#!/usr/bin/env node

/**
 * Post-install script to download required validation resources
 * This script is automatically run after npm/pnpm install
 * All users need validation capabilities, so this is mandatory
 */

import { SchematronDownloader } from '../dist_ts/formats/validation/schematron.downloader.js';
import * as path from 'path';
import * as fs from 'fs';
import * as crypto from 'crypto';

// Version for cache invalidation
const RESOURCES_VERSION = '1.0.0';

/**
 * Check if we're in a proper npm install context
 */
function isValidInstallContext(): boolean {
  // Skip if we're in a git install or similar
  if (process.env.npm_lifecycle_event !== 'postinstall') {
    return false;
  }
  
  // Skip in CI if explicitly disabled
  if (process.env.CI && process.env.EINVOICE_SKIP_RESOURCES) {
    console.log('⏭️  Skipping resource download (EINVOICE_SKIP_RESOURCES set)');
    return false;
  }
  
  return true;
}

/**
 * Create a checksum for a file
 */
function getFileChecksum(filePath: string): string | null {
  try {
    if (!fs.existsSync(filePath)) return null;
    const content = fs.readFileSync(filePath);
    return crypto.createHash('sha256').update(content).digest('hex');
  } catch {
    return null;
  }
}

/**
 * Check if resources are already downloaded and valid
 */
function checkExistingResources(): boolean {
  const versionFile = path.join('assets_downloaded', 'schematron', '.version');
  
  try {
    if (!fs.existsSync(versionFile)) return false;
    
    const version = fs.readFileSync(versionFile, 'utf-8').trim();
    if (version !== RESOURCES_VERSION) {
      console.log('📦 Resource version mismatch, re-downloading...');
      return false;
    }
    
    // Check if key files exist
    const keyFiles = [
      'assets_downloaded/schematron/EN16931-UBL-v1.3.14.sch',
      'assets_downloaded/schematron/EN16931-CII-v1.3.14.sch',
      'assets_downloaded/schematron/PEPPOL-EN16931-UBL-v3.0.17.sch'
    ];
    
    for (const file of keyFiles) {
      if (!fs.existsSync(file)) {
        console.log(`📦 Missing ${file}, re-downloading resources...`);
        return false;
      }
    }
    
    return true;
  } catch {
    return false;
  }
}

/**
 * Save version file after successful download
 */
function saveVersionFile(): void {
  const versionFile = path.join('assets_downloaded', 'schematron', '.version');
  try {
    fs.mkdirSync(path.dirname(versionFile), { recursive: true });
    fs.writeFileSync(versionFile, RESOURCES_VERSION);
  } catch (error) {
    console.warn('⚠️  Could not save version file:', error.message);
  }
}

async function downloadSchematron() {
  console.log('📥 Downloading Schematron validation files...\n');
  
  const downloader = new SchematronDownloader('assets_downloaded/schematron');
  await downloader.initialize();
  
  let successCount = 0;
  let failCount = 0;
  
  // Download EN16931 Schematron files
  console.log('🔵 Downloading EN16931 Schematron files...');
  try {
    const en16931Files = await downloader.downloadStandard('EN16931');
    console.log(`✅ Downloaded ${en16931Files.length} EN16931 files`);
    successCount += en16931Files.length;
  } catch (error) {
    console.error(`⚠️  Failed to download EN16931: ${error.message}`);
    failCount++;
  }
  
  // Download PEPPOL Schematron files
  console.log('\n🔵 Downloading PEPPOL Schematron files...');
  try {
    const peppolFiles = await downloader.downloadStandard('PEPPOL');
    console.log(`✅ Downloaded ${peppolFiles.length} PEPPOL files`);
    successCount += peppolFiles.length;
  } catch (error) {
    console.error(`⚠️  Failed to download PEPPOL: ${error.message}`);
    failCount++;
  }
  
