),
});

const MAX_FAILS_PER_15_MIN = 5;

// Mints an email-verification token (stored hashed, like password resets) and returns the
// clickable URL. The link hits the API directly — the vite dev proxy and the prod same-origin
// setup both route /api/* to this server.
async function createVerifyUrl(userId: string): Promise<string> {
  const rawToken = crypto.randomBytes(32).toString('base64url');
  const tokenHash = crypto.createHash('sha256').update(rawToken).digest('hex');
  const expiresAt = new Date(Date.now() + 24 * 60 * 60 * 1000); // 24 hours
  await getDb().insert(emailVerifications).values({ tokenHash, userId, expiresAt });
  return `${env.PUBLIC_URL}/api/auth/verify-email?token=${rawToken}`;
}

async function recentFailedAttempts(email: string, ip: string | null): Promise<number> {
  const since = new Date(Date.now() - 15 * 60 * 1000);
  const db = getDb();
  const conditions = [
    eq(loginAttempts.email, email),
    eq(loginAttempts.success, false),
    gte(loginAttempts.attemptedAt, since),
  ];
  // Key the lockout on (email, ip). A single IP that keeps failing against an account gets
  // throttled, but an attacker firing bad passwords from another IP can no longer lock the
  // legitimate owner out of their own account (previously this counted by email alone).
  if (ip) conditions.push(eq(loginAttempts.ip, ip));
  const rows = await db
    .select({ count: sql<number>`count(*)::int` })
    .from(loginAttempts)
    .where(and(...conditions));
  return rows[0]?.count ?? 0;
}

export async function authRoutes(app: FastifyInstance) {
  app.post(
    '/api/auth/signup',
    { config: { rateLimit: { max: 5, timeWindow: '1 hour' } } },
    async (req, reply) => {
    const body = signupBody.parse(req.body);
    const db = getDb();

    const existing = await db.select({ id: users.id }).from(users).where(eq(users.email, body.email)).limit(1);
    if (existing.length > 0) {
      return reply.code(409).send({ error: 'email_taken' });
    }

    const passwordHash = await hashPassword(body.password);

    const [firm] = await db.insert(firms).values({ name: body.firmName }).returning();
    if (!firm) return reply.code(500).send({ error: 'firm_create_failed' });

    const [user] = await db
      .insert(users)
      .values({
        email: body.email,
        passwordHash,
        fullName: body.fullName,
        firmId: firm.id,
        role: 'owner',
      })
      .returning();
    if (!user) return reply.code(500).send({ error: 'user_create_failed' });

    const isSuperadmin = await ensureSuperadminFlag(
      user.id,
      user.email,
      user.isSuperadmin,
      user.emailVerifiedAt,
    );

    const { token, expiresAt } = await createSession({
      userId: user.id,
      ip: req.ip,
      userAgent: req.headers['user-agent'] ?? null,
    });
    app.setSessionCookie(reply, token, expiresAt);
    app.setCsrfCookie(reply, generateCsrfToken());

    // Fire-and-forget welcome email with a verification link (no blocking)
    createVerifyUrl(user.id)
      .catch((err) => {
        app.log.warn({ err }, 'verify token create failed — sending welcome without link');
        return null;
      })
      .then((verifyUrl) => {
        const welcome = welcomeEmail(user.fullName, verifyUrl);
        return sendEmail({ to: user.email, ...welcome });
      })
      .catch((err) => app.log.warn({ err }, 'welcome email failed'));

    return reply.code(201).send({
      user: {
        id: user.id,
        email: user.email,
        fullName: user.fullName,
        firmId: firm.id,
        role: user.role,
        isSuperadmin,
        isSuspended: user.isSuspended,
        emailVerified: Boolean(user.emailVerifiedAt),
      },
    });
  });

