using System;
using System.Globalization;
using System.IO;
using Jellyfin.Api.Controllers;
using MediaBrowser.Controller.MediaEncoding;
using MediaBrowser.Model.Configuration;
using Xunit;

namespace Jellyfin.Api.Tests.Controllers
{
    /// <summary>
    /// Tests for the HA behaviour of <see cref="DynamicHlsController"/>: the session record it
    /// registers in <see cref="ITranscodeSessionStore"/> and the ffmpeg segmenting options it
    /// picks once a session is resumed on another pod.
    /// </summary>
    public class DynamicHlsHaModeTests
    {
        /// <summary>
        /// The registered session has to name the files it owns, otherwise
        /// <c>DeleteTranscodeFileTask</c> cannot recognise and protect them.
        /// </summary>
        [Fact]
        [Trait("Category", "UnitTest")]
        public void CreateSessionRecord_PopulatesPathsFromPlaylistPath()
        {
            const string PlaylistPath = "/transcodes/9e1c6f.m3u8";

            var session = DynamicHlsController.CreateSessionRecord("play-1", "media-1", PlaylistPath, TimeSpan.FromSeconds(30));

            Assert.Equal(PlaylistPath, session.ManifestPath);
            Assert.Equal("/transcodes/9e1c6f", session.SegmentPathPrefix);
            Assert.Equal("play-1", session.PlaySessionId);
            Assert.Equal("media-1", session.MediaSourceId);
            Assert.NotEmpty(session.OwnerPod);
            Assert.True(session.LeaseExpiresUtc > DateTime.UtcNow);
        }

        /// <summary>
        /// Every segment ffmpeg writes for the playlist has to start with the recorded prefix.
        /// Segment paths are built as <c>&lt;playlist without extension&gt;&lt;index&gt;&lt;extension&gt;</c>.
        /// </summary>
        [Theory]
        [InlineData(".ts")]
        [InlineData(".mp4")]
        [Trait("Category", "UnitTest")]
        public void GetSegmentPathPrefix_CoversEverySegmentPath(string segmentExtension)
        {
            const string PlaylistPath = "/transcodes/9e1c6f.m3u8";
            var prefix = TranscodeSession.GetSegmentPathPrefix(PlaylistPath);

            for (var index = 0; index < 5; index++)
            {
                var segmentPath = Path.Combine(
                    Path.GetDirectoryName(PlaylistPath)!,
                    Path.GetFileNameWithoutExtension(PlaylistPath) + index.ToString(CultureInfo.InvariantCulture) + segmentExtension);

                Assert.StartsWith(prefix, segmentPath, StringComparison.Ordinal);
            }
        }

        /// <summary>
        /// HA mode shortens segments and bounds the rolling buffer; the configured values are
        /// user-editable so they are clamped.
        /// </summary>
        [Theory]
        [InlineData(2, 2)]
        [InlineData(0, 1)]
        [InlineData(60, 6)]
        [Trait("Category", "UnitTest")]
        public void GetEffectiveSegmentLength_InHaMode_ClampsConfiguredRecoveryLength(int configured, int expected)
        {
            var options = new EncodingOptions { RecoverySegmentLengthSeconds = configured };

            Assert.Equal(expected, DynamicHlsController.GetEffectiveSegmentLength(true, 6, options));
        }

        /// <summary>
        /// Outside HA mode the requested segment length is used unchanged and the playlist is unbounded.
        /// </summary>
        [Fact]
        [Trait("Category", "UnitTest")]
        public void GetSegmentingOptions_OutsideHaMode_UsesRequestedValues()
        {
            var options = new EncodingOptions { RecoverySegmentLengthSeconds = 2, RecoverySegmentBufferCount = 5 };

            Assert.Equal(6, DynamicHlsController.GetEffectiveSegmentLength(false, 6, options));
            Assert.Equal(0, DynamicHlsController.GetHlsListSize(false, options));
        }

        /// <summary>
        /// HA mode keeps a bounded rolling buffer of segments for a takeover pod to serve.
        /// </summary>
        [Theory]
        [InlineData(5, 5)]
        [InlineData(0, 2)]
        [InlineData(100, 10)]
        [Trait("Category", "UnitTest")]
        public void GetHlsListSize_InHaMode_ClampsConfiguredBufferCount(int configured, int expected)
        {
            var options = new EncodingOptions { RecoverySegmentBufferCount = configured };

            Assert.Equal(expected, DynamicHlsController.GetHlsListSize(true, options));
        }
    }
}