using MAX.Core.DependencyInjection;
using MAX.Framework.Commons;
using MAX.Framework.Security;
using MAX.Framework.Validation;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Store.Modules.CloudProduct.Contracts;
using Store.Modules.CloudProduct.Dtos;
using Store.Modules.CloudProduct.Entities;
using System.ComponentModel.DataAnnotations;
using System.Text.Encodings.Web;
using System.Text.Json;
using System.Text.Unicode;

namespace Store.Modules.CloudProduct.Services;

/// <summary>商品检测业务入口，负责上传图片识别、MD5 缓存和当前用户的商品安全记录。</summary>
public sealed class ProductInspectionService(IInspectionIntegration integration, ICurrentUser user, ImageAnalysisQuotaService imageAnalysisQuotaService,
	[FromKeyedServices("CloudProductConnection")] IFreeSql database,
	[FromKeyedServices("ProductInspectionAnalysisGate")] SemaphoreSlim gate,
	ILogger<ProductInspectionService> logger
	) : IScopedDependency
{
	public const int MaxBytes = 10 * 1024 * 1024;

	// 缓存 JSON 保留中文原文，字符串中的引号和控制字符仍由序列化器转义。
	private static readonly JsonSerializerOptions CacheJsonOptions = new()
	{
		Encoder = JavaScriptEncoder.Create(UnicodeRanges.All)
	};

	// 每三个图片字节编码为四个 Base64 字符，末组向上取整。
	public const int MaxBase64Length = (MaxBytes + 2) / 3 * 4;

	public async Task<string[]> InspectAsync(InspectImageRequest request, CancellationToken cancellationToken)
	{
		RequestValidator.Validate(request);
		if (request.Md5.Length != 32 || !request.Md5.All(char.IsAsciiHexDigit))
			throw new ValidationException("md5 必须是 32 位十六进制缓存键。");
		var md5 = request.Md5.ToLowerInvariant();
		if (request.Image.Length > MaxBase64Length)
			throw new ValidationException("图片超过 10 MiB 或 Base64 文本过长。");

		byte[] image;
		try { image = Convert.FromBase64String(request.Image); }
		catch (FormatException) { throw new ValidationException("image 必须是有效的 Base64 字符串。"); }
		if (image.Length is < 12 or > MaxBytes)
			throw new ValidationException("图片为空、格式无效或超过 10 MiB。");
		// 依据文件签名识别允许的图片类型，避免信任客户端文件名和 MIME 类型。
		string mediaType;
		if (image[0] == 0xff && image[1] == 0xd8 && image[2] == 0xff) mediaType = "image/jpeg";
		else if (image.AsSpan(0, 8).SequenceEqual(new byte[] { 137, 80, 78, 71, 13, 10, 26, 10 })) mediaType = "image/png";
		else if (image.AsSpan(0, 4).SequenceEqual("RIFF"u8) && image.AsSpan(8, 4).SequenceEqual("WEBP"u8)) mediaType = "image/webp";
		else throw new ValidationException("请上传 JPEG、PNG 或 WebP 图片。");
		var cached = await database.Select<ImageAnalysisCache>().Where(x => x.CacheKey == md5).FirstAsync();
		var result = cached?.ReadFreshResult(DateTime.UtcNow);
		if (result is null)
		{
			await gate.WaitAsync(cancellationToken);

			try
			{
				var useImageQuota = await imageAnalysisQuotaService.GetUserImageAnalysisQuota(new UseImageAnalysisQuotaRequest
				{
					UserName = request.UserName
				});
				if (useImageQuota <= 0)
				{
					throw new AppException("AI检测可用数量为0");
				}
			}
			catch (Exception ex)
			{
				logger.LogError(ex, "调用图片识别扣费程序失败");
				throw new AppException("AI检测可用数量为0");
			}

			try
			{
				using var stream = new MemoryStream(image, writable: false);
				var recognized = await integration.AnalyzeAsync(stream, mediaType, cancellationToken);
				result = recognized.Distinct(StringComparer.Ordinal).ToArray();
				var entry = cached ?? new ImageAnalysisCache { CacheKey = md5 };
				var previousUpdate = entry.UpdatedAt;
				entry.RecognitionResult = JsonSerializer.Serialize(result, CacheJsonOptions);
				entry.RecordExpiration(result.Length == 0, DateTime.UtcNow);
				// 同一缓存失效后可能同时触发多次识别，只有首个写入者推进级别。
				if (cached is null)
					await database.InsertOrUpdate<ImageAnalysisCache>().SetSource(entry).IfExistsDoNothing().ExecuteAffrowsAsync();
				else
					await database.Update<ImageAnalysisCache>().SetSource(entry)
						.Where(x => x.UpdatedAt == previousUpdate).ExecuteAffrowsAsync();
			}
			finally { gate.Release(); }
		}
		try
		{
			var useRet = await imageAnalysisQuotaService.UseImageAnalysisQuotaAsync(new UseImageAnalysisQuotaRequest
			{
				UserName = request.UserName
			});
		}
		catch (Exception ex)
		{
			logger.LogError(ex, "调用图片识别扣费程序失败");
			//扣费失败显示空
			result = [];
		}

		return result;
	}

}