using System.Collections.Generic;
using AcDream.Core.Spells;

namespace AcDream.Core.Tests.Spells;

/// <summary>
/// Tests for <see cref="EnchantmentMath"/>. Issue #6 architecture
/// validation — confirms the family-stacking dedup + identity
/// semantics work correctly.
///
/// <para>
/// Note: until ISSUES.md #12 lands the wire-format extension that
/// captures StatMod (type/key/val) on <see cref="ActiveEnchantmentRecord"/>,
/// the per-enchantment modifier value isn't aggregated yet — we
/// always return <see cref="EnchantmentMath.VitalMod.Identity"/>.
/// These tests confirm the architectural shape is correct for the
/// follow-up wire wiring.
/// </para>
/// </summary>
public sealed class EnchantmentMathTests
{
    [Fact]
    public void Empty_ReturnsIdentity()
    {
        var mod = EnchantmentMath.GetMod(
            new List<ActiveEnchantmentRecord>(),
            SpellTable.Empty,
            EnchantmentMath.StatKey.MaxStamina);
        Assert.Equal(EnchantmentMath.VitalMod.Identity, mod);
    }

    [Fact]
    public void NoMatchingTableEntries_ReturnsIdentity()
    {
        // Active enchantments exist but none of them have entries in the
        // SpellTable (so we can't read Family) — they're skipped.
        var enchantments = new[]
        {
            new ActiveEnchantmentRecord(SpellId: 9999u, LayerId: 1u, Duration: 60f, CasterGuid: 0u),
            new ActiveEnchantmentRecord(SpellId: 8888u, LayerId: 2u, Duration: 60f, CasterGuid: 0u),
        };
        var mod = EnchantmentMath.GetMod(enchantments, SpellTable.Empty,
                                         EnchantmentMath.StatKey.MaxStamina);
        Assert.Equal(EnchantmentMath.VitalMod.Identity, mod);
    }

    [Fact]
    public void StatKey_ConstantsMatchAceEnum()
    {
        // ACE PropertyAttribute2nd enum: MaxHealth=1, MaxStamina=3, MaxMana=5.
        // Verified against named-retail/acclient.h line 37287-37301.
        Assert.Equal(1u, EnchantmentMath.StatKey.MaxHealth);
        Assert.Equal(3u, EnchantmentMath.StatKey.MaxStamina);
        Assert.Equal(5u, EnchantmentMath.StatKey.MaxMana);
    }

    [Fact]
    public void Identity_IsOneAndZero()
    {
        Assert.Equal(1.0f, EnchantmentMath.VitalMod.Identity.Multiplier);
        Assert.Equal(0.0f, EnchantmentMath.VitalMod.Identity.Additive);
    }

    [Fact]
    public void FamilyStacking_DeduplicatesByFamily_KeepsHigherSpellId()
    {
        // Build a SpellTable with 2 spells in the same Family (e.g.
        // Strength I and Strength VII, both Family=1). Both are in the
        // active enchantment list; only the higher spell id should
        // survive the family-stacking dedup.
        // The aggregator currently returns Identity regardless (see
        // class doc), but the dedup behaviour is observable by
        // counting which records would be folded — exercised here to
        // pin the architecture even before ISSUES.md #12 wires data.
        // Family=1 strength buffs example.
        var table = LoadTable(
            (1u, "Strength I", 1u),
            (132u, "Strength VII", 1u));   // same family
        var enchantments = new[]
        {
            new ActiveEnchantmentRecord(SpellId: 1u,   LayerId: 100u, Duration: 60f, CasterGuid: 0u),
            new ActiveEnchantmentRecord(SpellId: 132u, LayerId: 101u, Duration: 60f, CasterGuid: 0u),
        };
        // Currently: identity result (StatMod data not yet on records).
        // Test demonstrates the call doesn't throw + returns identity.
        var mod = EnchantmentMath.GetMod(enchantments, table,
                                         EnchantmentMath.StatKey.MaxStamina);
        Assert.Equal(EnchantmentMath.VitalMod.Identity, mod);
    }

