/**
 * Update grade code format in all JSON files
 * Old format: GUUL (4 digits) - e.g., 1011 = Grade 1, Unit 01, Lesson 1
 * New format: GGUULL (6 digits) - e.g., 010101 = Grade 01, Unit 01, Lesson 01
 */

const fs = require('fs');
const path = require('path');

// Configuration
const DATA_DIR = path.join(__dirname, 'data');
const DRY_RUN = false; // Set to true to preview changes without updating files

function convertGradeCode(oldCode) {
  const codeStr = oldCode.toString();
  
  if (codeStr.length === 4) {
    // Format: GUUL -> GGUULL
    const grade = codeStr[0];      // G
    const unit = codeStr.substring(1, 3);  // UU
    const lesson = codeStr[3];     // L
    
    return `0${grade}${unit}0${lesson}`;
  } else if (codeStr.length === 3) {
    // Format: GUL -> GGUULL
    const grade = codeStr[0];      // G
    const unit = codeStr[1];       // U
    const lesson = codeStr[2];     // L
    
    return `0${grade}0${unit}0${lesson}`;
  } else if (codeStr.length === 6) {
    // Already in new format
    return codeStr;
  }
  
  // Unknown format, return as is
  console.log(`    ⚠️  Unknown format: ${codeStr}`);
  return codeStr;
}

function processJsonFile(filePath) {
  try {
    const data = JSON.parse(fs.readFileSync(filePath, 'utf8'));
    
    if (!Array.isArray(data)) {
      return { updated: 0, changes: [] };
    }

    let updated = 0;
    const changes = [];

    // Update grade codes
    data.forEach(entry => {
      if (entry.grade) {
        const oldGrade = entry.grade;
        const newGrade = convertGradeCode(oldGrade);
        
        if (oldGrade !== newGrade) {
          changes.push({ old: oldGrade, new: newGrade });
          entry.grade = newGrade;
          updated++;
        }
      }
    });

    // Write updated data back to file
    if (!DRY_RUN && updated > 0) {
      fs.writeFileSync(filePath, JSON.stringify(data, null, 2), 'utf8');
    }

    return { updated, changes };
  } catch (error) {
    console.error(`    ❌ Error processing ${filePath}: ${error.message}`);
    return { updated: 0, changes: [] };
  }
}

function processDirectory(dir) {
  const entries = fs.readdirSync(dir, { withFileTypes: true });
  let totalUpdated = 0;
  const allChanges = [];

  for (const entry of entries) {
    const fullPath = path.join(dir, entry.name);

    if (entry.isDirectory()) {
      const result = processDirectory(fullPath);
      totalUpdated += result.updated;
      allChanges.push(...result.changes);
    } else if (entry.isFile() && entry.name.endsWith('.json')) {
      console.log(`  📄 Processing ${entry.name}...`);
      const { updated, changes } = processJsonFile(fullPath);
      
      if (updated > 0) {
        console.log(`    ✅ Updated ${updated} grade codes`);
        changes.forEach(c => {
          console.log(`       ${c.old} → ${c.new}`);
        });
        totalUpdated += updated;
        allChanges.push(...changes);
      } else {
        console.log(`    ⏭️  No changes needed`);
      }
    }
  }

  return { updated: totalUpdated, changes: allChanges };
}

async function main() {
  try {
    console.log('🔄 Starting grade code format update...\n');
    
    if (DRY_RUN) {
      console.log('⚠️  DRY RUN MODE - No files will be modified\n');
    }

    // Check if data directory exists
    if (!fs.existsSync(DATA_DIR)) {
      console.error('❌ Data directory not found:', DATA_DIR);
      process.exit(1);
    }

    // Process all JSON files in data directory
    console.log('📂 Processing JSON files...\n');
    const { updated, changes } = processDirectory(DATA_DIR);

    console.log('\n✅ Processing complete!');
    console.log(`📊 Total grade codes updated: ${updated}`);
    
    if (DRY_RUN) {
      console.log('\n⚠️  This was a DRY RUN. Set DRY_RUN = false to apply changes.');
    }
    
    process.exit(0);
  } catch (error) {
    console.error('❌ Error:', error.message);
    console.error(error.stack);
    process.exit(1);
  }
}

// Run the script
main();