pwa_pdf_service/Program.cs

using System.Collections.Generic;
using System.Data;
using FastReport;
using FastReport.Export.Pdf;
using Microsoft.AspNetCore.Mvc;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using PdfSharpCore.Pdf;
using PdfSharpCore.Pdf.IO;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddEndpointsApiExplorer();

var app = builder.Build();

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

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

// Render a single template + dataset to a PDF.
// Body shape:
// {
//   "template": "report_6",                        // resolves to wwwroot/reports/report_6.frx
//   "dataSourceName": "abnormal_meter_not_send_report",
//   "rows": [ { "field": "value", ... }, ... ],
//   "fileName": "report.pdf"                       // optional, response Content-Disposition
// }
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);
    return Results.File(pdf, "application/pdf", body.FileName ?? $"{body.Template}.pdf");
});

// Render multiple sections and merge them into a single PDF.
// Body shape: { "fileName": "merged.pdf", "sections": [ <RenderRequest>, ... ] }
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))).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)
{
    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 && req.Rows.Count > 0)
    {
        var dt = JArrayToDataTable(req.Rows, req.DataSourceName ?? "data");
        report.RegisterData(dt, dt.TableName);
        report.GetDataSource(dt.TableName).Enabled = true;
    }
    else if (!string.IsNullOrEmpty(req.DataSourceName))
    {
        // No rows but a name was given — register an empty table so the template
        // renders its bands without the "data source not found" error.
        var dt = new DataTable(req.DataSourceName);
        report.RegisterData(dt, dt.TableName);
    }

    report.Prepare();

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

// Resolves "report_6" → wwwroot/reports/report_6.frx, with "documents/uuid"
// supported for the empty-report templates that live under wwwroot/documents.
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; // let RenderSingle throw a clean FileNotFoundException
}

// Build a DataTable whose columns are the union of keys present across the
// JArray rows. FastReport binds .frx columns to DataTable columns by name.
static DataTable JArrayToDataTable(JArray rows, string tableName)
{
    var dt = new DataTable(tableName);

    foreach (var token in rows)
    {
        if (token is not JObject obj) continue;
        foreach (var prop in obj.Properties())
        {
            if (dt.Columns.Contains(prop.Name)) continue;
            dt.Columns.Add(prop.Name, InferColumnType(prop.Value));
        }
    }

    foreach (var token in rows)
    {
        if (token is not JObject obj) continue;
        var row = dt.NewRow();
        foreach (DataColumn col in dt.Columns)
        {
            var jt = obj[col.ColumnName];
            row[col.ColumnName] = JTokenToCell(jt, col.DataType);
        }
        dt.Rows.Add(row);
    }
    return dt;
}

static Type InferColumnType(JToken? value) => value?.Type switch
{
    JTokenType.Integer => typeof(long),
    JTokenType.Float   => typeof(decimal),
    JTokenType.Boolean => typeof(bool),
    JTokenType.Date    => typeof(DateTime),
    _                  => typeof(string),
};

static object JTokenToCell(JToken? jt, Type targetType)
{
    if (jt == null || jt.Type == JTokenType.Null || jt.Type == JTokenType.Undefined)
        return DBNull.Value;
    try
    {
        if (targetType == typeof(string)) return jt.ToString();
        return jt.ToObject(targetType) ?? (object)DBNull.Value;
    }
    catch
    {
        return jt.ToString();
    }
}

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 JArray? Rows { get; set; }
    public string? FileName { get; set; }
}

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