using QuestionsApi.Models;
using QuestionsApi.Services;
using Xunit;

namespace QuestionsApi.Tests;

public sealed class DashboardTests
{
    [Fact]
    public void PercentageRoundsToNearestWholeNumber()
    {
        Assert.Equal(67, DashboardStore.Percentage(2, 3));
        Assert.Equal(0, DashboardStore.Percentage(0, 0));
    }

    [Fact]
    public void StreakIncludesYesterdayWhenUserHasNotStudiedToday()
    {
        var today = new DateTime(2026, 7, 18, 0, 0, 0, DateTimeKind.Utc);
        var dates = new[] { today.AddDays(-1), today.AddDays(-2), today.AddDays(-3), today.AddDays(-5) };
        Assert.Equal(3, DashboardStore.CalculateCurrentStreak(dates, today));
    }

    [Fact]
    public void StreakStopsAtFirstMissingDay()
    {
        var today = new DateTime(2026, 7, 18, 0, 0, 0, DateTimeKind.Utc);
        var dates = new[] { today, today.AddDays(-1), today.AddDays(-3) };
        Assert.Equal(2, DashboardStore.CalculateCurrentStreak(dates, today));
    }

    [Fact]
    public void SystemPerformanceReturnsEveryOfficialSystemInOrder()
    {
        var attempts = new[]
        {
            Attempt("cardio-1", true),
            Attempt("cardio-2", false),
            Attempt("ethics-1", true),
            Attempt("ignored", true),
            Attempt("skipped-cardio", false, true)
        };
        var questions = new Dictionary<string, Question>
        {
            ["cardio-1"] = Question("Cardiology"),
            ["cardio-2"] = Question("Cardiovascular System"),
            ["ethics-1"] = Question("Medical Ethics"),
            ["ignored"] = Question("Unmapped Specialty"),
            ["skipped-cardio"] = Question("Cardiology")
        };

        var result = DashboardStore.BuildSystemPerformance(attempts, questions);

        Assert.Equal(14, result.Count);
        Assert.Equal(DashboardStore.Step3Systems, result.Select(value => value.System));
        var cardiovascular = result.Single(value => value.System == "Cardiovascular System");
        Assert.Equal(1, cardiovascular.Correct);
        Assert.Equal(2, cardiovascular.Total);
        Assert.Equal(50, cardiovascular.Accuracy);
        var social = result.Single(value => value.System.StartsWith("Social Sciences"));
        Assert.Equal(1, social.Correct);
        Assert.Equal(1, social.Total);
        Assert.All(result.Where(value => value.System != cardiovascular.System && value.System != social.System),
            value => Assert.Equal(0, value.Total));
    }

    [Theory]
    [InlineData("Preventive Medicine", "Human Development")]
    [InlineData("Infectious Disease", "Immune System, Blood & Lymphoreticular System, and Multisystem Processes/Disorders")]
    [InlineData("Dermatology", "Skin & Subcutaneous Tissue")]
    [InlineData("Pulmonary", "Respiratory System")]
    [InlineData("Pregnancy", "Pregnancy/Childbirth & Female Reproductive System & Breast")]
    [InlineData("Biostatistics", "Biostatistics & Epidemiology/Population Health & Interpretation of the Medical Literature")]
    [InlineData("Medical Ethics", "Social Sciences: Communication Skills/Ethics/Patient Safety")]
    [InlineData("Integumentary System", "Skin & Subcutaneous Tissue")]
    [InlineData("Eye & Adnexa", "Nervous System & Special Senses")]
    [InlineData("Toxicology", "Immune System, Blood & Lymphoreticular System, and Multisystem Processes/Disorders")]
    public void SystemAliasesMapToOfficialCategories(string source, string expected)
    {
        Assert.Equal(expected, DashboardStore.NormalizeStep3System(source));
    }

    [Fact]
    public void TrendCarriesRatingForwardAndLeavesInactiveAccuracyAsGapData()
    {
        var today = new DateTime(2026, 7, 25, 0, 0, 0, DateTimeKind.Utc);
        var baselineDate = today.AddDays(-2).AddHours(8);
        var attempts = new[]
        {
            Attempt("one", true, createdUtc: today.AddDays(-2).AddHours(9),
                rating: 1018, ratingUtc: today.AddDays(-2).AddHours(9)),
            Attempt("two", false, createdUtc: today.AddDays(-2).AddHours(10),
                rating: 1002, ratingUtc: today.AddDays(-2).AddHours(10)),
            Attempt("three", true, createdUtc: today.AddHours(11),
                rating: 1020, ratingUtc: today.AddHours(11)),
            Attempt("skip", false, true, today.AddDays(-1).AddHours(4),
                990, today.AddDays(-1).AddHours(4))
        };
        var rating = new UserRating
        {
            OverallElo = 1020,
            HistoryBaselineElo = 1000,
            HistoryStartedUtc = baselineDate
        };

        var result = DashboardStore.BuildPerformanceTrend(
            attempts, rating, Array.Empty<CcsAttempt>(), new CcsUserRating(), today);

