using System.Net;
using System.Text;
using LehrerApp.Core.Models;
using LehrerApp.Desktop.Services;
using Xunit;

namespace LehrerApp.Desktop.Tests;

public sealed class UntisReportCacheServiceTests
{
    private static readonly DateOnly Today = new(2026, 8, 25);
    private static readonly DateOnly HotStart = Today.AddDays(-14);

    // ── Plan(): reine Entscheidungslogik, keine Repositories/HTTP nötig ──────────

    [Fact]
    public void Plan_ErsterAufruf_LaedtHeissesFensterUndDeckungReichtBisFensteranfang()
    {
        var plan = UntisReportCacheService.Plan(null, Today, Today, Today, forceRefresh: false, DateTime.UtcNow);

        Assert.True(plan.RefreshHotWindow);
        Assert.Equal(HotStart, plan.HotWindowStart);
        Assert.Equal(Today, plan.HotWindowEnd);
        Assert.False(plan.FetchColdRange);
        Assert.Equal(Int(HotStart), plan.ResultingColdCoverageStartDate);
    }

    [Fact]
    public void Plan_InnerhalbEinerStunde_KeinErneutesHeissesFenster()
    {
        var state = new UntisCacheFetchState
        {
            ClassName = "10c", Kind = UntisCacheKind.Absences,
            HotWindowFetchedAt = DateTime.UtcNow.AddMinutes(-10), ColdCoverageStartDate = Int(HotStart),
        };

        var plan = UntisReportCacheService.Plan(state, Today, Today, Today, forceRefresh: false, DateTime.UtcNow);

        Assert.False(plan.RefreshHotWindow);
        Assert.False(plan.FetchColdRange);
    }

    [Fact]
    public void Plan_ForceRefresh_LoestTrotzKuerzlichemAbrufAus()
    {
        var state = new UntisCacheFetchState
        {
            ClassName = "10c", Kind = UntisCacheKind.Absences,
            HotWindowFetchedAt = DateTime.UtcNow.AddMinutes(-10), ColdCoverageStartDate = Int(HotStart),
        };

        var plan = UntisReportCacheService.Plan(state, Today, Today, Today, forceRefresh: true, DateTime.UtcNow);

        Assert.True(plan.RefreshHotWindow);
    }

    [Fact]
    public void Plan_MehrAlsEineStundeVergangen_FrischtHeissesFensterErneutAuf()
    {
        var state = new UntisCacheFetchState
        {
            ClassName = "10c", Kind = UntisCacheKind.Absences,
            HotWindowFetchedAt = DateTime.UtcNow.AddHours(-2), ColdCoverageStartDate = Int(HotStart),
        };

        var plan = UntisReportCacheService.Plan(state, Today, Today, Today, forceRefresh: false, DateTime.UtcNow);

        Assert.True(plan.RefreshHotWindow);
    }

    [Fact]
    public void Plan_AnfrageVorDemHeissenFenster_KeinHeissesFensterAberKalterErstabruf()
    {
        var requestStart = HotStart.AddDays(-30);
        var requestEnd = HotStart.AddDays(-5);

        var plan = UntisReportCacheService.Plan(null, requestStart, requestEnd, Today, forceRefresh: false, DateTime.UtcNow);

        Assert.False(plan.RefreshHotWindow);
        Assert.True(plan.FetchColdRange);
        Assert.Equal(requestStart, plan.ColdRangeStart);
        Assert.Equal(HotStart.AddDays(-1), plan.ColdRangeEnd);
        Assert.Equal(Int(requestStart), plan.ResultingColdCoverageStartDate);
    }

    [Fact]
    public void Plan_BereitsKaltAbgedeckterBereich_KeinAbrufNoetig()
    {
        var coveredSince = HotStart.AddDays(-60);
        var state = new UntisCacheFetchState
        {
            ClassName = "10c", Kind = UntisCacheKind.Absences,
            HotWindowFetchedAt = DateTime.UtcNow, ColdCoverageStartDate = Int(coveredSince),
        };

        var plan = UntisReportCacheService.Plan(state, coveredSince.AddDays(10), HotStart.AddDays(-20),
            Today, forceRefresh: false, DateTime.UtcNow);

