import fs from 'node:fs';
import path from 'node:path';
import { smsSitesConfigSchema, type SmsSitesConfig } from '@dynamic-sites/shared';
import { logger } from '../logger.js';

const REPO_ROOT = process.env.REPO_ROOT || '.';
const CONFIG_PATH = path.join(REPO_ROOT, 'config/sms-sites.json');

let cachedConfig: SmsSitesConfig | null = null;
let configLoadedAt = 0;
const CONFIG_TTL_MS = 60_000; // Reload every minute

function loadConfig(): SmsSitesConfig | null {
  const now = Date.now();
  if (cachedConfig && now - configLoadedAt < CONFIG_TTL_MS) return cachedConfig;

  try {
    const raw = fs.readFileSync(CONFIG_PATH, 'utf-8');
    const parsed = JSON.parse(raw);
    const result = smsSitesConfigSchema.safeParse(parsed);
    if (!result.success) {
      logger.warn({ event: 'sms.config_invalid', errors: result.error.message }, 'Invalid SMS sites config');
      return cachedConfig;
    }
    cachedConfig = result.data;
    configLoadedAt = now;
    return cachedConfig;
  } catch (err) {
    logger.warn({ event: 'sms.config_missing', error: (err as Error).message }, 'Could not load SMS sites config');
    return cachedConfig;
  }
}

/**
 * Check if a phone number is one of our own system numbers (the Telnyx numbers we send from).
 * Used to filter out Telnyx delivery receipts / echo of our own sent messages.
 */
export function isOwnNumber(phone: string): boolean {
  const config = loadConfig();
  if (!config) return false;
  return config.sites.some(site => site.phoneNumber === phone);
}

/**
 * Check if a sender is authorized to make edits for a given site.
 * Returns the matching site config if authorized, or null.
 */
export function findAuthorizedSite(from: string, to: string): { siteId: string; repoRoot: string } | null {
  const config = loadConfig();
  if (!config) return null;

  const site = config.sites.find(site =>
    site.phoneNumber === to && site.allowedSenders.includes(from)
  );
  if (!site) return null;
  return { siteId: site.siteId, repoRoot: site.repoRoot || '.' };
}