        Assert.Equal(30, result.Count);
        Assert.Null(result[^4].QuestionBankRating);
        Assert.Equal(1002, result[^3].QuestionBankRating);
        Assert.Equal(50, result[^3].Accuracy);
        Assert.Equal(2, result[^3].Total);
        Assert.Equal(990, result[^2].QuestionBankRating);
        Assert.Equal(0, result[^2].Total);
        Assert.Equal(1020, result[^1].QuestionBankRating);
        Assert.Equal(100, result[^1].Accuracy);
    }

    [Fact]
    public void TrendCarriesCcsRatingForwardIndependentlyOfQuestionBankRating()
    {
        var today = new DateTime(2026, 7, 25, 0, 0, 0, DateTimeKind.Utc);
        var baselineDate = today.AddDays(-2).AddHours(8);
        var rating = new UserRating();
        var ccsRating = new CcsUserRating
        {
            Elo = 1050,
            HistoryBaselineElo = 1000,
            HistoryStartedUtc = baselineDate
        };
        var ccsAttempts = new[]
        {
            RatedCcsAttempt("one", today.AddDays(-1).AddHours(9), 1030),
            RatedCcsAttempt("two", today.AddHours(10), 1050)
        };

        var result = DashboardStore.BuildPerformanceTrend(
            Array.Empty<QuestionAttempt>(), rating, ccsAttempts, ccsRating, today);

        Assert.Equal(30, result.Count);
        Assert.Equal(1000, result[^3].CcsRating);
        Assert.Equal(1030, result[^2].CcsRating);
        Assert.Equal(1050, result[^1].CcsRating);
    }

    private static CcsAttempt RatedCcsAttempt(string caseExternalId, DateTime appliedUtc, int userElo) => new()
    {
        CaseExternalId = caseExternalId,
        Rating = new CcsRatingChange { Rated = true, UserElo = userElo, AppliedUtc = appliedUtc }
    };

    private static QuestionAttempt Attempt(
        string questionId,
        bool correct,
        bool skip = false,
        DateTime? createdUtc = null,
        int? rating = null,
        DateTime? ratingUtc = null) => new()
        {
            QuestionExternalId = questionId,
            IsCorrect = correct,
            IsSkip = skip,
            CreatedUtc = createdUtc ?? DateTime.UtcNow,
            UserOverallEloAfter = rating,
            RatingAppliedUtc = ratingUtc
        };

    private static Question Question(string system) => new()
    {
        ExternalId = system,
        System = system
    };

    [Fact]
    public void PercentileReturnsNullWithNoUsers()
    {
        Assert.Null(DashboardStore.Percentile(0, 0));
    }

    [Fact]
    public void PercentileComputesTopPercentFromUsersRatedHigher()
    {
        // 18 of 100 users rate higher than this user - "top 18%"
        Assert.Equal(18, DashboardStore.Percentile(18, 100));
    }

    [Fact]
    public void PercentileNeverReturnsZero()
    {
        // Even the single best-rated user should read as "top 1%", not "top 0%"
        Assert.Equal(1, DashboardStore.Percentile(0, 100));
    }

    [Theory]
    [InlineData(0.85, "High")]
    [InlineData(0.7, "High")]
    [InlineData(0.55, "Medium")]
    [InlineData(0.4, "Medium")]
    [InlineData(0.1, "Low")]
    public void ReadinessLabelUsesPassProbabilityThresholds(double passProbability, string expected)
    {
        Assert.Equal(expected, DashboardStore.ReadinessLabel(passProbability));
    }

    [Fact]
    public void SelectLatestReadinessScoreSkipsSampleSimulationsEvenWhenMostRecent()
    {
        var today = new DateTime(2026, 7, 25, 0, 0, 0, DateTimeKind.Utc);
        var simulations = new[]
        {
            CompletedSimulation(isSample: true, completedUtc: today, passProbability: 0.98),
            CompletedSimulation(isSample: false, completedUtc: today.AddDays(-3), passProbability: 0.12)
        };

        var score = DashboardStore.SelectLatestReadinessScore(simulations);

        Assert.NotNull(score);
        Assert.Equal(0.12, score.PassProbability);
    }

    [Fact]
    public void SelectLatestReadinessScoreReturnsNullWhenOnlySamplesExist()
    {
        var simulations = new[] { CompletedSimulation(isSample: true, completedUtc: DateTime.UtcNow, passProbability: 0.98) };

        Assert.Null(DashboardStore.SelectLatestReadinessScore(simulations));
    }

    private static ExamSimulation CompletedSimulation(bool isSample, DateTime completedUtc, double passProbability) => new()
    {
        IsSample = isSample,
        CompletedUtc = completedUtc,
        Score = new ExamSimulationScore { PassProbability = passProbability }
    };
}