// Copyright (C) 2025, The Duplicati Team
// https://duplicati.com, hello@duplicati.com
// 
// Permission is hereby granted, free of charge, to any person obtaining a 
// copy of this software and associated documentation files (the "Software"), 
// to deal in the Software without restriction, including without limitation 
// the rights to use, copy, modify, merge, publish, distribute, sublicense, 
// and/or sell copies of the Software, and to permit persons to whom the 
// Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in 
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
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using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Duplicati.Library.Interface;
using Duplicati.Library.Main.Database;
using Duplicati.Library.Main.Volumes;
using Duplicati.Library.Utility;
using IFileEntry = Duplicati.Library.Interface.IFileEntry;

#nullable enable

namespace Duplicati.Library.Main;

/// <summary>
/// Interface for the backend manager
/// </summary>
internal interface IBackendManager : IDisposable
{
    /// <summary>
    /// Uploads a block volume to the backend, including an optional index volume
    /// </summary>
    /// <param name="blockVolume">The block volume to upload</param>
    /// <param name="indexVolume">The index volume to upload, if any</param>
    /// <param name="indexVolumeFinished">The action to call when the index volume is finished</param>
    /// <param name="waitForComplete">Whether to wait for the upload to complete</param>
    /// <param name="onDbUpdate">The action to call when the database should be updated</param>
    /// <param name="cancelToken">The cancellation token</param>
    /// <returns>An awaitable task</returns>
    Task PutAsync(VolumeWriterBase blockVolume, IndexVolumeWriter? indexVolume, Func<Task>? indexVolumeFinished, bool waitForComplete, Func<Task>? onDbUpdate, CancellationToken cancelToken);

    /// <summary>
    /// Uploads a file to the backend without encryption
    /// </summary>
    /// <param name="remotename">The name of the file to upload to</param>
    /// <param name="tempFile">The file to upload</param>
    /// <param name="cancelToken">The cancellation token</param>
    /// <returns>An awaitable task</returns>
    Task PutVerificationFileAsync(string remotename, TempFile tempFile, CancellationToken cancelToken);

    /// <summary>
    /// Waits for the backend queue to be empty
    /// </summary>
    /// <param name="cancellationToken">The cancellation token</param>
    /// <returns>An awaitable task</returns>
    Task WaitForEmptyAsync(CancellationToken cancellationToken);

    /// <summary>
    /// Waits for the backend queue to be empty and flushes any pending messages to the database
    /// </summary>
    /// <param name="database">The database to write pending messages to</param>
    /// <param name="cancellationToken">The cancellation token</param>
    /// <returns>An awaitable task</returns>
    Task WaitForEmptyAsync(LocalDatabase database, CancellationToken cancellationToken);

    /// <summary>
    /// Lists the files on the backend
    /// </summary>
    /// <param name="cancelToken">The cancellation token</param>
    /// <returns>An enumerable of file entries</returns>
    Task<IEnumerable<IFileEntry>> ListAsync(CancellationToken cancelToken);

    /// <summary>
    /// Decrypts the given file and returns the decrypted file
    /// </summary>
    /// <param name="volume">The file to decrypt</param>
    /// <param name="volume_name">The name of the file. Used for detecting encryption algorithm if not specified in options or if it differs from the options</param>
    /// <param name="options">The Duplicati options</param>
    /// <returns>The decrypted file</returns>
    TempFile DecryptFile(TempFile volume, string volume_name, Options options);

    /// <summary>
    /// Deletes a file on the backend
    /// </summary>
    /// <param name="remotename">The name of the file to delete</param>
    /// <param name="size">The size of the file to delete, or -1 if not known</param>
    /// <param name="waitForComplete">Whether to wait for the delete to complete</param>
    /// <param name="cancelToken">The cancellation token</param>
    /// <returns>An awaitable task</returns>
    Task DeleteAsync(string remotename, long size, bool waitForComplete, CancellationToken cancelToken);