  app.post(
    '/api/auth/login',
    { config: { rateLimit: { max: 10, timeWindow: '15 minutes' } } },
    async (req, reply) => {
    const body = loginBody.parse(req.body);
    const db = getDb();
    const ip = req.ip ?? null;

    const fails = await recentFailedAttempts(body.email, ip);
    if (fails >= MAX_FAILS_PER_15_MIN) {
      return reply.code(429).send({ error: 'too_many_attempts' });
    }

    const [user] = await db.select().from(users).where(eq(users.email, body.email)).limit(1);

    const ok = user ? await verifyPassword(user.passwordHash, body.password) : false;

    await db.insert(loginAttempts).values({ email: body.email, ip, success: ok });

    if (!ok || !user) {
      return reply.code(401).send({ error: 'invalid_credentials' });
    }

    if (user.isSuspended) {
      return reply.code(403).send({ error: 'account_suspended' });
    }

    const isSuperadmin = await ensureSuperadminFlag(
      user.id,
      user.email,
      user.isSuperadmin,
      user.emailVerifiedAt,
    );

    await db.update(users).set({ lastSeenAt: new Date() }).where(eq(users.id, user.id));

    const { token, expiresAt } = await createSession({
      userId: user.id,
      ip,
      userAgent: req.headers['user-agent'] ?? null,
    });
    app.setSessionCookie(reply, token, expiresAt);
    app.setCsrfCookie(reply, generateCsrfToken());

    return {
      user: {
        id: user.id,
        email: user.email,
        fullName: user.fullName,
        firmId: user.firmId,
        role: user.role,
        isSuperadmin,
        isSuspended: user.isSuspended,
        emailVerified: Boolean(user.emailVerifiedAt),
      },
    };
  });

  app.post('/api/auth/logout', async (req, reply) => {
    const token = req.cookies?.[SESSION_COOKIE];
    if (token) await destroySession(token);
    app.clearSessionCookie(reply);
    app.clearCsrfCookie(reply);
    return { ok: true };
  });

  app.get('/api/auth/me', async (req, reply) => {
    if (!req.user) return reply.code(401).send({ error: 'unauthorized' });
    return { user: req.user };
  });

  // ─────────────────────────── Password reset ───────────────────────────

  // Request a reset link. Always returns ok=true so an attacker can't enumerate emails.
  app.post(
    '/api/auth/request-password-reset',
    { config: { rateLimit: { max: 5, timeWindow: '15 minutes' } } },
    async (req) => {
      const parsed = z.object({ email: z.string().email().max(254).toLowerCase().trim() }).safeParse(req.body);
      if (!parsed.success) return { ok: true };

      const db = getDb();
      const [user] = await db.select().from(users).where(eq(users.email, parsed.data.email)).limit(1);
      if (!user || user.isSuspended) return { ok: true };

      const rawToken = crypto.randomBytes(32).toString('base64url');
      const tokenHash = crypto.createHash('sha256').update(rawToken).digest('hex');
      const expiresAt = new Date(Date.now() + 60 * 60 * 1000); // 1 hour

      await db.insert(passwordResets).values({ tokenHash, userId: user.id, expiresAt });

      const resetUrl = `${env.PUBLIC_URL}/reset-password?token=${rawToken}`;
      const tpl = passwordResetEmail(user.fullName, resetUrl);
      sendEmail({ to: user.email, ...tpl }).catch((err) =>
        app.log.warn({ err }, 'password reset email failed'),
      );

      return { ok: true };
    },
  );

