using System;
using Paca.Mobile.Core;
using Xunit;

namespace Paca.Tests.Core;

public class SubtitleSyncDrifterGateTests
{
    [Fact]
    public void Gate433_SubtitleSyncDrifter_ShiftsConstantOffset_Accurately()
    {
        var srt = @"1
00:01:20,000 --> 00:01:25,500
Hello World";

        var shifted = SubtitleSyncDrifter.ShiftOffsetSrt(srt, shiftSeconds: 2.5);

        Assert.Contains("00:01:22,500 --> 00:01:28,000", shifted);
        Assert.Contains("Hello World", shifted);
    }

    [Fact]
    public void Gate434_SubtitleSyncDrifter_PreventsNegativeTimestamps()
    {
        var srt = @"1
00:00:05,000 --> 00:00:08,000
Early cue";

        var shifted = SubtitleSyncDrifter.ShiftOffsetSrt(srt, shiftSeconds: -10.0);

        Assert.Contains("00:00:00,000 --> 00:00:00,000", shifted);
    }

    [Fact]
    public void Gate435_SubtitleSyncDrifter_RescalesTimeByFpsRatio()
    {
        var srt = @"1
00:01:40,000 --> 00:01:50,000
Pacing test"; // 100s to 110s

        // Speedup by 10% (speed factor 1.10 -> duration scales by 1/1.10 = 0.90909)
        var rescaled = SubtitleSyncDrifter.RescaleTimeSrt(srt, speedFactor: 1.10);

        // 100 / 1.10 = 90.909s = 00:01:30,909
        Assert.Contains("00:01:30,909", rescaled);
    }

    [Fact]
    public void Gate436_SubtitleSyncDrifter_ResyncsByTwoAnchorPoints()
    {
        // Anchor 1: at 100s, video speech is at 105s (+5s)
        // Anchor 2: at 1000s, video speech is at 1050s (+50s)
        // m = (1050 - 105) / (1000 - 100) = 945 / 900 = 1.05
        // b = 105 - (1.05 * 100) = 0
        var srt = @"1
00:08:20,000 --> 00:08:25,000
Middle dialogue"; // 500s -> 500 * 1.05 = 525s = 00:08:45,000

        var resynced = SubtitleSyncDrifter.ResyncByAnchorsSrt(srt, orig1: 100.0, target1: 105.0, orig2: 1000.0, target2: 1050.0);

        Assert.Contains("00:08:45,000", resynced);
        Assert.Contains("Middle dialogue", resynced);
    }
}