using System;
using System.Collections.Generic;
using System.Linq;

namespace ShrinkModFramework
{
    internal interface IShrinkOwnedRegistry
    {
        void RemoveOwnedEntries(string ownerModId);
    }

    public sealed class ShrinkModRegistry<T> : IShrinkOwnedRegistry
    {
        private readonly Dictionary<string, ShrinkRegistryEntry<T>> _entries = new();

        public string Name { get; }

        internal ShrinkModRegistry(string name)
        {
            if (string.IsNullOrWhiteSpace(name))
                throw new ArgumentException("注册表名称不能为空。", nameof(name));

            Name = name.Trim();
        }

        public IReadOnlyCollection<ShrinkRegistryEntry<T>> Entries => _entries.Values.ToArray();

        public void Register(string ownerModId, string key, T value)
        {
            if (string.IsNullOrWhiteSpace(ownerModId))
                throw new ArgumentException("归属模组 ID 不能为空。", nameof(ownerModId));
            if (string.IsNullOrWhiteSpace(key))
                throw new ArgumentException("注册键不能为空。", nameof(key));

            key = key.Trim();
            if (_entries.ContainsKey(key))
                throw new InvalidOperationException($"注册表 '{Name}' 中已存在键 '{key}'。");

            _entries.Add(key, new ShrinkRegistryEntry<T>(ownerModId.Trim(), key, value));
        }

        public bool Contains(string key) => !string.IsNullOrWhiteSpace(key) && _entries.ContainsKey(key.Trim());

        public bool TryGet(string key, out T value)
        {
            if (!string.IsNullOrWhiteSpace(key) && _entries.TryGetValue(key.Trim(), out var entry))
            {
                value = entry.Value;
                return true;
            }

            value = default;
            return false;
        }

        public bool TryGetEntry(string key, out ShrinkRegistryEntry<T> entry)
        {
            if (!string.IsNullOrWhiteSpace(key))
                return _entries.TryGetValue(key.Trim(), out entry);

            entry = default;
            return false;
        }

        void IShrinkOwnedRegistry.RemoveOwnedEntries(string ownerModId)
        {
            if (string.IsNullOrWhiteSpace(ownerModId))
                return;

            var keys = _entries
                .Where(pair => string.Equals(pair.Value.OwnerModId, ownerModId, StringComparison.Ordinal))
                .Select(pair => pair.Key)
                .ToArray();
            foreach (var key in keys)
                _entries.Remove(key);
        }
    }

    public readonly struct ShrinkRegistryEntry<T>
    {
        public string OwnerModId { get; }
        public string Key { get; }
        public T Value { get; }

        public ShrinkRegistryEntry(string ownerModId, string key, T value)
        {
            OwnerModId = ownerModId;
            Key = key;
            Value = value;
        }
    }
}