// Copyright © 2022 Dmitry Sikorsky. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Azure.Storage.Blobs;
using Azure.Storage.Blobs.Models;
using ExtCore.FileStorage.Abstractions;

namespace ExtCore.FileStorage.Azure;

/// <summary>
/// Implements the <see cref="IDirectoryProxy">IDirectoryProxy</see> interface and represents a file in a Azure Storage account.
/// </summary>
public class FileProxy : IFileProxy
{
  private readonly string connectionString;
  private readonly string filepath;
  private readonly string containerName;
  private readonly string blobName;

  /// <summary>
  /// The path of the underlying file relatively to the root one.
  /// </summary>
  public string RelativePath { get; private set; }

  /// <summary>
  /// The filename of the underlying file.
  /// </summary>
  public string Filename { get; private set; }

  /// <summary>
  /// Initializes a new instance of the <see cref="FileProxy">FileProxy</see> class.
  /// </summary>
  /// <param name="connectionString">The Azure Storage account connection string.</param>
  /// <param name="rootPath">The root path of the underlying file's relative one.</param>
  /// <param name="relativePath">The path of the underlying file relatively to the root one.</param>
  /// <param name="filename">The filename of the underlying file.</param>
  /// <exception cref="ArgumentException"></exception>
  /// <exception cref="ArgumentNullException"></exception>
  public FileProxy(string connectionString, string rootPath, string relativePath, string filename)
  {
    if (connectionString == string.Empty)
      throw new ArgumentException($"Value can't be empty. Parameter name: connectionString.");

    if (connectionString == null)
      throw new ArgumentNullException($"Value can't be null. Parameter name: connectionString.", default(Exception));

    if (filename == string.Empty)
      throw new ArgumentException($"Value can't be empty. Parameter name: filename.");

    if (filename == null)
      throw new ArgumentNullException($"Value can't be null. Parameter name: filename.", default(Exception));

    this.connectionString = connectionString;
    this.RelativePath = RelativeUrl.Combine(relativePath);
    this.Filename = filename;
    this.filepath = RelativeUrl.Combine(rootPath, this.RelativePath, this.Filename);

    string[] urlSegments = filepath.Split('/');

    this.containerName = urlSegments.First();
    this.blobName = string.Join("/", urlSegments.Skip(1));
  }

  /// <summary>
  /// Checks if the underlying file exists.
  /// </summary>
  /// <returns>Returns a flag indicating if the underlying file exists.</returns>
  public async Task<bool> ExistsAsync()
  {
    try
    {
      BlobClient blobClient = await this.GetBlobClient();

      return await blobClient.ExistsAsync();
    }

    catch
    {
      return false;
    }
  }

  /// <summary>
  /// Reads content of the underlying file as a byte array.
  /// </summary>
  /// <returns>Content of the underlying file as a byte array.</returns>
  /// <exception cref="AccessDeniedException"></exception>
  /// <exception cref="DirectoryNotFoundException"></exception>
  /// <exception cref="FileNotFoundException"></exception>
  /// <exception cref="PathTooLongException"></exception>
  /// <exception cref="FileStorageException"></exception>
  public async Task<Stream> ReadStreamAsync()
  {
    try
    {
      BlobClient blobClient = await this.GetBlobClient();
      MemoryStream stream = new MemoryStream();

      await blobClient.DownloadToAsync(stream);
      stream.Position = 0;
      return stream;
    }

    catch (Exception e)
    {
      throw new FileStorageException($"Generic file storage exception: \"{this.filepath}\". See inner exception for details.", e);
    }
  }

  /// <summary>
  /// Reads content of the underlying file as a byte array.
  /// </summary>
  /// <returns>Content of the underlying file as a byte array.</returns>
  /// <exception cref="AccessDeniedException"></exception>
  /// <exception cref="DirectoryNotFoundException"></exception>
  /// <exception cref="FileNotFoundException"></exception>
  /// <exception cref="PathTooLongException"></exception>
  /// <exception cref="FileStorageException"></exception>
  public async Task<byte[]> ReadBytesAsync()
  {
    try
    {
      BlobClient blobClient = await this.GetBlobClient();
      BlobDownloadResult downloadResult = await blobClient.DownloadContentAsync();

      return downloadResult.Content.ToArray();
    }

    catch (Exception e)
    {
      throw new FileStorageException($"Generic file storage exception: \"{this.filepath}\". See inner exception for details.", e);
    }
  }

