using System.Collections.Generic;
using System.Linq;
using Theriapolis.Core.Data;

namespace Theriapolis.GodotHost.UI;

/// <summary>
/// Final ability score math — base assignment + clade and species mods.
/// Used by StepStats and Aside to render the score breakdown with a
/// "+N from Canidae · +2 from Wolf" hover popover.
///
/// For hybrids the lineage contribution comes from BOTH parent clades
/// (each tagged with its lineage in the source label) and the dominant
/// species. Core's CharacterBuilder.TryBuildHybrid is the authority on
/// the final mechanical rules at character-finalize time; this is a
/// preview-display helper.
/// </summary>
public static class AbilityCalc
{
    public readonly record struct ModSource(string Label, int Value);

    public static List<ModSource> Sources(string ability, CharacterDraft draft)
    {
        var list = new List<ModSource>();
        if (draft.IsHybrid)
        {
            // Hybrids: take ONE ability modifier from each parent clade.
            // Picks stack if they happen to land on the same ability — the
            // original "no stack, take +1 + free elsewhere" rule was
            // dropped per project decision. Species mods don't apply.
            if (draft.SireChosenAbility == ability)
                AddCladeChoice(list, ability, CodexContent.Clade(draft.SireCladeId), " (sire)");
            if (draft.DamChosenAbility == ability)
                AddCladeChoice(list, ability, CodexContent.Clade(draft.DamCladeId),  " (dam)");
        }
        else
        {
            AddCladeSource(list, ability, CodexContent.Clade(draft.CladeId), "");
            var sp = CodexContent.SpeciesById(draft.EffectiveSpeciesId);
            if (sp is not null) AddDictSource(list, ability, sp.Name, sp.AbilityMods);
        }

        return list;
    }

    /// <summary>The chosen-mod path: one mod from a parent clade. The value
    /// is the clade's actual mod for that ability (so picking CON from
    /// canidae yields +1 while picking CON from ursidae yields +2).</summary>
    private static void AddCladeChoice(List<ModSource> list, string ability, CladeDef? clade, string suffix)
    {
        if (clade is null) return;
        if (clade.AbilityMods.TryGetValue(ability, out int v) && v != 0)
            list.Add(new ModSource(clade.Name + suffix, v));
    }

    public static int TotalBonus(string ability, CharacterDraft draft)
        => Sources(ability, draft).Sum(s => s.Value);

    public static int BaseScore(string ability, CharacterDraft draft)
        => draft.StatAssign.ContainsKey(ability) ? (int)draft.StatAssign[ability] : 0;

    public static int FinalScore(string ability, CharacterDraft draft)
        => BaseScore(ability, draft) + TotalBonus(ability, draft);

    public static int D20Modifier(int score) => (int)System.Math.Floor((score - 10) / 2.0);

    public static string FormatSigned(int n) => n >= 0 ? $"+{n}" : n.ToString();

    /// <summary>"+1 from Canidae · +2 from Wolf" — empty when no sources.</summary>
    public static string FormatBreakdown(IEnumerable<ModSource> sources) =>
        string.Join(" · ", sources.Select(s => $"{FormatSigned(s.Value)} from {s.Label}"));

    private static void AddCladeSource(List<ModSource> list, string ability, CladeDef? clade, string suffix)
    {
        if (clade is null) return;
        AddDictSource(list, ability, clade.Name + suffix, clade.AbilityMods);
    }

    private static void AddDictSource(List<ModSource> list, string ability, string sourceName, Dictionary<string, int> mods)
    {
        if (mods.TryGetValue(ability, out int v) && v != 0)
            list.Add(new ModSource(sourceName, v));
    }
}