import { db } from "./db.mjs";
import { json, readBody } from "./http.mjs";
import { clearSessionCookie, createSession, deleteSession, getSession, parseCookies, sessionCookie } from "./session.mjs";
import { hashPassword, verifyPassword } from "./security.mjs";
import { hasPermission, publicPermissions } from "./permissions.mjs";

export function publicUser(user) {
  if (!user) return null;

  return {
    id: user.id,
    email: user.email,
    name: user.name,
    avatarUrl: user.avatar_url,
    role: user.role,
    status: user.status || "active",
    emailVerified: Boolean(user.email_verified),
    createdAt: user.created_at,
    updatedAt: user.updated_at,
    lastLoginAt: user.last_login_at,
    permissions: publicPermissions(user),
  };
}

export function getRequestSession(request) {
  const cookies = parseCookies(request.headers.cookie);
  const sessionId = cookies.vpc_session;
  const session = getSession(sessionId);
  return { sessionId, session };
}

export function requireCmsUser(request, response) {
  const { session } = getRequestSession(request);

  if (!session?.user?.id) {
    json(response, 401, { error: "Not signed in" });
    return undefined;
  }

  return session.user;
}

export function requirePermission(request, response, permission) {
  const user = requireCmsUser(request, response);

  if (!user) return undefined;

  if (!hasPermission(user, permission)) {
    json(response, 403, { error: "Permission denied" });
    return undefined;
  }

  return user;
}

function settingEnabled(key, fallback = false) {
  const row = db.prepare("SELECT value FROM system_settings WHERE key = ?").get(key);
  return (row?.value ?? String(fallback)) === "true";
}

function validateEmail(email) {
  return /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(email);
}

async function handleMe(request, response) {
  const { session } = getRequestSession(request);
  json(response, 200, { user: session?.user ?? null });
}

async function handleOptions(request, response) {
  json(response, 200, {
    options: {
      allowEmailLogin: settingEnabled("auth.allow_email_login", true),
      allowGitHubLogin: settingEnabled("auth.allow_github_login", true),
      allowRegistration: settingEnabled("auth.allow_registration", false),
    },
  });
}

async function handleLogin(request, response) {
  if (!settingEnabled("auth.allow_email_login", true)) {
    json(response, 403, { error: "Email login is disabled" });
    return;
  }

  const body = JSON.parse(await readBody(request) || "{}");
  const email = String(body.email || "").trim().toLowerCase();
  const password = String(body.password || "");

  if (!email || !password) {
    json(response, 400, { error: "Email and password are required" });
    return;
  }

  const user = db.prepare("SELECT * FROM users WHERE email = ?").get(email);

  if (!user?.password_hash || !verifyPassword(password, user.password_hash)) {
    json(response, 401, { error: "Invalid email or password" });
    return;
  }

  if ((user.status || "active") !== "active") {
    json(response, 403, { error: "This account is disabled" });
    return;
  }

  db.prepare("UPDATE users SET last_login_at = CURRENT_TIMESTAMP, updated_at = CURRENT_TIMESTAMP WHERE id = ?").run(user.id);
  const nextUser = db.prepare("SELECT * FROM users WHERE id = ?").get(user.id);

  const sessionUser = publicUser(nextUser);
  const sessionId = createSession({
    user: sessionUser,
  });

  json(response, 200, { user: sessionUser }, { "Set-Cookie": sessionCookie(sessionId) });
}

async function handleRegister(request, response) {
  if (!settingEnabled("auth.allow_registration", false)) {
    json(response, 403, { error: "Registration is disabled" });
    return;
  }

  const body = JSON.parse((await readBody(request)) || "{}");
  const email = String(body.email || "").trim().toLowerCase();
  const name = String(body.name || "").trim();
  const password = String(body.password || "");

  if (!validateEmail(email)) {
    json(response, 400, { error: "A valid email is required" });
    return;
  }

  if (!name) {
    json(response, 400, { error: "Name is required" });
    return;
  }

