SPMS.API/Controllers/FileController.cs

@@ -63,6 +63,29 @@ public class FileController : ControllerBase
         return Ok(ApiResponse.Success());
     }
 
+    [HttpPost("csv/validate")]
+    [SwaggerOperation(Summary = "CSV 검증", Description = "대용량 발송용 CSV 파일을 검증합니다.")]
+    [RequestSizeLimit(52_428_800)] // 50MB
+    public async Task<IActionResult> ValidateCsvAsync(IFormFile file, [FromForm] string message_code)
+    {
+        var serviceId = GetServiceId();
+
+        using var stream = file.OpenReadStream();
+        var result = await _fileService.ValidateCsvAsync(serviceId, stream, file.FileName, message_code);
+
+        return Ok(ApiResponse<CsvValidateResponseDto>.Success(result));
+    }
+
+    [HttpPost("csv/template")]
+    [SwaggerOperation(Summary = "CSV 템플릿 다운로드", Description = "메시지별 CSV 템플릿을 다운로드합니다.")]
+    public async Task<IActionResult> GetCsvTemplateAsync([FromBody] CsvTemplateRequestDto request)
+    {
+        var serviceId = GetServiceId();
+        var csvBytes = await _fileService.GetCsvTemplateAsync(serviceId, request.MessageCode);
+
+        return File(csvBytes, "text/csv", $"template_{request.MessageCode}.csv");
+    }
+
     private long GetServiceId()
     {
         if (HttpContext.Items.TryGetValue("ServiceId", out var serviceIdObj) && serviceIdObj is long serviceId)

SPMS.Application/DTOs/File/CsvTemplateRequestDto.cs

@@ -0,0 +1,11 @@
+using System.ComponentModel.DataAnnotations;
+using System.Text.Json.Serialization;
+
+namespace SPMS.Application.DTOs.File;
+
+public class CsvTemplateRequestDto
+{
+    [Required]
+    [JsonPropertyName("message_code")]
+    public string MessageCode { get; set; } = string.Empty;
+}

SPMS.Application/DTOs/File/CsvValidateErrorDto.cs

@@ -0,0 +1,12 @@
+using System.Text.Json.Serialization;
+
+namespace SPMS.Application.DTOs.File;
+
+public class CsvValidateErrorDto
+{
+    [JsonPropertyName("row")]
+    public int Row { get; set; }
+
+    [JsonPropertyName("error")]
+    public string Error { get; set; } = string.Empty;
+}

SPMS.Application/DTOs/File/CsvValidateResponseDto.cs

@@ -0,0 +1,27 @@
+using System.Text.Json.Serialization;
+
+namespace SPMS.Application.DTOs.File;
+
+public class CsvValidateResponseDto
+{
+    [JsonPropertyName("total_rows")]
+    public int TotalRows { get; set; }
+
+    [JsonPropertyName("valid_rows")]
+    public int ValidRows { get; set; }
+
+    [JsonPropertyName("invalid_rows")]
+    public int InvalidRows { get; set; }
+
+    [JsonPropertyName("columns")]
+    public List<string> Columns { get; set; } = new();
+
+    [JsonPropertyName("required_variables")]
+    public List<string> RequiredVariables { get; set; } = new();
+
+    [JsonPropertyName("matched")]
+    public bool Matched { get; set; }
+
+    [JsonPropertyName("errors")]
+    public List<CsvValidateErrorDto> Errors { get; set; } = new();
+}

SPMS.Application/Interfaces/IFileService.cs

@@ -8,4 +8,6 @@ public interface IFileService
     Task<FileInfoResponseDto> GetInfoAsync(long serviceId, long fileId);
     Task<FileListResponseDto> GetListAsync(long serviceId, FileListRequestDto request);
     Task DeleteAsync(long serviceId, long fileId);
+    Task<CsvValidateResponseDto> ValidateCsvAsync(long serviceId, Stream csvStream, string fileName, string messageCode);
+    Task<byte[]> GetCsvTemplateAsync(long serviceId, string messageCode);
 }

