import { dev } from '$app/environment';
import { getDatabase } from '$lib/server/database';
import type { Cookies } from '@sveltejs/kit';
import { createHash, randomBytes, randomUUID } from 'node:crypto';
import { avatarUrl } from '$lib/avatar';

const COOKIE_NAME = 'shd_session';
const SESSION_SECONDS = 60 * 60 * 24 * 30;

export type AuthUser = {
  id: string;
  username: string;
  loginUsername: string | null;
  displayName: string;
  publicSlug: string | null;
  role: string;
  discordLinked: boolean;
  avatarUrl: string;
};

type LoginRequestContext = {
  request?: Request;
  getClientAddress?: () => string;
  failureReason?: string | null;
  credentialId?: string | null;
  sessionId?: string | null;
  riskFlags?: string[] | null;
};

function hashToken(token: string): string {
  return createHash('sha256').update(token).digest('hex');
}

export async function createSession(
  cookies: Cookies,
  userId: string,
): Promise<string> {
  const database = await getDatabase();
  const token = randomBytes(32).toString('base64url');
  const sessionId = randomUUID();
  const now = new Date();
  const expiresAt = new Date(now.getTime() + SESSION_SECONDS * 1000);
  const insert = await database.prepare(
    'INSERT INTO sessions (id, user_id, token_hash, expires_at, created_at) VALUES (?, ?, ?, ?, ?)',
  );

  await insert.run(
    sessionId,
    userId,
    hashToken(token),
    expiresAt.toISOString(),
    now.toISOString(),
  );

  cookies.set(COOKIE_NAME, token, {
    path: '/',
    httpOnly: true,
    sameSite: 'lax',
    secure: !dev,
    maxAge: SESSION_SECONDS,
  });
  return sessionId;
}

function describeClient(userAgent: string) {
  const clientName = /Edg\//.test(userAgent)
    ? 'Edge'
    : /Firefox\//.test(userAgent)
      ? 'Firefox'
      : /Chrome\//.test(userAgent)
        ? 'Chrome'
        : /Safari\//.test(userAgent)
          ? 'Safari'
          : 'Other';
  const operatingSystem = /Windows/.test(userAgent)
    ? 'Windows'
    : /Android/.test(userAgent)
      ? 'Android'
      : /iPhone|iPad/.test(userAgent)
        ? 'iOS/iPadOS'
        : /Mac OS X/.test(userAgent)
          ? 'macOS'
          : /Linux/.test(userAgent)
            ? 'Linux'
            : 'Other';
  const deviceType = /Mobile|Android|iPhone/.test(userAgent)
    ? 'Mobile'
    : /iPad|Tablet/.test(userAgent)
      ? 'Tablet'
      : 'Desktop';
  return { clientName, operatingSystem, deviceType };
}

export async function purgeExpiredLoginMetadata(): Promise<void> {
  const database = await getDatabase();
  const cutoff = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000).toISOString();
  const now = new Date().toISOString();
  await (
    await database.prepare(`UPDATE login_events SET ip_address=NULL,user_agent=NULL,client_name=NULL,
		operating_system=NULL,device_type=NULL,location_country=NULL,location_region=NULL,location_city=NULL,
		credential_id=NULL,session_id=NULL,sensitive_purged_at=?
		WHERE created_at<? AND sensitive_purged_at IS NULL`)
  ).run(now, cutoff);
}

export async function recordLogin(
  userId: string | null,
  provider: 'password' | 'discord' | 'magic_link' | 'passkey',
  succeeded: boolean,
  context: LoginRequestContext = {},
): Promise<void> {
  const database = await getDatabase();
  const userAgent =
    context.request?.headers.get('user-agent')?.slice(0, 1000) ?? null;
  const headers = context.request?.headers;
  const locationCountry =
    headers?.get('cf-ipcountry') ??
    headers?.get('x-vercel-ip-country') ??
    headers?.get('x-geo-country');
  const locationRegion =
    headers?.get('x-vercel-ip-country-region') ?? headers?.get('x-geo-region');
  const locationCity =
    headers?.get('x-vercel-ip-city') ?? headers?.get('x-geo-city');
  const client = describeClient(userAgent ?? '');
  const riskFlags =
    context.riskFlags ??
    (!succeeded
      ? [userId ? 'failed_authentication' : 'unknown_account_attempt']
      : []);
  let ipAddress: string | null = null;
  try {
    ipAddress = context.getClientAddress?.() ?? null;
  } catch {
    /* unavailable in some development adapters */
  }
  await (
    await database.prepare(`INSERT INTO login_events(id,user_id,provider,succeeded,ip_address,user_agent,
		client_name,operating_system,device_type,location_country,location_region,location_city,
		failure_reason,risk_flags,credential_id,session_id,created_at)
		VALUES(?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)`)
  ).run(
    randomUUID(),
    userId,
    provider,
    succeeded ? 1 : 0,
    ipAddress,
    userAgent,
    client.clientName,
    client.operatingSystem,
    client.deviceType,
    locationCountry?.slice(0, 100) ?? null,
    locationRegion?.slice(0, 100) ?? null,
    locationCity?.slice(0, 100) ?? null,
    context.failureReason ?? null,
    riskFlags.length ? riskFlags.join(',') : null,
    context.credentialId ?? null,
    context.sessionId ?? null,
    new Date().toISOString(),
  );
  await purgeExpiredLoginMetadata();
}

