import {
  APIErrorCode,
  APIException,
  type RegisterUserRequest,
  type UpdateUserRequest,
  type User,
} from "../model/interfaces.ts";
import { db, isUserRow, userApiToRow, userRowToApi } from "../model/db.ts";
import { disconnectUser } from "./ws-service.ts";

import { hashPassword } from "../lib/jwt.ts";
import { linkAttachments } from "./attachment-service.ts";

const USER_SELECT =
  `SELECT u.id, u.username, u.password_hash, u.is_admin, u.created_at, u.updated_at, u.avatar_mime, u.description, u.invited_by, u.email,
          i.username as invited_by_username
   FROM users u
   LEFT JOIN users i ON i.id = u.invited_by`;

export async function createUser(
  request: RegisterUserRequest,
  inviterId: string | null,
): Promise<User> {
  const userId = crypto.randomUUID();
  const createdAt = new Date();

  const existingUser = db.prepare(
    "SELECT id FROM users WHERE username = ?;",
  ).get(request.username);

  if (existingUser) {
    throw new APIException(
      APIErrorCode.VALIDATION_ERROR,
      400,
      "Username already exists",
    );
  }

  const passwordHash = await hashPassword(request.password);

  db.prepare(
    `INSERT INTO users (id, username, password_hash, is_admin, created_at, invited_by, email)
      VALUES (?, ?, ?, ?, ?, ?, ?);`,
  ).run(
    userId,
    request.username,
    passwordHash,
    0,
    createdAt.toISOString(),
    inviterId,
    request.email,
  );

  return {
    id: userId,
    username: request.username,
    passwordHash,
    isAdmin: false,
    createdAt,
    email: request.email,
  };
}

export function getUserById(userId: string): User {
  const userRow = db.prepare(
    `${USER_SELECT} WHERE u.id = ?`,
  ).get(userId);

  if (!userRow || !isUserRow(userRow)) {
    throw new APIException(APIErrorCode.NOT_FOUND, 404, "User not found");
  }

  return userRowToApi(userRow);
}

export function getUserByUsername(username: string): User {
  const userRow = db.prepare(
    `${USER_SELECT} WHERE u.username = ?`,
  ).get(username);

  if (!userRow || !isUserRow(userRow)) {
    throw new APIException(APIErrorCode.NOT_FOUND, 404, "User not found");
  }

  return userRowToApi(userRow);
}

export function getUserByEmail(email: string): User | null {
  const userRow = db.prepare(
    `${USER_SELECT} WHERE u.email = ?`,
  ).get(email);

  if (!userRow || !isUserRow(userRow)) return null;
  return userRowToApi(userRow);
}

export function searchUsers(
  query: string,
  limit: number,
): { id: string; username: string; avatarMime: string | null }[] {
  if (!query) return [];
  const rows = db.prepare(
    `SELECT id, username, avatar_mime FROM users WHERE username LIKE ? ORDER BY username LIMIT ?;`,
  ).all(`${query}%`, limit) as {
    id: string;
    username: string;
    avatar_mime: string | null;
  }[];
  return rows.map((r) => ({
    id: r.id,
    username: r.username,
    avatarMime: r.avatar_mime,
  }));
}

export function searchUsersGlobal(query: string, limit: number): User[] {
  if (!query.trim()) return [];
  const pattern = `%${query}%`;
  const rows = db.prepare(
    `${USER_SELECT} WHERE (u.username LIKE ? OR u.description LIKE ?) ORDER BY u.username LIMIT ?;`,
  ).all(pattern, pattern, limit);
  return rows.filter(isUserRow).map(userRowToApi);
}

export function listUsers(): User[] {
  const userRows = db.prepare(
    `${USER_SELECT}`,
  ).all();

  if (!userRows || !userRows.every(isUserRow)) {
    throw new APIException(APIErrorCode.NOT_FOUND, 404, "No user found");
  }

  return userRows.map(userRowToApi);
}

export async function updateUser(
  userId: string,
  request: UpdateUserRequest,
): Promise<User> {
  const user = getUserById(userId);

  const { password, description, email, ...requestFields } = request;

  const now = new Date();
  const updatedUser: User = {
    ...user,
    passwordHash: password ? await hashPassword(password) : user.passwordHash,
    ...requestFields,
    description: description ?? user.description,
    email: email ?? user.email,
    updatedAt: now,
  };

  const updatedUserRow = userApiToRow(updatedUser);

  const userResult = db.prepare(
    `UPDATE users SET username = ?, password_hash = ?, is_admin = ?, description = ?, email = ?, updated_at = ? WHERE id = ?`,
  ).run(
    updatedUserRow.username,
    updatedUserRow.password_hash,
    updatedUserRow.is_admin,
    updatedUserRow.description,
    updatedUserRow.email,
    now.toISOString(),
    updatedUserRow.id,
  );

  if (userResult.changes === 0) {
    throw new APIException(APIErrorCode.NOT_FOUND, 404, "Dump not found");
  }

  if (updatedUser.description) {
    linkAttachments(updatedUser.description, userId);
  }

  return updatedUser;
}

export function updateUserAvatar(userId: string, mime: string): void {
  const result = db.prepare(
    `UPDATE users SET avatar_mime = ?, updated_at = ? WHERE id = ?`,
  ).run(mime, new Date().toISOString(), userId);

  if (result.changes === 0) {
    throw new APIException(APIErrorCode.NOT_FOUND, 404, "User not found");
  }
}

export function getInviteTree(
  userId: string,
): {
  id: string;
  username: string;
  avatarMime?: string;
  invitedById: string;
  createdAt: Date;
}[] {
  const rows = db.prepare(`
    WITH RECURSIVE tree AS (
      SELECT id, username, avatar_mime, invited_by, created_at, 0 AS depth
      FROM users
      WHERE invited_by = ?
      UNION ALL
      SELECT u.id, u.username, u.avatar_mime, u.invited_by, u.created_at, t.depth + 1
      FROM users u
      INNER JOIN tree t ON u.invited_by = t.id
      WHERE t.depth < 10
    )
    SELECT * FROM tree ORDER BY created_at;
  `).all(userId) as {
    id: string;
    username: string;
    avatar_mime: string | null;
    invited_by: string;
    created_at: string;
  }[];

  return rows.map((r) => ({
    id: r.id,
    username: r.username,
    avatarMime: r.avatar_mime ?? undefined,
    invitedById: r.invited_by,
    createdAt: new Date(r.created_at),
  }));
}

export function deleteUser(userId: string): void {
  disconnectUser(userId);

  const result = db.prepare(
    `DELETE FROM users WHERE id = ?;`,
  ).run(userId);

  if (result.changes === 0) {
    throw new APIException(APIErrorCode.NOT_FOUND, 404, "User not found");
  }
}