using System.Collections.Immutable;
using Connected.Entities.Caching;
using Connected.ServiceModel;

namespace Common.Globalization;

internal interface ILanguageCache : IEntityCacheClient<Language, int>
{
	Language? Select(string mappings);
}
/// <summary>
/// Represents stateful cache of the <see cref="Language"/> entities.
/// </summary>
internal class LanguageCache : EntityCacheClient<Language, int>, ILanguageCache
{
	private readonly Dictionary<string, Language> _mappings;
	public LanguageCache(IEntityCacheContext context) : base(context, Language.CacheKey)
	{
		_mappings = new Dictionary<string, Language>(StringComparer.OrdinalIgnoreCase);
	}

	private Dictionary<string, Language> Mappings => _mappings;
	protected override async Task<ImmutableList<Language>> OnInitializing(IContext context)
	{
		var result = await base.OnInitializing(context);

		await ResetMappings();

		return result;
	}

	protected override async Task<Language> OnInvalidating(IContext context, int id)
	{
		var result = await base.OnInvalidating(context, id);

		await ResetMappings();

		return result;
	}

	public Language? Select(string mappings)
	{
		if (string.IsNullOrWhiteSpace(mappings))
			return null;

		var tokens = mappings.Split(',', StringSplitOptions.RemoveEmptyEntries);

		foreach (var token in tokens)
		{
			if (Mappings.TryGetValue(token.Trim(), out Language? language))
				return language;
		}

		return null;
	}

	private async Task ResetMappings()
	{
		Mappings.Clear();

		foreach (var language in await All())
		{
			if (string.IsNullOrWhiteSpace(language.Mappings))
				continue;

			var tokens = language.Mappings.Split(',', StringSplitOptions.RemoveEmptyEntries);

			foreach (var token in tokens)
			{
				if (Mappings.TryGetValue(token.Trim(), out _))
					continue;

				Mappings.Add(token.Trim(), language);
			}
		}
	}
}