#!/usr/bin/env node

import { createClient } from '@supabase/supabase-js';
import { readFileSync } from 'fs';
import { fileURLToPath } from 'url';
import { dirname, join } from 'path';
import dotenv from 'dotenv';

// Load environment variables
dotenv.config();

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

// Configuration
const SUPABASE_URL = process.env.SUPABASE_URL;
const SUPABASE_SERVICE_ROLE_KEY = process.env.SUPABASE_SERVICE_ROLE_KEY;

if (!SUPABASE_URL || !SUPABASE_SERVICE_ROLE_KEY) {
  console.error('❌ Missing required environment variables:');
  console.error('   - SUPABASE_URL');
  console.error('   - SUPABASE_SERVICE_ROLE_KEY');
  console.error('\nPlease check your .env file and try again.');
  process.exit(1);
}

// Initialize Supabase client with service role key
const supabase = createClient(SUPABASE_URL, SUPABASE_SERVICE_ROLE_KEY);

// Configuration
const BATCH_SIZE = 100;
const MAX_RETRIES = 3;

class DataMigrator {
  constructor(tableName, taskType) {
    this.tableName = tableName;
    this.taskType = taskType;
    this.stats = {
      total: 0,
      processed: 0,
      inserted: 0,
      updated: 0,
      skipped: 0,
      errors: 0
    };
  }

  async loadJsonlFile(filePath) {
    try {
      console.log(`📄 Reading JSONL file: ${filePath}`);
      const content = readFileSync(filePath, 'utf-8');
      
      const records = content
        .split(/\r?\n/)
        .filter(line => line.trim().length > 0)
        .map(line => {
          try {
            return JSON.parse(line);
          } catch (parseError) {
            console.warn(`⚠️  Skipping invalid JSON line: ${line.substring(0, 50)}...`);
            return null;
          }
        })
        .filter(record => record !== null);

      console.log(`✅ Loaded ${records.length} records from JSONL file`);
      return records;
    } catch (error) {
      console.error(`❌ Error reading JSONL file: ${error.message}`);
      throw error;
    }
  }

  transformRecord(record) {
    return {
      id: record.id,
      task_type: record.task_type,
      task_description: record.task_description || null,
      rephrased_task: record.rephrased_task || null,
      vocabulary: record.vocabulary || null,
      response: record.response || null,
      response_alternative: record.response_alternative || null,
      brainstorm: record.brainstorm || null,
      brainstorm_alternative: record.brainstorm_alternative || null,
      updated_at: new Date().toISOString()
    };
  }

  async upsertRecord(record, retryCount = 0) {
    try {
      const transformedRecord = this.transformRecord(record);
      
      // Use upsert to handle duplicates (insert or update based on id and task_type)
      const { data, error, status } = await supabase
        .from(this.tableName)
        .upsert(transformedRecord, {
          onConflict: 'id,task_type',
          ignoreDuplicates: false
        })
        .select();

      if (error) {
        throw error;
      }

      // Check if this was an insert or update based on the response
      if (status === 201) {
        this.stats.inserted++;
        console.log(`✅ Inserted record: ${record.id}-${record.task_type}`);
      } else if (status === 200) {
        this.stats.updated++;
        console.log(`🔄 Updated record: ${record.id}-${record.task_type}`);
      } else {
        this.stats.skipped++;
        console.log(`⏭️  Skipped record: ${record.id}-${record.task_type}`);
      }

      return { success: true, data };

    } catch (error) {
      if (retryCount < MAX_RETRIES) {
        console.log(`🔄 Retrying record ${record.id}-${record.task_type} (attempt ${retryCount + 1}/${MAX_RETRIES})`);
        await new Promise(resolve => setTimeout(resolve, 1000 * (retryCount + 1)));
        return this.upsertRecord(record, retryCount + 1);
      }

      this.stats.errors++;
      console.error(`❌ Failed to process record ${record.id}-${record.task_type}: ${error.message}`);
      return { success: false, error: error.message };
    }
  }

  async processBatch(records, startIndex) {
    const endIndex = Math.min(startIndex + BATCH_SIZE, records.length);
    const batch = records.slice(startIndex, endIndex);

    console.log(`\n📦 Processing batch ${Math.floor(startIndex / BATCH_SIZE) + 1}: records ${startIndex + 1}-${endIndex}`);

    const promises = batch.map(record => this.upsertRecord(record));
    const results = await Promise.allSettled(promises);

    const successful = results.filter(r => r.status === 'fulfilled' && r.value.success).length;
    const failed = results.filter(r => r.status === 'rejected' || !r.value.success).length;

    console.log(`📊 Batch completed: ${successful} successful, ${failed} failed`);

    return endIndex;
  }

  async migrateFile(filePath) {
    try {
      console.log(`🚀 Starting migration for ${this.taskType} tasks...\n`);

      const records = await this.loadJsonlFile(filePath);
      this.stats.total = records.length;

      if (records.length === 0) {
        console.log('⚠️  No records to migrate');
        return this.stats;
      }