        Assert.False(plan.RefreshHotWindow);
        Assert.False(plan.FetchColdRange);
    }

    [Fact]
    public void Plan_ErweitertKalteAbdeckungNurBisZumBenoetigtenStart()
    {
        var coveredSince = HotStart.AddDays(-30);
        var earlierStart = HotStart.AddDays(-90);
        var state = new UntisCacheFetchState
        {
            ClassName = "10c", Kind = UntisCacheKind.Absences,
            HotWindowFetchedAt = DateTime.UtcNow, ColdCoverageStartDate = Int(coveredSince),
        };

        var plan = UntisReportCacheService.Plan(state, earlierStart, HotStart.AddDays(-40),
            Today, forceRefresh: false, DateTime.UtcNow);

        Assert.False(plan.RefreshHotWindow);
        Assert.True(plan.FetchColdRange);
        Assert.Equal(earlierStart, plan.ColdRangeStart);
        Assert.Equal(coveredSince.AddDays(-1), plan.ColdRangeEnd);
        Assert.Equal(Int(earlierStart), plan.ResultingColdCoverageStartDate);
    }

    private static int Int(DateOnly date) => date.Year * 10000 + date.Month * 100 + date.Day;

    // ── Ende-zu-Ende: erster Aufruf ruft WebUntis ab, zweiter Aufruf binnen einer Stunde nicht ──

    [Fact]
    public async Task GetClassRegisterEventsAsync_ZweiterAufrufBinnenEinerStunde_RuftWebUntisNichtErneutAb()
    {
        var todayLabel = DateTime.Today.ToString("dd.MM.yy");
        var csv = Encoding.UTF8.GetBytes(
            "Klasse\tDatum\tFach\tName\tBenutzer\tEintragskategorie\tKategoriegruppe\tText\r\n" +
            $"10c\t{todayLabel}\tNAT\tMuster Max\tmueller\tMitarb. über Erwart.\tPositiv\tArbeitet gut mit.\r\n");
        var handler = new QueueHandler(
            Json("{\"result\":{\"sessionId\":\"s\"}}"),
            Json("{\"result\":[{\"id\":1,\"name\":\"2026/27\",\"startDate\":20260801,\"endDate\":20270731}]}"),
            Json("{\"data\":{\"finished\":true,\"error\":false," +
                 "\"reportParams\":\"get=rpt.tmp&name=ClassregEventPerStudent&format=csv\"}}"),
            new HttpResponseMessage(HttpStatusCode.OK) { Content = new ByteArrayContent(csv) });
        var settings = TestSupport.BuildWebUntisSettingsService();
        await using var untis = new WebUntisIntegrationService(new HttpClient(handler), settings);
        await untis.ConnectAsync(new WebUntisCredentials("bk-ostvest", "arche.webuntis.com", "lehrkraft", "geheim"));

        var absenceCache = new FakeUntisAbsenceCache();
        var classRegisterCache = new FakeUntisClassRegisterCache();
        var fetchStates = new FakeUntisCacheFetchStates();
        var cache = new UntisReportCacheService(untis, absenceCache, classRegisterCache, fetchStates);
        var today = DateOnly.FromDateTime(DateTime.Today);

        var first = await cache.GetClassRegisterEventsAsync("10c", today, today);
        Assert.Single(first);
        Assert.Equal(4, handler.Requests.Count);

        var second = await cache.GetClassRegisterEventsAsync("10c", today, today);
        Assert.Single(second);
        Assert.Equal(4, handler.Requests.Count); // keine weiteren Anfragen - aus dem Cache bedient
    }

    private static HttpResponseMessage Json(string json) => new(HttpStatusCode.OK)
    {
        Content = new StringContent(json, Encoding.UTF8, "application/json"),
    };

    private sealed class QueueHandler(params HttpResponseMessage[] responses) : HttpMessageHandler
    {
        private readonly Queue<HttpResponseMessage> _responses = new(responses);
        public List<string> Requests { get; } = [];

        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request,
            CancellationToken cancellationToken)
        {
            Requests.Add(request.RequestUri?.ToString() ?? "");
            await Task.Yield();
            return _responses.Dequeue();
        }
    }
}