// 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 
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// 
// 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 
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using Duplicati.Library.Backend.GoogleServices;
using Duplicati.Library.Common.IO;
using Duplicati.Library.Interface;
using Duplicati.Library.Utility;
using Duplicati.Library.Utility.Options;
using System.Net.Http.Json;
using System.Runtime.CompilerServices;
using System.Text;

namespace Duplicati.Library.Backend.GoogleDrive
{
    // ReSharper disable once UnusedMember.Global
    // This class is instantiated dynamically in the BackendLoader.
    public class GoogleDrive : IBackend, IStreamingBackend, IQuotaEnabledBackend, IRenameEnabledBackend, IFolderEnabledBackend
    {
        private const string TEAMDRIVE_ID = "googledrive-teamdrive-id";
        private const string FOLDER_MIMETYPE = "application/vnd.google-apps.folder";

        private static readonly string TOKEN_URL = AuthIdOptionsHelper.GetOAuthLoginUrl("googledrive", null);

        private readonly string m_path;
        private readonly string? m_teamDriveID;
        private readonly OAuthHelperHttpClient m_oauth;
        private readonly Dictionary<string, GoogleDriveFolderItem[]> m_filecache;
        private readonly TimeoutOptionsHelper.Timeouts m_timeouts;

        private string? m_currentFolderId;

        public GoogleDrive()
        {
            m_path = null!;
            m_oauth = null!;
            m_filecache = null!;
            m_timeouts = null!;
        }

        public GoogleDrive(string url, Dictionary<string, string?> options)
        {
            var uri = new Utility.Uri(url);

            m_path = Util.AppendDirSeparator(uri.HostAndPath, "/");

            var auth = AuthIdOptionsHelper.Parse(options)
                .RequireCredentials(TOKEN_URL);

            m_timeouts = TimeoutOptionsHelper.Parse(options);
            m_teamDriveID = options.GetValueOrDefault(TEAMDRIVE_ID);
            m_oauth = new OAuthHelperHttpClient(auth.AuthId!, this.ProtocolKey, auth.OAuthUrl) { AutoAuthHeader = true };
            m_filecache = new Dictionary<string, GoogleDriveFolderItem[]>();
        }

        private async Task<string> GetFolderIdAsync(string path, bool autocreate, CancellationToken cancelToken)
        {
            var curparent = string.IsNullOrWhiteSpace(m_teamDriveID)
                ? (await GetAboutInfoAsync(cancelToken).ConfigureAwait(false)).rootFolderId
                : m_teamDriveID;

            if (string.IsNullOrEmpty(curparent))
                throw new UserInformationException("Unable to get root folder", "GoogleDriveNoRootFolder");

            var curdisplay = new StringBuilder("/");

            foreach (var p in path.Split(new char[] { '/' }, StringSplitOptions.RemoveEmptyEntries))
            {
                var res = await ListFolder(curparent, true, p, cancelToken).ToArrayAsync(cancelToken).ConfigureAwait(false);
                if (res.Length == 0)
                {
                    if (!autocreate)
                        throw new FolderMissingException();

                    curparent = (await CreateFolderAsync(p, curparent, cancelToken)).id;
                }
                else if (res.Length > 1)
                {
                    throw new UserInformationException(Strings.GoogleDrive.MultipleEntries(p, curdisplay.ToString()), "GoogleDriveMultipleEntries");
                }
                else
                {
                    curparent = res[0].id;
                }

                curdisplay.Append(p).Append("/");

                if (string.IsNullOrWhiteSpace(curparent))
                    throw new UserInformationException($"Unable to get folder id for {curdisplay}", "GoogleDriveNoFolderId");

            }

            return curparent;
        }

        private async Task<string> GetCurrentFolderIdAsync(CancellationToken cancelToken)
        {
            if (string.IsNullOrEmpty(m_currentFolderId))
                m_currentFolderId = await GetFolderIdAsync(m_path, false, cancelToken).ConfigureAwait(false);

            return m_currentFolderId;
        }

        private async Task<GoogleDriveFolderItem[]?> GetFileEntriesAsync(string remotename, bool throwMissingException, CancellationToken cancelToken)
        {
            m_filecache.TryGetValue(remotename, out var entries);
            if (entries != null)
                return entries;

            if (remotename.Contains('/'))
            {
                var parts = GetAbsolutePath(remotename).Split('/', StringSplitOptions.RemoveEmptyEntries);
                if (parts.Length == 0)
                    throw new FileMissingException();

                var fileName = parts.Last();
                var folderPath = string.Join("/", parts.Take(parts.Length - 1));

