feat: 메시지 유효성 검사 서비스 구현 (#118)

- MessageValidationService: title/body/image_url/link_url/link_type/data 검증
- POST /v1/in/message/validate 엔드포인트 추가
- MessageController 기반 구성

Closes #118

SPMS.API/Controllers/MessageController.cs

@@ -0,0 +1,36 @@
+using Microsoft.AspNetCore.Mvc;
+using Swashbuckle.AspNetCore.Annotations;
+using SPMS.Application.DTOs.Message;
+using SPMS.Application.Interfaces;
+using SPMS.Domain.Common;
+
+namespace SPMS.API.Controllers;
+
+[ApiController]
+[Route("v1/in/message")]
+[ApiExplorerSettings(GroupName = "message")]
+public class MessageController : ControllerBase
+{
+    private readonly IMessageValidationService _validationService;
+
+    public MessageController(IMessageValidationService validationService)
+    {
+        _validationService = validationService;
+    }
+
+    [HttpPost("validate")]
+    [SwaggerOperation(Summary = "메시지 유효성 검사", Description = "메시지 내용의 유효성을 검사합니다.")]
+    public IActionResult ValidateAsync([FromBody] MessageValidateRequestDto request)
+    {
+        var result = _validationService.Validate(request);
+        return Ok(ApiResponse<MessageValidationResultDto>.Success(result));
+    }
+
+    private long GetServiceId()
+    {
+        if (HttpContext.Items.TryGetValue("ServiceId", out var serviceIdObj) && serviceIdObj is long serviceId)
+            return serviceId;
+
+        throw new Domain.Exceptions.SpmsException(ErrorCodes.BadRequest, "서비스 식별 정보가 없습니다.", 400);
+    }
+}

SPMS.Application/DTOs/Message/MessageValidateRequestDto.cs

@@ -0,0 +1,20 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace SPMS.Application.DTOs.Message;
+
+public class MessageValidateRequestDto
+{
+    [Required]
+    public string Title { get; set; } = string.Empty;
+
+    [Required]
+    public string Body { get; set; } = string.Empty;
+
+    public string? ImageUrl { get; set; }
+
+    public string? LinkUrl { get; set; }
+
+    public string? LinkType { get; set; }
+
+    public string? Data { get; set; }
+}

SPMS.Application/DTOs/Message/MessageValidationResultDto.cs

@@ -0,0 +1,13 @@
+namespace SPMS.Application.DTOs.Message;
+
+public class MessageValidationResultDto
+{
+    public bool IsValid { get; set; }
+    public List<ValidationErrorDto> Errors { get; set; } = [];
+}
+
+public class ValidationErrorDto
+{
+    public string Field { get; set; } = string.Empty;
+    public string Message { get; set; } = string.Empty;
+}

SPMS.Application/DependencyInjection.cs

@@ -19,6 +19,7 @@ public static class DependencyInjection
         services.AddScoped<IDeviceService, DeviceService>();
         services.AddScoped<IFileService, FileService>();
         services.AddScoped<IPushService, PushService>();
+        services.AddSingleton<IMessageValidationService, MessageValidationService>();
 
         return services;
     }

SPMS.Application/Interfaces/IMessageValidationService.cs

@@ -0,0 +1,8 @@
+using SPMS.Application.DTOs.Message;
+
+namespace SPMS.Application.Interfaces;
+
+public interface IMessageValidationService
+{
+    MessageValidationResultDto Validate(MessageValidateRequestDto request);
+}

