/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "CheckerboardReportService.h"

#include "jsapi.h"                    // for JS_Now
#include "MainThreadUtils.h"          // for NS_IsMainThread
#include "mozilla/Assertions.h"       // for MOZ_ASSERT
#include "mozilla/ClearOnShutdown.h"  // for ClearOnShutdown
#include "mozilla/Preferences.h"
#include "mozilla/Services.h"
#include "mozilla/StaticPrefs_apz.h"
#include "mozilla/dom/CheckerboardReportServiceBinding.h"  // for dom::CheckerboardReports
#include "mozilla/gfx/GPUParent.h"
#include "mozilla/gfx/GPUProcessManager.h"
#include "nsContentUtils.h"  // for nsContentUtils
#include "nsIObserverService.h"
#include "nsXULAppAPI.h"

namespace mozilla {
namespace layers {

/*static*/
StaticRefPtr<CheckerboardEventStorage> CheckerboardEventStorage::sInstance;

/*static*/
already_AddRefed<CheckerboardEventStorage>
CheckerboardEventStorage::GetInstance() {
  // The instance in the parent process does all the work, so if this is getting
  // called in the child process something is likely wrong.
  MOZ_ASSERT(XRE_IsParentProcess());

  MOZ_ASSERT(NS_IsMainThread());
  if (!sInstance) {
    sInstance = new CheckerboardEventStorage();
    ClearOnShutdown(&sInstance);
  }
  RefPtr<CheckerboardEventStorage> instance = sInstance.get();
  return instance.forget();
}

void CheckerboardEventStorage::Report(uint32_t aSeverity,
                                      const std::string& aLog) {
  if (!NS_IsMainThread()) {
    RefPtr<Runnable> task = NS_NewRunnableFunction(
        "layers::CheckerboardEventStorage::Report",
        [aSeverity, aLog]() -> void {
          CheckerboardEventStorage::Report(aSeverity, aLog);
        });
    NS_DispatchToMainThread(task.forget());
    return;
  }

  if (XRE_IsGPUProcess()) {
    if (gfx::GPUParent* gpu = gfx::GPUParent::GetSingleton()) {
      nsCString log(aLog.c_str());
      (void)gpu->SendReportCheckerboard(aSeverity, log);
    }
    return;
  }

  RefPtr<CheckerboardEventStorage> storage = GetInstance();
  storage->ReportCheckerboard(aSeverity, aLog);
}

void CheckerboardEventStorage::ReportCheckerboard(uint32_t aSeverity,
                                                  const std::string& aLog) {
  MOZ_ASSERT(NS_IsMainThread());

  if (aSeverity == 0) {
    // This code assumes all checkerboard reports have a nonzero severity.
    return;
  }

  CheckerboardReport severe(aSeverity, JS_Now(), aLog);
  CheckerboardReport recent;

  // First look in the "severe" reports to see if the new one belongs in that
  // list.
  for (int i = 0; i < SEVERITY_MAX_INDEX; i++) {
    if (mCheckerboardReports[i].mSeverity >= severe.mSeverity) {
      continue;
    }
    // The new one deserves to be in the "severe" list. Take the one getting
    // bumped off the list, and put it in |recent| for possible insertion into
    // the recents list.
    recent = mCheckerboardReports[SEVERITY_MAX_INDEX - 1];

    // Shuffle the severe list down, insert the new one.
    for (int j = SEVERITY_MAX_INDEX - 1; j > i; j--) {
      mCheckerboardReports[j] = mCheckerboardReports[j - 1];
    }
    mCheckerboardReports[i] = severe;
    severe.mSeverity = 0;  // mark |severe| as inserted
    break;
  }

  // If |severe.mSeverity| is nonzero, the incoming report didn't get inserted
  // into the severe list; put it into |recent| for insertion into the recent
  // list.
  if (severe.mSeverity) {
    MOZ_ASSERT(recent.mSeverity == 0, "recent should be empty here");
    recent = std::move(severe);
  }  // else |recent| may hold a report that got knocked out of the severe list.

  if (recent.mSeverity == 0) {
    // Nothing to be inserted into the recent list.
    return;
  }

