#!/usr/bin/env node
// poll-sitemaps.mjs — Poll Microsoft Learn sitemaps for lastmod changes.
// Updates url-registry.json with current sitemap_lastmod values.
// Usage: node poll-sitemaps.mjs [--force] [--verbose]

import { dirname, join } from 'node:path';
import { fileURLToPath } from 'node:url';
import { normalizeUrl } from './lib/url-normalize.mjs';
import { loadRegistry, saveRegistry } from './lib/registry-io.mjs';
import { fetchSitemapIndex, streamSitemap } from './lib/sitemap-stream.mjs';

const __dirname = dirname(fileURLToPath(import.meta.url));
const DATA_DIR = join(__dirname, 'data');
const force = process.argv.includes('--force');
const verbose = process.argv.includes('--verbose');

// Target child sitemaps — covers all URL path prefixes in the registry.
// Derived from analyzing which sitemaps contain our 1342 tracked URLs.
const TARGET_PREFIXES = [
  'azure_en-us_',
  'microsoft-copilot-studio_en-us_',
  'security_en-us_',
  'fabric_en-us_',
  'power-platform_en-us_',
  'ai_en-us_',
  'copilot_en-us_',
  'compliance_en-us_',
  'agent-framework_en-us_',
  'semantic-kernel_en-us_',
  'entra_en-us_',
  'purview_en-us_',
  'microsoftteams_en-us_',
  'sharepoint_en-us_',
  'microsoft-365_en-us_',
  'training_en-us_',
  'cloud-computing_en-us_',
  'privacy_en-us_',
  // dotnet_en-us_ excluded: 75 sitemaps, only 12 matches. Not worth weekly polling.
  // Re-enable with --force if needed.
];

function extractChildName(loc) {
  // https://learn.microsoft.com/_sitemaps/azure_en-us_7.xml → azure_en-us_7
  const match = loc.match(/\/_sitemaps\/([^/]+)\.xml$/);
  return match ? match[1] : null;
}

function isTargetChild(childName) {
  return TARGET_PREFIXES.some(p => childName.startsWith(p));
}

// --- Main ---
async function main() {
  const registry = loadRegistry(DATA_DIR);
  const urlIndex = new Map();
  for (const [url, entry] of Object.entries(registry.urls)) {
    urlIndex.set(url, entry);
  }

  console.log(`Registry loaded: ${urlIndex.size} URLs`);

  // Step 1: Fetch sitemap index
  console.log('Fetching sitemap index...');
  const indexEntries = await fetchSitemapIndex();
  console.log(`Sitemap index: ${indexEntries.length} child sitemaps found`);

  // Step 2: Filter to target children
  const targetChildren = indexEntries
    .map(e => ({ ...e, name: extractChildName(e.loc) }))
    .filter(e => e.name && isTargetChild(e.name));

  console.log(`Target children: ${targetChildren.length}`);

  let totalMatched = 0;
  let totalUpdated = 0;
  let childrenPolled = 0;
  let childrenSkipped = 0;

  // Step 3: Poll each child
  for (const child of targetChildren) {
    const prevState = registry.sitemap_state[child.name];

    // Skip if unchanged since last check (unless --force)
    if (!force && prevState && prevState.lastmod === child.lastmod) {
      if (verbose) console.log(`  Skipping ${child.name} (unchanged since ${child.lastmod})`);
      childrenSkipped++;
      continue;
    }

    console.log(`  Polling ${child.name} (lastmod: ${child.lastmod})...`);
    childrenPolled++;

    let matchedInChild = 0;
    let updatedInChild = 0;

    try {
      for await (const entry of streamSitemap(child.loc)) {
        const normalized = normalizeUrl(entry.loc);
        if (!normalized) continue;

        const registryEntry = urlIndex.get(normalized);
        if (!registryEntry) continue;

        matchedInChild++;

        // Update lastmod if changed
        if (entry.lastmod && registryEntry.sitemap_lastmod !== entry.lastmod) {
          registryEntry.sitemap_lastmod = entry.lastmod;
          updatedInChild++;
        }
        registryEntry.status = 'tracked';
      }
    } catch (err) {
      console.error(`  ERROR polling ${child.name}: ${err.message}`);
      continue;
    }

    console.log(`    Matched: ${matchedInChild}, Updated: ${updatedInChild}`);
    totalMatched += matchedInChild;
    totalUpdated += updatedInChild;

    // Record child state
    registry.sitemap_state[child.name] = {
      lastmod: child.lastmod,
      checked_at: new Date().toISOString(),
    };
  }

  // Step 4: Mark remaining unpolled URLs
  let notInSitemap = 0;
  for (const entry of Object.values(registry.urls)) {
    if (entry.status === 'unpolled') {
      entry.status = 'not_in_sitemap';
      notInSitemap++;
    }
  }

  // Step 5: Save
  registry.last_poll = new Date().toISOString();
  saveRegistry(registry, DATA_DIR);

  // Summary
  const tracked = Object.values(registry.urls).filter(u => u.status === 'tracked').length;
  console.log('\n=== Poll Summary ===');
  console.log(`Children polled: ${childrenPolled}, skipped: ${childrenSkipped}`);
  console.log(`URLs matched: ${totalMatched}, lastmod updated: ${totalUpdated}`);
  console.log(`Registry: ${tracked} tracked, ${notInSitemap} not in sitemap`);
  console.log(`Match rate: ${((tracked / urlIndex.size) * 100).toFixed(1)}%`);
}

main().catch(err => {
  console.error('Fatal error:', err.message);
  process.exit(1);
});