#!/usr/bin/env node

const fs = require('fs');
const path = require('path');
const { promisify } = require('util');

const readdir = promisify(fs.readdir);
const readFile = promisify(fs.readFile);
const writeFile = promisify(fs.writeFile);
const stat = promisify(fs.stat);

// Regex to match import statements with relative paths without extensions
const importRegex = /import\s+(?:(?:[\w*\s{},]*)\s+from\s+)?['"](\.[^'"]*)['"]/g;

async function processFile(filePath) {
  try {
    // Read file content
    const content = await readFile(filePath, 'utf8');
    
    // Skip files that are already processed or don't need processing
    if (!content.match(importRegex)) {
      return { filePath, changed: false };
    }
    
    // Replace imports without extensions
    let modifiedContent = content.replace(importRegex, (match, importPath) => {
      // Skip if already has an extension
      if (path.extname(importPath)) {
        return match;
      }
      
      // Add .js extension
      return match.replace(importPath, `${importPath}.js`);
    });
    
    // Only write if content changed
    if (content !== modifiedContent) {
      await writeFile(filePath, modifiedContent, 'utf8');
      return { filePath, changed: true };
    }
    
    return { filePath, changed: false };
  } catch (error) {
    return { filePath, error: error.message };
  }
}

async function walkDir(dir, fileTypes = ['.ts', '.tsx', '.js', '.jsx']) {
  const entries = await readdir(dir, { withFileTypes: true });
  const files = [];
  
  for (const entry of entries) {
    const fullPath = path.join(dir, entry.name);
    
    if (entry.isDirectory()) {
      // Skip node_modules and .git directories
      if (entry.name !== 'node_modules' && entry.name !== '.git') {
        files.push(...await walkDir(fullPath, fileTypes));
      }
    } else if (entry.isFile()) {
      const ext = path.extname(entry.name);
      if (fileTypes.includes(ext)) {
        files.push(fullPath);
      }
    }
  }
  
  return files;
}

async function main() {
  const rootDir = process.argv[2] || path.resolve(process.cwd(), 'src');
  
  console.log(`Scanning directory: ${rootDir}`);
  
  try {
    const files = await walkDir(rootDir);
    console.log(`Found ${files.length} files to process`);
    
    const results = await Promise.all(files.map(processFile));
    
    // Collect statistics
    const changed = results.filter(r => r.changed);
    const errors = results.filter(r => r.error);
    
    console.log('\nSummary:');
    console.log(`- Total files scanned: ${files.length}`);
    console.log(`- Files modified: ${changed.length}`);
    console.log(`- Errors encountered: ${errors.length}`);
    
    if (changed.length > 0) {
      console.log('\nModified files:');
      changed.forEach(({ filePath }) => {
        console.log(`- ${path.relative(process.cwd(), filePath)}`);
      });
    }
    
    if (errors.length > 0) {
      console.log('\nErrors:');
      errors.forEach(({ filePath, error }) => {
        console.log(`- ${path.relative(process.cwd(), filePath)}: ${error}`);
      });
    }
  } catch (error) {
    console.error('Error:', error.message);
    process.exit(1);
  }
}

main().catch(console.error);