  // Download XRechnung Schematron files
  console.log('\n🔵 Downloading XRechnung Schematron files...');
  try {
    const xrechnungFiles = await downloader.downloadStandard('XRECHNUNG');
    console.log(`✅ Downloaded ${xrechnungFiles.length} XRechnung files`);
    successCount += xrechnungFiles.length;
  } catch (error) {
    console.error(`⚠️  Failed to download XRechnung: ${error.message}`);
    failCount++;
  }
  
  // Report results
  if (successCount > 0) {
    saveVersionFile();
    console.log(`\n✅ Successfully downloaded ${successCount} validation files`);
  }
  
  if (failCount > 0) {
    console.log(`⚠️  Failed to download ${failCount} resource sets`);
    console.log('   Some validation features may be limited');
  }
  
  return { successCount, failCount };
}

async function main() {
  // Check if we should run
  if (!isValidInstallContext()) {
    return;
  }
  
  console.log('='.repeat(60));
  console.log('🚀 @fin.cx/einvoice - Validation Resources Setup');
  console.log('='.repeat(60));
  console.log();
  
  try {
    // Check if resources already exist and are current
    if (checkExistingResources()) {
      console.log('✅ Validation resources already installed and up-to-date');
      console.log();
      return;
    }
    
    // Check if we're in the right directory
    const packageJsonPath = path.join(process.cwd(), 'package.json');
    if (!fs.existsSync(packageJsonPath)) {
      console.error('❌ Error: package.json not found');
      console.error('   Installation context issue - skipping resource download');
      return;
    }
    
    // Check if dist_ts exists (module should be built)
    const distPath = path.join(process.cwd(), 'dist_ts');
    if (!fs.existsSync(distPath)) {
      console.log('⚠️  Module not yet built - skipping resource download');
      console.log('   Resources will be downloaded on first use');
      return;
    }
    
    // Check network connectivity (simple DNS check)
    try {
      await import('dns').then(dns => 
        new Promise((resolve, reject) => {
          dns.lookup('github.com', (err) => {
            if (err) reject(err);
            else resolve(true);
          });
        })
      );
    } catch {
      console.log('⚠️  No network connectivity detected');
      console.log('   Validation resources will be downloaded on first use');
      console.log('   when network is available');
      return;
    }
    
    // Download resources with retry logic
    let attempts = 0;
    const maxAttempts = 3;
    let lastError;
    
    while (attempts < maxAttempts) {
      attempts++;
      
      if (attempts > 1) {
        console.log(`\n🔄 Retry attempt ${attempts}/${maxAttempts}...`);
      }
      
      try {
        const { successCount, failCount } = await downloadSchematron();
        
        if (successCount > 0) {
          console.log();
          console.log('='.repeat(60));
          console.log('✅ Validation resources installed successfully!');
          console.log('='.repeat(60));
          console.log();
          return;
        }
        
        if (failCount > 0 && attempts < maxAttempts) {
          console.log(`\n⚠️  Some downloads failed, retrying...`);
          await new Promise(resolve => setTimeout(resolve, 2000)); // Wait 2s before retry
          continue;
        }
        
        break;
      } catch (error) {
        lastError = error;
        if (attempts < maxAttempts) {
          console.log(`\n⚠️  Download failed: ${error.message}`);
          console.log('   Retrying...');
          await new Promise(resolve => setTimeout(resolve, 3000)); // Wait 3s before retry
        }
      }
    }
    
    // If we get here, downloads failed after retries
    console.error();
    console.error('⚠️  Could not download all validation resources');
    console.error('   The library will work but validation features may be limited');
    console.error('   Resources will be attempted again on first use');
    console.error();
    
    if (lastError) {
      console.error('   Last error:', lastError.message);
    }
    
  } catch (error) {
    // Catch-all for unexpected errors
    console.error();
    console.error('⚠️  Unexpected error during resource setup:', error.message);
    console.error('   This won\'t affect library installation');
    console.error('   Resources will be downloaded on first use');
    console.error();
  }
}

// Only run if this is the main module
if (import.meta.url === `file://${process.argv[1]}`) {
  main().catch(error => {
    console.error('⚠️  Resource setup error:', error.message);
    // Never fail the install
    process.exit(0);
  });
}

export default main;