/**
 * SIM Domain - Validation
 * 
 * Business validation functions for SIM subscriptions.
 * These functions contain no infrastructure dependencies.
 */

import type { Subscription } from "../subscriptions/schema.js";

/**
 * Check if a subscription is a SIM service
 * 
 * Business rule: A subscription is considered a SIM service if its product name
 * or group name contains "SIM" (case-insensitive).
 * 
 * @param subscription - The subscription to check
 * @returns true if this is a SIM subscription
 */
export function isSimSubscription(subscription: Subscription): boolean {
  const productName = subscription.productName?.toLowerCase() || "";
  const groupName = subscription.groupName?.toLowerCase() || "";
  
  return productName.includes("sim") || groupName.includes("sim");
}

/**
 * Extract SIM account identifier from subscription data
 * 
 * The SIM account identifier (typically a phone number/MSISDN) can be stored
 * in various places depending on the subscription source and configuration.
 * This function tries multiple locations in priority order.
 * 
 * @param subscription - The subscription to extract the account from
 * @returns The SIM account identifier (phone number), or null if not found
 */
export function extractSimAccountFromSubscription(
  subscription: Subscription
): string | null {
  // 1. Try domain field first (most common location)
  if (subscription.domain && subscription.domain.trim()) {
    return subscription.domain.trim();
  }

  // 2. Check custom fields for phone number/MSISDN
  if (subscription.customFields) {
    const account = extractFromCustomFields(subscription.customFields);
    if (account) return account;
  }

  // 3. Check if order number looks like a phone number (10-11 digits)
  if (subscription.orderNumber) {
    const orderNum = subscription.orderNumber.toString();
    if (/^\d{10,11}$/.test(orderNum)) {
      return orderNum;
    }
  }

  return null;
}

/**
 * Extract account from custom fields using known field names
 * 
 * WHMCS and other billing systems may store the SIM phone number in various
 * custom field names. This function checks all known variations.
 * 
 * @param customFields - The custom fields record to search
 * @returns The SIM account if found, null otherwise
 */
function extractFromCustomFields(
  customFields: Record<string, unknown>
): string | null {
  // Known field names for SIM phone numbers across different WHMCS configurations
  const phoneFields = [
    // Standard field names
    "phone",
    "msisdn",
    "phonenumber",
    "phone_number",
    "mobile",
    "sim_phone",
    
    // Title case variations
    "Phone Number",
    "MSISDN",
    "Phone",
    "Mobile",
    "SIM Phone",
    "PhoneNumber",
    
    // Additional variations
    "mobile_number",
    "sim_number",
    "account_number",
    "Account Number",
    "SIM Account",
    "Phone Number (SIM)",
    "Mobile Number",
    "SIM Number",
    
    // Underscore variations
    "SIM_Number",
    "SIM_Phone_Number",
    "Phone_Number_SIM",
    "Mobile_SIM_Number",
    "SIM_Account_Number",
  ];

  for (const fieldName of phoneFields) {
    const value = customFields[fieldName];
    if (value !== undefined && value !== null && value !== "") {
      return String(value);
    }
  }

  return null;
}

/**
 * Clean SIM account format
 * 
 * Removes common formatting characters (hyphens, spaces, parentheses)
 * from phone numbers to get a clean numeric string.
 * 
 * @param account - The account string to clean
 * @returns Cleaned account string with only digits
 */
export function cleanSimAccount(account: string): string {
  return account.replace(/[-\s()]/g, "");
}