pwa_pdf_service/Program.cs

using System.Collections;
using System.Reflection;
using FastReport;
using FastReport.Export.Pdf;
using Newtonsoft.Json;
using PdfSharpCore.Pdf;
using PdfSharpCore.Pdf.IO;

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

var templateRoot = Path.Combine(
    AppContext.BaseDirectory,
    builder.Configuration["TemplateRoot"] ?? "wwwroot");
app.Logger.LogInformation("Template root: {TemplateRoot}", templateRoot);

// Index every public type in this assembly by its short name so the JSON
// payload can refer to a model class by name (e.g. "abnormal_meter_not_send_report").
var typeIndex = Assembly.GetExecutingAssembly().GetTypes()
    .Where(t => t.IsClass && t.IsPublic)
    .ToDictionary(t => t.Name, t => t, StringComparer.Ordinal);

app.MapGet("/health", () => Results.Ok(new { status = "ok", time = DateTime.UtcNow }));

// Render a single template + dataset to a PDF.
// Body shape:
// {
//   "template": "report_6",
//   "dataSourceName": "abnormal_meter_not_send_report",
//   "typeName": "abnormal_meter_not_send_report",   // class in shared report models
//   "rows": [ { ...same JSON as the C# object would serialize... } ],
//   "fileName": "report.pdf"
// }
app.MapPost("/render", async (HttpRequest req) =>
{
    using var sr = new StreamReader(req.Body);
    var bodyText = await sr.ReadToEndAsync();
    var body = JsonConvert.DeserializeObject<RenderRequest>(bodyText)
               ?? throw new ArgumentException("Empty body");
    var pdf = RenderSingle(templateRoot, body, typeIndex);
    return Results.File(pdf, "application/pdf", body.FileName ?? $"{body.Template}.pdf");
});

// Render multiple sections and merge them into a single PDF.
app.MapPost("/render/multi", async (HttpRequest req) =>
{
    using var sr = new StreamReader(req.Body);
    var bodyText = await sr.ReadToEndAsync();
    var body = JsonConvert.DeserializeObject<MultiRenderRequest>(bodyText)
               ?? throw new ArgumentException("Empty body");

    if (body.Sections == null || body.Sections.Count == 0)
        return Results.BadRequest(new { error = "sections must contain at least one entry" });

    var streams = body.Sections.Select(s => new MemoryStream(RenderSingle(templateRoot, s, typeIndex))).ToList();
    var merged = MergePdfs(streams);
    foreach (var s in streams) s.Dispose();
    return Results.File(merged, "application/pdf", body.FileName ?? "merged.pdf");
});

app.Run();
return;

// ---- helpers --------------------------------------------------------------

static byte[] RenderSingle(string templateRoot, RenderRequest req, Dictionary<string, Type> typeIndex)
{
    if (string.IsNullOrWhiteSpace(req.Template))
        throw new ArgumentException("template is required");

    var path = ResolveTemplatePath(templateRoot, req.Template);
    if (!File.Exists(path))
        throw new FileNotFoundException($"Template not found: {req.Template}", path);

    using var report = new Report();
    report.Load(path);

    if (req.Rows != null && !string.IsNullOrEmpty(req.TypeName))
    {
        if (!typeIndex.TryGetValue(req.TypeName, out var elementType))
            throw new ArgumentException($"Unknown typeName: {req.TypeName}. Add the class to pwa_api/Modules/Report/Models/ so the sidecar can compile it in.");

        var listType = typeof(List<>).MakeGenericType(elementType);
        var typedList = (IList?)JsonConvert.DeserializeObject(req.Rows.ToString(), listType);
        if (typedList == null)
            throw new ArgumentException("Failed to deserialize rows.");

        var dsName = req.DataSourceName ?? elementType.Name;
        report.RegisterData((IEnumerable)typedList, dsName);
        var ds = report.GetDataSource(dsName);
        if (ds != null) ds.Enabled = true;
    }

    report.Prepare();

    using var ms = new MemoryStream();
    var pdfExport = new PDFExport();
    report.Export(pdfExport, ms);
    return ms.ToArray();
}

static string ResolveTemplatePath(string root, string name)
{
    if (name.EndsWith(".frx", StringComparison.OrdinalIgnoreCase))
    {
        var direct = Path.Combine(root, name);
        if (File.Exists(direct)) return direct;
    }
    var withExt = name.EndsWith(".frx") ? name : name + ".frx";
    var inReports = Path.Combine(root, "reports", withExt);
    if (File.Exists(inReports)) return inReports;
    var inDocuments = Path.Combine(root, "documents", withExt);
    if (File.Exists(inDocuments)) return inDocuments;
    return inReports;
}

static byte[] MergePdfs(IEnumerable<MemoryStream> sources)
{
    using var output = new PdfDocument();
    foreach (var src in sources)
    {
        src.Position = 0;
        using var input = PdfReader.Open(src, PdfDocumentOpenMode.Import);
        for (var i = 0; i < input.PageCount; i++)
            output.AddPage(input.Pages[i]);
    }
    using var ms = new MemoryStream();
    output.Save(ms, false);
    return ms.ToArray();
}

// ---- DTOs -----------------------------------------------------------------

public class RenderRequest
{
    public string Template { get; set; } = "";
    public string? DataSourceName { get; set; }
    public string? TypeName { get; set; }
    public Newtonsoft.Json.Linq.JArray? Rows { get; set; }
    public string? FileName { get; set; }
}

public class MultiRenderRequest
{
    public string? FileName { get; set; }
    public List<RenderRequest>? Sections { get; set; }
}