                var folderId = await GetFolderIdAsync(folderPath, false, cancelToken).ConfigureAwait(false);
                entries = await ListFolder(folderId, false, fileName, cancelToken).ToArrayAsync(cancelToken).ConfigureAwait(false);
            }
            else
            {
                var currentFolderId = await GetCurrentFolderIdAsync(cancelToken).ConfigureAwait(false);
                entries = await ListFolder(currentFolderId, false, remotename, cancelToken).ToArrayAsync(cancelToken).ConfigureAwait(false);
            }

            if (entries == null || entries.Length == 0)
            {
                if (throwMissingException)
                    throw new FileMissingException(Strings.GoogleDrive.FilenotFound(remotename));
                else
                    return null;
            }

            return m_filecache[remotename] = entries;
        }

        private IFileEntry ParseEntry(GoogleDriveFolderItem n)
        {
            FileEntry fe;
            if (n.fileSize == null)
                fe = new FileEntry(n.title);
            else if (n.modifiedDate == null)
                fe = new FileEntry(n.title, n.fileSize.Value);
            else
                fe = new FileEntry(n.title, n.fileSize.Value, n.modifiedDate.Value, n.modifiedDate.Value);

            fe.IsFolder = FOLDER_MIMETYPE.Equals(n.mimeType, StringComparison.OrdinalIgnoreCase);
            if (fe.IsFolder && !fe.Name.EndsWith("/"))
                fe.Name += "/";

            return fe;
        }

        private string GetAbsolutePath(string? path)
        {
            if (string.IsNullOrWhiteSpace(path))
                return m_path;

            var p = path.Replace(Path.DirectorySeparatorChar, '/').Trim('/');
            if (string.IsNullOrWhiteSpace(m_path) || m_path == "/")
                return "/" + p;
            else
                return Util.AppendDirSeparator(m_path, "/") + p;
        }

        public async IAsyncEnumerable<IFileEntry> ListAsync(string? path, [EnumeratorCancellation] CancellationToken cancellationToken)
        {
            var fullPath = GetAbsolutePath(path);
            string folderId;
            try
            {
                folderId = await GetFolderIdAsync(fullPath, false, cancellationToken).ConfigureAwait(false);
            }
            catch (FolderMissingException)
            {
                yield break;
            }

            await foreach (var n in ListFolder(folderId, null, null, cancellationToken).ConfigureAwait(false))
            {
                yield return ParseEntry(n);
            }
        }

        public async Task<IFileEntry?> GetEntryAsync(string path, CancellationToken cancellationToken)
        {
            var fullPath = GetAbsolutePath(path);
            var curparent = string.IsNullOrWhiteSpace(m_teamDriveID)
                ? (await GetAboutInfoAsync(cancellationToken).ConfigureAwait(false)).rootFolderId
                : m_teamDriveID;

            if (string.IsNullOrWhiteSpace(curparent))
                throw new UserInformationException("Unable to get root folder", "GoogleDriveNoRootFolder");

            var parts = fullPath.Split(new char[] { '/' }, StringSplitOptions.RemoveEmptyEntries);
            if (parts.Length == 0)
                return new FileEntry(string.Empty) { IsFolder = true };

            GoogleDriveFolderItem? currentItem = null;

            for (var i = 0; i < parts.Length; i++)
            {
                var p = parts[i];
                var isLast = i == parts.Length - 1;

                // For intermediate parts, we need folders.
                // For the last part, it can be file or folder.
                var onlyFolders = isLast ? (bool?)null : true;

                var res = await ListFolder(curparent, onlyFolders, p, cancellationToken).ToArrayAsync(cancellationToken).ConfigureAwait(false);

                if (res.Length == 0)
                    return null;

                if (res.Length > 1)
                    throw new UserInformationException(Strings.GoogleDrive.MultipleEntries(p, fullPath), "GoogleDriveMultipleEntries");

                currentItem = res[0];
                if (string.IsNullOrWhiteSpace(currentItem.id))
                    return null;

                curparent = currentItem.id;
            }

            if (currentItem == null) return null;

            return ParseEntry(currentItem);
        }

        private static string EscapeTitleEntries(string title)
        {
            return title.Replace("'", "\\'");
        }

