import { betterAuth } from 'better-auth';
import { drizzleAdapter } from 'better-auth/adapters/drizzle';

import { db } from '@/lib/db';

/**
 * Better Auth server configuration.
 *
 * Sessions are stored in PostgreSQL (not Redis) per SECURITY-GUIDELINES.md §1.2.
 * The drizzle adapter handles session persistence via the existing `sessions` table.
 */
/**
 * In dev, allow requests from any LAN IP so the same `pnpm dev` instance can
 * serve both localhost (Mac) and the LAN IP (iPhone on Wi-Fi). In production,
 * trustedOrigins is locked down to NEXT_PUBLIC_APP_URL only.
 */
/**
 * In dev, allow localhost + any LAN-IP origin so the same `pnpm dev` instance
 * can serve both Mac (localhost) and iPhone-on-Wi-Fi (192.168.x.x). The
 * function form is preferred over a static list because the LAN IP can vary
 * across networks. In production, lock down to NEXT_PUBLIC_APP_URL only.
 */
const isProd = process.env.NODE_ENV === 'production';
const DEV_ORIGIN_PATTERNS = [
  /^https?:\/\/(localhost|127\.0\.0\.1)(:\d+)?$/,
  /^https?:\/\/192\.168\.\d+\.\d+(:\d+)?$/,
  /^https?:\/\/10\.\d+\.\d+\.\d+(:\d+)?$/,
];

const trustedOrigins: (request?: Request) => Promise<string[]> = async (request) => {
  if (isProd) {
    const prodUrl = process.env.NEXT_PUBLIC_APP_URL;
    return prodUrl ? [prodUrl] : [];
  }
  const origin = request?.headers.get('origin') ?? '';
  if (origin && DEV_ORIGIN_PATTERNS.some((re) => re.test(origin))) {
    return [origin];
  }
  return ['http://localhost:3000', 'http://localhost:3001'];
};

/**
 * `betterAuth(...)` is wrapped in a lazy initializer so the auth singleton
 * is constructed on first property access (i.e. first request) rather than
 * at module import. This is required so that Next.js's "collect page data"
 * phase during `pnpm build` doesn't trigger better-auth's "default secret"
 * check against the unset BETTER_AUTH_SECRET — at build time the auth
 * config is never accessed, and at runtime the env is fully populated.
 *
 * Call sites continue to use `auth.api.foo(...)` unchanged; the Proxy
 * intercepts the property access and resolves the real instance just-in-
 * time. `typeof auth.$Infer.Session` is a type-only access and never
 * triggers the Proxy at runtime.
 */
function buildAuth() {
  return betterAuth({
    database: drizzleAdapter(db, {
      provider: 'pg',
    }),

    trustedOrigins,

    emailAndPassword: {
      enabled: true,
      minPasswordLength: 9,
      // Accounts are admin-created only - no self-service email verification flow.
      requireEmailVerification: false,
      // Self-service password reset for CRM users. The reset link lands
      // on the existing /reset-password page (which already handles
      // better-auth's token + new-password POST). The email send goes
      // through the shared SMTP infra so EMAIL_REDIRECT_TO honours it
      // in dev.
      sendResetPassword: async ({ user, url }) => {
        const { sendEmail } = await import('@/lib/email');
        const subject = 'Reset your Port Nimara CRM password';
        const html = `
        <p>Hi ${user.name || 'there'},</p>
        <p>You requested a password reset for your Port Nimara CRM account.</p>
        <p><a href="${url}">Click here to set a new password</a> — the link expires in 1 hour.</p>
        <p>If you didn't request this, you can safely ignore this email.</p>
      `;
        const text = `Reset your password: ${url}`;
        await sendEmail(user.email, subject, html, undefined, text);
      },
    },

    session: {
      // Enable cookie-level session caching to reduce DB reads (5-minute cache).
      cookieCache: {
        enabled: true,
        maxAge: 5 * 60,
      },
      // Absolute session lifetime: 24 hours.
      expiresIn: 60 * 60 * 24,
      // Refresh the session whenever the user is active in the last 25% of its lifetime (6h).
      updateAge: 60 * 60 * 6,
    },

    advanced: {
      cookiePrefix: 'pn-crm',
      defaultCookieAttributes: {
        httpOnly: true,
        secure: process.env.NODE_ENV === 'production',
        sameSite: 'strict' as const,
      },
    },

    logger: {
      disabled: false,
      level: 'error' as const,
    },
  });
}

type AuthInstance = ReturnType<typeof buildAuth>;

let _authInstance: AuthInstance | null = null;
function getAuth(): AuthInstance {
  if (!_authInstance) _authInstance = buildAuth();
  return _authInstance;
}

export const auth = new Proxy({} as AuthInstance, {
  get(_target, prop) {
    return Reflect.get(getAuth(), prop);
  },
});

export type Session = typeof auth.$Infer.Session;
export type User = typeof auth.$Infer.Session.user;