SPMS.Application/Services/FileService.cs

@@ -1,3 +1,5 @@
+using System.Text;
+using System.Text.RegularExpressions;
 using SPMS.Application.DTOs.File;
 using SPMS.Application.DTOs.Notice;
 using SPMS.Application.Interfaces;
@@ -14,6 +16,7 @@ public class FileService : IFileService
     private readonly IFileStorageService _fileStorageService;
     private readonly IServiceRepository _serviceRepository;
     private readonly IAdminRepository _adminRepository;
+    private readonly IMessageRepository _messageRepository;
     private readonly IUnitOfWork _unitOfWork;
 
     private static readonly HashSet<string> AllowedImageExtensions = new(StringComparer.OrdinalIgnoreCase)
@@ -29,12 +32,14 @@ public class FileService : IFileService
         IFileStorageService fileStorageService,
         IServiceRepository serviceRepository,
         IAdminRepository adminRepository,
+        IMessageRepository messageRepository,
         IUnitOfWork unitOfWork)
     {
         _fileRepository = fileRepository;
         _fileStorageService = fileStorageService;
         _serviceRepository = serviceRepository;
         _adminRepository = adminRepository;
+        _messageRepository = messageRepository;
         _unitOfWork = unitOfWork;
     }
 
@@ -137,6 +142,113 @@ public class FileService : IFileService
         await _unitOfWork.SaveChangesAsync();
     }
 
+    public async Task<CsvValidateResponseDto> ValidateCsvAsync(
+        long serviceId, Stream csvStream, string fileName, string messageCode)
+    {
+        var extension = Path.GetExtension(fileName).ToLowerInvariant();
+        if (extension != ".csv")
+            throw new SpmsException(ErrorCodes.FileTypeNotAllowed, "CSV 파일만 검증할 수 있습니다.", 400);
+
+        var message = await _messageRepository.GetByMessageCodeAndServiceAsync(messageCode, serviceId);
+        if (message == null)
+            throw new SpmsException(ErrorCodes.NotFound, "존재하지 않는 메시지입니다.", 404);
+
+        var requiredVariables = ExtractTemplateVariables(message.Body);
+
+        using var reader = new StreamReader(csvStream, Encoding.UTF8);
+        var headerLine = await reader.ReadLineAsync();
+        if (string.IsNullOrWhiteSpace(headerLine))
+            throw new SpmsException(ErrorCodes.BadRequest, "CSV 파일이 비어있습니다.", 400);
+
+        var columns = headerLine.Split(',').Select(c => c.Trim()).ToList();
+        var hasDeviceId = columns.Contains("device_id", StringComparer.OrdinalIgnoreCase);
+        var matched = hasDeviceId && requiredVariables.All(v =>
+            columns.Contains(v, StringComparer.OrdinalIgnoreCase));
+
+        var errors = new List<CsvValidateErrorDto>();
+
+        if (!hasDeviceId)
+            errors.Add(new CsvValidateErrorDto { Row = 0, Error = "device_id 컬럼이 없습니다." });
+
+        foreach (var variable in requiredVariables.Where(v =>
+            !columns.Contains(v, StringComparer.OrdinalIgnoreCase)))
+        {
+            errors.Add(new CsvValidateErrorDto { Row = 0, Error = $"변수 '{variable}'이 CSV에 없습니다." });
+        }
+
+        var deviceIdIndex = columns.FindIndex(c =>
+            c.Equals("device_id", StringComparison.OrdinalIgnoreCase));
+
+        var totalRows = 0;
+        var invalidRows = 0;
+        var rowNumber = 1;
+
+        while (await reader.ReadLineAsync() is { } line)
+        {
+            totalRows++;
+            rowNumber++;
+
+            if (string.IsNullOrWhiteSpace(line))
+            {
+                invalidRows++;
+                errors.Add(new CsvValidateErrorDto { Row = rowNumber, Error = "빈 행입니다." });
+                continue;
+            }
+
+            var values = line.Split(',');
+
+            if (deviceIdIndex >= 0 && deviceIdIndex < values.Length)
+            {
+                var deviceIdValue = values[deviceIdIndex].Trim();
+                if (string.IsNullOrWhiteSpace(deviceIdValue))
+                {
+                    invalidRows++;
+                    errors.Add(new CsvValidateErrorDto { Row = rowNumber, Error = "device_id 누락" });
+                }
+                else if (!long.TryParse(deviceIdValue, out _))
+                {
+                    invalidRows++;
+                    errors.Add(new CsvValidateErrorDto { Row = rowNumber, Error = "잘못된 device_id 형식" });
+                }
+            }
+        }
+
+        return new CsvValidateResponseDto
+        {
+            TotalRows = totalRows,
+            ValidRows = totalRows - invalidRows,
+            InvalidRows = invalidRows,
+            Columns = columns,
+            RequiredVariables = requiredVariables,
+            Matched = matched,
+            Errors = errors
+        };
+    }
+
+    public async Task<byte[]> GetCsvTemplateAsync(long serviceId, string messageCode)
+    {
+        var message = await _messageRepository.GetByMessageCodeAndServiceAsync(messageCode, serviceId);
+        if (message == null)
+            throw new SpmsException(ErrorCodes.NotFound, "존재하지 않는 메시지입니다.", 404);
+
+        var variables = ExtractTemplateVariables(message.Body);
+        var headers = new List<string> { "device_id" };
+        headers.AddRange(variables);
+
+        var sb = new StringBuilder();
+        sb.AppendLine(string.Join(",", headers));
+        sb.AppendLine(string.Join(",", headers.Select(h =>
+            h == "device_id" ? "(여기에 데이터 입력)" : $"예시_{h}")));
+
+        return Encoding.UTF8.GetPreamble().Concat(Encoding.UTF8.GetBytes(sb.ToString())).ToArray();
+    }
+
+    private static List<string> ExtractTemplateVariables(string template)
+    {
+        var matches = Regex.Matches(template, @"\{\{(\w+)\}\}");
+        return matches.Select(m => m.Groups[1].Value).Distinct().ToList();
+    }
+
     private static void ValidateFileType(string fileType, string fileName, long fileSize)
     {
         var extension = Path.GetExtension(fileName).ToLowerInvariant();