  /// <summary>
  /// Reads content of the underlying file as a text string.
  /// </summary>
  /// <returns>Content of the underlying file as a text string.</returns>
  /// <exception cref="AccessDeniedException"></exception>
  /// <exception cref="DirectoryNotFoundException"></exception>
  /// <exception cref="FileNotFoundException"></exception>
  /// <exception cref="PathTooLongException"></exception>
  /// <exception cref="FileStorageException"></exception>
  public async Task<string> ReadTextAsync()
  {
    try
    {
      BlobClient blobClient = await this.GetBlobClient();
      BlobDownloadResult downloadResult = await blobClient.DownloadContentAsync();

      return downloadResult.Content.ToString();
    }

    catch (Exception e)
    {
      throw new FileStorageException($"Generic file storage exception: \"{this.filepath}\". See inner exception for details.", e);
    }
  }

  /// <summary>
  /// Writes content to the underlying file as a stream.
  /// </summary>
  /// <param name="inputStream">Content to write to the underlying file as a stream.</param>
  /// <exception cref="ArgumentNullException"></exception>
  /// <exception cref="AccessDeniedException"></exception>
  /// <exception cref="DirectoryNotFoundException"></exception>
  /// <exception cref="PathTooLongException"></exception>
  /// <exception cref="FileStorageException"></exception>
  public async Task WriteStreamAsync(Stream inputStream)
  {
    try
    {
      BlobClient blobClient = await this.GetBlobClient();

      await blobClient.UploadAsync(inputStream);
    }

    catch (Exception e)
    {
      throw new FileStorageException($"Generic file storage exception: \"{this.filepath}\". See inner exception for details.", e);
    }
  }

  /// <summary>
  /// Writes content to the underlying file as a byte array.
  /// </summary>
  /// <param name="bytes">Content to write to the underlying file as a byte array.</param>
  /// <exception cref="ArgumentNullException"></exception>
  /// <exception cref="AccessDeniedException"></exception>
  /// <exception cref="DirectoryNotFoundException"></exception>
  /// <exception cref="PathTooLongException"></exception>
  /// <exception cref="FileStorageException"></exception>
  public async Task WriteBytesAsync(byte[] bytes)
  {
    try
    {
      BlobClient blobClient = await this.GetBlobClient();

      await blobClient.UploadAsync(BinaryData.FromBytes(bytes));
    }

    catch (Exception e)
    {
      throw new FileStorageException($"Generic file storage exception: \"{this.filepath}\". See inner exception for details.", e);
    }
  }

  /// <summary>
  /// Writes content to the underlying file as a text string.
  /// </summary>
  /// <param name="text">Content to write to the underlying file as a text string.</param>
  /// <exception cref="ArgumentNullException"></exception>
  /// <exception cref="AccessDeniedException"></exception>
  /// <exception cref="DirectoryNotFoundException"></exception>
  /// <exception cref="PathTooLongException"></exception>
  /// <exception cref="FileStorageException"></exception>
  public async Task WriteTextAsync(string text)
  {
    try
    {
      BlobClient blobClient = await this.GetBlobClient();

      await blobClient.UploadAsync(BinaryData.FromString(text));
    }

    catch (Exception e)
    {
      throw new FileStorageException($"Generic file storage exception: \"{this.filepath}\". See inner exception for details.", e);
    }
  }

  /// <summary>
  /// Deletes the underlying file.
  /// </summary>
  /// <exception cref="AccessDeniedException"></exception>
  /// <exception cref="DirectoryNotFoundException"></exception>
  /// <exception cref="FileNotFoundException"></exception>
  /// <exception cref="PathTooLongException"></exception>
  /// <exception cref="FileStorageException"></exception>
  public async Task DeleteAsync()
  {
    try
    {
      BlobClient blobClient = await this.GetBlobClient();

      await blobClient.DeleteAsync();
    }

    catch (Exception e)
    {
      throw new FileStorageException($"Generic file storage exception: \"{this.filepath}\". See inner exception for details.", e);
    }
  }

  private async Task<BlobClient> GetBlobClient()
  {
    BlobServiceClient blobServiceClient = new BlobServiceClient(this.connectionString);
    BlobContainerClient blobContainerClient = blobServiceClient.GetBlobContainerClient(this.containerName);

    await blobContainerClient.CreateIfNotExistsAsync();
    return blobContainerClient.GetBlobClient(this.blobName);
  }
}