using AcDream.App.Net;
using AcDream.Core.CharGen;
using DatReaderWriter.DBObjs;
using DatReaderWriter.Enums;
using DatReaderWriter.Types;

namespace AcDream.App.Tests.Net;

public sealed class RetailSkillFormulaTests
{
    [Fact]
    public void ZeroDivisorIsTheOnlyFormulaFailureGate()
    {
        SkillFormula invalid = Formula(w: 7, x: 1, y: 1, z: 0);
        Assert.False(RetailSkillFormula.TryCalculate(invalid, 10u, 20u, out uint invalidResult));
        Assert.Equal(0u, invalidResult);

        SkillFormula zeroX = Formula(w: 7, x: 0, y: 2, z: 3);
        Assert.True(RetailSkillFormula.TryCalculate(zeroX, 10u, 4u, out uint validResult));
        Assert.Equal(5u, validResult);
    }

    [Theory]
    [InlineData(9u, 4u, 2u)]
    [InlineData(10u, 4u, 3u)]
    [InlineData(11u, 4u, 3u)]
    [InlineData(12u, 4u, 3u)]
    public void DivisionRoundsToNearestWithExactHalvesUp(
        uint numerator,
        uint divisor,
        uint expected)
    {
        SkillFormula formula = Formula(w: 0, x: 1, y: 0, z: divisor);

        Assert.True(RetailSkillFormula.TryCalculate(
            formula,
            numerator,
            0u,
            out uint result));
        Assert.Equal(expected, result);
    }

    [Fact]
    public void AdditiveWordIsInsideTheNumerator()
    {
        SkillFormula formula = Formula(w: 3, x: 1, y: 1, z: 4);

        Assert.True(RetailSkillFormula.TryCalculate(formula, 4u, 2u, out uint result));

        Assert.Equal(2u, result);
    }

    [Fact]
    public void NumeratorUsesUnsignedThirtyTwoBitWrap()
    {
        SkillFormula formula = Formula(w: 1, x: 2, y: 0, z: 2);

        Assert.True(RetailSkillFormula.TryCalculate(
            formula,
            uint.MaxValue,
            0u,
            out uint result));

        Assert.Equal(0x80000000u, result);
    }

    [Fact]
    public void SignedDatStorageIsReinterpretedAsRetailUnsignedWords()
    {
        SkillFormula formula = Formula(w: -1, x: 0, y: 0, z: 1);

        Assert.True(RetailSkillFormula.TryCalculate(formula, 0u, 0u, out uint result));

        Assert.Equal(uint.MaxValue, result);
    }

    /// <summary>
    /// F13 (night-round review): <see cref="RetailSkillFormula.FormatFormula"/>
    /// previously read the raw signed <c>int</c> fields directly instead of
    /// the SAME unsigned reinterpretation <see cref="RetailSkillFormula.TryCalculate"/>
    /// uses. A multiplier whose stored bit pattern has the high bit set
    /// would read as a small negative number here (failing the
    /// <c>&gt;= 1</c> hasAttr gate, or printing a negative multiplier) instead
    /// of the huge unsigned value <c>TryCalculate</c> actually computes
    /// with for the SAME formula.
    /// </summary>
    [Fact]
    public void FormatFormula_MultiplierIsReinterpretedAsRetailUnsignedWord()
    {
        SkillFormula formula = Formula(w: 0, x: -1, y: 0, z: 1);
        formula.Attribute1 = AttributeId.Strength;

        string? text = RetailSkillFormula.FormatFormula(formula);

        Assert.NotNull(text);
        Assert.Contains(uint.MaxValue.ToString(), text);
        Assert.DoesNotContain("-1", text);
    }

    /// <summary>Same reinterpretation, but for the divisor and additive-bonus
    /// suffixes rather than the multiplier — both must read unsigned too.</summary>
    [Fact]
    public void FormatFormula_DivisorAndAdditiveBonusAreReinterpretedAsRetailUnsignedWords()
    {
        SkillFormula formula = Formula(w: -1, x: 1, y: 0, z: unchecked((uint)-2));
        formula.Attribute1 = AttributeId.Strength;

        string? text = RetailSkillFormula.FormatFormula(formula);

        Assert.NotNull(text);
        Assert.Contains($"/ {unchecked((uint)-2)}", text);
        Assert.Contains($"+{uint.MaxValue}", text);
        Assert.DoesNotContain("-1", text);
        Assert.DoesNotContain("-2", text);
    }

    [Fact]
    public void LiveResolverLooksUpTheDatFormulaAndTreatsMissingAttributesAsZero()
    {
        const uint skillId = 0x345u;
        const uint firstAttributeId = 1u;
        const uint secondAttributeId = 2u;
        var skillTable = new SkillTable();
        skillTable.Skills.Add((SkillId)skillId, new SkillBase
        {
            Formula = new SkillFormula
            {
                AdditiveBonus = 1,
                Attribute1Multiplier = 1,
                Attribute2Multiplier = 2,
                Divisor = 3,
                Attribute1 = (AttributeId)firstAttributeId,
                Attribute2 = (AttributeId)secondAttributeId,
            },
        });
        var resolver = new LiveSkillCreditResolver(skillTable);

        uint result = resolver.Resolve(
            skillId,
            new Dictionary<uint, uint> { [firstAttributeId] = 8u });

