using LehrerApp.Core.Interfaces;
using LehrerApp.Core.Models;
using LehrerApp.Core.Services;
using Xunit;

namespace LehrerApp.Tests;

public sealed class CompetencyCatalogImportServiceTests
{
    private static readonly Guid SubjectId = Guid.NewGuid();

    [Fact]
    public void Analyze_UngueltigeDatei_VeraendertDenKatalogNicht()
    {
        var repository = RepositoryWithExistingCatalog();
        var service = new CompetencyCatalogImportService(repository);

        Assert.Throws<InvalidDataException>(() =>
            service.Analyze("{ kaputt", SubjectId, "Mathematik", 7));

        Assert.False(repository.ReplaceWasCalled);
        Assert.Equal("Alte Beschreibung", repository.Current.Single().Items.Single().Description);
    }

    [Fact]
    public void Analyze_ErkenntNeueUnveraenderteUndKonflikte()
    {
        var service = new CompetencyCatalogImportService(RepositoryWithExistingCatalog());

        var preview = service.Analyze(JsonWithConflictAndNewItem(), SubjectId, "Mathematik", 7);

        Assert.Equal(0, preview.NewDomains);
        Assert.Equal(1, preview.NewCompetencies);
        Assert.Single(preview.Conflicts);
        Assert.Equal("item:A1", preview.Conflicts[0].Id);
    }

    [Fact]
    public void Apply_MergeBehaeltBeiKonfliktStandardmaessigDenVorhandenenWert()
    {
        var repository = RepositoryWithExistingCatalog();
        var service = new CompetencyCatalogImportService(repository);
        var preview = service.Analyze(JsonWithConflictAndNewItem(), SubjectId, "Mathematik", 7);

        service.Apply(preview, CompetencyCatalogImportMode.Merge);

        Assert.True(repository.ReplaceWasCalled);
        var items = repository.Current.Single().Items;
        Assert.Equal("Alte Beschreibung", items.Single(x => x.Code == "A1").Description);
        Assert.Equal("Neue Kompetenz", items.Single(x => x.Code == "A2").Description);
    }

    [Fact]
    public void Apply_MergeKannImportiertenKonfliktwertUebernehmen()
    {
        var repository = RepositoryWithExistingCatalog();
        var service = new CompetencyCatalogImportService(repository);
        var preview = service.Analyze(JsonWithConflictAndNewItem(), SubjectId, "Mathematik", 7);

        service.Apply(preview, CompetencyCatalogImportMode.Merge, new HashSet<string> { "item:A1" });

        Assert.Equal("Importierte Beschreibung",
            repository.Current.Single().Items.Single(x => x.Code == "A1").Description);
    }

    [Fact]
    public void Apply_NeuerBereichMitVorhandenemCode_ErzeugtKeinenDoppeltenKompetenzcode()
    {
        var repository = RepositoryWithExistingCatalog();
        var service = new CompetencyCatalogImportService(repository);
        const string json = """
            { "domains": [
              { "code": "B", "name": "Neuer Bereich", "competencies": [
                { "code": "A1", "description": "Andere Fassung" }
              ] }
            ] }
            """;
        var preview = service.Analyze(json, SubjectId, "Mathematik", 7);

        service.Apply(preview, CompetencyCatalogImportMode.Merge);

        Assert.Single(repository.Current.SelectMany(x => x.Items), x => x.Code == "A1");
        Assert.Equal("Alte Beschreibung",
            repository.Current.SelectMany(x => x.Items).Single(x => x.Code == "A1").Description);
    }

    [Fact]
    public void Apply_ReplaceErsetztDenGesamtenAusgewaehltenKatalog()
    {
        var repository = RepositoryWithExistingCatalog();
        var service = new CompetencyCatalogImportService(repository);
        var preview = service.Analyze(JsonWithConflictAndNewItem(), SubjectId, "Mathematik", 7);

        service.Apply(preview, CompetencyCatalogImportMode.Replace);

        Assert.Equal(2, repository.Current.Single().Items.Count);
        Assert.Equal("Importierte Beschreibung",
            repository.Current.Single().Items.Single(x => x.Code == "A1").Description);
    }

