/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* 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 "mozilla/dom/TextDecoder.h"

#include "mozilla/dom/UnionTypes.h"

#include "mozilla/Encoding.h"

#include "mozilla/UniquePtrExtensions.h"

#include "nsContentUtils.h"

#include <stdint.h>

namespace mozilla {

namespace dom {

void

TextDecoder::Init(const nsAString& aLabel,

                  const TextDecoderOptions& aOptions,

                  ErrorResult& aRv)

{

  // Let encoding be the result of getting an encoding from label.

  // If encoding is failure or replacement, throw a RangeError

  // (https://encoding.spec.whatwg.org/#dom-textdecoder).

  const Encoding* encoding = Encoding::ForLabelNoReplacement(aLabel);

  if (!encoding) {

    nsAutoString label(aLabel);

    label.Trim(" \t\n\f\r");

    aRv.ThrowRangeError<MSG_ENCODING_NOT_SUPPORTED>(label);

    return;

  }

  InitWithEncoding(WrapNotNull(encoding), aOptions);

}

void

TextDecoder::InitWithEncoding(NotNull<const Encoding*> aEncoding,

                              const TextDecoderOptions& aOptions)

{

  aEncoding->Name(mEncoding);

  // Store the flags passed via our options dictionary.

  mFatal = aOptions.mFatal;

  mIgnoreBOM = aOptions.mIgnoreBOM;

  // Create a decoder object for mEncoding.

  if (mIgnoreBOM) {

    mDecoder = aEncoding->NewDecoderWithoutBOMHandling();

  } else {

    mDecoder = aEncoding->NewDecoderWithBOMRemoval();

  }

}

void

TextDecoder::Decode(Span<const uint8_t> aInput,

                    const bool aStream,

                    nsAString& aOutDecodedString,

                    ErrorResult& aRv)

{

  aOutDecodedString.Truncate();

  CheckedInt<size_t> needed = mDecoder->MaxUTF16BufferLength(aInput.Length());

  if (!needed.isValid() ||

      needed.value() > MaxValue<nsAString::size_type>::value) {

    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);

    return;

  }

  if (!aOutDecodedString.SetLength(needed.value(), fallible)) {

    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);

    return;

  }

  uint32_t result;

  size_t read;

  size_t written;

  bool hadErrors;

  if (mFatal) {

    Tie(result, read, written) = mDecoder->DecodeToUTF16WithoutReplacement(

      aInput, aOutDecodedString, !aStream);

    if (result != kInputEmpty) {

      aRv.ThrowTypeError<MSG_DOM_DECODING_FAILED>();

      return;

    }

  } else {

    Tie(result, read, written, hadErrors) =

      mDecoder->DecodeToUTF16(aInput, aOutDecodedString, !aStream);

  }

  MOZ_ASSERT(result == kInputEmpty);

  MOZ_ASSERT(read == aInput.Length());

  MOZ_ASSERT(written <= aOutDecodedString.Length());

  Unused << hadErrors;

  if (!aOutDecodedString.SetLength(written, fallible)) {

    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);

    return;

  }

  // If the internal streaming flag of the decoder object is not set,

  // then reset the encoding algorithm state to the default values

  if (!aStream) {

    mDecoder->Encoding()->NewDecoderWithBOMRemovalInto(*mDecoder);

  }

}

void

TextDecoder::Decode(const Optional<ArrayBufferViewOrArrayBuffer>& aBuffer,

                    const TextDecodeOptions& aOptions,

                    nsAString& aOutDecodedString,

                    ErrorResult& aRv)

{

  if (!aBuffer.WasPassed()) {

    Decode(nullptr, aOptions.mStream, aOutDecodedString, aRv);

    return;

  }

  const ArrayBufferViewOrArrayBuffer& buf = aBuffer.Value();

  uint8_t* data;

  uint32_t length;

  if (buf.IsArrayBufferView()) {

    buf.GetAsArrayBufferView().ComputeLengthAndData();

    data = buf.GetAsArrayBufferView().Data();

    length = buf.GetAsArrayBufferView().Length();

  } else {

    MOZ_ASSERT(buf.IsArrayBuffer());

    buf.GetAsArrayBuffer().ComputeLengthAndData();

    data = buf.GetAsArrayBuffer().Data();

    length = buf.GetAsArrayBuffer().Length();

  }

  Decode(MakeSpan(data, length), aOptions.mStream, aOutDecodedString, aRv);

}

void

TextDecoder::GetEncoding(nsAString& aEncoding)

{

  CopyASCIItoUTF16(mEncoding, aEncoding);

  nsContentUtils::ASCIIToLower(aEncoding);

}

} // namespace dom

} // namespace mozilla