import path from 'path';
import fs from 'fs/promises';

async function copyMissingKeys(sourceFilePath, targetFilePath) {
  try {
    // Read the files
    const sourceContent = await fs.readFile(sourceFilePath, 'utf8');
    const targetContent = await fs.readFile(targetFilePath, 'utf8');

    // Parse JSON
    const sourcePackage = JSON.parse(sourceContent);
    const targetPackage = JSON.parse(targetContent);

    // Count missing keys before update
    const missingKeysBefore = Object.keys(sourcePackage).filter(key => !(key in targetPackage));
    console.log(`Found ${missingKeysBefore.length} missing keys: ${missingKeysBefore.join(', ')}`);

    // Copy over missing keys
    let modifiedCount = 0;
    for (const key of Object.keys(sourcePackage)) {
      if (!(key in targetPackage)) {
        targetPackage[key] = sourcePackage[key];
        modifiedCount++;
      }
    }

    if (modifiedCount === 0) {
      console.log('No missing keys to copy. Target file remains unchanged.');
      return;
    }

    // Write the updated target file
    const updatedContent = JSON.stringify(targetPackage, null, 2);
    await fs.writeFile(targetFilePath, updatedContent);
    
    console.log(`Successfully copied ${modifiedCount} missing keys from ${path.basename(sourceFilePath)} to ${path.basename(targetFilePath)}`);
  } catch (error) {
    console.error('Error:', error.message);
    process.exit(1);
  }
}

// Check if file paths are provided as arguments
const args = process.argv.slice(2);
if (args.length !== 2) {
  console.error('Usage: node copy-missing-keys.js <source-package.json> <target-package.json>');
  process.exit(1);
}

const [sourceFilePath, targetFilePath] = args;

// Execute the function
copyMissingKeys(sourceFilePath, targetFilePath);