using File.Application.Features.Files.Services;
using File.Domain.Entities.FileMeta;
using File.Infrastructure.Persistence;
using File.Infrastructure.Storage;
using FluentAssertions;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using Moq;
using Xunit;

namespace BuildFlow.File.Tests;

/// <summary>后台文件大小修复的结果语义、批量边界与 S3 并发上限测试。</summary>
public class FileSizeVerificationProcessorTests
{
    private const string Bucket = "files";

    [Fact]
    public async Task PositiveObjectSizeUpdatesAndMarksVerified()
    {
        await using var db = CreateDbContext();
        db.Files.Add(CreateFile(0));
        await db.SaveChangesAsync();
        var s3 = new Mock<IS3StorageService>();
        s3.Setup(x => x.GetObjectSizeAsync(Bucket, "key-0", It.IsAny<CancellationToken>()))
            .ReturnsAsync(128L);
        var processor = CreateProcessor(db, s3);

        var processed = await processor.ProcessAsync(100, 4, CancellationToken.None);

        processed.Should().Be(1);
        var file = await db.Files.SingleAsync();
        file.Size.Should().Be(128);
        file.SizeVerified.Should().BeTrue();
    }

    [Fact]
    public async Task ZeroByteObjectMarksVerified()
    {
        await using var db = CreateDbContext();
        db.Files.Add(CreateFile(0));
        await db.SaveChangesAsync();
        var s3 = new Mock<IS3StorageService>();
        s3.Setup(x => x.GetObjectSizeAsync(Bucket, "key-0", It.IsAny<CancellationToken>()))
            .ReturnsAsync(0L);
        var processor = CreateProcessor(db, s3);

        await processor.ProcessAsync(100, 4, CancellationToken.None);

        var file = await db.Files.SingleAsync();
        file.Size.Should().Be(0);
        file.SizeVerified.Should().BeTrue();
    }

    [Fact]
    public async Task MissingObjectLogsWarningAndMarksVerified()
    {
        await using var db = CreateDbContext();
        db.Files.Add(CreateFile(0));
        await db.SaveChangesAsync();
        var s3 = new Mock<IS3StorageService>();
        s3.Setup(x => x.GetObjectSizeAsync(Bucket, "key-0", It.IsAny<CancellationToken>()))
            .ReturnsAsync((long?)null);
        var logger = new Mock<ILogger<FileSizeVerificationProcessor>>();
        var processor = new FileSizeVerificationProcessor(db, s3.Object, logger.Object);

        await processor.ProcessAsync(100, 4, CancellationToken.None);

        var file = await db.Files.SingleAsync();
        file.Size.Should().Be(0);
        file.SizeVerified.Should().BeTrue();
        WarningCount(logger).Should().Be(1);
    }

    [Fact]
    public async Task TransientFailureLogsWarningAndRemainsUnverified()
    {
        await using var db = CreateDbContext();
        db.Files.Add(CreateFile(0));
        await db.SaveChangesAsync();
        var s3 = new Mock<IS3StorageService>();
        s3.Setup(x => x.GetObjectSizeAsync(Bucket, "key-0", It.IsAny<CancellationToken>()))
            .ThrowsAsync(new HttpRequestException("temporary"));
        var logger = new Mock<ILogger<FileSizeVerificationProcessor>>();
        var processor = new FileSizeVerificationProcessor(db, s3.Object, logger.Object);

        await processor.ProcessAsync(100, 4, CancellationToken.None);

        var file = await db.Files.SingleAsync();
        file.SizeVerified.Should().BeFalse();
        WarningCount(logger).Should().Be(1);
    }