SPMS.Application/Services/MessageValidationService.cs

@@ -0,0 +1,107 @@
+using System.Text.Json;
+using SPMS.Application.DTOs.Message;
+using SPMS.Application.Interfaces;
+
+namespace SPMS.Application.Services;
+
+public class MessageValidationService : IMessageValidationService
+{
+    private const int MaxTitleLength = 100;
+    private const int MaxBodyLength = 2000;
+    private const int MaxDataSizeBytes = 4096;
+    private static readonly string[] AllowedLinkTypes = ["deeplink", "web", "none"];
+
+    public MessageValidationResultDto Validate(MessageValidateRequestDto request)
+    {
+        var errors = new List<ValidationErrorDto>();
+
+        ValidateTitle(request.Title, errors);
+        ValidateBody(request.Body, errors);
+        ValidateImageUrl(request.ImageUrl, errors);
+        ValidateLinkUrl(request.LinkUrl, errors);
+        ValidateLinkType(request.LinkType, errors);
+        ValidateData(request.Data, errors);
+
+        return new MessageValidationResultDto
+        {
+            IsValid = errors.Count == 0,
+            Errors = errors
+        };
+    }
+
+    private static void ValidateTitle(string title, List<ValidationErrorDto> errors)
+    {
+        if (string.IsNullOrWhiteSpace(title))
+        {
+            errors.Add(new ValidationErrorDto { Field = "title", Message = "제목은 필수입니다." });
+            return;
+        }
+
+        if (title.Length > MaxTitleLength)
+            errors.Add(new ValidationErrorDto { Field = "title", Message = $"제목은 {MaxTitleLength}자를 초과할 수 없습니다." });
+    }
+
+    private static void ValidateBody(string body, List<ValidationErrorDto> errors)
+    {
+        if (string.IsNullOrWhiteSpace(body))
+        {
+            errors.Add(new ValidationErrorDto { Field = "body", Message = "본문은 필수입니다." });
+            return;
+        }
+
+        if (body.Length > MaxBodyLength)
+            errors.Add(new ValidationErrorDto { Field = "body", Message = $"본문은 {MaxBodyLength}자를 초과할 수 없습니다." });
+    }
+
+    private static void ValidateImageUrl(string? imageUrl, List<ValidationErrorDto> errors)
+    {
+        if (string.IsNullOrWhiteSpace(imageUrl))
+            return;
+
+        if (!Uri.TryCreate(imageUrl, UriKind.Absolute, out var uri) ||
+            (uri.Scheme != "http" && uri.Scheme != "https"))
+            errors.Add(new ValidationErrorDto { Field = "image_url", Message = "유효한 URL 형식이 아닙니다." });
+    }
+
+    private static void ValidateLinkUrl(string? linkUrl, List<ValidationErrorDto> errors)
+    {
+        if (string.IsNullOrWhiteSpace(linkUrl))
+            return;
+
+        if (!Uri.TryCreate(linkUrl, UriKind.Absolute, out _))
+            errors.Add(new ValidationErrorDto { Field = "link_url", Message = "유효한 URL 형식이 아닙니다." });
+    }
+
+    private static void ValidateLinkType(string? linkType, List<ValidationErrorDto> errors)
+    {
+        if (string.IsNullOrWhiteSpace(linkType))
+            return;
+
+        if (!AllowedLinkTypes.Contains(linkType.ToLowerInvariant()))
+            errors.Add(new ValidationErrorDto { Field = "link_type", Message = "link_type은 deeplink, web, none 중 하나여야 합니다." });
+    }
+
+    private static void ValidateData(string? data, List<ValidationErrorDto> errors)
+    {
+        if (string.IsNullOrWhiteSpace(data))
+            return;
+
+        try
+        {
+            using var doc = JsonDocument.Parse(data);
+            if (doc.RootElement.ValueKind != JsonValueKind.Object)
+            {
+                errors.Add(new ValidationErrorDto { Field = "data", Message = "data는 JSON 객체여야 합니다." });
+                return;
+            }
+        }
+        catch (JsonException)
+        {
+            errors.Add(new ValidationErrorDto { Field = "data", Message = "유효한 JSON 형식이 아닙니다." });
+            return;
+        }
+
+        if (System.Text.Encoding.UTF8.GetByteCount(data) > MaxDataSizeBytes)
+            errors.Add(new ValidationErrorDto { Field = "data", Message = $"data는 {MaxDataSizeBytes / 1024}KB를 초과할 수 없습니다." });
+    }
+}