using FluentAssertions;
using Microsoft.Extensions.Options;
using SatelliteProvider.Common.Configs;
using SatelliteProvider.Common.DTO;
using SatelliteProvider.Services.TileDownloader;
using SatelliteProvider.Tests.TestUtilities;

namespace SatelliteProvider.Tests;

public class UavTileQualityGateTests
{
    private const string JpegContentType = "image/jpeg";

    [Fact]
    public void Validate_NonJpegContentType_RejectsInvalidFormat()
    {
        // Arrange
        var gate = BuildGate();
        var bytes = UavTileImageFactory.CreatePng();
        var metadata = ValidMetadata();

        // Act
        var result = gate.Validate(bytes, "image/png", metadata);

        // Assert
        result.Accepted.Should().BeFalse();
        result.Reason.Should().Be(UavTileRejectReasons.InvalidFormat);
    }

    [Fact]
    public void Validate_WrongMagicBytes_RejectsInvalidFormat()
    {
        // Arrange
        var gate = BuildGate();
        var bytes = new byte[6_000];
        bytes[0] = 0x89; bytes[1] = 0x50; bytes[2] = 0x4E; bytes[3] = 0x47;
        var metadata = ValidMetadata();

        // Act
        var result = gate.Validate(bytes, JpegContentType, metadata);

        // Assert
        result.Accepted.Should().BeFalse();
        result.Reason.Should().Be(UavTileRejectReasons.InvalidFormat);
    }

    [Fact]
    public void Validate_ValidJpeg_PassesFormatRule()
    {
        // Arrange
        var gate = BuildGate();
        var bytes = UavTileImageFactory.CreateRandomJpeg();
        var metadata = ValidMetadata();

        // Act
        var result = gate.Validate(bytes, JpegContentType, metadata);

        // Assert
        result.Accepted.Should().BeTrue();
    }

    [Fact]
    public void Validate_TooSmall_RejectsSizeOutOfBand()
    {
        // Arrange
        var bytes = new byte[200];
        bytes[0] = 0xFF; bytes[1] = 0xD8; bytes[2] = 0xFF;
        var gate = BuildGate();

        // Act
        var result = gate.Validate(bytes, JpegContentType, ValidMetadata());

        // Assert
        result.Accepted.Should().BeFalse();
        result.Reason.Should().Be(UavTileRejectReasons.SizeOutOfBand);
    }

    [Fact]
    public void Validate_TooLarge_RejectsSizeOutOfBand()
    {
        // Arrange — craft a JPEG-prefixed byte blob just over the configured MaxBytes ceiling.
        var qualityConfig = new UavQualityConfig { MaxBytes = 8 * 1024 };
        var oversized = new byte[qualityConfig.MaxBytes + 1];
        oversized[0] = 0xFF; oversized[1] = 0xD8; oversized[2] = 0xFF;
        var gate = BuildGate(qualityConfig);

        // Act
        var result = gate.Validate(oversized, JpegContentType, ValidMetadata());

        // Assert
        result.Accepted.Should().BeFalse();
        result.Reason.Should().Be(UavTileRejectReasons.SizeOutOfBand);
    }

    [Fact]
    public void Validate_WrongDimensions_RejectsWrongDimensions()
    {
        // Arrange
        var bytes = UavTileImageFactory.CreateRandomJpeg(width: 512, height: 512);
        var gate = BuildGate();

        // Act
        var result = gate.Validate(bytes, JpegContentType, ValidMetadata());

        // Assert
        result.Accepted.Should().BeFalse();
        result.Reason.Should().Be(UavTileRejectReasons.WrongDimensions);
    }

    [Fact]
    public void Validate_CapturedAtFuture_RejectsCapturedAtFuture()
    {
        // Arrange
        var now = new DateTime(2026, 5, 11, 12, 0, 0, DateTimeKind.Utc);
        var gate = BuildGate(timeProvider: new FixedTimeProvider(now));
        var bytes = UavTileImageFactory.CreateRandomJpeg();
        var metadata = ValidMetadata() with { CapturedAt = now.AddHours(1) };

        // Act
        var result = gate.Validate(bytes, JpegContentType, metadata);

        // Assert
        result.Accepted.Should().BeFalse();
        result.Reason.Should().Be(UavTileRejectReasons.CapturedAtFuture);
    }

