import { db } from "./db.mjs";
import { requirePermission, publicUser } from "./auth.mjs";
import { json, readBody } from "./http.mjs";
import { permissions } from "./permissions.mjs";
import { hashPassword } from "./security.mjs";

const roles = new Set(["system_admin", "admin", "editor", "viewer", "user"]);
const statuses = new Set(["active", "disabled"]);

function listUsers() {
  return db
    .prepare(`
      SELECT id, email, name, avatar_url, role, status, email_verified, created_at, updated_at, last_login_at
      FROM users
      ORDER BY created_at DESC, id DESC
    `)
    .all()
    .map(publicUser);
}

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

async function handleListUsers(request, response) {
  if (!requirePermission(request, response, permissions.usersManage)) return;
  json(response, 200, { users: listUsers() });
}

async function handleCreateUser(request, response) {
  if (!requirePermission(request, response, permissions.usersManage)) 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 || "");
  const role = String(body.role || "user");

  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;
  }

  if (!roles.has(role)) {
    json(response, 400, { error: "Invalid role" });
    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 (?, ?, ?, ?, 1)")
    .run(email, hashPassword(password), name, role);

  json(response, 201, { user: publicUser(db.prepare("SELECT * FROM users WHERE id = ?").get(result.lastInsertRowid)) });
}

async function handleUpdateUser(request, response, userId) {
  const actor = requirePermission(request, response, permissions.usersManage);
  if (!actor) return;

  const target = db.prepare("SELECT * FROM users WHERE id = ?").get(userId);
  if (!target) {
    json(response, 404, { error: "User not found" });
    return;
  }

  const body = JSON.parse((await readBody(request)) || "{}");
  const nextRole = body.role === undefined ? target.role : String(body.role);
  const nextStatus = body.status === undefined ? target.status || "active" : String(body.status);

  if (!roles.has(nextRole)) {
    json(response, 400, { error: "Invalid role" });
    return;
  }

  if (!statuses.has(nextStatus)) {
    json(response, 400, { error: "Invalid status" });
    return;
  }

  if (Number(actor.id) === Number(userId) && nextStatus !== "active") {
    json(response, 400, { error: "You cannot disable your own account" });
    return;
  }

  if (target.role === "system_admin" && nextRole !== "system_admin") {
    const adminCount = db.prepare("SELECT COUNT(*) AS count FROM users WHERE role = 'system_admin'").get().count;
    if (adminCount <= 1) {
      json(response, 400, { error: "At least one system admin is required" });
      return;
    }
  }

  db.prepare("UPDATE users SET role = ?, status = ?, updated_at = CURRENT_TIMESTAMP WHERE id = ?").run(
    nextRole,
    nextStatus,
    userId,
  );

  json(response, 200, { user: publicUser(db.prepare("SELECT * FROM users WHERE id = ?").get(userId)) });
}

export async function handleUsersApi(request, response, url) {
  try {
    if (url.pathname === "/api/admin/users" && request.method === "GET") {
      await handleListUsers(request, response);
      return true;
    }

    if (url.pathname === "/api/admin/users" && request.method === "POST") {
      await handleCreateUser(request, response);
      return true;
    }

    const match = url.pathname.match(/^\/api\/admin\/users\/(\d+)$/);
    if (match && request.method === "PATCH") {
      await handleUpdateUser(request, response, Number(match[1]));
      return true;
    }

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