    [Fact]
    public async Task BatchSizeLimitsS3CallsToOldestFiles()
    {
        await using var db = CreateDbContext();
        db.Files.AddRange(Enumerable.Range(0, 5).Select(CreateFile));
        await db.SaveChangesAsync();
        var s3 = new Mock<IS3StorageService>();
        s3.Setup(x => x.GetObjectSizeAsync(
                It.IsAny<string>(),
                It.IsAny<string>(),
                It.IsAny<CancellationToken>()))
            .ReturnsAsync(1L);
        var processor = CreateProcessor(db, s3);

        var processed = await processor.ProcessAsync(2, 2, CancellationToken.None);

        processed.Should().Be(2);
        s3.Verify(x => x.GetObjectSizeAsync(
            It.IsAny<string>(),
            It.IsAny<string>(),
            It.IsAny<CancellationToken>()), Times.Exactly(2));
        var verifiedKeys = await db.Files
            .Where(file => file.SizeVerified)
            .OrderBy(file => file.CreatedAt)
            .Select(file => file.S3Key)
            .ToListAsync();
        verifiedKeys.Should().Equal("key-0", "key-1");
    }

    [Fact]
    public async Task S3CallsRespectMaximumConcurrency()
    {
        await using var db = CreateDbContext();
        db.Files.AddRange(Enumerable.Range(0, 8).Select(CreateFile));
        await db.SaveChangesAsync();
        var active = 0;
        var maximum = 0;
        var s3 = new Mock<IS3StorageService>();
        s3.Setup(x => x.GetObjectSizeAsync(
                It.IsAny<string>(),
                It.IsAny<string>(),
                It.IsAny<CancellationToken>()))
            .Returns(async (string _, string _, CancellationToken ct) =>
            {
                var current = Interlocked.Increment(ref active);
                UpdateMaximum(ref maximum, current);
                try
                {
                    await Task.Delay(30, ct);
                    return 1L;
                }
                finally
                {
                    Interlocked.Decrement(ref active);
                }
            });
        var processor = CreateProcessor(db, s3);

        await processor.ProcessAsync(8, 3, CancellationToken.None);

        maximum.Should().BeGreaterThan(1);
        maximum.Should().BeLessThanOrEqualTo(3);
    }

    [Theory]
    [InlineData(0, 1)]
    [InlineData(1001, 1)]
    [InlineData(1, 0)]
    [InlineData(1, 33)]
    public async Task OutOfRangeLimitsAreRejected(int batchSize, int maxConcurrency)
    {
        await using var db = CreateDbContext();
        var processor = CreateProcessor(db, new Mock<IS3StorageService>());

        var act = () => processor.ProcessAsync(batchSize, maxConcurrency, CancellationToken.None);

        await act.Should().ThrowAsync<ArgumentOutOfRangeException>();
    }

    private static FileSizeVerificationProcessor CreateProcessor(
        FileDbContext db,
        Mock<IS3StorageService> s3)
        => new(db, s3.Object, new Mock<ILogger<FileSizeVerificationProcessor>>().Object);

    private static FileDbContext CreateDbContext()
    {
        var options = new DbContextOptionsBuilder<FileDbContext>()
            .UseInMemoryDatabase($"file-size-processor-{Guid.NewGuid():N}")
            .Options;
        return new FileDbContext(options);
    }

    private static FileMetaEntity CreateFile(int index)
        => new()
        {
            Id = Guid.NewGuid(),
            Name = $"file-{index}.bin",
            S3Key = $"key-{index}",
            S3Bucket = Bucket,
            ContentType = "application/octet-stream",
            OwnerId = "user-001",
            Size = 0,
            SizeVerified = false,
            CreatedBy = "test",
            CreatedAt = new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc).AddMinutes(index),
            UpdatedBy = "test",
            UpdatedAt = new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc).AddMinutes(index),
            OperatorIP = "127.0.0.1",
        };

    private static int WarningCount(Mock<ILogger<FileSizeVerificationProcessor>> logger)
        => logger.Invocations.Count(invocation =>
            invocation.Method.Name == nameof(ILogger.Log)
            && invocation.Arguments[0] is LogLevel.Warning);

    private static void UpdateMaximum(ref int maximum, int candidate)
    {
        while (true)
        {
            var observed = Volatile.Read(ref maximum);
            if (candidate <= observed
                || Interlocked.CompareExchange(ref maximum, candidate, observed) == observed)
            {
                return;
            }
        }
    }
}