    [Fact]
    public void Apply_NachZwischenzeitlicherAenderung_VerlangtNeueVorschau()
    {
        var repository = RepositoryWithExistingCatalog();
        var service = new CompetencyCatalogImportService(repository);
        var preview = service.Analyze(JsonWithConflictAndNewItem(), SubjectId, "Mathematik", 7);
        repository.Current[0].UpdatedAt = repository.Current[0].UpdatedAt.AddSeconds(1);

        var exception = Assert.Throws<InvalidOperationException>(() =>
            service.Apply(preview, CompetencyCatalogImportMode.Merge));

        Assert.Contains("Vorschau", exception.Message);
        Assert.False(repository.ReplaceWasCalled);
    }

    [Fact]
    public void Analyze_AbweichendesFachUndKlassenstufe_ErzeugtWarnungen()
    {
        var service = new CompetencyCatalogImportService(RepositoryWithExistingCatalog());
        var json = JsonWithConflictAndNewItem()
            .Replace("Mathematik", "Deutsch")
            .Replace("\"gradeLevel\": 7", "\"gradeLevel\": 8");

        var preview = service.Analyze(json, SubjectId, "Mathematik", 7);

        Assert.Equal(2, preview.Warnings.Count);
    }

    [Fact]
    public void Analyze_DoppelterKompetenzcode_WirdAbgelehnt()
    {
        var service = new CompetencyCatalogImportService(RepositoryWithExistingCatalog());
        const string json = """
            { "domains": [
              { "name": "A", "competencies": [{ "code": "X1", "description": "Eins" }] },
              { "name": "B", "competencies": [{ "code": "X1", "description": "Zwei" }] }
            ] }
            """;

        Assert.Throws<InvalidDataException>(() =>
            service.Analyze(json, SubjectId, "Mathematik", 7));
    }

    private static InMemoryCompetencyDomainRepository RepositoryWithExistingCatalog() => new(
    [
        new CompetencyDomain
        {
            SubjectId = SubjectId,
            GradeLevel = 7,
            Code = "A",
            Name = "Arithmetik",
            Items =
            [
                new CompetencyItem { Code = "A1", Description = "Alte Beschreibung" },
            ],
        },
    ]);

    private static string JsonWithConflictAndNewItem() => """
        {
          "subject": "Mathematik",
          "gradeLevel": 7,
          "domains": [
            {
              "code": "A",
              "name": "Arithmetik",
              "competencies": [
                { "code": "A1", "description": "Importierte Beschreibung" },
                { "code": "A2", "description": "Neue Kompetenz" }
              ]
            }
          ]
        }
        """;

    private sealed class InMemoryCompetencyDomainRepository(List<CompetencyDomain> initial)
        : ICompetencyDomainRepository
    {
        public List<CompetencyDomain> Current { get; private set; } = initial;
        public bool ReplaceWasCalled { get; private set; }

        public List<CompetencyDomain> GetBySubjectAndGrade(Guid subjectId, int gradeLevel) =>
            Current.Where(x => x.SubjectId == subjectId && x.GradeLevel == gradeLevel).ToList();
        public List<CompetencyDomain> GetBySubject(Guid subjectId) =>
            Current.Where(x => x.SubjectId == subjectId).ToList();
        public CompetencyDomain? GetById(Guid id) => Current.FirstOrDefault(x => x.Id == id);

        public void Save(CompetencyDomain domain) => Current.Add(domain);
        public void Delete(Guid id) => Current.RemoveAll(x => x.Id == id);
        public void DeleteBySubjectAndGrade(Guid subjectId, int gradeLevel) =>
            Current.RemoveAll(x => x.SubjectId == subjectId && x.GradeLevel == gradeLevel);

        public void ReplaceForSubjectAndGrade(Guid subjectId, int gradeLevel, List<CompetencyDomain> domains)
        {
            ReplaceWasCalled = true;
            Current.RemoveAll(x => x.SubjectId == subjectId && x.GradeLevel == gradeLevel);
            Current.AddRange(domains);
        }
    }
}