using Azure.Identity;
using Microsoft.Graph;
using Microsoft.Graph.Drives.Item.Items.Item.CreateUploadSession;
using Microsoft.Graph.Models;

namespace OneDriveBackupService;

public class OneDriveClient {

    private readonly ConfigData _config;
    private readonly GraphServiceClient _client;

    public OneDriveClient(ConfigData config) {
        _config = config;

        var credential = new ClientSecretCredential(_config.TenantId, _config.ClientId, _config.ClientSecret);
        _client = new GraphServiceClient(credential);
    }

    public async Task<UploadResult<DriveItem>> UploadFile(string filePath, CancellationToken token) {
        var fileName = Path.GetFileName(filePath);
        var remoteFilePath = _config.BackupUploadRoot.Trim('/') + '/' + fileName;

        var defaultDrive = await _client.Users[_config.UserId].Drive.GetAsync(cancellationToken: token);

        var driveFile = _client.Drives[defaultDrive!.Id].Items[$"root:/{remoteFilePath}:"]!;
        var uploadSession = await driveFile.CreateUploadSession.PostAsync(new CreateUploadSessionPostRequestBody {
            Item = new DriveItemUploadableProperties {
                AdditionalData = new Dictionary<string, object> {
                    { "@microsoft.graph.conflictBehavior", "replace" }
                }
            }
        }, cancellationToken: token);

        await using var stream = File.OpenRead(filePath);
        var uploader = new LargeFileUploadTask<DriveItem>(uploadSession, stream);
        var result = await uploader.UploadAsync(cancellationToken: token);

        return result;
    }

    public async Task<int> DeleteOldFiles(CancellationToken token) {
        var defaultDrive = await _client.Users[_config.UserId].Drive.GetAsync(cancellationToken: token);

        var remoteFolder = _config.BackupUploadRoot.Trim('/');
        var backupFiles = await _client.Drives[defaultDrive!.Id]
            .Items[$"root:/{remoteFolder}:"]
            .Children.GetAsync(cancellationToken: token);

        if (backupFiles == null || backupFiles.Value == null || backupFiles.Value.Count == 0)
            return 0;

        var sortedFiles = backupFiles.Value
            .Where(i =>
                i.File != null &&
                i.Name != null &&
                i.Name.StartsWith("backup_") &&
                i.Name.EndsWith(".tar.gz"))
            .OrderByDescending(i => i.CreatedDateTime)
            .ToList();

        if (sortedFiles.Count < _config.KeepLast)
            return 0;

        int deletedCount = 0;
        foreach (var backupFile in sortedFiles.Skip(_config.KeepLast)) {
            if (backupFile.Id == null) continue;

            await _client.Drives[defaultDrive.Id].Items[backupFile.Id].DeleteAsync(cancellationToken: token);
            deletedCount++;
        }

        return deletedCount;
    }
    
}