      // Process records in batches
      let currentIndex = 0;
      while (currentIndex < records.length) {
        currentIndex = await this.processBatch(records, currentIndex);
        this.stats.processed = currentIndex;

        // Show progress
        const progress = ((currentIndex / records.length) * 100).toFixed(1);
        console.log(`📈 Progress: ${progress}% (${currentIndex}/${records.length})`);
      }

      console.log('\n✅ Migration completed!');
      this.printStats();
      return this.stats;

    } catch (error) {
      console.error(`❌ Migration failed: ${error.message}`);
      throw error;
    }
  }

  printStats() {
    console.log('\n📊 Migration Statistics:');
    console.log(`   Total records:     ${this.stats.total}`);
    console.log(`   Processed:         ${this.stats.processed}`);
    console.log(`   Inserted:          ${this.stats.inserted}`);
    console.log(`   Updated:           ${this.stats.updated}`);
    console.log(`   Skipped:           ${this.stats.skipped}`);
    console.log(`   Errors:            ${this.stats.errors}`);
    console.log(`   Success rate:      ${((this.stats.inserted + this.stats.updated) / this.stats.total * 100).toFixed(1)}%`);
  }

  async verifyMigration() {
    try {
      console.log(`\n🔍 Verifying migration for table: ${this.tableName}`);
      
      const { count, error } = await supabase
        .from(this.tableName)
        .select('*', { count: 'exact', head: true });

      if (error) {
        throw error;
      }

      console.log(`✅ Table ${this.tableName} contains ${count} records`);
      return count;

    } catch (error) {
      console.error(`❌ Verification failed: ${error.message}`);
      throw error;
    }
  }
}


async function main() {
  console.log(' Starting data migration process...\n');

  const args = process.argv.slice(2);
  
  // Parse command line arguments
  const flags = {
    help: args.includes('--help') || args.includes('-h'),
    dryRun: args.includes('--dry-run'),
    file: null,
    type: null
  };

  // Parse --file and --type arguments
  const fileArg = args.find(arg => arg.startsWith('--file='));
  const typeArg = args.find(arg => arg.startsWith('--type='));
  
  if (fileArg) flags.file = fileArg.split('=')[1];
  if (typeArg) flags.type = typeArg.split('=')[1];

  // Show help
  if (flags.help) {
    console.log(`
📋 Usage: node migrate-data.js [options]

Required:
  --file=<path>     Path to JSONL file to migrate
  --type=<type>     Type of tasks: 'speaking' or 'writing'

Options:
  --dry-run         Show what would be migrated without doing it
  --help, -h        Show this help message

Examples:
  node migrate-data.js --file=data/speaking01.jsonl --type=speaking
  node migrate-data.js --file=data/writing.jsonl --type=writing
  node migrate-data.js --file=data/speaking01.jsonl --type=speaking --dry-run
`);
    process.exit(0);
  }

  // Validate required arguments
  if (!flags.file || !flags.type) {
    console.error('❌ Missing required arguments:');
    if (!flags.file) console.error('   --file=<path> (required)');
    if (!flags.type) console.error('   --type=<speaking|writing> (required)');
    console.error('\nUse --help for usage information.');
    process.exit(1);
  }

  // Validate type
  if (!['speaking', 'writing'].includes(flags.type)) {
    console.error('❌ Invalid type. Must be "speaking" or "writing"');
    process.exit(1);
  }

  // Check if file exists
  try {
    readFileSync(flags.file, 'utf-8');
  } catch (error) {
    console.error(`❌ File not found or not readable: ${flags.file}`);
    process.exit(1);
  }

  try {
    // Determine table name
    const tableName = flags.type === 'speaking' ? 'speaking_tasks' : 'writing_tasks';
    
    // Create migrator
    const migrator = new DataMigrator(tableName, flags.type);

    if (flags.dryRun) {
      console.log('🔍 DRY RUN MODE - No changes will be made\n');
      const records = await migrator.loadJsonlFile(flags.file);
      console.log(`📊 Would migrate ${records.length} ${flags.type} tasks`);
      console.log('   Run without --dry-run to perform the migration');
    } else {
      // Perform migration
      await migrator.migrateFile(flags.file);
      
      // Verify migration
      await migrator.verifyMigration();
    }

    console.log('\n🎉 Migration process completed!');

  } catch (error) {
    console.error('\n❌ Migration failed:', error.message);
    process.exit(1);
  }
}

// Run the script
main().catch(console.error);