        Assert.Equal(3u, result);
        Assert.Equal(0u, resolver.Resolve(0x999u, new Dictionary<uint, uint>()));
    }

    private static SkillFormula Formula(int w, int x, int y, uint z) => new()
    {
        AdditiveBonus = w,
        Attribute1Multiplier = x,
        Attribute2Multiplier = y,
        Divisor = unchecked((int)z),
    };

    // ── CC5 re-review residual round, R2 (2026-08-16): RetailSkillFormula.
    // ── CalculateChargenScore / ChargenSkillScoreResolver had zero direct
    // ── coverage — the F12(d) test substitutes `skillId * 10` instead of
    // ── exercising the real formula. ─────────────────────────────────────

    /// <summary>
    /// <see cref="RetailSkillFormula.CalculateChargenScore"/>'s level bonus:
    /// Untrained adds nothing, Trained adds 5, Specialized adds 10, on top
    /// of the SAME base <see cref="RetailSkillFormula.TryCalculate"/> result
    /// (formula here: <c>w=0, x=1, y=0, z=1</c> against
    /// <c>attribute1=5</c> -&gt; base 5).
    /// </summary>
    [Theory]
    [InlineData(ChargenSkillAdvancementClass.Untrained, 5u)]
    [InlineData(ChargenSkillAdvancementClass.Trained, 10u)]
    [InlineData(ChargenSkillAdvancementClass.Specialized, 15u)]
    public void CalculateChargenScore_AddsTheLevelBonusOnTopOfTheBaseFormula(
        ChargenSkillAdvancementClass level,
        uint expected)
    {
        var skillBase = new SkillBase { Formula = Formula(w: 0, x: 1, y: 0, z: 1) };

        uint result = RetailSkillFormula.CalculateChargenScore(skillBase, attribute1: 5u, attribute2: 0u, level);

        Assert.Equal(expected, result);
    }

    /// <summary>
    /// The divisor-zero skip path: <see cref="RetailSkillFormula.TryCalculate"/>'s
    /// own failure gate short-circuits <see cref="RetailSkillFormula.CalculateChargenScore"/>
    /// to a flat 0 BEFORE the level bonus is ever added — even for
    /// Specialized, which would otherwise add 10.
    /// </summary>
    [Fact]
    public void CalculateChargenScore_ZeroDivisor_ReturnsZero_RegardlessOfLevel()
    {
        var skillBase = new SkillBase { Formula = Formula(w: 7, x: 1, y: 1, z: 0) };

        Assert.Equal(0u, RetailSkillFormula.CalculateChargenScore(
            skillBase, 10u, 20u, ChargenSkillAdvancementClass.Untrained));
        Assert.Equal(0u, RetailSkillFormula.CalculateChargenScore(
            skillBase, 10u, 20u, ChargenSkillAdvancementClass.Trained));
        Assert.Equal(0u, RetailSkillFormula.CalculateChargenScore(
            skillBase, 10u, 20u, ChargenSkillAdvancementClass.Specialized));
    }

    /// <summary>
    /// <see cref="ChargenSkillScoreResolver.Resolve"/>'s six-way
    /// <c>ResolveAttribute</c> switch — one case per
    /// <see cref="AttributeId"/> (Strength=1..Self=6) — resolving through a
    /// formula that reads ONLY <c>Attribute1</c> (<c>x=1, y=0</c>) so the
    /// result unambiguously reports which of the six
    /// <see cref="ChargenAttributeValues"/> fields the switch actually read.
    /// </summary>
    [Theory]
    [InlineData(AttributeId.Strength)]
    [InlineData(AttributeId.Endurance)]
    [InlineData(AttributeId.Coordination)]
    [InlineData(AttributeId.Quickness)]
    [InlineData(AttributeId.Focus)]
    [InlineData(AttributeId.Self)]
    public void ChargenSkillScoreResolver_ResolvesEachAttributeIdThroughTheSixWaySwitch(
        AttributeId attributeId)
    {
        const uint skillId = 0x10u;
        var skillTable = new SkillTable();
        skillTable.Skills.Add((SkillId)skillId, new SkillBase
        {
            Formula = new SkillFormula
            {
                AdditiveBonus = 0,
                Attribute1Multiplier = 1,
                Attribute2Multiplier = 0,
                Divisor = 1,
                Attribute1 = attributeId,
                // Attribute2 deliberately left at its zero default (Strength) —
                // Attribute2Multiplier=0 means whatever it reads contributes
                // nothing, so it cannot mask a wrong Attribute1 case.
            },
        });
        var resolver = new ChargenSkillScoreResolver(skillTable);
        ChargenAttributeValues attributes = AttributeValuesWith(attributeId, 42);

        uint result = resolver.Resolve(skillId, attributes, ChargenSkillAdvancementClass.Untrained);

        Assert.Equal(42u, result);
    }

    private static ChargenAttributeValues AttributeValuesWith(AttributeId attributeId, int value) =>
        attributeId switch
        {
            AttributeId.Strength => new ChargenAttributeValues(value, 0, 0, 0, 0, 0),
            AttributeId.Endurance => new ChargenAttributeValues(0, value, 0, 0, 0, 0),
            AttributeId.Coordination => new ChargenAttributeValues(0, 0, value, 0, 0, 0),
            AttributeId.Quickness => new ChargenAttributeValues(0, 0, 0, value, 0, 0),
            AttributeId.Focus => new ChargenAttributeValues(0, 0, 0, 0, value, 0),
            AttributeId.Self => new ChargenAttributeValues(0, 0, 0, 0, 0, value),
            _ => default,
        };
}