using FluentAssertions;
using PiiRedaction.Core.Detection;
using PiiRedaction.Core.Models;
using PiiRedaction.Infrastructure.Onnx;

namespace PiiRedaction.Infrastructure.Tests.Onnx;

[TestFixture]
public sealed class RoutingOnnxNerModelRunnerTests
{
    [Test]
    public void PredictEntities_LatinOnly_UsesEnglishRunnerOnly()
    {
        var english = new FakeLanguageNerRunner("Ravi Kumar", NerModelOrigin.English);
        var tamil = new FakeLanguageNerRunner("தமிழ் பெயர்", NerModelOrigin.Tamil);
        var router = new RoutingOnnxNerModelRunner(english, tamil, enableTamilNer: true);

        var result = router.PredictEntities("Customer Ravi Kumar called.");

        result.Entities.Should().ContainSingle(entity =>
            entity.Value == "Ravi Kumar" && entity.ModelOrigin == NerModelOrigin.English);
        result.InvokedModels.Should().Equal(NerModelOrigin.English);
        english.CallCount.Should().Be(1);
        tamil.CallCount.Should().Be(0);
    }

    [Test]
    public void PredictEntities_TamilOnly_UsesTamilRunnerOnly()
    {
        var english = new FakeLanguageNerRunner("Ravi Kumar", NerModelOrigin.English);
        var tamil = new FakeLanguageNerRunner("ராஜேஷ்", NerModelOrigin.Tamil);
        var router = new RoutingOnnxNerModelRunner(english, tamil, enableTamilNer: true);

        var result = router.PredictEntities("வாடிக்கையாளர் ராஜேஷ்");

        result.Entities.Should().ContainSingle(entity =>
            entity.Value == "ராஜேஷ்" && entity.ModelOrigin == NerModelOrigin.Tamil);
        result.InvokedModels.Should().Equal(NerModelOrigin.Tamil);
        english.CallCount.Should().Be(0);
        tamil.CallCount.Should().Be(1);
    }

    [Test]
    public void PredictEntities_Mixed_InvokesBothRunnersAndTagsOrigins()
    {
        var english = new FakeLanguageNerRunner("Priya", NerModelOrigin.English);
        var tamil = new FakeLanguageNerRunner("மற்றும்", NerModelOrigin.Tamil);
        var router = new RoutingOnnxNerModelRunner(english, tamil, enableTamilNer: true);

        var result = router.PredictEntities("Rajesh மற்றும் Priya");

        english.CallCount.Should().Be(1);
        tamil.CallCount.Should().Be(1);
        result.InvokedModels.Should().Equal(NerModelOrigin.English, NerModelOrigin.Tamil);
        result.Entities.Should().Contain(entity => entity.ModelOrigin == NerModelOrigin.English);
        result.Entities.Should().Contain(entity => entity.ModelOrigin == NerModelOrigin.Tamil);
    }

    [Test]
    public void PredictEntities_NoLetters_InvokesNeither()
    {
        var english = new FakeLanguageNerRunner("ignored", NerModelOrigin.English);
        var tamil = new FakeLanguageNerRunner("ignored", NerModelOrigin.Tamil);
        var router = new RoutingOnnxNerModelRunner(english, tamil, enableTamilNer: true);

        var result = router.PredictEntities("9876543210");

        result.Entities.Should().BeEmpty();
        result.InvokedModels.Should().BeEmpty();
        english.CallCount.Should().Be(0);
        tamil.CallCount.Should().Be(0);
    }

    [Test]
    public void PredictEntities_TamilDisabled_SkipsTamilRunnerForMixedText()
    {
        var english = new FakeLanguageNerRunner("EnglishName", NerModelOrigin.English);
        var tamil = new FakeLanguageNerRunner("தமிழ்", NerModelOrigin.Tamil);
        var router = new RoutingOnnxNerModelRunner(english, tamil, enableTamilNer: false);

        var result = router.PredictEntities("Rajesh மற்றும் Priya");

        english.CallCount.Should().Be(1);
        tamil.CallCount.Should().Be(0);
        result.InvokedModels.Should().Equal(NerModelOrigin.English);
    }

    [Test]
    public void MergePersonSpans_PrefersLongerOverlappingSpan()
    {
        var entities = new[]
        {
            CreatePerson("Raj", 0, 3, NerModelOrigin.English),
            CreatePerson("Rajesh", 0, 6, NerModelOrigin.Tamil)
        };

        var merged = RoutingOnnxNerModelRunner.MergePersonSpans(entities);

        merged.Should().ContainSingle(entity =>
            entity.Value == "Rajesh" && entity.ModelOrigin == NerModelOrigin.Tamil);
    }

    private static PiiEntity CreatePerson(string value, int start, int length, NerModelOrigin origin) =>
        new(PiiEntityType.Person, value, start, length, PiiDetectionSource.Ner, ModelOrigin: origin);

    private sealed class FakeLanguageNerRunner : IOnnxNerModelRunner
    {
        private readonly string _personValue;
        private readonly NerModelOrigin _origin;

        public FakeLanguageNerRunner(string personValue, NerModelOrigin origin)
        {
            _personValue = personValue;
            _origin = origin;
        }

        public int CallCount { get; private set; }

        public bool IsModelAvailable => true;

        public NerPredictionResult PredictEntities(string text)
        {
            CallCount++;
            var start = text.IndexOf(_personValue, StringComparison.Ordinal);
            if (start < 0)
            {
                start = 0;
            }

            return new NerPredictionResult(
            [
                new PiiEntity(
                    PiiEntityType.Person,
                    _personValue,
                    start,
                    _personValue.Length,
                    PiiDetectionSource.Ner,
                    ModelOrigin: _origin)
            ],
            [_origin]);
        }
    }
}