    [Fact]
    public void Family_Zero_DoesNotDedup()
    {
        // Family 0 means "no stacking bucket" — each enchantment is
        // its own bucket (synthetic key per layer). When ISSUES.md #12
        // lands and we aggregate StatMods, both these buffs will
        // contribute simultaneously.
        var table = LoadTable(
            (10u, "Buff A", 0u),
            (20u, "Buff B", 0u));
        var enchantments = new[]
        {
            new ActiveEnchantmentRecord(SpellId: 10u, LayerId: 100u, Duration: 60f, CasterGuid: 0u),
            new ActiveEnchantmentRecord(SpellId: 20u, LayerId: 101u, Duration: 60f, CasterGuid: 0u),
        };
        var mod = EnchantmentMath.GetMod(enchantments, table,
                                         EnchantmentMath.StatKey.MaxStamina);
        // Identity for now; architecture confirmed via no-throw + result shape.
        Assert.Equal(EnchantmentMath.VitalMod.Identity, mod);
    }

    [Fact]
    public void GetMod_MultiplicativeBucket_AppliesProductWhenStatKeyMatches()
    {
        // Two multiplicative enchantments on MaxStamina (key=3): values
        // 1.2 and 1.1 → final multiplier = 1.2 × 1.1 = 1.32.
        // Different families so neither dedups the other.
        var table = LoadTable(
            (10u, "Buff10", 100u),
            (11u, "Buff11", 200u));
        var enchantments = new[]
        {
            MakeMultRecord(spellId: 10, layer: 1, statKey: 3u, val: 1.2f),
            MakeMultRecord(spellId: 11, layer: 2, statKey: 3u, val: 1.1f),
        };
        var mod = EnchantmentMath.GetMod(enchantments, table,
                                         EnchantmentMath.StatKey.MaxStamina);
        Assert.Equal(1.32f, mod.Multiplier, precision: 4);
        Assert.Equal(0.0f, mod.Additive);
    }

    [Fact]
    public void GetMod_AdditiveBucket_SumsValueWhenStatKeyMatches()
    {
        var table = LoadTable(
            (20u, "Add1", 300u),
            (21u, "Add2", 301u));
        var enchantments = new[]
        {
            MakeAddRecord(spellId: 20, layer: 1, statKey: 5u /* MaxMana */, val: 25f),
            MakeAddRecord(spellId: 21, layer: 2, statKey: 5u, val: 50f),
        };
        var mod = EnchantmentMath.GetMod(enchantments, table,
                                         EnchantmentMath.StatKey.MaxMana);
        Assert.Equal(1.0f, mod.Multiplier);
        Assert.Equal(75.0f, mod.Additive);
    }

    [Fact]
    public void GetMod_StatKeyMismatch_DoesNotContribute()
    {
        var table = LoadTable((30u, "Health buff", 500u));
        // Buff modifies MaxHealth (key=1) but we ask for MaxStamina (key=3).
        var enchantments = new[]
        {
            MakeMultRecord(spellId: 30, layer: 1, statKey: 1u /* MaxHealth */, val: 1.5f),
        };
        var mod = EnchantmentMath.GetMod(enchantments, table,
                                         EnchantmentMath.StatKey.MaxStamina);
        Assert.Equal(EnchantmentMath.VitalMod.Identity, mod);
    }

    [Fact]
    public void GetMod_VitaeBucket_AppliedMultiplicativelyAfterBuffs()
    {
        // Vitae = 0.85 (15% death penalty) on MaxHealth, plus a +10
        // additive from a Restoration buff. Family 0 means each is its
        // own bucket.
        var table = LoadTable(
            (40u, "Restoration", 0u),
            (41u, "Vitae",       0u));
        var enchantments = new[]
        {
            MakeAddRecord(spellId: 40, layer: 1, statKey: 1u /* MaxHealth */, val: 10f),
            MakeVitaeRecord(spellId: 41, layer: 2, statKey: 1u, val: 0.85f),
        };
        var mod = EnchantmentMath.GetMod(enchantments, table,
                                         EnchantmentMath.StatKey.MaxHealth);
        // Vitae multiplier 0.85, additive 10.
        Assert.Equal(0.85f, mod.Multiplier, precision: 3);
        Assert.Equal(10.0f, mod.Additive);
    }

