module.exports = (sequelize, DataTypes) => {
  const Plan = sequelize.define('Plan', {
    id: {
      type: DataTypes.UUID,
      defaultValue: DataTypes.UUIDV4,
      primaryKey: true
    },
    conversation_id: {
      type: DataTypes.UUID,
      allowNull: false,
      references: {
        model: 'conversations',
        key: 'id'
      }
    },
    title: {
      type: DataTypes.STRING,
      allowNull: false
    },
    description: {
      type: DataTypes.TEXT,
      allowNull: false
    },
    steps: {
      type: DataTypes.JSONB,
      allowNull: false
    },
    status: {
      type: DataTypes.ENUM('draft', 'pending_approval', 'approved', 'rejected', 'executing', 'completed', 'failed'),
      defaultValue: 'draft'
    },
    approval_feedback: {
      type: DataTypes.TEXT,
      allowNull: true
    },
    execution_result: {
      type: DataTypes.JSONB,
      defaultValue: {}
    },
    tools_required: {
      type: DataTypes.ARRAY(DataTypes.STRING),
      defaultValue: []
    },
    estimated_duration: {
      type: DataTypes.INTEGER, // in minutes
      allowNull: true
    },
    complexity_score: {
      type: DataTypes.FLOAT,
      defaultValue: 0
    },
    metadata: {
      type: DataTypes.JSONB,
      defaultValue: {}
    }
  }, {
    tableName: 'plans',
    indexes: [
      { fields: ['conversation_id'] },
      { fields: ['status'] },
      { fields: ['created_at'] }
    ]
  });

  return Plan;
};