module.exports = (sequelize, DataTypes) => {
  const ServiceAlert = sequelize.define('ServiceAlert', {
    id: {
      type: DataTypes.UUID,
      defaultValue: DataTypes.UUIDV4,
      primaryKey: true
    },
    serviceId: {
      type: DataTypes.UUID,
      allowNull: false,
      references: {
        model: 'customer_services',
        key: 'id'
      }
    },
    alertType: {
      type: DataTypes.ENUM('usage_threshold', 'billing_threshold', 'service_down', 'maintenance', 'expiry_warning'),
      allowNull: false
    },
    severity: {
      type: DataTypes.ENUM('low', 'medium', 'high', 'critical'),
      allowNull: false,
      defaultValue: 'medium'
    },
    title: {
      type: DataTypes.STRING,
      allowNull: false
    },
    message: {
      type: DataTypes.TEXT,
      allowNull: false
    },
    status: {
      type: DataTypes.ENUM('active', 'acknowledged', 'resolved', 'dismissed'),
      allowNull: false,
      defaultValue: 'active'
    },
    threshold: {
      type: DataTypes.JSON,
      allowNull: true
    },
    currentValue: {
      type: DataTypes.JSON,
      allowNull: true
    },
    acknowledgedAt: {
      type: DataTypes.DATE,
      allowNull: true
    },
    resolvedAt: {
      type: DataTypes.DATE,
      allowNull: true
    },
    metadata: {
      type: DataTypes.JSON,
      defaultValue: {}
    }
  }, {
    tableName: 'service_alerts',
    indexes: [
      {
        fields: ['service_id']
      },
      {
        fields: ['alert_type']
      },
      {
        fields: ['severity']
      },
      {
        fields: ['status']
      },
      {
        fields: ['created_at']
      }
    ]
  });

  // Class methods
  ServiceAlert.associate = function(models) {
    ServiceAlert.belongsTo(models.CustomerService, {
      foreignKey: 'serviceId',
      as: 'service'
    });
  };

  return ServiceAlert;
};