using MAX.Core.DependencyInjection;
using Microsoft.Extensions.Configuration;
using System.IO.Compression;
using System.Text;

namespace Store.Modules.CloudProduct.Services
{
	/// <summary>
	/// 商品原始数据文件存储：按 goodsId % 100 分目录，文件名即商品ID，GZip 压缩保存。
	/// </summary>
	public interface IRawDataStorage : IScopedDependency
	{
		/// <summary>
		/// 保存原始数据，返回保存后的完整路径。
		/// </summary>
		Task<string> SaveAsync(long goodsId, string rawData);

		/// <summary>
		/// 读取并解压原始数据；文件不存在时返回 null。
		/// </summary>
		Task<string?> ReadAsync(long goodsId);

		/// <summary>
		/// 判断指定商品的原始数据文件是否存在。
		/// </summary>
		bool Exists(long goodsId);
	}

	internal class RawDataStorage : IRawDataStorage
	{
		private readonly string _rootPath;

		public RawDataStorage(IConfiguration configuration)
		{
			var configured = configuration.GetValue<string>("RawData:Path");
			if (string.IsNullOrWhiteSpace(configured))
				configured = "RawData";

			_rootPath = Path.GetFullPath(configured);
		}

		/// <inheritdoc />
		public async Task<string> SaveAsync(long goodsId, string rawData)
		{
			var filePath = GetFilePath(goodsId);
			var dir = Path.GetDirectoryName(filePath)!;
			Directory.CreateDirectory(dir);

			await using var fileStream = new FileStream(filePath, FileMode.Create, FileAccess.Write, FileShare.None);
			await using var gzip = new GZipStream(fileStream, CompressionLevel.Fastest);
			await using var writer = new StreamWriter(gzip, new UTF8Encoding(false));
			await writer.WriteAsync(rawData);

			return filePath;
		}

		/// <inheritdoc />
		public async Task<string?> ReadAsync(long goodsId)
		{
			var filePath = GetFilePath(goodsId);
			if (!File.Exists(filePath))
				return null;

			await using var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
			await using var gzip = new GZipStream(fileStream, CompressionMode.Decompress);
			using var reader = new StreamReader(gzip, new UTF8Encoding(false));
			return await reader.ReadToEndAsync();
		}

		/// <inheritdoc />
		public bool Exists(long goodsId)
		{
			return File.Exists(GetFilePath(goodsId));
		}

		private string GetFilePath(long goodsId)
		{
			var subDir = (goodsId % 100).ToString();
			return Path.Combine(_rootPath, subDir, goodsId.ToString());
		}
	}
}