        #region IStreamingBackend implementation

        public async Task PutAsync(string remotename, Stream stream, CancellationToken cancelToken)
        {
            try
            {
                // Figure out if we update or create the file
                if (m_filecache.Count == 0)
                    await foreach (var file in ListAsync(cancelToken).ConfigureAwait(false)) { /* Enumerate the full listing */ }

                m_filecache.TryGetValue(remotename, out var files);

                string? fileId = null;
                if (files != null)
                {
                    if (files.Length == 1)
                        fileId = files[0].id;
                    else
                        await DeleteAsync(remotename, cancelToken);
                }

                var isUpdate = !string.IsNullOrWhiteSpace(fileId);

                var url = WebApi.GoogleDrive.PutUrl(fileId, m_teamDriveID != null);
                var currentFolderId = await GetCurrentFolderIdAsync(cancelToken).ConfigureAwait(false);

                var item = new GoogleDriveFolderItem
                {
                    title = remotename,
                    description = remotename,
                    mimeType = "application/octet-stream",
                    labels = new GoogleDriveFolderItemLabels { hidden = true },
                    parents = [new GoogleDriveParentReference { id = currentFolderId }],
                    teamDriveId = m_teamDriveID
                };

                var res = await GoogleCommon.ChunkedUploadWithResumeAsync<GoogleDriveFolderItem, GoogleDriveFolderItem>(m_oauth, item, url, stream, m_timeouts.ShortTimeout, m_timeouts.ReadWriteTimeout, cancelToken, isUpdate ? HttpMethod.Put : HttpMethod.Post).ConfigureAwait(false);
                m_filecache[remotename] = [res];
            }
            catch
            {
                m_filecache.Clear();
                throw;
            }
        }

        public async Task GetAsync(string remotename, Stream stream, CancellationToken cancelToken)
        {
            // Prevent repeated download url lookups
            if (m_filecache.Count == 0)
                await foreach (var file in ListAsync(cancelToken).ConfigureAwait(false)) { /* Enumerate the full listing */ }

            var fileId = (await GetFileEntriesAsync(remotename, true, cancelToken).ConfigureAwait(false))?.OrderByDescending(x => x.createdDate).FirstOrDefault()?.id;
            if (string.IsNullOrEmpty(fileId))
                throw new FileMissingException(Strings.GoogleDrive.FilenotFound(remotename));

            var req = await m_oauth.CreateRequestAsync(WebApi.GoogleDrive.GetUrl(fileId), HttpMethod.Get, cancelToken).ConfigureAwait(false);
            using var resp = await Utility.Utility.WithTimeout(m_timeouts.ShortTimeout, cancelToken, ct => m_oauth.GetResponseAsync(req, HttpCompletionOption.ResponseHeadersRead, ct)).ConfigureAwait(false);
            using var rs = await Utility.Utility.WithTimeout(m_timeouts.ShortTimeout, cancelToken, ct => resp.Content.ReadAsStreamAsync(ct)).ConfigureAwait(false);
            using (var ts = rs.ObserveReadTimeout(m_timeouts.ReadWriteTimeout))
                await Utility.Utility.CopyStreamAsync(ts, stream, cancelToken);
        }

        #endregion

        #region IBackend implementation

        /// <inheritdoc />
        public async IAsyncEnumerable<IFileEntry> ListAsync([EnumeratorCancellation] CancellationToken cancelToken)

        {
            bool success = false;
            try
            {
                m_filecache.Clear();

                // For now, this class assumes that List() fully populates the file cache
                var currentFolderId = await GetCurrentFolderIdAsync(cancelToken).ConfigureAwait(false);
                await foreach (var n in ListFolder(currentFolderId, null, null, cancelToken).ConfigureAwait(false))
                {
                    var fe = ParseEntry(n);

                    if (!fe.IsFolder)
                    {
                        if (!m_filecache.TryGetValue(fe.Name, out var lst))
                        {
                            m_filecache[fe.Name] = [n];
                        }
                        else
                        {
                            Array.Resize(ref lst, lst.Length + 1);
                            lst[lst.Length - 1] = n;
                        }
                    }

                    yield return fe;
                }

                success = true;
            }
            finally
            {
                // If the enumeration either failed or didn't complete, clear the file cache.
                // This way, other operations which require a fully populated file cache will see an empty one and can populate it themselves.
                if (!success)
                {
                    m_filecache.Clear();
                }
            }
        }

        public async Task PutAsync(string remotename, string filename, CancellationToken cancelToken)
        {
            using (var fs = File.OpenRead(filename))
                await PutAsync(remotename, fs, cancelToken).ConfigureAwait(false);
        }

        public async Task GetAsync(string remotename, string filename, CancellationToken cancelToken)
        {
            using (var fs = File.Create(filename))
                await GetAsync(remotename, fs, cancelToken);
        }

