'use strict';

module.exports = {
  async up(queryInterface, Sequelize) {
    // Create task_events table
    await queryInterface.createTable('task_events', {
      id: {
        type: Sequelize.INTEGER,
        primaryKey: true,
        autoIncrement: true,
        allowNull: false
      },
      task_id: {
        type: Sequelize.INTEGER,
        allowNull: false,
        references: {
          model: 'tasks',
          key: 'id'
        },
        onUpdate: 'CASCADE',
        onDelete: 'CASCADE'
      },
      user_id: {
        type: Sequelize.INTEGER,
        allowNull: false,
        references: {
          model: 'users',
          key: 'id'
        },
        onUpdate: 'CASCADE',
        onDelete: 'CASCADE'
      },
      event_type: {
        type: Sequelize.STRING,
        allowNull: false,
        // Common event types: 'created', 'status_changed', 'priority_changed', 
        // 'due_date_changed', 'project_changed', 'name_changed', 'description_changed',
        // 'completed', 'archived', 'deleted', 'restored'
      },
      old_value: {
        type: Sequelize.TEXT,
        allowNull: true,
        // JSON string of the old value(s) - for tracking what changed from
      },
      new_value: {
        type: Sequelize.TEXT,
        allowNull: true,
        // JSON string of the new value(s) - for tracking what changed to
      },
      field_name: {
        type: Sequelize.STRING,
        allowNull: true,
        // The name of the field that was changed (status, priority, due_date, etc.)
      },
      metadata: {
        type: Sequelize.TEXT,
        allowNull: true,
        // Additional context as JSON string (e.g., source of change: 'web', 'api', 'telegram')
      },
      created_at: {
        type: Sequelize.DATE,
        allowNull: false,
        defaultValue: Sequelize.literal('CURRENT_TIMESTAMP')
      }
    });

    // Add indexes for better query performance
    await queryInterface.addIndex('task_events', ['task_id']);
    await queryInterface.addIndex('task_events', ['user_id']);
    await queryInterface.addIndex('task_events', ['event_type']);
    await queryInterface.addIndex('task_events', ['created_at']);
    await queryInterface.addIndex('task_events', ['task_id', 'event_type']);
    await queryInterface.addIndex('task_events', ['task_id', 'created_at']);
  },

  async down(queryInterface, Sequelize) {
    // Remove indexes first
    await queryInterface.removeIndex('task_events', ['task_id', 'created_at']);
    await queryInterface.removeIndex('task_events', ['task_id', 'event_type']);
    await queryInterface.removeIndex('task_events', ['created_at']);
    await queryInterface.removeIndex('task_events', ['event_type']);
    await queryInterface.removeIndex('task_events', ['user_id']);
    await queryInterface.removeIndex('task_events', ['task_id']);
    
    // Drop the table
    await queryInterface.dropTable('task_events');
  }
};