using System.Collections.Generic;
  using Amazon.DynamoDBv2;
  using Amazon.DynamoDBv2.DataModel;
  using RoboforkApp.AWS.Contracts;
  
  namespace RoboforkApp.AWS.DynamoDb
  {
      public class DynamoService : ITableDataService
      {
          public readonly DynamoDBContext DbContext;
          public AmazonDynamoDBClient DynamoClient;
  
          public DynamoService()
          {
              DynamoClient = new AmazonDynamoDBClient();
  
              DbContext = new DynamoDBContext(DynamoClient, new DynamoDBContextConfig
              {
                  //Setting the Consistent property to true ensures that you'll always get the latest 
                  ConsistentRead = true,
                  SkipVersionCheck = true
              });
          }
  
          /// <summary>
          /// The Store method allows you to save a POCO to DynamoDb
          /// </summary>
          /// <typeparam name="T"></typeparam>
          /// <param name="item"></param>
          public void Store<T>(T item) where T : new()
          {
              DbContext.Save(item);
          }
  
          /// <summary>
          /// The BatchStore Method allows you to store a list of items of type T to dynamoDb
          /// </summary>
          /// <typeparam name="T"></typeparam>
          /// <param name="items"></param>
          public void BatchStore<T>(IEnumerable<T> items) where T : class
          {
              var itemBatch = DbContext.CreateBatchWrite<T>();
  
              foreach (var item in items)
              {
                  itemBatch.AddPutItem(item);
              }
  
              itemBatch.Execute();
          }
          /// <summary>
          /// Uses the scan operator to retrieve all items in a table
          /// <remarks>[CAUTION] This operation can be very expensive if your table is large</remarks>
          /// </summary>
          /// <typeparam name="T"></typeparam>
          /// <returns></returns>
          public IEnumerable<T> GetAll<T>() where T : class
          {
              IEnumerable<T> items = DbContext.Scan<T>();
              return items;
          }
  
          /// <summary>
          /// Retrieves an item based on a search key
          /// </summary>
          /// <typeparam name="T"></typeparam>
          /// <param name="key"></param>
          /// <returns></returns>
          public T GetItem<T>(string key) where T : class
          {
              return DbContext.Load<T>(key);
          }
  
          /// <summary>
          /// Method Updates and existing item in the table
          /// </summary>
          /// <typeparam name="T"></typeparam>
          /// <param name="item"></param>
          public void UpdateItem<T>(T item) where T : class
          {
              T savedItem = DbContext.Load(item);
  
              if (savedItem == null)
              {
                  throw new AmazonDynamoDBException("The item does not exist in the Table");
              }
  
              DbContext.Save(item);
          }
  
          /// <summary>
          /// Deletes an Item from the table.
          /// </summary>
          /// <typeparam name="T"></typeparam>
          /// <param name="item"></param>
          public void DeleteItem<T>(T item)
          {
              var savedItem = DbContext.Load(item);
  
              if (savedItem == null)
              {
                  throw new AmazonDynamoDBException("The item does not exist in the Table");
              }
  
              DbContext.Delete(item);
          }
  
      }
  }