const { sequelize } = require('./src/config/database');
const { QueryTypes } = require('sequelize');

async function runMigration() {
  try {
    console.log('🚀 Starting member_number migration...\n');
    
    // Step 1: Add column (if not exists)
    console.log('Step 1: Adding member_number column...');
    await sequelize.query(`
      ALTER TABLE group_members 
      ADD COLUMN IF NOT EXISTS member_number INTEGER
    `);
    console.log('✓ Column added\n');
    
    // Step 2: Populate for existing members
    console.log('Step 2: Assigning numbers to existing members...');
    const [results] = await sequelize.query(`
      WITH numbered_members AS (
        SELECT 
          id,
          ROW_NUMBER() OVER (
            PARTITION BY group_id 
            ORDER BY joined_date ASC, created_at ASC
          ) as assigned_number
        FROM group_members
        WHERE member_number IS NULL
      )
      UPDATE group_members gm
      SET member_number = nm.assigned_number
      FROM numbered_members nm
      WHERE gm.id = nm.id
      RETURNING gm.member_number
    `);
    console.log(`✓ Assigned numbers to ${results.length} existing members\n`);
    
    // Step 3: Make NOT NULL
    console.log('Step 3: Setting NOT NULL constraint...');
    await sequelize.query(`
      ALTER TABLE group_members 
      ALTER COLUMN member_number SET NOT NULL
    `);
    console.log('✓ NOT NULL constraint set\n');
    
    // Step 4: Add unique index
    console.log('Step 4: Creating unique index...');
    await sequelize.query(`
      CREATE UNIQUE INDEX IF NOT EXISTS idx_group_members_member_number 
      ON group_members(group_id, member_number)
    `);
    console.log('✓ Unique index created\n');
    
    // Step 5: Verify
    console.log('Step 5: Verifying migration...');
    const members = await sequelize.query(
      `SELECT 
        gm.member_number,
        u.full_name,
        cg.name as group_name
      FROM group_members gm
      JOIN users u ON gm.user_id = u.id
      JOIN chit_groups cg ON gm.group_id = cg.id
      ORDER BY cg.name, gm.member_number
      LIMIT 20`,
      { type: QueryTypes.SELECT }
    );
    
    console.log('\n✅ Migration completed successfully!\n');
    console.log('Sample members with assigned numbers:');
    console.log('─'.repeat(70));
    members.forEach(m => {
      console.log(`#${m.member_number}\t${m.full_name}\t(${m.group_name})`);
    });
    console.log('─'.repeat(70));
    console.log(`\n✓ Total members checked: ${members.length}`);
    console.log('\n🎉 Member numbers are now active!');
    console.log('   Restart your backend server to see them in action.');
    
    await sequelize.close();
    process.exit(0);
  } catch (error) {
    console.error('\n❌ Migration failed:', error.message);
    console.error('\nFull error:', error);
    await sequelize.close();
    process.exit(1);
  }
}

console.log('═'.repeat(70));
console.log('  MEMBER NUMBER MIGRATION');
console.log('  Adding readable serial numbers (1, 2, 3...) to members');
console.log('═'.repeat(70));
console.log('');

runMigration();