    /// <summary>
    /// Applies or updates an object lock on a remote volume.
    /// </summary>
    /// <param name="remotename">The name of the file to lock</param>
    /// <param name="lockUntilUtc">The UTC time the lock should be in effect until</param>
    /// <param name="cancelToken">The cancellation token</param>
    Task SetObjectLockUntilAsync(string remotename, DateTime lockUntilUtc, CancellationToken cancelToken);

    /// <summary>
    /// Gets the object lock expiration time for a remote volume.
    /// </summary>
    /// <param name="remotename">The name of the file to check</param>
    /// <param name="cancelToken">The cancellation token</param>
    /// <returns>The UTC time the lock expires, or null if no lock is set</returns>
    Task<DateTime?> GetObjectLockUntilAsync(string remotename, CancellationToken cancelToken);

    /// <summary>
    /// Gets the quota information for the backend
    /// </summary>
    /// <param name="cancelToken">The cancellation token</param>
    /// <returns>The quota information, or null if not available or disabled</returns>
    Task<IQuotaInfo?> GetQuotaInfoAsync(CancellationToken cancelToken);

    /// <summary>
    /// Gets a file with the hash and size
    /// </summary>
    /// <param name="remotename">The name of the file to get</param>
    /// <param name="hash">The hash of the file to get, or <c>null</c> if not known</param>
    /// <param name="size">The size of the file to get, or -1 if not known</param>
    /// <param name="cancelToken">The cancellation token</param>
    /// <returns>The file, hash, and size</returns>
    Task<(TempFile File, string Hash, long Size)> GetWithInfoAsync(string remotename, string hash, long size, CancellationToken cancelToken);

    /// <summary>
    /// Gets a file from the backend
    /// </summary>
    /// <param name="remotename">The name of the file to get</param>
    /// <param name="hash">The hash of the file to get, or <c>null</c> if not known</param>
    /// <param name="size">The size of the file to get, or -1 if not known</param>
    /// <param name="cancelToken">The cancellation token</param>
    /// <returns>The downloaded file</returns>
    Task<TempFile> GetAsync(string remotename, string hash, long size, CancellationToken cancelToken);

    /// <summary>
    /// Gets a file from the backend without decrypting it
    /// </summary>
    /// <param name="remotename">The name of the remote volume</param>
    /// <param name="hash">The hash of the volume</param>
    /// <param name="size">The size of the volume</param>
    /// <param name="cancelToken">The cancellation token</param>
    /// <returns>The downloaded file</returns>
    Task<TempFile> GetDirectAsync(string remotename, string hash, long size, CancellationToken cancelToken);

    /// <summary>
    /// Performs a download of the files specified, with pre-fetch to overlap the download and processing
    /// </summary>
    /// <param name="volumes">The volumes to download</param>
    /// <param name="cancelToken">The cancellation token</param>
    /// <returns>The downloaded files, hash, size, and name</returns>
    IAsyncEnumerable<(TempFile File, string Hash, long Size, string Name)> GetFilesOverlappedAsync(IEnumerable<IRemoteVolume> volumes, CancellationToken cancelToken);

    /// <summary>
    /// Flushes the database messages to the database
    /// </summary>
    /// <param name="database">The database to write to</param>
    /// <param name="cancellationToken">The cancellation token</param>
    /// <returns></returns>
    Task FlushPendingMessagesAsync(LocalDatabase database, CancellationToken cancellationToken);

    /// <summary>
    /// Updates the throttle values for upload and download
    /// </summary>
    /// <param name="maxUploadPrSecond">The maximum upload speed in bytes per second</param>
    /// <param name="maxDownloadPrSecond">The maximum download speed in bytes per second</param>
    void UpdateThrottleValues(long maxUploadPrSecond, long maxDownloadPrSecond);

    /// <summary>
    /// Indicates whether the backend supports object locking operations.
    /// </summary>
    bool SupportsObjectLocking { get; }

}