SPMS.Domain/Interfaces/IMessageRepository.cs

@@ -5,4 +5,5 @@ namespace SPMS.Domain.Interfaces;
 public interface IMessageRepository : IRepository<Message>
 {
     Task<Message?> GetByMessageCodeAsync(string messageCode);
+    Task<Message?> GetByMessageCodeAndServiceAsync(string messageCode, long serviceId);
 }

SPMS.Infrastructure/DependencyInjection.cs

@@ -33,6 +33,7 @@ public static class DependencyInjection
         services.AddScoped<IAppConfigRepository, AppConfigRepository>();
         services.AddScoped<IDeviceRepository, DeviceRepository>();
         services.AddScoped<IFileRepository, FileRepository>();
+        services.AddScoped<IMessageRepository, MessageRepository>();
 
         // External Services
         services.AddScoped<IJwtService, JwtService>();

SPMS.Infrastructure/Persistence/Repositories/MessageRepository.cs

@@ -0,0 +1,22 @@
+using Microsoft.EntityFrameworkCore;
+using SPMS.Domain.Entities;
+using SPMS.Domain.Interfaces;
+
+namespace SPMS.Infrastructure.Persistence.Repositories;
+
+public class MessageRepository : Repository<Message>, IMessageRepository
+{
+    public MessageRepository(AppDbContext context) : base(context) { }
+
+    public async Task<Message?> GetByMessageCodeAsync(string messageCode)
+    {
+        return await _dbSet
+            .FirstOrDefaultAsync(m => m.MessageCode == messageCode && !m.IsDeleted);
+    }
+
+    public async Task<Message?> GetByMessageCodeAndServiceAsync(string messageCode, long serviceId)
+    {
+        return await _dbSet
+            .FirstOrDefaultAsync(m => m.MessageCode == messageCode && m.ServiceId == serviceId && !m.IsDeleted);
+    }
+}