  if (password.length < 8) {
    json(response, 400, { error: "Password must be at least 8 characters" });
    return;
  }

  const existing = db.prepare("SELECT id FROM users WHERE email = ?").get(email);
  if (existing) {
    json(response, 409, { error: "Email already exists" });
    return;
  }

  const result = db
    .prepare("INSERT INTO users (email, password_hash, name, role, email_verified) VALUES (?, ?, ?, 'user', 0)")
    .run(email, hashPassword(password), name);

  const user = publicUser(db.prepare("SELECT * FROM users WHERE id = ?").get(result.lastInsertRowid));
  const sessionId = createSession({ user });

  json(response, 201, { user }, { "Set-Cookie": sessionCookie(sessionId) });
}

async function handleLogout(request, response) {
  const { sessionId } = getRequestSession(request);
  deleteSession(sessionId);
  json(response, 200, { ok: true }, { "Set-Cookie": clearSessionCookie() });
}

async function handleUpdateProfile(request, response) {
  const { sessionId, session } = getRequestSession(request);

  if (!session?.user?.id) {
    json(response, 401, { error: "Not signed in" });
    return;
  }

  const body = JSON.parse((await readBody(request)) || "{}");
  const name = String(body.name || "").trim();

  if (!name) {
    json(response, 400, { error: "Name is required" });
    return;
  }

  db.prepare("UPDATE users SET name = ?, updated_at = CURRENT_TIMESTAMP WHERE id = ?").run(name, session.user.id);
  const user = db.prepare("SELECT * FROM users WHERE id = ?").get(session.user.id);
  const sessionUser = publicUser(user);

  delete session.user;
  const nextSession = {
    ...session,
    user: sessionUser,
  };
  deleteSession(sessionId);
  const nextSessionId = createSession(nextSession);

  json(response, 200, { user: sessionUser }, { "Set-Cookie": sessionCookie(nextSessionId) });
}

async function handleChangePassword(request, response) {
  const { session } = getRequestSession(request);

  if (!session?.user?.id) {
    json(response, 401, { error: "Not signed in" });
    return;
  }

  const body = JSON.parse((await readBody(request)) || "{}");
  const currentPassword = String(body.currentPassword || "");
  const newPassword = String(body.newPassword || "");
  const user = db.prepare("SELECT * FROM users WHERE id = ?").get(session.user.id);

  if (newPassword.length < 8) {
    json(response, 400, { error: "New password must be at least 8 characters" });
    return;
  }

  if (user.password_hash && !verifyPassword(currentPassword, user.password_hash)) {
    json(response, 403, { error: "Current password is incorrect" });
    return;
  }

  db.prepare("UPDATE users SET password_hash = ?, updated_at = CURRENT_TIMESTAMP WHERE id = ?").run(
    hashPassword(newPassword),
    session.user.id,
  );

  json(response, 200, { ok: true });
}

export async function handleAuthApi(request, response, url) {
  try {
    if (url.pathname === "/api/auth/me" && request.method === "GET") {
      await handleMe(request, response);
      return true;
    }

    if (url.pathname === "/api/auth/options" && request.method === "GET") {
      await handleOptions(request, response);
      return true;
    }

    if (url.pathname === "/api/auth/login" && request.method === "POST") {
      await handleLogin(request, response);
      return true;
    }

    if (url.pathname === "/api/auth/register" && request.method === "POST") {
      await handleRegister(request, response);
      return true;
    }

    if (url.pathname === "/api/auth/logout" && request.method === "POST") {
      await handleLogout(request, response);
      return true;
    }

    if (url.pathname === "/api/auth/profile" && request.method === "PATCH") {
      await handleUpdateProfile(request, response);
      return true;
    }

    if (url.pathname === "/api/auth/password" && request.method === "POST") {
      await handleChangePassword(request, response);
      return true;
    }

    return false;
  } catch (error) {
    json(response, 500, {
      error: error instanceof Error ? error.message : "Unknown auth API error",
    });
    return true;
  }
}