using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Threading.Tasks;
using Microsoft.WindowsAzure.StorageClient;
namespace HeuristicLab.Clients.Hive.CloudManager.Azure {
  public static class CloudBlobExtension {
    private class BlockTransferDetail {
      public int StartPosition { get; set; }
      public int BytesToRead { get; set; }
      public string BlockId { get; set; }
    }

    //check if a blob exists
    // see: http://stackoverflow.com/questions/2642919/checking-if-a-blob-exists-in-azure-storage
    public static bool Exists(this CloudBlob blob) {
      try {
        blob.FetchAttributes();
        return true;
      }
      catch (StorageClientException ex) {
        if (ex.ErrorCode == StorageErrorCode.ResourceNotFound) {
          return false;
        } else {
          throw;
        }
      }
    }

    public static void UploadParallel(this CloudBlockBlob blob, string filePath) {
      FileInfo file = new FileInfo(filePath);
      //CloudBlockBlob blob = blobContainer.GetBlockBlobReference(file.Name);
      blob.Properties.ContentType = "application/octet-stream";

      // init
      int blockSize = 262144;
      long fileSize = file.Length;
      long leftToRead = fileSize;
      int startPosition = 0;

      int blockCount = ((int)Math.Floor((double)(fileSize / blockSize))) + 1;
      BlockTransferDetail[] transferDetails = new BlockTransferDetail[blockCount];
      List<string> blockIdList = new List<string>();

      // setup control array
      for (int j = 0; j < transferDetails.Length; j++) {
        int toRead = (int)(leftToRead > blockSize ? blockSize : leftToRead);
        string blockId = Convert.ToBase64String(ASCIIEncoding.ASCII.GetBytes(string.Format("BlockId{0}", j.ToString("0000000"))));
        transferDetails[j] = new BlockTransferDetail() { StartPosition = startPosition, BytesToRead = toRead, BlockId = blockId };
        if (toRead > 0) {
          blockIdList.Add(blockId);
        }
        startPosition += toRead;
        leftToRead -= toRead;
      }

      // perform parallel upload
      var result = Parallel.For(0, transferDetails.Length, j => {
        using (FileStream fs = new FileStream(file.FullName, FileMode.Open, FileAccess.Read)) {
          byte[] buffer = new byte[transferDetails[j].BytesToRead];
          BinaryReader br = new BinaryReader(fs);
          fs.Seek(transferDetails[j].StartPosition, SeekOrigin.Begin);
          br.Read(buffer, 0, transferDetails[j].BytesToRead);
          if (buffer.Length > 0) {
            using (MemoryStream ms = new MemoryStream(buffer)) {
              blob.PutBlock(transferDetails[j].BlockId, ms, null);
            }
          }
        }
      });
      blob.PutBlockList(blockIdList);
    }

    public static bool Exists(this CloudBlobContainer blob) {
      try {
        blob.FetchAttributes();
        return true;
      }
      catch (StorageClientException ex) {
        if (ex.ErrorCode == StorageErrorCode.ResourceNotFound) {
          return false;
        } else {
          throw;
        }
      }
    }
  }
}