        public async Task DeleteAsync(string remotename, CancellationToken cancelToken)
        {
            try
            {
                var entries = await GetFileEntriesAsync(remotename, true, cancelToken).ConfigureAwait(false);
                if (entries == null)
                    throw new FileMissingException(Strings.GoogleDrive.FilenotFound(remotename));

                foreach (var fileid in entries.Select(x => x.id).WhereNotNullOrWhiteSpace())
                {
                    var url = WebApi.GoogleDrive.DeleteUrl(Library.Utility.Uri.UrlPathEncode(fileid), m_teamDriveID);
                    await Utility.Utility.WithTimeout(m_timeouts.ShortTimeout, cancelToken,
                        async ct =>
                        {
                            using var req = await m_oauth.CreateRequestAsync(url, HttpMethod.Delete, ct).ConfigureAwait(false);
                            using var resp = await m_oauth.GetResponseAsync(req, HttpCompletionOption.ResponseContentRead, ct).ConfigureAwait(false);
                        }).ConfigureAwait(false);
                }

                m_filecache.Remove(remotename);
            }
            catch
            {
                m_filecache.Clear();

                throw;
            }
        }

        public Task TestAsync(CancellationToken cancelToken)
            => this.TestReadWritePermissionsAsync(cancelToken);

        public async Task CreateFolderAsync(CancellationToken cancelToken)
        {
            m_filecache.Clear();
            m_currentFolderId = await GetFolderIdAsync(m_path, true, cancelToken).ConfigureAwait(false);
        }

        /// <inheritdoc/>
        public string DisplayName => Strings.GoogleDrive.DisplayName;

        /// <inheritdoc/>
        public string ProtocolKey => "googledrive";

        /// <inheritdoc/>
        public bool SupportsStreaming => true;

        /// <inheritdoc/>
        public IList<ICommandLineArgument> SupportedCommands =>
        [
            .. AuthIdOptionsHelper.GetOptions(TOKEN_URL),
            new CommandLineArgument(TEAMDRIVE_ID,
                                    CommandLineArgument.ArgumentType.String,
                                    Strings.GoogleDrive.TeamDriveIdShort,
                                    Strings.GoogleDrive.TeamDriveIdLong),
            .. TimeoutOptionsHelper.GetOptions(),
        ];

        /// <inheritdoc/>
        public string Description => Strings.GoogleDrive.Description;

        #endregion

        #region IQuotaEnabledBackend implementation
        public async Task<IQuotaInfo?> GetQuotaInfoAsync(CancellationToken cancelToken)
        {
            try
            {
                var about = await this.GetAboutInfoAsync(cancelToken).ConfigureAwait(false);
                return new QuotaInfo(about.quotaBytesTotal ?? -1, about.quotaBytesTotal - about.quotaBytesUsed ?? -1);
            }
            catch
            {
                return null;
            }
        }

        public Task<string[]> GetDNSNamesAsync(CancellationToken cancelToken) => Task.FromResult(WebApi.GoogleDrive.Hosts());

        #endregion

        #region IRenameEnabledBackend implementation
        public async Task RenameAsync(string oldname, string newname, CancellationToken cancellationToken)
        {
            try
            {
                var files = await GetFileEntriesAsync(oldname, true, cancellationToken).ConfigureAwait(false);
                if (files == null)
                    throw new FileMissingException(Strings.GoogleDrive.FilenotFound(oldname));
                if (files.Length > 1)
                    throw new UserInformationException(Strings.GoogleDrive.MultipleEntries(oldname, m_path), "GoogleDriveMultipleEntries");

                using var stream = new MemoryStream();
                await GetAsync(oldname, stream, cancellationToken).ConfigureAwait(false);
                await PutAsync(newname, stream, cancellationToken).ConfigureAwait(false);
                await DeleteAsync(oldname, cancellationToken).ConfigureAwait(false);

                m_filecache.Remove(oldname);
            }
            catch
            {
                m_filecache.Clear();

                throw;
            }

        }
        #endregion

        #region IDisposable implementation

        public void Dispose()
        {
        }

        #endregion

        private class GoogleDriveParentReference
        {
            public string? id { get; set; }
        }

        private class GoogleDriveListResponse
        {
            public string? nextPageToken { get; set; }
            public GoogleDriveFolderItem[]? items { get; set; }
        }

        private class GoogleDriveFolderItemLabels
        {
            public bool hidden { get; set; }
        }

