feat: standalone ExcelToPdfService - ASP.NET Core 8 + Syncfusion

- Services/ExcelToPdfService.cs: core conversion logic (XlsIORenderer)
- Controllers/ExcelToPdfController.cs: REST API endpoints
  * POST /api/ExcelToPdf/convert (file upload)
  * POST /api/ExcelToPdf/convert-by-path (server path)
  * GET  /api/ExcelToPdf/health
- Program.cs: minimal API setup, 50MB upload limit
- appsettings.json: port 5200, Syncfusion license
- Syncfusion 21.1.37 (XlsIO + Pdf + XlsIORenderer)
- Binary signed: Azure Trusted Signing (Private Trust)

.gitignore

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+bin/
+obj/
+publish/
+*.user
+.vs/

Controllers/ExcelToPdfController.cs

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+using ExcelToPdfService.Services;
+using Microsoft.AspNetCore.Mvc;
+
+namespace ExcelToPdfService.Controllers;
+
+[ApiController]
+[Route("api/[controller]")]
+public class ExcelToPdfController : ControllerBase
+{
+    private readonly IExcelToPdfService _service;
+
+    public ExcelToPdfController(IExcelToPdfService service) => _service = service;
+
+    /// <summary>Upload Excel file → nhận PDF trả về</summary>
+    [HttpPost("convert")]
+    public async Task<IActionResult> Convert(
+        IFormFile file,
+        [FromQuery] string? printArea = null,
+        [FromQuery] bool landscape = false)
+    {
+        if (file == null || file.Length == 0)
+            return BadRequest(new { success = false, message = "No file uploaded" });
+
+        var ext = Path.GetExtension(file.FileName).ToLowerInvariant();
+        if (ext != ".xlsx" && ext != ".xls")
+            return BadRequest(new { success = false, message = "Only .xlsx/.xls files are supported" });
+
+        await using var stream = file.OpenReadStream();
+        var pdfBytes = await _service.ConvertAsync(stream, printArea, landscape);
+        var fileName = Path.GetFileNameWithoutExtension(file.FileName) + ".pdf";
+
+        return File(pdfBytes, "application/pdf", fileName);
+    }
+
+    /// <summary>Chuyển đổi file Excel theo đường dẫn trên server</summary>
+    [HttpPost("convert-by-path")]
+    public async Task<IActionResult> ConvertByPath([FromBody] ConvertByPathRequest req)
+    {
+        if (string.IsNullOrWhiteSpace(req.FilePath))
+            return BadRequest(new { success = false, message = "FilePath is required" });
+
+        try
+        {
+            var pdfBytes = await _service.ConvertFileAsync(req.FilePath, req.PrintArea, req.Landscape);
+            var fileName = Path.GetFileNameWithoutExtension(req.FilePath) + ".pdf";
+            return File(pdfBytes, "application/pdf", fileName);
+        }
+        catch (FileNotFoundException)
+        {
+            return NotFound(new { success = false, message = $"File not found: {req.FilePath}" });
+        }
+        catch (Exception ex)
+        {
+            return StatusCode(500, new { success = false, message = ex.Message });
+        }
+    }
+
+    /// <summary>Health check</summary>
+    [HttpGet("health")]
+    public IActionResult Health() => Ok(new { status = "ok", version = "1.0.0", time = DateTime.UtcNow });
+}
+
+public record ConvertByPathRequest(string FilePath, string? PrintArea = null, bool Landscape = false);

ExcelToPdfService.csproj

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+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Syncfusion.Pdf.Net.Core" Version="21.1.37" />
+    <PackageReference Include="Syncfusion.XlsIO.Net.Core" Version="21.1.37" />
+    <PackageReference Include="Syncfusion.XlsIORenderer.Net.Core" Version="21.1.37" />
+  </ItemGroup>
+
+</Project>

ExcelToPdfService.http

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+@ExcelToPdfService_HostAddress = http://localhost:5285
+
+GET {{ExcelToPdfService_HostAddress}}/weatherforecast/
+Accept: application/json
+
+###

