class ModifyCustomersTable < ActiveRecord::Migration[7.1]
  def up
    # First, remove the foreign key constraint from reservations
    remove_foreign_key :reservations, :customers if foreign_key_exists?(:reservations, :customers)
    
    # Create temporary columns without constraints
    add_column :customers, :first_name, :string unless column_exists?(:customers, :first_name)
    add_column :customers, :surname, :string unless column_exists?(:customers, :surname)
    add_column :customers, :original_phone, :string unless column_exists?(:customers, :original_phone)
    
    # Copy data
    execute <<-SQL
      UPDATE customers 
      SET first_name = name,
          surname = '',
          original_phone = phone
    SQL
    
    # Now add the NOT NULL constraints
    change_column_null :customers, :surname, false
    change_column_null :customers, :original_phone, false
    
    # Remove old name column
    remove_column :customers, :name if column_exists?(:customers, :name)
    
    # Remove existing indexes
    remove_index :customers, name: :index_customers_composite_with_company, if_exists: true
    remove_index :customers, name: :index_customers_on_name_and_company_id, if_exists: true
    remove_index :customers, name: :index_customers_on_company_id, if_exists: true
    remove_index :customers, name: :index_customers_on_composite_key, if_exists: true
    remove_index :customers, name: :index_customers_on_composite_key_and_company, if_exists: true
    
    # Create new indexes
    add_index :customers, [:first_name, :surname, :original_phone], 
              unique: true,
              name: 'index_customers_on_composite_key'
    
    add_index :customers, [:first_name, :surname, :original_phone, :company_id], 
              unique: true,
              name: 'index_customers_on_composite_key_and_company'
              
    # Add a non-unique index on company_id for performance
    add_index :customers, :company_id, 
              name: 'index_customers_on_company_id'
              
    # Add new columns to reservations
    add_column :reservations, :customer_first_name, :string
    add_column :reservations, :customer_surname, :string
    add_column :reservations, :customer_original_phone, :string
    
    # Update reservations data
    execute <<-SQL
      UPDATE reservations 
      SET customer_first_name = (SELECT first_name FROM customers WHERE customers.id = reservations.customer_id),
          customer_surname = (SELECT surname FROM customers WHERE customers.id = reservations.customer_id),
          customer_original_phone = (SELECT original_phone FROM customers WHERE customers.id = reservations.customer_id)
    SQL
    
    # Add foreign key constraint
    add_foreign_key :reservations, :customers, 
                    primary_key: [:first_name, :surname, :original_phone],
                    column: [:customer_first_name, :customer_surname, :customer_original_phone]
                    
    # Remove old columns
    remove_column :customers, :id if column_exists?(:customers, :id)
    remove_column :reservations, :customer_id if column_exists?(:reservations, :customer_id)
  end

  def down
    # Add back the id columns
    add_column :customers, :id, :primary_key
    add_column :reservations, :customer_id, :integer
    
    # Remove the composite foreign key
    remove_foreign_key :reservations, :customers if foreign_key_exists?(:reservations, :customers)
    remove_column :reservations, :customer_first_name
    remove_column :reservations, :customer_surname
    remove_column :reservations, :customer_original_phone
    
    # Add back the original foreign key
    add_foreign_key :reservations, :customers
    
    # Drop composite indexes safely
    execute <<-SQL
      DROP INDEX IF EXISTS index_customers_on_composite_key;
      DROP INDEX IF EXISTS index_customers_on_composite_key_and_company;
    SQL
    
    # Restore the original columns
    add_column :customers, :name, :string
    execute "UPDATE customers SET name = first_name"
    
    remove_column :customers, :first_name
    remove_column :customers, :surname
    remove_column :customers, :original_phone
  end
end