feat: 實作完整錯誤日誌系統

- 新增 ErrorHandlingMiddleware 全域錯誤處理
- 升級日誌配置到 Debug 層級
- 添加詳細的認證流程日誌
- 改進 AuthController 錯誤處理
- 包含請求詳情和錯誤堆疊追蹤
- 支援結構化日誌記錄

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

backend/DramaLing.Api/Controllers/AuthController.cs

@@ -35,9 +35,17 @@ public class AuthController : ControllerBase
     {
         try
         {
+            _logger.LogInformation("Registration attempt for user: {Username}, Email: {Email}",
+                request.Username, request.Email);
+
             // 驗證請求
             if (!ModelState.IsValid)
+            {
+                _logger.LogWarning("Invalid model state for registration: {@ModelErrors}",
+                    ModelState.Where(x => x.Value?.Errors.Count > 0)
+                    .ToDictionary(x => x.Key, x => x.Value?.Errors.Select(e => e.ErrorMessage)));
                 return BadRequest(new { Success = false, Error = "Invalid request data" });
+            }
 
             // 檢查Email是否已存在
             if (await _context.Users.AnyAsync(u => u.Email == request.Email))
@@ -90,11 +98,17 @@ public class AuthController : ControllerBase
         }
         catch (Exception ex)
         {
-            _logger.LogError(ex, "Error during user registration");
+            _logger.LogError(ex, "Error during user registration. Request: {@Request}", new {
+                Username = request.Username,
+                Email = request.Email,
+                StackTrace = ex.StackTrace,
+                InnerException = ex.InnerException?.Message
+            });
             return StatusCode(500, new
             {
                 Success = false,
                 Error = "Registration failed",
+                Details = ex.Message,
                 Timestamp = DateTime.UtcNow
             });
         }
@@ -105,9 +119,16 @@ public class AuthController : ControllerBase
     {
         try
         {
+            _logger.LogInformation("Login attempt for email: {Email}", request.Email);
+
             // 驗證請求
             if (!ModelState.IsValid)
+            {
+                _logger.LogWarning("Invalid model state for login: {@ModelErrors}",
+                    ModelState.Where(x => x.Value?.Errors.Count > 0)
+                    .ToDictionary(x => x.Key, x => x.Value?.Errors.Select(e => e.ErrorMessage)));
                 return BadRequest(new { Success = false, Error = "Invalid request data" });
+            }
 
             // 查找用戶
             var user = await _context.Users.FirstOrDefaultAsync(u => u.Email == request.Email);
@@ -143,11 +164,16 @@ public class AuthController : ControllerBase
         }
         catch (Exception ex)
         {
-            _logger.LogError(ex, "Error during user login");
+            _logger.LogError(ex, "Error during user login. Request: {@Request}", new {
+                Email = request.Email,
+                StackTrace = ex.StackTrace,
+                InnerException = ex.InnerException?.Message
+            });
             return StatusCode(500, new
             {
                 Success = false,
                 Error = "Login failed",
+                Details = ex.Message,
                 Timestamp = DateTime.UtcNow
             });
         }

backend/DramaLing.Api/Middleware/ErrorHandlingMiddleware.cs

@@ -0,0 +1,66 @@
+using System.Net;
+using System.Text.Json;
+
+namespace DramaLing.Api.Middleware;
+
+public class ErrorHandlingMiddleware
+{
+    private readonly RequestDelegate _next;
+    private readonly ILogger<ErrorHandlingMiddleware> _logger;
+
+    public ErrorHandlingMiddleware(RequestDelegate next, ILogger<ErrorHandlingMiddleware> logger)
+    {
+        _next = next;
+        _logger = logger;
+    }
+
+    public async Task InvokeAsync(HttpContext context)
+    {
+        try
+        {
+            await _next(context);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "An unhandled exception occurred during request execution. Request: {Method} {Path}",
+                context.Request.Method, context.Request.Path);
+
+            await HandleExceptionAsync(context, ex);
+        }
+    }
+
+    private async Task HandleExceptionAsync(HttpContext context, Exception exception)
+    {
+        context.Response.ContentType = "application/json";
+
+        var errorResponse = new
+        {
+            Success = false,
+            Error = "An error occurred while processing your request",
+            Details = exception.Message,
+            Timestamp = DateTime.UtcNow,
+            RequestId = context.TraceIdentifier
+        };
+
+        var statusCode = exception switch
+        {
+            ArgumentException => HttpStatusCode.BadRequest,
+            UnauthorizedAccessException => HttpStatusCode.Unauthorized,
+            KeyNotFoundException => HttpStatusCode.NotFound,
+            NotImplementedException => HttpStatusCode.NotImplemented,
+            TimeoutException => HttpStatusCode.RequestTimeout,
+            _ => HttpStatusCode.InternalServerError
+        };
+
+        context.Response.StatusCode = (int)statusCode;
+
+        var jsonResponse = JsonSerializer.Serialize(errorResponse, new JsonSerializerOptions
+        {
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase
+        });
+
+        _logger.LogError("Error response sent: {StatusCode} - {Response}", statusCode, jsonResponse);
+
+        await context.Response.WriteAsync(jsonResponse);
+    }
+}

backend/DramaLing.Api/Program.cs

@@ -1,6 +1,7 @@
 using Microsoft.EntityFrameworkCore;
 using DramaLing.Api.Data;
 using DramaLing.Api.Services;
+using DramaLing.Api.Middleware;
 using Microsoft.AspNetCore.Authentication.JwtBearer;
 using Microsoft.IdentityModel.Tokens;
 using System.Text;
@@ -111,6 +112,10 @@ builder.Services.AddSwaggerGen(c =>
 var app = builder.Build();
 
 // Configure the HTTP request pipeline.
+
+// 全域錯誤處理中介軟體 (必須放在最前面)
+app.UseMiddleware<ErrorHandlingMiddleware>();
+
 if (app.Environment.IsDevelopment())
 {
     app.UseSwagger();

backend/DramaLing.Api/appsettings.json

@@ -1,9 +1,18 @@
 {
   "Logging": {
     "LogLevel": {
-      "Default": "Information",
+      "Default": "Debug",
-      "Microsoft.AspNetCore": "Warning",
+      "Microsoft.AspNetCore": "Information",
-      "Microsoft.EntityFrameworkCore": "Warning"
+      "Microsoft.EntityFrameworkCore": "Information",
+      "DramaLing.Api": "Debug",
+      "System": "Information",
+      "Microsoft": "Information"
+    },
+    "Console": {
+      "IncludeScopes": true,
+      "LogLevel": {
+        "Default": "Debug"
+      }
     }
   },
   "AllowedHosts": "*",