using System.Net;

namespace dy.net.model.dto
{
    public enum MediaDownloadFailureKind
    {
        None = 0,
        SourceUnavailable = 1,
        SourceForbidden = 2,
        SourceUnauthorized = 3,
        SourceNotFound = 4,
        SourceRateLimited = 5,
        SourceInvalidContent = 6,
        StorageUnavailable = 7,
        IntegrityCheckFailed = 8,
        Cancelled = 9
    }

    public sealed class MediaDownloadResult
    {
        public bool Success { get; init; }
        public string ActualSavePath { get; init; }
        public MediaDownloadFailureKind FailureKind { get; init; }
        public int? HttpStatusCode { get; init; }
        public string SourceHost { get; init; }
        public int AttemptedUrlCount { get; init; }
        public DateTime? RetryAfter { get; init; }
        public string Message { get; init; }

        public void Deconstruct(out bool success, out string actualSavePath)
        {
            success = Success;
            actualSavePath = ActualSavePath;
        }

        public Exception ToException() => FailureKind switch
        {
            MediaDownloadFailureKind.StorageUnavailable => new MediaStorageException(Message ?? "媒体存储写入失败。"),
            MediaDownloadFailureKind.IntegrityCheckFailed => new MediaIntegrityException(Message ?? "媒体完整性校验失败。"),
            MediaDownloadFailureKind.Cancelled => new OperationCanceledException(Message ?? "媒体下载已取消。"),
            _ => new MediaSourceException(FailureKind, Message ?? "媒体来源不可用。", HttpStatusCode, SourceHost, RetryAfter)
        };

        public static MediaDownloadResult Succeeded(string path, string host, int attempted) => new()
        {
            Success = true,
            ActualSavePath = path,
            SourceHost = host,
            AttemptedUrlCount = attempted
        };
    }

    public sealed class MediaSourceException : Exception
    {
        public MediaSourceException(
            MediaDownloadFailureKind kind,
            string message,
            int? statusCode = null,
            string sourceHost = null,
            DateTime? retryAfter = null,
            Exception innerException = null) : base(message, innerException)
        {
            FailureKind = kind;
            StatusCode = statusCode;
            SourceHost = sourceHost;
            RetryAfter = retryAfter;
        }

        public MediaDownloadFailureKind FailureKind { get; }
        public int? StatusCode { get; }
        public string SourceHost { get; }
        public DateTime? RetryAfter { get; }
    }

    public sealed class MediaStorageException : IOException
    {
        public MediaStorageException(string message, Exception innerException = null) : base(message, innerException) { }
    }

    public sealed class MediaIntegrityException : IOException
    {
        public MediaIntegrityException(string message, Exception innerException = null) : base(message, innerException) { }
    }

    public enum SourceFailureDisposition
    {
        Continue = 0,
        WaitForSource = 1,
        RequiresAuthorization = 2
    }

    public sealed class SourceAccessDecision
    {
        public bool Allowed { get; init; }
        public bool IsProbe { get; init; }
        public string Message { get; init; }
        public DateTime? RetryAt { get; init; }
    }
}