export async function getSessionUser(
  cookies: Cookies,
): Promise<AuthUser | null> {
  const token = cookies.get(COOKIE_NAME);
  if (!token) return null;

  const database = await getDatabase();
  const statement = await database.prepare(`
		SELECT users.id, users.username, users.login_username, COALESCE(user_profiles.display_name,users.username) AS display_name,
			user_profiles.public_slug,
			users.role, users.discord_id, user_avatars.source AS avatar_source,
			user_avatars.value AS avatar_value, user_avatars.updated_at AS avatar_updated_at,
			user_status.last_active_at,user_status.blocked_at,user_status.banned_until,
			deleted_accounts.deleted_at
		FROM sessions
		JOIN users ON users.id = sessions.user_id
		LEFT JOIN user_profiles ON user_profiles.user_id=users.id
		LEFT JOIN user_avatars ON user_avatars.user_id=users.id
		LEFT JOIN user_status ON user_status.user_id=users.id
		LEFT JOIN deleted_accounts ON deleted_accounts.user_id=users.id
		WHERE sessions.token_hash = ? AND sessions.expires_at > ?
	`);
  const user = await statement.get(hashToken(token), new Date().toISOString());

  if (!user) {
    cookies.delete(COOKIE_NAME, { path: '/' });
    return null;
  }
  const now = new Date();
  const banned =
    typeof user.banned_until === 'string' && new Date(user.banned_until) > now;
  if (user.deleted_at || user.blocked_at || banned) {
    await (
      await database.prepare('DELETE FROM sessions WHERE token_hash=?')
    ).run(hashToken(token));
    cookies.delete(COOKIE_NAME, { path: '/' });
    return null;
  }
  if (
    !user.last_active_at ||
    now.getTime() - new Date(String(user.last_active_at)).getTime() >
      5 * 60 * 1000
  ) {
    await (
      await database.prepare(`INSERT INTO user_status(user_id,last_active_at,updated_at) VALUES(?,?,?)
			ON CONFLICT(user_id) DO UPDATE SET last_active_at=excluded.last_active_at,updated_at=excluded.updated_at`)
    ).run(String(user.id), now.toISOString(), now.toISOString());
  }

  return {
    id: String(user.id),
    username: String(user.username),
    loginUsername:
      typeof user.login_username === 'string' ? user.login_username : null,
    displayName: String(user.display_name),
    publicSlug: typeof user.public_slug === 'string' ? user.public_slug : null,
    role: String(user.role),
    discordLinked: typeof user.discord_id === 'string',
    avatarUrl: avatarUrl(
      user.avatar_source,
      user.avatar_value,
      String(user.id),
      user.avatar_updated_at,
    ),
  };
}

export async function destroySession(cookies: Cookies): Promise<void> {
  const token = cookies.get(COOKIE_NAME);

  if (token) {
    const database = await getDatabase();
    const session = await (
      await database.prepare('SELECT id FROM sessions WHERE token_hash=?')
    ).get(hashToken(token));
    if (session?.id) {
      await (
        await database.prepare(
          'UPDATE login_events SET session_ended_at=?,session_end_reason=? WHERE session_id=?',
        )
      ).run(new Date().toISOString(), 'user_logout', session.id);
    }
    const statement = await database.prepare(
      'DELETE FROM sessions WHERE token_hash = ?',
    );
    await statement.run(hashToken(token));
  }

  cookies.delete(COOKIE_NAME, { path: '/' });
}