    [Fact]
    public void Validate_CapturedAtTooOld_RejectsCapturedAtTooOld()
    {
        // Arrange
        var now = new DateTime(2026, 5, 11, 12, 0, 0, DateTimeKind.Utc);
        var gate = BuildGate(timeProvider: new FixedTimeProvider(now));
        var bytes = UavTileImageFactory.CreateRandomJpeg();
        var metadata = ValidMetadata() with { CapturedAt = now.AddDays(-8) };

        // Act
        var result = gate.Validate(bytes, JpegContentType, metadata);

        // Assert
        result.Accepted.Should().BeFalse();
        result.Reason.Should().Be(UavTileRejectReasons.CapturedAtTooOld);
    }

    [Fact]
    public void Validate_CapturedAtSlightlyInFuture_WithinSkew_Accepts()
    {
        // Arrange
        var now = new DateTime(2026, 5, 11, 12, 0, 0, DateTimeKind.Utc);
        var gate = BuildGate(timeProvider: new FixedTimeProvider(now));
        var bytes = UavTileImageFactory.CreateRandomJpeg();
        var metadata = ValidMetadata() with { CapturedAt = now.AddSeconds(20) };

        // Act
        var result = gate.Validate(bytes, JpegContentType, metadata);

        // Assert
        result.Accepted.Should().BeTrue();
    }

    [Fact]
    public void Validate_UniformGreyImage_RejectsImageTooUniform()
    {
        // Arrange — uniform-color JPEGs compress to far below the
        // default 5 KiB MinBytes (rule 2). Drop MinBytes so rule 5
        // remains the active filter for this test.
        var bytes = UavTileImageFactory.CreateUniformGreyJpeg(value: 128);
        var gate = BuildGate(new UavQualityConfig { MinBytes = 1 });

        // Act
        var result = gate.Validate(bytes, JpegContentType, ValidMetadata());

        // Assert
        result.Accepted.Should().BeFalse();
        result.Reason.Should().Be(UavTileRejectReasons.ImageTooUniform);
    }

    [Fact]
    public void Validate_FirstFailingRuleWins_FormatBeforeDimensions()
    {
        // Arrange — a PNG resized to 512x512 fails BOTH rule 1 (content-type
        // says JPEG but magic bytes don't) AND rule 3 (dimensions != 256).
        // Rule 1 runs first so we expect INVALID_FORMAT.
        var bytes = UavTileImageFactory.CreatePng(width: 512, height: 512);
        var gate = BuildGate();

        // Act
        var result = gate.Validate(bytes, JpegContentType, ValidMetadata());

        // Assert
        result.Accepted.Should().BeFalse();
        result.Reason.Should().Be(UavTileRejectReasons.InvalidFormat);
    }

    [Fact]
    public void Validate_HappyPath_RandomNoiseJpeg_Accepts()
    {
        // Act
        var result = BuildGate().Validate(UavTileImageFactory.CreateRandomJpeg(), JpegContentType, ValidMetadata());

        // Assert
        result.Accepted.Should().BeTrue();
        result.Reason.Should().BeNull();
    }

    private static UavTileQualityGate BuildGate(UavQualityConfig? quality = null, MapConfig? map = null, TimeProvider? timeProvider = null)
    {
        return new UavTileQualityGate(
            Options.Create(quality ?? new UavQualityConfig()),
            Options.Create(map ?? new MapConfig { TileSizePixels = 256 }),
            timeProvider ?? new FixedTimeProvider(new DateTime(2026, 5, 11, 12, 0, 0, DateTimeKind.Utc)));
    }

    private static UavTileMetadata ValidMetadata() => new()
    {
        Latitude = 47.461747,
        Longitude = 37.647063,
        TileZoom = 18,
        TileSizeMeters = 200.0,
        CapturedAt = new DateTime(2026, 5, 11, 11, 30, 0, DateTimeKind.Utc),
    };

    private sealed class FixedTimeProvider : TimeProvider
    {
        private readonly DateTime _utcNow;

        public FixedTimeProvider(DateTime utcNow)
        {
            if (utcNow.Kind != DateTimeKind.Utc)
            {
                throw new ArgumentException("DateTime must be UTC", nameof(utcNow));
            }
            _utcNow = utcNow;
        }

        public override DateTimeOffset GetUtcNow() => new(_utcNow, TimeSpan.Zero);
    }
}