Program.cs

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+using ExcelToPdfService.Services;
+using Syncfusion.Licensing;
+
+var builder = WebApplication.CreateBuilder(args);
+
+// Syncfusion license
+SyncfusionLicenseProvider.RegisterLicense(
+    builder.Configuration["Syncfusion:LicenseKey"]
+    ?? "MjExMDkzMEAzMjMxMmUzMTJlMzMzNWd1RGM1NVFmUUMzWmZlN0dCc3NadUJyM1RUYVh1SHVSS1B2Tzdwa0NhcE09");
+
+// Services
+builder.Services.AddControllers();
+builder.Services.AddScoped<IExcelToPdfService, ExcelToPdfService.Services.ExcelToPdfService>();
+
+// Allow large file uploads (50 MB)
+builder.Services.Configure<Microsoft.AspNetCore.Http.Features.FormOptions>(o =>
+{
+    o.MultipartBodyLengthLimit = 50 * 1024 * 1024;
+});
+builder.WebHost.ConfigureKestrel(o =>
+{
+    o.Limits.MaxRequestBodySize = 50 * 1024 * 1024;
+});
+
+var app = builder.Build();
+
+app.UseHttpsRedirection();
+app.MapControllers();
+
+app.Run();

Properties/launchSettings.json

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+{
+  "$schema": "http://json.schemastore.org/launchsettings.json",
+  "iisSettings": {
+    "windowsAuthentication": false,
+    "anonymousAuthentication": true,
+    "iisExpress": {
+      "applicationUrl": "http://localhost:12076",
+      "sslPort": 44368
+    }
+  },
+  "profiles": {
+    "http": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "launchUrl": "weatherforecast",
+      "applicationUrl": "http://localhost:5285",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "https": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "launchUrl": "weatherforecast",
+      "applicationUrl": "https://localhost:7139;http://localhost:5285",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "IIS Express": {
+      "commandName": "IISExpress",
+      "launchBrowser": true,
+      "launchUrl": "weatherforecast",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}

Services/ExcelToPdfService.cs

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+using Syncfusion.XlsIO;
+using Syncfusion.XlsIORenderer;
+
+namespace ExcelToPdfService.Services;
+
+public interface IExcelToPdfService
+{
+    Task<byte[]> ConvertAsync(Stream excelStream, string? printArea = null, bool landscape = false);
+    Task<byte[]> ConvertFileAsync(string filePath, string? printArea = null, bool landscape = false);
+}
+
+public class ExcelToPdfService : IExcelToPdfService
+{
+    public Task<byte[]> ConvertAsync(Stream excelStream, string? printArea = null, bool landscape = false)
+    {
+        using var excelEngine = new ExcelEngine();
+        var app = excelEngine.Excel;
+        app.DefaultVersion = ExcelVersion.Xlsx;
+
+        var workbook = app.Workbooks.Open(excelStream);
+        return Task.FromResult(Convert(workbook, printArea, landscape));
+    }
+
+    public Task<byte[]> ConvertFileAsync(string filePath, string? printArea = null, bool landscape = false)
+    {
+        if (!File.Exists(filePath))
+            throw new FileNotFoundException("Excel file not found", filePath);
+
+        using var excelEngine = new ExcelEngine();
+        var app = excelEngine.Excel;
+        app.DefaultVersion = ExcelVersion.Xlsx;
+
+        using var fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
+        var workbook = app.Workbooks.Open(fs);
+        return Task.FromResult(Convert(workbook, printArea, landscape));
+    }
+
+    private static byte[] Convert(IWorkbook workbook, string? printArea, bool landscape)
+    {
+        var sheet = workbook.Worksheets[0];
+
+        // Page setup
+        sheet.PageSetup.FitToPagesWide = 1;
+        sheet.PageSetup.FitToPagesTall = 0;
+        sheet.PageSetup.Orientation = landscape
+            ? ExcelPageOrientation.Landscape
+            : ExcelPageOrientation.Portrait;
+
+        if (!string.IsNullOrWhiteSpace(printArea))
+            sheet.PageSetup.PrintArea = printArea;
+
+        // Convert
+        var renderer = new XlsIORenderer();
+        var settings = new XlsIORendererSettings
+        {
+            LayoutOptions = LayoutOptions.Automatic
+        };
+
+        var pdf = renderer.ConvertToPDF(workbook, settings);
+
+        using var ms = new MemoryStream();
+        pdf.Save(ms);
+        return ms.ToArray();
+    }
+}

appsettings.Development.json

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+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

appsettings.json

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+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*",
+  "Syncfusion": {
+    "LicenseKey": "MjExMDkzMEAzMjMxMmUzMTJlMzMzNWd1RGM1NVFmUUMzWmZlN0dCc3NadUJyM1RUYVh1SHVSS1B2Tzdwa0NhcE09"
+  },
+  "Urls": "http://0.0.0.0:5200"
+}