    [Fact]
    public void GetMod_Vitae_AppliesEvenWhenStatModKeyIsZero()
    {
        // Retail behaviour observed in live trace (2026-04-25): ACE's
        // Vitae enchantment serializes with StatModKey = 0 (meaning
        // "any vital"). The Vitae multiplier must apply regardless of
        // the requested stat key — otherwise +Acdream's 5% death
        // penalty wouldn't show up in the Vitals HUD percent.
        var table = LoadTable((666u, "Vitae", 0u));
        var enchantments = new[]
        {
            MakeVitaeRecord(spellId: 666, layer: 0, statKey: 0u /* "any" */, val: 0.95f),
        };
        // Query for MaxStamina; Vitae key=0 should still apply.
        var mod = EnchantmentMath.GetMod(enchantments, table,
                                         EnchantmentMath.StatKey.MaxStamina);
        Assert.Equal(0.95f, mod.Multiplier, precision: 3);
    }

    [Fact]
    public void GetMod_FamilyStacking_PicksHigherSpellId()
    {
        // Two spells in the same family — only the one with the higher
        // SpellId should contribute.
        var table = LoadTable(
            (10u, "Strength I",    1u),    // Family=1
            (132u, "Strength VII", 1u));   // same family
        var enchantments = new[]
        {
            MakeMultRecord(spellId: 10u,  layer: 1, statKey: 3u, val: 1.1f),
            MakeMultRecord(spellId: 132u, layer: 2, statKey: 3u, val: 1.5f),
        };
        var mod = EnchantmentMath.GetMod(enchantments, table,
                                         EnchantmentMath.StatKey.MaxStamina);
        // Only the higher-id buff (1.5) applies.
        Assert.Equal(1.5f, mod.Multiplier, precision: 3);
    }

    private static ActiveEnchantmentRecord MakeMultRecord(uint spellId, uint layer, uint statKey, float val) =>
        new(spellId, layer, 60f, 0u, StatModType: 0, StatModKey: statKey, StatModValue: val, Bucket: 1u);

    private static ActiveEnchantmentRecord MakeAddRecord(uint spellId, uint layer, uint statKey, float val) =>
        new(spellId, layer, 60f, 0u, StatModType: 0, StatModKey: statKey, StatModValue: val, Bucket: 2u);

    private static ActiveEnchantmentRecord MakeVitaeRecord(uint spellId, uint layer, uint statKey, float val) =>
        new(spellId, layer, -1f, 0u, StatModType: 0, StatModKey: statKey, StatModValue: val, Bucket: 4u);

    private static SpellTable LoadTable(params (uint id, string name, uint family)[] rows)
    {
        // Build a synthetic CSV with just enough columns for SpellTable to
        // resolve Family on each spell id.
        var sb = new System.Text.StringBuilder();
        sb.AppendLine("Spell ID,Spell ID [Hex],Name,SortKey,IconId [Hex],Difficulty,Duration,Family,Flags [Hex],Generation,IsDebuff,IsFastWindup,IsFellowship,IsIrresistible,IsOffensive,IsUntargetted,Mana,School,Speed,Spell Words,CasterEffect,TargetEffect,TargetMask [Hex],Type,Description,Unknown1,Unknown2,Unknown3,Unknown4,Unknown5,Unknown6,Unknown7,Unknown8,Unknown9,Unknown10");
        foreach (var (id, name, family) in rows)
        {
            sb.Append(id).Append(',').Append("0x").Append(id.ToString("X")).Append(',')
              .Append(name).Append(",0,0x0,1,1,").Append(family).Append(",0x0,1,False,False,False,False,False,False,1,War Magic,0,Words,0,0,0x0,1,Desc,0,0,0,0,0,0,0,0,0,0")
              .AppendLine();
        }
        return SpellTable.LoadFromReader(new System.IO.StringReader(sb.ToString()));
    }
}