feat: finalize core modules and gateway

src/Infrastructure/TakeoutSaaS.Infrastructure/Common/Persistence/DatabaseConnectionFactory.cs

@@ -0,0 +1,121 @@
+using System.ComponentModel.DataAnnotations;
+using System.Linq;
+using System.Security.Cryptography;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using TakeoutSaaS.Infrastructure.Common.Options;
+using TakeoutSaaS.Shared.Abstractions.Data;
+
+namespace TakeoutSaaS.Infrastructure.Common.Persistence;
+
+/// <summary>
+/// 数据库连接工厂，支持读写分离及连接配置校验。
+/// </summary>
+public sealed class DatabaseConnectionFactory(
+    IOptionsMonitor<DatabaseOptions> optionsMonitor,
+    IConfiguration configuration,
+    ILogger<DatabaseConnectionFactory> logger) : IDatabaseConnectionFactory
+{
+    private const int DefaultCommandTimeoutSeconds = 30;
+    private const int DefaultMaxRetryCount = 3;
+    private const int DefaultMaxRetryDelaySeconds = 5;
+
+    /// <summary>
+    /// 获取指定数据源与读写角色的连接信息。
+    /// </summary>
+    /// <param name="dataSourceName">逻辑数据源名称。</param>
+    /// <param name="role">连接角色。</param>
+    /// <returns>连接串与超时/重试配置。</returns>
+    public DatabaseConnectionDetails GetConnection(string dataSourceName, DatabaseConnectionRole role)
+    {
+        if (string.IsNullOrWhiteSpace(dataSourceName))
+        {
+            logger.LogWarning("请求的数据源名称为空，使用默认连接。");
+            return BuildFallbackConnection();
+        }
+
+        var options = optionsMonitor.CurrentValue.Find(dataSourceName);
+        if (options != null)
+        {
+            if (!ValidateOptions(dataSourceName, options))
+            {
+                return BuildFallbackConnection();
+            }
+
+            var connectionString = ResolveConnectionString(options, role);
+            return new DatabaseConnectionDetails(
+                connectionString,
+                options.CommandTimeoutSeconds,
+                options.MaxRetryCount,
+                options.MaxRetryDelaySeconds);
+        }
+
+        var fallback = configuration.GetConnectionString(dataSourceName);
+        if (string.IsNullOrWhiteSpace(fallback))
+        {
+            logger.LogError("缺少数据源 {DataSource} 的连接配置，回退到默认本地连接。", dataSourceName);
+            return BuildFallbackConnection();
+        }
+
+        logger.LogWarning("未找到数据源 {DataSource} 的 Database 节配置，回退使用 ConnectionStrings。", dataSourceName);
+        return new DatabaseConnectionDetails(
+            fallback,
+            DefaultCommandTimeoutSeconds,
+            DefaultMaxRetryCount,
+            DefaultMaxRetryDelaySeconds);
+    }
+
+    /// <summary>
+    /// 校验数据源配置完整性。
+    /// </summary>
+    /// <param name="dataSourceName">数据源名称。</param>
+    /// <param name="options">数据源配置。</param>
+    /// <exception cref="InvalidOperationException">配置不合法时抛出。</exception>
+    private bool ValidateOptions(string dataSourceName, DatabaseDataSourceOptions options)
+    {
+        var results = new List<ValidationResult>();
+        var context = new ValidationContext(options);
+        if (!Validator.TryValidateObject(options, context, results, validateAllProperties: true))
+        {
+            var errorMessages = string.Join("; ", results.Select(result => result.ErrorMessage));
+            logger.LogError("数据源 {DataSource} 配置非法：{Errors}，回退到默认连接。", dataSourceName, errorMessages);
+            return false;
+        }
+
+        return true;
+    }
+
+    /// <summary>
+    /// 根据读写角色选择连接串，从读连接随机分配。
+    /// </summary>
+    /// <param name="options">数据源配置。</param>
+    /// <param name="role">连接角色。</param>
+    /// <returns>可用连接串。</returns>
+    private string ResolveConnectionString(DatabaseDataSourceOptions options, DatabaseConnectionRole role)
+    {
+        if (role == DatabaseConnectionRole.Read && options.Reads.Count > 0)
+        {
+            var index = RandomNumberGenerator.GetInt32(options.Reads.Count);
+            return options.Reads[index];
+        }
+
+        if (string.IsNullOrWhiteSpace(options.Write))
+        {
+            return BuildFallbackConnection().ConnectionString;
+        }
+
+        return options.Write;
+    }
+
+    private DatabaseConnectionDetails BuildFallbackConnection()
+    {
+        const string fallback = "Host=localhost;Port=5432;Database=postgres;Username=postgres;Password=postgres;Pooling=true;Minimum Pool Size=1;Maximum Pool Size=20";
+        logger.LogWarning("使用默认回退连接串：{Connection}", fallback);
+        return new DatabaseConnectionDetails(
+            fallback,
+            DefaultCommandTimeoutSeconds,
+            DefaultMaxRetryCount,
+            DefaultMaxRetryDelaySeconds);
+    }
+}