// DisplayConfig helper for spike S2: list targets, detach/attach a target
// from the desktop topology, and try monitor specialization.
//
//   dispctl list
//   dispctl detach <targetId>     remove target from active desktop topology
//   dispctl extend                re-extend desktop to all displays
//   dispctl specialize <targetId> [0|1]   set monitor specialization flag

#include <windows.h>

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <vector>

static const char* err(LONG e) {
  switch (e) {
    case ERROR_SUCCESS: return "OK";
    case ERROR_ACCESS_DENIED: return "ACCESS_DENIED";
    case ERROR_NOT_SUPPORTED: return "NOT_SUPPORTED";
    case ERROR_INVALID_PARAMETER: return "INVALID_PARAMETER";
    case ERROR_GEN_FAILURE: return "GEN_FAILURE";
    default: return "?";
  }
}

int main(int argc, char** argv) {
  const char* cmd = argc > 1 ? argv[1] : "list";
  long want = argc > 2 ? atol(argv[2]) : -1;

  UINT32 np = 0, nm = 0;
  if (GetDisplayConfigBufferSizes(QDC_ALL_PATHS, &np, &nm) != ERROR_SUCCESS) return 1;
  std::vector<DISPLAYCONFIG_PATH_INFO> paths(np);
  std::vector<DISPLAYCONFIG_MODE_INFO> modes(nm);
  if (QueryDisplayConfig(QDC_ALL_PATHS, &np, paths.data(), &nm, modes.data(),
                         nullptr) != ERROR_SUCCESS)
    return 1;
  paths.resize(np);
  modes.resize(nm);

  if (strcmp(cmd, "list") == 0) {
    for (auto& p : paths) {
      DISPLAYCONFIG_TARGET_DEVICE_NAME tn{};
      tn.header.type = DISPLAYCONFIG_DEVICE_INFO_GET_TARGET_NAME;
      tn.header.size = sizeof(tn);
      tn.header.adapterId = p.targetInfo.adapterId;
      tn.header.id = p.targetInfo.id;
      DisplayConfigGetDeviceInfo(&tn.header);
      printf("target id=%u luid=0x%x active=%d available=%d name='%ls'\n",
             p.targetInfo.id, p.targetInfo.adapterId.LowPart,
             (p.flags & DISPLAYCONFIG_PATH_ACTIVE) ? 1 : 0,
             p.targetInfo.targetAvailable, tn.monitorFriendlyDeviceName);
    }
    return 0;
  }

  if (strcmp(cmd, "detach") == 0) {
    // rebuild from ACTIVE paths only, minus the requested target
    UINT32 anp = 0, anm = 0;
    GetDisplayConfigBufferSizes(QDC_ONLY_ACTIVE_PATHS, &anp, &anm);
    std::vector<DISPLAYCONFIG_PATH_INFO> ap(anp);
    std::vector<DISPLAYCONFIG_MODE_INFO> am(anm);
    if (QueryDisplayConfig(QDC_ONLY_ACTIVE_PATHS, &anp, ap.data(), &anm, am.data(),
                           nullptr) != ERROR_SUCCESS)
      return 1;
    ap.resize(anp);
    std::vector<DISPLAYCONFIG_PATH_INFO> keep;
    for (auto& p : ap)
      if ((long)p.targetInfo.id != want) keep.push_back(p);
    if (keep.size() == ap.size()) {
      printf("target %ld not in active topology (already detached)\n", want);
      return 0;
    }
    LONG r = SetDisplayConfig((UINT32)keep.size(), keep.data(), anm, am.data(),
                              SDC_APPLY | SDC_USE_SUPPLIED_DISPLAY_CONFIG |
                                  SDC_ALLOW_CHANGES | SDC_SAVE_TO_DATABASE);
    printf("SetDisplayConfig(detach %ld) = %ld (%s)\n", want, r, err(r));
    return r == ERROR_SUCCESS ? 0 : 1;
  }

  if (strcmp(cmd, "extend") == 0) {
    LONG r = SetDisplayConfig(0, nullptr, 0, nullptr, SDC_APPLY | SDC_TOPOLOGY_EXTEND);
    printf("SetDisplayConfig(extend) = %ld (%s)\n", r, err(r));
    return r == ERROR_SUCCESS ? 0 : 1;
  }

  if (strcmp(cmd, "spec-get") == 0) {
    for (auto& p : paths) {
      if ((long)p.targetInfo.id != want) continue;
      DISPLAYCONFIG_GET_MONITOR_SPECIALIZATION gs{};
      gs.header.type = DISPLAYCONFIG_DEVICE_INFO_GET_MONITOR_SPECIALIZATION;
      gs.header.size = sizeof(gs);
      gs.header.adapterId = p.targetInfo.adapterId;
      gs.header.id = p.targetInfo.id;
      LONG r = DisplayConfigGetDeviceInfo(&gs.header);
      printf("spec-get(%ld) = %ld (%s): enabled=%u availForMonitor=%u availForSystem=%u\n",
             want, r, err(r), gs.isSpecializationEnabled,
             gs.isSpecializationAvailableForMonitor,
             gs.isSpecializationAvailableForSystem);
      return r == ERROR_SUCCESS ? 0 : 1;
    }
    printf("target %ld not found\n", want);
    return 1;
  }

  if (strcmp(cmd, "specialize") == 0) {
    bool enable = argc > 3 ? atoi(argv[3]) != 0 : true;
    for (auto& p : paths) {
      if ((long)p.targetInfo.id != want) continue;
      DISPLAYCONFIG_SET_MONITOR_SPECIALIZATION ms{};
      ms.header.type = DISPLAYCONFIG_DEVICE_INFO_SET_MONITOR_SPECIALIZATION;
      ms.header.size = sizeof(ms);
      ms.header.adapterId = p.targetInfo.adapterId;
      ms.header.id = p.targetInfo.id;
      ms.isSpecializationEnabled = enable ? 1 : 0;
      wcscpy_s(ms.specializationApplicationName, L"sauna");
      LONG r = DisplayConfigSetDeviceInfo(&ms.header);
      printf("DisplayConfigSetDeviceInfo(specialize %ld -> %d) = %ld (%s)\n", want,
             (int)enable, r, err(r));
      return r == ERROR_SUCCESS ? 0 : 1;
    }
    printf("target %ld not found\n", want);
    return 1;
  }

  fprintf(stderr, "unknown command\n");
  return 1;
}