// Authentication Service
const API_BASE_URL = process.env.REACT_APP_API_URL || "http://localhost:5000";

/**
 * Login user with username and password
 * @param {string} username - User's email/username
 * @param {string} password - User's password
 * @returns {Promise<Object>} - Authentication response with token and user data
 */
export async function login(username, password) {
  const response = await fetch(`${API_BASE_URL}/api/Authentication/login`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      Username: username,
      Password: password,
    }),
  });

  if (!response.ok) {
    if (response.status === 401) {
      throw new Error("Invalid credentials");
    }
    throw new Error("Login failed");
  }

  const data = await response.json();
  return data;
}

/**
 * Logout user - clear local storage
 */
export function logout() {
  localStorage.removeItem("token");
  localStorage.removeItem("user");
}

/**
 * Check if user is authenticated
 * @returns {boolean}
 */
export function isAuthenticated() {
  const token = localStorage.getItem("token");
  if (!token) return false;

  // Check if token is expired
  try {
    const payload = JSON.parse(atob(token.split(".")[1]));
    const expiration = new Date(payload.exp * 1000);
    return expiration > new Date();
  } catch (e) {
    return false;
  }
}

/**
 * Get current user from local storage
 * @returns {Object|null}
 */
export function getCurrentUser() {
  const userStr = localStorage.getItem("user");
  if (!userStr) return null;
  
  try {
    return JSON.parse(userStr);
  } catch (e) {
    return null;
  }
}

/**
 * Get authentication token
 * @returns {string|null}
 */
export function getToken() {
  return localStorage.getItem("token");
}

/**
 * Change user password
 * @param {string} currentPassword - Current password
 * @param {string} newPassword - New password
 * @param {string} confirmPassword - Confirm new password
 * @returns {Promise<Object>}
 */
export async function changePassword(currentPassword, newPassword, confirmPassword) {
  const token = getToken();
  const response = await fetch(`${API_BASE_URL}/api/Authentication/ChangePassword`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "Authorization": `Bearer ${token}`,
    },
    body: JSON.stringify({
      Currentpassword: currentPassword,
      Newpassword: newPassword,
      Confirmpassword: confirmPassword,
    }),
  });

  if (!response.ok) {
    throw new Error("Failed to change password");
  }

  return await response.json();
}

/**
 * Request password reset
 * @param {string} email - User's email
 * @returns {Promise<Object>}
 */
export async function forgotPassword(email) {
  const response = await fetch(`${API_BASE_URL}/api/Authentication/ForgetPassword?Email=${encodeURIComponent(email)}`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
  });

  if (!response.ok) {
    throw new Error("Failed to send password reset email");
  }

  return await response.json();
}

/**
 * Verify password reset code
 * @param {string} code - Verification code
 * @returns {Promise<Object>}
 */
export async function verifyResetCode(code) {
  const response = await fetch(`${API_BASE_URL}/api/Authentication/VerificationCode?code=${encodeURIComponent(code)}`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
  });

  if (!response.ok) {
    throw new Error("Invalid verification code");
  }

  return await response.json();
}

/**
 * Reset password with code
 * @param {string} email - User's email
 * @param {string} code - Verification code
 * @param {string} password - New password
 * @returns {Promise<Object>}
 */
export async function resetPassword(email, code, password) {
  const response = await fetch(`${API_BASE_URL}/api/Authentication/ResetPassword`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      Email: email,
      Code: code,
      Password: password,
    }),
  });

  if (!response.ok) {
    throw new Error("Failed to reset password");
  }

  return await response.json();
}