#!/usr/bin/env node

/**
 * Migrate legacy 'public' field to modern 'visibility' field
 *
 * SECURITY: Safe migration with dry-run support
 * - Migrates public: true → visibility: 'public'
 * - Migrates public: false → visibility: 'internal'
 * - Preserves documents that already have visibility set
 * - Removes the deprecated 'public' field after migration
 */

const { getCollection } = require('../src/utils/db.util');

async function migrate(dryRun = false) {
  try {
    const collection = await getCollection('documents');

    // Find documents with public field but no visibility
    const docsWithPublicOnly = await collection.find({
      public: { $exists: true },
      visibility: { $exists: false }
    }).toArray();

    // Find documents with both fields (inconsistent state)
    const docsWithBoth = await collection.find({
      public: { $exists: true },
      visibility: { $exists: true }
    }).toArray();

    console.log('\n📊 Migration Analysis:');
    console.log(`   Documents with only 'public' field: ${docsWithPublicOnly.length}`);
    console.log(`   Documents with both fields: ${docsWithBoth.length}`);
    console.log(`   Total to migrate: ${docsWithPublicOnly.length + docsWithBoth.length}`);

    if (docsWithPublicOnly.length === 0 && docsWithBoth.length === 0) {
      console.log('\n✅ No documents need migration. All documents already use visibility field.');
      return;
    }

    if (dryRun) {
      console.log('\n🔍 DRY RUN - No changes will be made\n');

      // Show what would be migrated
      if (docsWithPublicOnly.length > 0) {
        console.log('Documents with only public field:');
        docsWithPublicOnly.forEach(doc => {
          const newVisibility = doc.public ? 'public' : 'internal';
          console.log(`   - ${doc.title} (${doc.slug})`);
          console.log(`     public: ${doc.public} → visibility: '${newVisibility}'`);
        });
      }

      if (docsWithBoth.length > 0) {
        console.log('\nDocuments with both fields (will remove public):');
        docsWithBoth.forEach(doc => {
          console.log(`   - ${doc.title} (${doc.slug})`);
          console.log(`     current: public=${doc.public}, visibility='${doc.visibility}'`);
          console.log(`     action: Keep visibility='${doc.visibility}', remove public field`);
        });
      }

      console.log('\n💡 Run with --execute to perform migration');
      return;
    }

    // Perform actual migration
    console.log('\n🔄 Performing migration...\n');

    let migratedCount = 0;

    // Migrate documents with only public field
    for (const doc of docsWithPublicOnly) {
      const visibility = doc.public ? 'public' : 'internal';

      await collection.updateOne(
        { _id: doc._id },
        {
          $set: { visibility },
          $unset: { public: "" }
        }
      );

      console.log(`✓ ${doc.title}: public=${doc.public} → visibility='${visibility}'`);
      migratedCount++;
    }

    // Clean up documents with both fields (keep visibility, remove public)
    for (const doc of docsWithBoth) {
      await collection.updateOne(
        { _id: doc._id },
        { $unset: { public: "" } }
      );

      console.log(`✓ ${doc.title}: Removed public field, kept visibility='${doc.visibility}'`);
      migratedCount++;
    }

    console.log(`\n✅ Migration complete! ${migratedCount} documents updated.`);

    // Verify results
    const remainingWithPublic = await collection.countDocuments({ public: { $exists: true } });
    const totalWithVisibility = await collection.countDocuments({ visibility: { $exists: true } });

    console.log('\n📊 Post-migration verification:');
    console.log(`   Documents with 'public' field: ${remainingWithPublic}`);
    console.log(`   Documents with 'visibility' field: ${totalWithVisibility}`);

    if (remainingWithPublic > 0) {
      console.warn('\n⚠️  Warning: Some documents still have the public field. Review manually.');
    } else {
      console.log('\n✅ All documents successfully migrated to visibility field!');
    }

  } catch (error) {
    console.error('❌ Migration failed:', error);
    throw error;
  }
}

// CLI interface
const args = process.argv.slice(2);
const dryRun = !args.includes('--execute');

if (dryRun) {
  console.log('🔍 Running in DRY RUN mode (no changes will be made)');
  console.log('   Use --execute flag to perform actual migration\n');
}

migrate(dryRun)
  .then(() => {
    console.log('\n✨ Script complete');
    process.exit(0);
  })
  .catch((error) => {
    console.error('\n💥 Script failed:', error);
    process.exit(1);
  });