/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* 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 "WebGL2Context.h"

#include "GLContext.h"
#include "WebGLBuffer.h"
#include "WebGLTransformFeedback.h"

namespace mozilla {

// -------------------------------------------------------------------------
// Buffer objects

void WebGL2Context::CopyBufferSubData(GLenum readTarget, GLenum writeTarget,
                                      GLintptr readOffset, GLintptr writeOffset,
                                      GLsizeiptr size) {
  const char funcName[] = "copyBufferSubData";
  if (IsContextLost()) return;

  const auto& readBuffer = ValidateBufferSelection(funcName, readTarget);
  if (!readBuffer) return;

  const auto& writeBuffer = ValidateBufferSelection(funcName, writeTarget);
  if (!writeBuffer) return;

  if (!ValidateNonNegative(funcName, "readOffset", readOffset) ||
      !ValidateNonNegative(funcName, "writeOffset", writeOffset) ||
      !ValidateNonNegative(funcName, "size", size)) {
    return;
  }

  const auto fnValidateOffsetSize = [&](const char* info, GLintptr offset,
                                        const WebGLBuffer* buffer) {
    const auto neededBytes = CheckedInt<size_t>(offset) + size;
    if (!neededBytes.isValid() || neededBytes.value() > buffer->ByteLength()) {
      ErrorInvalidValue("%s: Invalid %s range.", funcName, info);
      return false;
    }
    return true;
  };

  if (!fnValidateOffsetSize("read", readOffset, readBuffer) ||
      !fnValidateOffsetSize("write", writeOffset, writeBuffer)) {
    return;
  }

  if (readBuffer == writeBuffer) {
    MOZ_ASSERT((CheckedInt<WebGLsizeiptr>(readOffset) + size).isValid());
    MOZ_ASSERT((CheckedInt<WebGLsizeiptr>(writeOffset) + size).isValid());

    const bool separate =
        (readOffset + size <= writeOffset || writeOffset + size <= readOffset);
    if (!separate) {
      ErrorInvalidValue(
          "%s: ranges [readOffset, readOffset + size) and"
          " [writeOffset, writeOffset + size) overlap",
          funcName);
      return;
    }
  }

  const auto& readType = readBuffer->Content();
  const auto& writeType = writeBuffer->Content();
  MOZ_ASSERT(readType != WebGLBuffer::Kind::Undefined);
  MOZ_ASSERT(writeType != WebGLBuffer::Kind::Undefined);
  if (writeType != readType) {
    ErrorInvalidOperation(
        "%s: Can't copy %s data to %s data.", funcName,
        (readType == WebGLBuffer::Kind::OtherData) ? "other" : "element",
        (writeType == WebGLBuffer::Kind::OtherData) ? "other" : "element");
    return;
  }

  const ScopedLazyBind readBind(gl, readTarget, readBuffer);
  const ScopedLazyBind writeBind(gl, writeTarget, writeBuffer);
  gl->fCopyBufferSubData(readTarget, writeTarget, readOffset, writeOffset,
                         size);

  writeBuffer->ResetLastUpdateFenceId();
}

void WebGL2Context::GetBufferSubData(GLenum target, GLintptr srcByteOffset,
                                     const dom::ArrayBufferView& dstData,
                                     GLuint dstElemOffset,
                                     GLuint dstElemCountOverride) {
  const char funcName[] = "getBufferSubData";
  if (IsContextLost()) return;

  if (!ValidateNonNegative(funcName, "srcByteOffset", srcByteOffset)) return;

  uint8_t* bytes;
  size_t byteLen;
  if (!ValidateArrayBufferView(funcName, dstData, dstElemOffset,
                               dstElemCountOverride, &bytes, &byteLen)) {
    return;
  }

  ////

  const auto& buffer = ValidateBufferSelection(funcName, target);
  if (!buffer) return;

  if (!buffer->ValidateRange(funcName, srcByteOffset, byteLen)) return;

  ////

  if (!CheckedInt<GLsizeiptr>(byteLen).isValid()) {
    ErrorOutOfMemory("%s: Size too large.", funcName);
    return;
  }
  const GLsizeiptr glByteLen(byteLen);

  ////

  switch (buffer->mUsage) {
    case LOCAL_GL_STATIC_READ:
    case LOCAL_GL_STREAM_READ:
    case LOCAL_GL_DYNAMIC_READ:
      if (mCompletedFenceId < buffer->mLastUpdateFenceId) {
        GenerateWarning(
            "%s: Reading from a buffer without checking for previous"
            " command completion likely causes pipeline stalls."
            " Please use FenceSync.",
            funcName);
      }
      break;
    default:
      GenerateWarning(
          "%s: Reading from a buffer with usage other than *_READ"
          " causes pipeline stalls. Copy through a STREAM_READ buffer.",
          funcName);
      break;
  }

  ////

  const ScopedLazyBind readBind(gl, target, buffer);

  if (byteLen) {
    const bool isTF = (target == LOCAL_GL_TRANSFORM_FEEDBACK_BUFFER);
    GLenum mapTarget = target;
    if (isTF) {
      gl->fBindTransformFeedback(LOCAL_GL_TRANSFORM_FEEDBACK, mEmptyTFO);
      gl->fBindBuffer(LOCAL_GL_ARRAY_BUFFER, buffer->mGLName);
      mapTarget = LOCAL_GL_ARRAY_BUFFER;
    }

    const auto mappedBytes = gl->fMapBufferRange(
        mapTarget, srcByteOffset, glByteLen, LOCAL_GL_MAP_READ_BIT);
    memcpy(bytes, mappedBytes, byteLen);
    gl->fUnmapBuffer(mapTarget);

    if (isTF) {
      const GLuint vbo = (mBoundArrayBuffer ? mBoundArrayBuffer->mGLName : 0);
      gl->fBindBuffer(LOCAL_GL_ARRAY_BUFFER, vbo);
      const GLuint tfo =
          (mBoundTransformFeedback ? mBoundTransformFeedback->mGLName : 0);
      gl->fBindTransformFeedback(LOCAL_GL_TRANSFORM_FEEDBACK, tfo);
    }
  }
}

}  // namespace mozilla