using System;
using System.Collections.Generic;
using System.IO;
using Paca.Mobile.Core;
using Xunit;

namespace Paca.Tests.Core;

/// <summary>
/// Gate 211 ~ 214: 스마트 중복 다운로드 방지 및 파일명 충돌 해소 엔진 기계적 검증
/// </summary>
public class SmartDeduplicationAndCollisionGateTests
{
    [Fact]
    public void Gate211_Deduplication_Identifies_Same_Video_Id()
    {
        var existingLibrary = new List<DeduplicationRecord>
        {
            new("dQw4w9WgXcQ", "Rick Astley - Never Gonna Give You Up.mp4", "/media/rick.mp4", 50_000_000)
        };

        var engine = new MediaDeduplicationEngine(existingLibrary);

        // 다른 URL 형식이지만 동일한 YouTube 비디오 ID
        var result = engine.CheckDuplicate("https://youtu.be/dQw4w9WgXcQ?si=trackingToken");

        Assert.True(result.IsDuplicate);
        Assert.Equal("Rick Astley - Never Gonna Give You Up.mp4", result.ExistingFileName);
        Assert.True(result.CanReuseExisting);
    }

    [Fact]
    public void Gate212_Deduplication_Allows_New_Video()
    {
        var existingLibrary = new List<DeduplicationRecord>
        {
            new("dQw4w9WgXcQ", "Rick.mp4", "/media/rick.mp4", 50_000_000)
        };

        var engine = new MediaDeduplicationEngine(existingLibrary);
        var result = engine.CheckDuplicate("https://www.youtube.com/watch?v=newVideoId999");

        Assert.False(result.IsDuplicate);
        Assert.Null(result.ExistingFileName);
    }

    [Fact]
    public void Gate213_CollisionResolver_Generates_Numbered_Suffix()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), "Paca_Collision_Test_" + Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);

        try
        {
            // 원본 파일 생성
            var originalPath = Path.Combine(tempDir, "Nature_4K.mp4");
            File.WriteAllText(originalPath, "original");

            // 1차 충돌 시 -> Nature_4K (1).mp4
            var safePath1 = FileCollisionResolver.ResolveSafePath(tempDir, "Nature_4K.mp4");
            Assert.Equal(Path.Combine(tempDir, "Nature_4K (1).mp4"), safePath1);

            // Nature_4K (1).mp4도 생성해둠
            File.WriteAllText(safePath1, "existing (1)");

            // 2차 충돌 시 -> Nature_4K (2).mp4
            var safePath2 = FileCollisionResolver.ResolveSafePath(tempDir, "Nature_4K.mp4");
            Assert.Equal(Path.Combine(tempDir, "Nature_4K (2).mp4"), safePath2);
        }
        finally
        {
            if (Directory.Exists(tempDir)) Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public void Gate214_CollisionResolver_Preserves_When_No_Conflict()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), "Paca_NoCollision_" + Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);

        try
        {
            var safePath = FileCollisionResolver.ResolveSafePath(tempDir, "FreshVideo.mp4");
            Assert.Equal(Path.Combine(tempDir, "FreshVideo.mp4"), safePath);
        }
        finally
        {
            if (Directory.Exists(tempDir)) Directory.Delete(tempDir, recursive: true);
        }
    }
}