  // If it wasn't in the "severe" list, add it to the "recent" list.
  for (int i = SEVERITY_MAX_INDEX; i < RECENT_MAX_INDEX; i++) {
    if (mCheckerboardReports[i].mTimestamp >= recent.mTimestamp) {
      continue;
    }
    // |recent| needs to be inserted at |i|. Shuffle the remaining ones down
    // and insert it.
    for (int j = RECENT_MAX_INDEX - 1; j > i; j--) {
      mCheckerboardReports[j] = mCheckerboardReports[j - 1];
    }
    mCheckerboardReports[i] = std::move(recent);
    break;
  }
}

void CheckerboardEventStorage::GetReports(
    nsTArray<dom::CheckerboardReport>& aOutReports) {
  MOZ_ASSERT(NS_IsMainThread());

  for (int i = 0; i < RECENT_MAX_INDEX; i++) {
    CheckerboardReport& r = mCheckerboardReports[i];
    if (r.mSeverity == 0) {
      continue;
    }
    dom::CheckerboardReport report;
    report.mSeverity.Construct() = r.mSeverity;
    report.mTimestamp.Construct() = r.mTimestamp / 1000;  // micros to millis
    report.mLog.Construct() =
        NS_ConvertUTF8toUTF16(r.mLog.c_str(), r.mLog.size());
    report.mReason.Construct() = (i < SEVERITY_MAX_INDEX)
                                     ? dom::CheckerboardReason::Severe
                                     : dom::CheckerboardReason::Recent;
    aOutReports.AppendElement(report);
  }
}

}  // namespace layers

namespace dom {

NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(CheckerboardReportService, mParent)

/*static*/
bool CheckerboardReportService::IsEnabled(JSContext* aCtx, JSObject* aGlobal) {
  // Only allow this in the parent process
  if (!XRE_IsParentProcess()) {
    return false;
  }
  // Allow privileged code or about:checkerboard (unprivileged) to access this.
  return nsContentUtils::IsSystemCaller(aCtx) ||
         nsContentUtils::IsSpecificAboutPage(aGlobal, "about:checkerboard");
}

/*static*/
already_AddRefed<CheckerboardReportService>
CheckerboardReportService::Constructor(const dom::GlobalObject& aGlobal) {
  RefPtr ces = MakeRefPtr<CheckerboardReportService>(aGlobal.GetAsSupports());
  return ces.forget();
}

CheckerboardReportService::CheckerboardReportService(nsISupports* aParent)
    : mParent(aParent) {}

JSObject* CheckerboardReportService::WrapObject(
    JSContext* aCtx, JS::Handle<JSObject*> aGivenProto) {
  return CheckerboardReportService_Binding::Wrap(aCtx, this, aGivenProto);
}

nsISupports* CheckerboardReportService::GetParentObject() { return mParent; }

void CheckerboardReportService::GetReports(
    nsTArray<dom::CheckerboardReport>& aOutReports) {
  RefPtr<mozilla::layers::CheckerboardEventStorage> instance =
      mozilla::layers::CheckerboardEventStorage::GetInstance();
  MOZ_ASSERT(instance);
  instance->GetReports(aOutReports);
}

bool CheckerboardReportService::IsRecordingEnabled() const {
  return StaticPrefs::apz_record_checkerboarding();
}

void CheckerboardReportService::SetRecordingEnabled(bool aEnabled) {
  Preferences::SetBool("apz.record_checkerboarding", aEnabled);
}

void CheckerboardReportService::FlushActiveReports() {
  MOZ_ASSERT(XRE_IsParentProcess());
  gfx::GPUProcessManager* gpm = gfx::GPUProcessManager::Get();
  if (gpm && gpm->FlushActiveCheckerboardReports()) {
    return;
  }

  // We failed to dispatch the observer event, either because we have shutdown
  // or the GPU process is temporarily down. In that case, let the callers know
  // we are done.
  nsCOMPtr<nsIObserverService> obsSvc = mozilla::services::GetObserverService();
  MOZ_ASSERT(obsSvc);
  if (obsSvc) {
    obsSvc->NotifyObservers(nullptr, "APZ:FlushActiveCheckerboard:Done",
                            nullptr);
  }
}

}  // namespace dom
}  // namespace mozilla