namespace Aeshnidae.CombatWindow;

/// <summary>
/// The evade and resist window (Tom, 2026-09-19: "An extra 10 skill you go from
/// resisting nothing to everything. It makes content after retail either you survive
/// it or you don't.").
///
/// ACE decides every evade and every resist with one curve, SkillCheck.GetSkillChance:
///     chance to land = 1 / (1 + e^(-slope x (attack - defense)))
/// with the slope 0.03. That number IS the window: 73 skill points under and you land
/// one hit in ten, 73 over and nine in ten, and ten points around even swings the
/// outcome by 7.5%. Against monsters scaled by tier the gap opens fast, and past it
/// nothing lands or nothing misses. Two knobs widen it:
///
///   - a gentler slope: 0.02 makes the 10%-90% span 110 points instead of 73, 0.015
///     makes it 146;
///   - a floor and a ceiling: however wide the gap, a hit still lands (and still
///     misses) some of the time, so no fight is decided before the first swing.
///
/// Combat only - melee and missile evasion (DamageEvent.GetEvadeChance) and spell
/// resistance (WorldObject.TryResistSpell). Lockpicking, healing, mana conversion and
/// the rest keep retail's curve. Players and monsters alike: the curve has no side.
/// </summary>
public class Settings
{
    public const string FileName = "Settings.json";

    public bool Enabled { get; set; } = true;

    // ---- THE NUMBERS ---------------------------------------------------------

    /// <summary>Slope of the curve for melee and missile evasion. Retail 0.03.</summary>
    public double EvadeSlope { get; set; } = 0.02;

    /// <summary>Slope of the curve for spell resistance. Retail 0.03.</summary>
    public double ResistSlope { get; set; } = 0.02;

    /// <summary>
    /// The least chance an attack has to land, and the least chance a target has to
    /// evade - whatever the gap. 0.05 is one in twenty. 0 is retail (no floor).
    /// </summary>
    public double MinLandChance { get; set; } = 0.05;

    /// <summary>The most an attack can have to land; 1 - this is the least a target can evade. 0.95.</summary>
    public double MaxLandChance { get; set; } = 0.95;

    /// <summary>The least chance a spell has to land, and the least a target has to resist.</summary>
    public double MinSpellLandChance { get; set; } = 0.05;

    public double MaxSpellLandChance { get; set; } = 0.95;

    /// <summary>The chance to land at a given skill gap, on these terms.</summary>
    public double LandChance(int attack, int defense, bool spell)
    {
        var slope = spell ? ResistSlope : EvadeSlope;
        var chance = 1.0 - 1.0 / (1.0 + Math.Exp(slope * (attack - defense)));
        var min = spell ? MinSpellLandChance : MinLandChance;
        var max = spell ? MaxSpellLandChance : MaxLandChance;

        return Math.Clamp(chance, Math.Clamp(min, 0, 1), Math.Clamp(max, 0, 1));
    }

    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        WriteIndented = true,
        ReadCommentHandling = JsonCommentHandling.Skip,
        AllowTrailingCommas = true,
    };

    public static Settings Load(string modPath)
    {
        var path = Path.Combine(modPath, FileName);

        try
        {
            if (File.Exists(path))
                return JsonSerializer.Deserialize<Settings>(File.ReadAllText(path), JsonOptions) ?? new Settings();

            var defaults = new Settings();
            defaults.Save(modPath);
            ModManager.Log($"[{Mod.Name}] wrote default settings to {path}");
            return defaults;
        }
        catch (Exception ex)
        {
            ModManager.Log($"[{Mod.Name}] could not read {path}, using defaults: {ex.Message}", ModManager.LogLevel.Warn);
            return new Settings();
        }
    }

    public void Save(string modPath)
    {
        try
        {
            File.WriteAllText(Path.Combine(modPath, FileName), JsonSerializer.Serialize(this, JsonOptions));
        }
        catch (Exception ex)
        {
            ModManager.Log($"[{Mod.Name}] could not save settings: {ex.Message}", ModManager.LogLevel.Error);
        }
    }
}