/* 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 "XMLHttpRequestString.h"

#include "js/String.h"
#include "mozilla/dom/DOMString.h"
#include "nsISupportsImpl.h"

namespace mozilla::dom {

class XMLHttpRequestStringBuffer final {
  friend class XMLHttpRequestStringSnapshot;
  friend class XMLHttpRequestStringWriterHelper;

 public:
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(XMLHttpRequestStringBuffer)
  NS_DECL_OWNINGTHREAD

  XMLHttpRequestStringBuffer() : mMutex("XMLHttpRequestStringBuffer::mMutex") {}

  uint32_t Length() {
    MutexAutoLock lock(mMutex);
    return mData.Length();
  }

  uint32_t UnsafeLength() const MOZ_NO_THREAD_SAFETY_ANALYSIS {
    return mData.Length();
  }

  mozilla::Result<mozilla::BulkWriteHandle<char16_t>, nsresult> UnsafeBulkWrite(
      uint32_t aCapacity) MOZ_NO_THREAD_SAFETY_ANALYSIS {
    return mData.BulkWrite(aCapacity, UnsafeLength(), false);
  }

  void Append(const nsAString& aString) {
    NS_ASSERT_OWNINGTHREAD(XMLHttpRequestStringBuffer);

    MutexAutoLock lock(mMutex);
    mData.Append(aString);
  }

  [[nodiscard]] bool GetAsString(nsAString& aString) {
    MutexAutoLock lock(mMutex);
    return aString.Assign(mData, fallible);
  }

  size_t SizeOfThis(MallocSizeOf aMallocSizeOf) {
    MutexAutoLock lock(mMutex);
    return mData.SizeOfExcludingThisIfUnshared(aMallocSizeOf);
  }

  void CreateSnapshot(XMLHttpRequestStringSnapshot& aSnapshot) {
    MutexAutoLock lock(mMutex);
    aSnapshot.Set(this);
  }

 private:
  ~XMLHttpRequestStringBuffer() = default;

  Mutex mMutex;

  // The following member variable is protected by mutex.
  nsString mData MOZ_GUARDED_BY(mMutex);
};

// ---------------------------------------------------------------------------
// XMLHttpRequestString

XMLHttpRequestString::XMLHttpRequestString()
    : mBuffer(new XMLHttpRequestStringBuffer()) {}

XMLHttpRequestString::~XMLHttpRequestString() = default;

void XMLHttpRequestString::Truncate() {
  mBuffer = new XMLHttpRequestStringBuffer();
}

uint32_t XMLHttpRequestString::Length() const { return mBuffer->Length(); }

void XMLHttpRequestString::Append(const nsAString& aString) {
  mBuffer->Append(aString);
}

bool XMLHttpRequestString::GetAsString(nsAString& aString) const {
  return mBuffer->GetAsString(aString);
}

size_t XMLHttpRequestString::SizeOfThis(MallocSizeOf aMallocSizeOf) const {
  return mBuffer->SizeOfThis(aMallocSizeOf);
}

bool XMLHttpRequestString::IsEmpty() const { return !mBuffer->Length(); }

void XMLHttpRequestString::CreateSnapshot(
    XMLHttpRequestStringSnapshot& aSnapshot) {
  mBuffer->CreateSnapshot(aSnapshot);
}

// ---------------------------------------------------------------------------
// XMLHttpRequestStringSnapshot

XMLHttpRequestStringSnapshot::XMLHttpRequestStringSnapshot() : mVoid(false) {}

XMLHttpRequestStringSnapshot::~XMLHttpRequestStringSnapshot() = default;

void XMLHttpRequestStringSnapshot::ResetInternal(bool aIsVoid) {
  mBuffer = nullptr;
  mVoid = aIsVoid;
}

void XMLHttpRequestStringSnapshot::Set(XMLHttpRequestStringBuffer* aBuffer) {
  MOZ_ASSERT(aBuffer);

  mBuffer = aBuffer;
  mVoid = false;
}

bool XMLHttpRequestStringSnapshot::GetAsString(DOMString& aString) const {
  if (mBuffer) {
    MOZ_ASSERT(!mVoid);
    return mBuffer->GetAsString(aString);
  }

  if (mVoid) {
    aString.SetNull();
  }

  return true;
}

JSString* XMLHttpRequestStringSnapshot::GetAsJSStringCopy(
    JSContext* aCx) const {
  MutexAutoLock lock(mBuffer->mMutex);
  return JS_NewUCStringCopyN(aCx, mBuffer->mData.BeginReading(),
                             mBuffer->mData.Length());
}

// ---------------------------------------------------------------------------
// XMLHttpRequestStringWriterHelper

XMLHttpRequestStringWriterHelper::XMLHttpRequestStringWriterHelper(
    XMLHttpRequestString& aString)
    : mBuffer(aString.mBuffer), mLock(aString.mBuffer->mMutex) {}

XMLHttpRequestStringWriterHelper::~XMLHttpRequestStringWriterHelper() = default;

uint32_t XMLHttpRequestStringWriterHelper::Length() const {
  return mBuffer->UnsafeLength();
}

mozilla::Result<mozilla::BulkWriteHandle<char16_t>, nsresult>
XMLHttpRequestStringWriterHelper::BulkWrite(uint32_t aCapacity) {
  return mBuffer->UnsafeBulkWrite(aCapacity);
}

}  // namespace mozilla::dom