using System.Collections;
using System.Diagnostics.CodeAnalysis;

namespace Nbt.Tag;

public interface INbtCompound : INbtTag, IEnumerable<NamedTag>
{
    int Count { get; }

    new INbtTag this[string tagName] { get; set; }

    void Add(NamedTag namedTag);
    void Add(string tagName, INbtTag tag);

    void Set(NamedTag namedTag);
    void Set(string tagName, INbtTag tag);

    INbtTag Get(string tagName);
    T Get<T>(string tagName) where T : INbtTag;

    bool TryGet(string tagName, [MaybeNullWhen(false)] out INbtTag tag);
    bool TryGet<T>(string tagName, [MaybeNullWhen(false)] out T tag) where T : INbtTag;

    bool ContainsKey(string tagName);
    bool Contains(NamedTag namedTag);
    bool Contains(string tagName, INbtTag tag);

    bool Remove(string tagName);
    bool Remove(NamedTag namedTag);
    bool Remove(string tagName, INbtTag tag);
    bool Remove(string tagName, [MaybeNullWhen(false)] out INbtTag tag);

    void Clear();
}

public class NbtCompound : INbtCompound
{
    private readonly Dictionary<string, INbtTag> entries = [];

    private static string EnsureName(string tagName) => tagName ?? throw new ArgumentNullException(nameof(tagName));

    private static INbtTag EnsureValue(INbtTag tag) => tag ?? throw new ArgumentNullException(nameof(tag));

    public NbtTagType Type => NbtTagType.Compound;

    INbtCompound INbtTag.AsCompound() => this;

    INbtTag INbtTag.Copy() => Copy();
    public NbtCompound Copy()
    {
        var copy = new NbtCompound();

        foreach (var e in entries)
        {
            copy.entries[e.Key] = e.Value.Copy();
        }

        return copy;
    }

    public int Count => entries.Count;

    public INbtTag this[string tagName]
    {
        get => entries[tagName];
        set => entries[EnsureName(tagName)] = EnsureValue(value);
    }

    INbtTag INbtTag.this[INbtPathElement tagPath]
    {
        get => tagPath is NbtName tagName ? this[tagName] : throw new UnsupportedPathElementException();
        set => this[tagPath is NbtName tagName ? tagName : throw new UnsupportedPathElementException()] = value;
    }

    public void Add(NamedTag namedTag) => Add(namedTag.Name, namedTag.Tag);
    public void Add(string tagName, INbtTag tag) => entries.Add(EnsureName(tagName), EnsureValue(tag));

    public void Set(NamedTag namedTag) => Set(namedTag.Name, namedTag.Tag);
    public void Set(string tagName, INbtTag tag) => this[tagName] = tag;

    public INbtTag Get(string tagName) => this[tagName];
    public T Get<T>(string tagName) where T : INbtTag => (T)Get(tagName);

    public bool TryGet(string tagName, [MaybeNullWhen(false)] out INbtTag tag) => entries.TryGetValue(tagName, out tag);
    public bool TryGet<T>(string tagName, [MaybeNullWhen(false)] out T tag) where T : INbtTag
    {
        if (TryGet(tagName, out var t))
        {
            tag = (T)t;
            return true;
        }

        tag = default;
        return false;
    }

    public bool ContainsKey(string tagName) => entries.ContainsKey(tagName);
    public bool Contains(NamedTag namedTag) => Contains(namedTag.Name, namedTag.Tag);
    public bool Contains(string tagName, INbtTag tag) => entries.Contains(KeyValuePair.Create(tagName, tag));

    public bool Remove(string tagName) => entries.Remove(tagName);
    public bool Remove(NamedTag namedTag) => Remove(namedTag.Name, namedTag.Tag);
    public bool Remove(string tagName, INbtTag tag) => ((IDictionary<string, INbtTag>)entries).Remove(KeyValuePair.Create(tagName, tag));
    public bool Remove(string tagName, [MaybeNullWhen(false)] out INbtTag tag) => entries.Remove(tagName, out tag);

    public void Clear() => entries.Clear();

    public bool Equals(INbtTag? other) => ReferenceEquals(other, this) || other is NbtCompound o && Utils.DictionaryEquals(entries, o.entries);

    public override bool Equals(object? obj) => ReferenceEquals(obj, this) || obj is INbtCompound other && Equals(other);

    public override int GetHashCode() => entries.GetHashCode();

    public IEnumerator<NamedTag> GetEnumerator() => entries.Select(e => new NamedTag(e.Key, e.Value)).GetEnumerator();

    IEnumerator IEnumerable.GetEnumerator() => ((IEnumerable)entries).GetEnumerator();
}