        private class GoogleDriveFolderItem
        {
            public string? id { get; set; }
            public string? title { get; set; }
            public string? description { get; set; }
            public string? mimeType { get; set; }
            public GoogleDriveFolderItemLabels? labels { get; set; }
            public DateTime? createdDate { get; set; }
            public DateTime? modifiedDate { get; set; }
            public long? fileSize { get; set; }
            public string? teamDriveId { get; set; }
            public GoogleDriveParentReference[]? parents { get; set; }
        }

        private class GoogleDriveAboutResponse
        {
            public long? quotaBytesTotal { get; set; }
            public long? quotaBytesUsed { get; set; }
            public string? rootFolderId { get; set; }
        }

        private async IAsyncEnumerable<GoogleDriveFolderItem> ListFolder(string parentfolder, bool? onlyFolders, string? name, [EnumeratorCancellation] CancellationToken cancelToken)
        {
            var fileQuery = new string?[] {
                string.IsNullOrEmpty(name) ? null : string.Format("title = '{0}'", EscapeTitleEntries(name)),
                onlyFolders == null ? null : string.Format("mimeType {0}= '{1}'", onlyFolders.Value ? "" : "!", FOLDER_MIMETYPE),
                string.Format("'{0}' in parents", EscapeTitleEntries(parentfolder)),
                "trashed=false"
            };

            var encodedFileQuery = Utility.Uri.UrlEncode(string.Join(" and ", fileQuery.Where(x => x != null)));
            var url = WebApi.GoogleDrive.ListUrl(encodedFileQuery, m_teamDriveID);

            while (true)
            {
                var res = await Utility.Utility.WithTimeout(m_timeouts.ListTimeout, cancelToken,
                async ct =>
                {
                    using var req = await m_oauth.CreateRequestAsync(url, HttpMethod.Get, ct).ConfigureAwait(false);
                    using var resp = await m_oauth.GetResponseAsync(req, HttpCompletionOption.ResponseHeadersRead, ct).ConfigureAwait(false);
                    return await resp.Content.ReadFromJsonAsync<GoogleDriveListResponse>(ct).ConfigureAwait(false)
                        ?? throw new UserInformationException(Strings.GoogleDrive.ListResponseError, "GoogleDriveListResponseError");
                }).ConfigureAwait(false);

                foreach (var n in res.items ?? [])
                    yield return n;

                var token = res.nextPageToken;
                if (string.IsNullOrWhiteSpace(token))
                    break;

                url = WebApi.GoogleDrive.ListUrl(encodedFileQuery, m_teamDriveID, token);
            }
        }

        private Task<GoogleDriveAboutResponse> GetAboutInfoAsync(CancellationToken cancelToken)
            => Utility.Utility.WithTimeout(m_timeouts.ShortTimeout, cancelToken,
            async ct =>
            {
                using var req = await m_oauth.CreateRequestAsync(WebApi.GoogleDrive.AboutInfoUrl(), HttpMethod.Get, ct).ConfigureAwait(false);
                using var resp = await m_oauth.GetResponseAsync(req, HttpCompletionOption.ResponseHeadersRead, ct).ConfigureAwait(false);
                return await resp.Content.ReadFromJsonAsync<GoogleDriveAboutResponse>(ct).ConfigureAwait(false)
                    ?? throw new UserInformationException(Strings.GoogleDrive.AboutResponseError, "GoogleDriveAboutResponseError");
            });

        private Task<GoogleDriveFolderItem> CreateFolderAsync(string name, string parent, CancellationToken cancelToken)
        {
            var folder = new GoogleDriveFolderItem()
            {
                title = name,
                description = name,
                mimeType = FOLDER_MIMETYPE,
                labels = new GoogleDriveFolderItemLabels { hidden = true },
                parents = [new GoogleDriveParentReference { id = parent }]
            };

            return Utility.Utility.WithTimeout(m_timeouts.ShortTimeout, cancelToken,
            async ct =>
            {
                using var req = await m_oauth.CreateRequestAsync(WebApi.GoogleDrive.CreateFolderUrl(m_teamDriveID), HttpMethod.Post, ct).ConfigureAwait(false);
                req.Content = JsonContent.Create(folder);

                using var resp = await m_oauth.GetResponseAsync(req, HttpCompletionOption.ResponseHeadersRead, ct).ConfigureAwait(false);
                return await resp.Content.ReadFromJsonAsync<GoogleDriveFolderItem>(ct).ConfigureAwait(false)
                    ?? throw new UserInformationException(Strings.GoogleDrive.CreateFolderResponseError, "GoogleDriveListResponseError");
            });
        }
    }
}