using System;
using System.IO;
using System.Net.Http;
using System.Net.Mime;
using System.Threading;
using System.Threading.Tasks;
using Jellyfin.Api.Models.StreamingDtos;
using MediaBrowser.Controller.MediaEncoding;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Net.Http.Headers;

namespace Jellyfin.Api.Helpers;

/// <summary>
/// The stream response helpers.
/// </summary>
public static class FileStreamResponseHelpers
{
    /// <summary>
    /// Returns a static file from a remote source.
    /// </summary>
    /// <param name="state">The current <see cref="StreamState"/>.</param>
    /// <param name="httpClient">The <see cref="HttpClient"/> making the remote request.</param>
    /// <param name="httpContext">The current http context.</param>
    /// <param name="cancellationToken">A cancellation token that can be used to cancel the operation.</param>
    /// <returns>A <see cref="Task{ActionResult}"/> containing the API response.</returns>
    public static async Task<ActionResult> GetStaticRemoteStreamResult(
        StreamState state,
        HttpClient httpClient,
        HttpContext httpContext,
        CancellationToken cancellationToken = default)
    {
        if (state.RemoteHttpHeaders.TryGetValue(HeaderNames.UserAgent, out var useragent))
        {
            httpClient.DefaultRequestHeaders.Add(HeaderNames.UserAgent, useragent);
        }

        // Can't dispose the response as it's required up the call chain.
        var response = await httpClient.GetAsync(new Uri(state.MediaPath), cancellationToken).ConfigureAwait(false);
        var contentType = response.Content.Headers.ContentType?.ToString() ?? MediaTypeNames.Text.Plain;

        httpContext.Response.Headers[HeaderNames.AcceptRanges] = "none";

        return new FileStreamResult(await response.Content.ReadAsStreamAsync(cancellationToken).ConfigureAwait(false), contentType);
    }

    /// <summary>
    /// Returns a static file from the server.
    /// </summary>
    /// <param name="path">The path to the file.</param>
    /// <param name="contentType">The content type of the file.</param>
    /// <returns>An <see cref="ActionResult"/> the file.</returns>
    public static ActionResult GetStaticFileResult(
        string path,
        string contentType)
    {
        return new PhysicalFileResult(path, contentType) { EnableRangeProcessing = true };
    }

    /// <summary>
    /// Returns a transcoded file from the server.
    /// </summary>
    /// <param name="state">The current <see cref="StreamState"/>.</param>
    /// <param name="isHeadRequest">Whether the current request is a HTTP HEAD request so only the headers get returned.</param>
    /// <param name="httpContext">The current http context.</param>
    /// <param name="transcodingJobHelper">The <see cref="TranscodingJobHelper"/> singleton.</param>
    /// <param name="ffmpegCommandLineArguments">The command line arguments to start ffmpeg.</param>
    /// <param name="transcodingJobType">The <see cref="TranscodingJobType"/>.</param>
    /// <param name="cancellationTokenSource">The <see cref="CancellationTokenSource"/>.</param>
    /// <returns>A <see cref="Task{ActionResult}"/> containing the transcoded file.</returns>
    public static async Task<ActionResult> GetTranscodedFile(
        StreamState state,
        bool isHeadRequest,
        HttpContext httpContext,
        TranscodingJobHelper transcodingJobHelper,
        string ffmpegCommandLineArguments,
        TranscodingJobType transcodingJobType,
        CancellationTokenSource cancellationTokenSource)
    {
        // Use the command line args with a dummy playlist path
        var outputPath = state.OutputFilePath;

        httpContext.Response.Headers[HeaderNames.AcceptRanges] = "none";

        var contentType = state.GetMimeType(outputPath);

        // Headers only
        if (isHeadRequest)
        {
            httpContext.Response.Headers[HeaderNames.ContentType] = contentType;
            return new OkResult();
        }

        var transcodingLock = transcodingJobHelper.GetTranscodingLock(outputPath);
        await transcodingLock.WaitAsync(cancellationTokenSource.Token).ConfigureAwait(false);
        try
        {
            TranscodingJobDto? job;
            if (!File.Exists(outputPath))
            {
                job = await transcodingJobHelper.StartFfMpeg(state, outputPath, ffmpegCommandLineArguments, httpContext.Request, transcodingJobType, cancellationTokenSource).ConfigureAwait(false);
            }
            else
            {
                job = transcodingJobHelper.OnTranscodeBeginRequest(outputPath, TranscodingJobType.Progressive);
                state.Dispose();
            }

            var stream = new ProgressiveFileStream(outputPath, job, transcodingJobHelper);
            return new FileStreamResult(stream, contentType);
        }
        finally
        {
            transcodingLock.Release();
        }
    }
}