VILLASnode/lib/api/requests/graph.cpp

/* The "stats" API request.
 *
 * Author: Steffen Vogel <post@steffenvogel.de>
 * SPDX-FileCopyrightText: 2014-2023 Institute for Automation of Complex Power Systems, RWTH Aachen University
 * SPDX-License-Identifier: Apache-2.0
 */

extern "C" {
#include <graphviz/gvc.h>
}

#include <villas/api/request.hpp>
#include <villas/api/response.hpp>
#include <villas/timing.hpp>

namespace villas {
namespace node {
namespace api {

class GraphRequest : public Request {

protected:
  GVC_t *gvc;

  std::string layout;
  std::string format;

public:
  GraphRequest(Session *s)
      : Request(s), gvc(gvContext()), layout(getQueryArg("layout")) {
    if (layout.empty())
      layout = "neato";
  }

  ~GraphRequest() { gvFreeContext(gvc); }

  virtual Response *execute() {
    if (method != Session::Method::GET)
      throw InvalidMethod(this);

    if (body != nullptr)
      throw BadRequest("Status endpoint does not accept any body data");

    auto *sn = session->getSuperNode();
    auto *graph = sn->getGraph();

    char *data;
    unsigned len;

    std::list<std::string> supportedLayouts = {
        "circo", "dot",   "fdp",       "neato", "nop",  "nop1",
        "nop2",  "osage", "patchwork", "sfdp",  "twopi"};
    std::list<std::string> supportedFormats = {
        "ps",  "eps",  "txt", "svg", "svgz", "gif",  "png",
        "jpg", "jpeg", "bmp", "dot", "fig",  "json", "pdf"};

    format = matches[1];

    auto lit =
        std::find(supportedLayouts.begin(), supportedLayouts.end(), layout);
    if (lit == supportedLayouts.end())
      throw BadRequest("Unsupported layout: {}", layout);

    auto fit =
        std::find(supportedFormats.begin(), supportedFormats.end(), format);
    if (fit == supportedFormats.end())
      throw BadRequest("Unsupported format: {}", format);

    std::string ct = "text/plain";
    if (format == "svg")
      ct = "image/svg+xml";
    else if (format == "eps" || format == "ps")
      ct = "application/postscript";
    else if (format == "txt")
      ct = "text/plain";
    else if (format == "gif")
      ct = "image/gif";
    else if (format == "png")
      ct = "image/png";
    else if (format == "jpg" || format == "jpeg")
      ct = "image/jpeg";
    else if (format == "bmp")
      ct = "image/bmp";
    else if (format == "dot")
      ct = "text/vnd.graphviz";
    else if (format == "json")
      ct = "application/json";
    else if (format == "pdf")
      ct = "application/pdf";

    gvLayout(gvc, graph, layout.c_str());
    gvRenderData(gvc, graph, format.c_str(), &data, &len);

    auto buf = Buffer(data, len);
    auto *resp = new Response(session, HTTP_STATUS_OK, ct, buf);

    if (format == "svgz")
      resp->setHeader("Content-Encoding", "gzip");

#if 0
		gvFreeRenderData(data);
#endif
    gvFreeLayout(gvc, graph);

    return resp;
  }
};

// Register API request
static char n[] = "graph";
static char r[] = "/graph\\.([a-z]+)";
static char d[] = "get graph representation of configuration";
static RequestPlugin<GraphRequest, n, r, d> p;

} // namespace api
} // namespace node
} // namespace villas