using System.Diagnostics.CodeAnalysis;
using PkmnLib.Static.Utils;

namespace PkmnLib.Static.Libraries;

/// <summary>
/// All data related to types and their effectiveness.
/// </summary>
public interface IReadOnlyTypeLibrary
{
    /// <summary>
    /// Gets the type identifier for a type with a name.
    /// </summary>
    bool TryGetTypeIdentifier(StringKey key, out TypeIdentifier typeIdentifier);

    /// <summary>
    /// Gets the type name from the type identifier.
    /// </summary>
    bool TryGetTypeName(TypeIdentifier t, [NotNullWhen(true)] out StringKey? stringKey);

    /// <summary>
    /// Gets the effectiveness for a single attacking type against a single defending type.
    /// </summary>
    float GetSingleEffectiveness(TypeIdentifier attacking, TypeIdentifier defending);

    /// <summary>
    /// Gets the effectiveness for a single attacking type against an amount of defending types.
    /// This is equivalent to running get_single_effectiveness on each defending type, and multiplying the results with each other.
    /// </summary>
    float GetEffectiveness(TypeIdentifier attacking, IEnumerable<TypeIdentifier> defending);

    IEnumerable<(TypeIdentifier type, float effectiveness)> GetAllEffectivenessFromAttacking(TypeIdentifier attacking);
}

/// <inheritdoc />
public class TypeLibrary : IReadOnlyTypeLibrary
{
    private readonly Dictionary<StringKey, TypeIdentifier> _types = new();
    private readonly List<List<float>> _effectiveness = new();

    /// <inheritdoc />
    public bool TryGetTypeIdentifier(StringKey key, out TypeIdentifier type) => _types.TryGetValue(key, out type);

    /// <inheritdoc />
    public bool TryGetTypeName(TypeIdentifier t, [NotNullWhen(true)] out StringKey? stringKey)
    {
        foreach (var (key, value) in _types)
        {
            if (value == t)
            {
                stringKey = key;
                return true;
            }
        }

        stringKey = default;
        return false;
    }

    /// <inheritdoc />
    public float GetSingleEffectiveness(TypeIdentifier attacking, TypeIdentifier defending)
    {
        if (attacking.Value < 1 || attacking.Value > _effectiveness.Count)
            throw new ArgumentOutOfRangeException(nameof(attacking));
        if (defending.Value < 1 || defending.Value > _effectiveness.Count)
            throw new ArgumentOutOfRangeException(nameof(defending));
        return _effectiveness[attacking.Value - 1][defending.Value - 1];
    }

    /// <inheritdoc />
    public float GetEffectiveness(TypeIdentifier attacking, IEnumerable<TypeIdentifier> defending) =>
        defending.Aggregate<TypeIdentifier, float>(1,
            (current, type) => current * GetSingleEffectiveness(attacking, type));

    /// <inheritdoc />
    public IEnumerable<(TypeIdentifier, float)> GetAllEffectivenessFromAttacking(TypeIdentifier attacking)
    {
        if (attacking.Value < 1 || attacking.Value > _effectiveness.Count)
            throw new ArgumentOutOfRangeException(nameof(attacking));
        for (var i = 0; i < _effectiveness.Count; i++)
        {
            yield return (new TypeIdentifier((byte)(i + 1)), _effectiveness[attacking.Value - 1][i]);
        }
    }

    /// <summary>
    /// Registers a new type in the library.
    /// </summary>
    public TypeIdentifier RegisterType(StringKey name)
    {
        var id = new TypeIdentifier((byte)(_types.Count + 1));
        _types.Add(name, id);
        _effectiveness.Add(Enumerable.Repeat(1.0f, _effectiveness.Count).ToList());
        foreach (var list in _effectiveness)
        {
            list.Add(1);
        }
        return id;
    }

    /// <summary>
    /// Sets the effectiveness for an attacking type against a defending type.
    /// </summary>
    public void SetEffectiveness(TypeIdentifier attacking, TypeIdentifier defending, float effectiveness)
    {
        if (attacking.Value < 1 || attacking.Value > _effectiveness.Count)
            throw new ArgumentOutOfRangeException(nameof(attacking));
        if (defending.Value < 1 || defending.Value > _effectiveness.Count)
            throw new ArgumentOutOfRangeException(nameof(defending));
        _effectiveness[attacking.Value - 1][defending.Value - 1] = effectiveness;
    }
}