  // Apply a new password using the token from the email.
  app.post(
    '/api/auth/reset-password',
    { config: { rateLimit: { max: 10, timeWindow: '15 minutes' } } },
    async (req, reply) => {
      const parsed = z
        .object({
          token: z.string().min(20).max(200),
          password: z.string().min(10).max(200),
        })
        .safeParse(req.body);
      if (!parsed.success) return reply.code(400).send({ error: 'invalid_input' });

      const tokenHash = crypto.createHash('sha256').update(parsed.data.token).digest('hex');
      const db = getDb();

      const [reset] = await db
        .select()
        .from(passwordResets)
        .where(and(eq(passwordResets.tokenHash, tokenHash), isNull(passwordResets.consumedAt)))
        .limit(1);

      if (!reset) return reply.code(400).send({ error: 'invalid_or_used_token' });
      if (reset.expiresAt.getTime() < Date.now()) {
        return reply.code(400).send({ error: 'token_expired' });
      }

      const [user] = await db.select().from(users).where(eq(users.id, reset.userId)).limit(1);
      if (!user) return reply.code(400).send({ error: 'user_not_found' });
      if (user.isSuspended) return reply.code(403).send({ error: 'account_suspended' });

      const passwordHash = await hashPassword(parsed.data.password);

      await db.transaction(async (tx) => {
        await tx
          .update(users)
          .set({ passwordHash, updatedAt: new Date() })
          .where(eq(users.id, user.id));
        await tx
          .update(passwordResets)
          .set({ consumedAt: new Date() })
          .where(eq(passwordResets.tokenHash, tokenHash));
        // Revoke all existing sessions for this user — they should re-login with the new password
        await tx.delete(sessionsTable).where(eq(sessionsTable.userId, user.id));
      });

      // Security notice — lets the real owner react fast if the reset wasn't theirs.
      const tpl = passwordChangedEmail(user.fullName);
      sendEmail({ to: user.email, ...tpl }).catch((err) =>
        app.log.warn({ err }, 'password changed email failed'),
      );

      return { ok: true };
    },
  );

  // ─────────────────────────── Email verification ───────────────────────────

  // Landing endpoint for the link in welcome/verification emails. Redirects to the web app
  // either way; ?verified=1|0 lets the UI show a toast.
  app.get('/api/auth/verify-email', async (req, reply) => {
    const parsed = z.object({ token: z.string().min(20).max(200) }).safeParse(req.query);
    if (!parsed.success) return reply.redirect(`${env.PUBLIC_URL}/login?verified=0`);

    const tokenHash = crypto.createHash('sha256').update(parsed.data.token).digest('hex');
    const db = getDb();

    const [row] = await db
      .select()
      .from(emailVerifications)
      .where(and(eq(emailVerifications.tokenHash, tokenHash), isNull(emailVerifications.consumedAt)))
      .limit(1);

    if (!row || row.expiresAt.getTime() < Date.now()) {
      return reply.redirect(`${env.PUBLIC_URL}/login?verified=0`);
    }

    await db.transaction(async (tx) => {
      await tx
        .update(users)
        .set({ emailVerifiedAt: new Date(), updatedAt: new Date() })
        .where(and(eq(users.id, row.userId), isNull(users.emailVerifiedAt)));
      await tx
        .update(emailVerifications)
        .set({ consumedAt: new Date() })
        .where(eq(emailVerifications.tokenHash, tokenHash));
    });

    return reply.redirect(`${env.PUBLIC_URL}/login?verified=1`);
  });

  // Re-send the verification email for the logged-in user.
  app.post(
    '/api/auth/resend-verification',
    { config: { rateLimit: { max: 3, timeWindow: '15 minutes' } } },
    async (req, reply) => {
      if (!req.user) return reply.code(401).send({ error: 'unauthorized' });

      const db = getDb();
      const [user] = await db.select().from(users).where(eq(users.id, req.user.id)).limit(1);
      if (!user) return reply.code(404).send({ error: 'user_not_found' });
      if (user.emailVerifiedAt) return { ok: true, alreadyVerified: true };

      const verifyUrl = await createVerifyUrl(user.id);
      const tpl = verifyEmailEmail(user.fullName, verifyUrl);
      sendEmail({ to: user.email, ...tpl }).catch((err) =>
        app.log.warn({ err }, 'verification email failed'),
      );

      return { ok: true };
    },
  );
}