// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "android_webview/browser/scoped_app_gl_state_restore.h"

#include "base/debug/trace_event.h"
#include "base/lazy_instance.h"
#include "ui/gl/gl_context.h"
#include "ui/gl/gl_surface_stub.h"

namespace android_webview {

namespace {

// "App" context is a bit of a stretch. Basically we use this context while
// saving and restoring the App GL state.
class AppContextSurface {
 public:
  AppContextSurface()
      : surface(new gfx::GLSurfaceStub),
        context(gfx::GLContext::CreateGLContext(NULL,
                                                surface.get(),
                                                gfx::PreferDiscreteGpu)) {}
  void MakeCurrent() { context->MakeCurrent(surface.get()); }

 private:
  scoped_refptr<gfx::GLSurfaceStub> surface;
  scoped_refptr<gfx::GLContext> context;

  DISALLOW_COPY_AND_ASSIGN(AppContextSurface);
};

base::LazyInstance<AppContextSurface> g_app_context_surface =
    LAZY_INSTANCE_INITIALIZER;

// Make the global g_app_context_surface current so that the gl_binding is not
// NULL for making gl* calls. The binding can be null if another GlContext was
// destroyed immediately before gl* calls here.
void MakeAppContextCurrent() {
  g_app_context_surface.Get().MakeCurrent();
}

void GLEnableDisable(GLenum cap, bool enable) {
  if (enable)
    glEnable(cap);
  else
    glDisable(cap);
}

GLint g_gl_max_texture_units = 0;

}  // namespace

ScopedAppGLStateRestore::ScopedAppGLStateRestore(CallMode mode) : mode_(mode) {
  TRACE_EVENT0("android_webview", "AppGLStateSave");
  MakeAppContextCurrent();

  glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &vertex_array_buffer_binding_);
  glGetIntegerv(GL_ELEMENT_ARRAY_BUFFER_BINDING, &index_array_buffer_binding_);

  switch(mode_) {
    case MODE_DRAW:
      DCHECK_EQ(0, vertex_array_buffer_binding_);
      DCHECK_EQ(0, index_array_buffer_binding_);
      break;
    case MODE_RESOURCE_MANAGEMENT:
      glGetBooleanv(GL_BLEND, &blend_enabled_);
      glGetIntegerv(GL_BLEND_SRC_RGB, &blend_src_rgb_);
      glGetIntegerv(GL_BLEND_SRC_ALPHA, &blend_src_alpha_);
      glGetIntegerv(GL_BLEND_DST_RGB, &blend_dest_rgb_);
      glGetIntegerv(GL_BLEND_DST_ALPHA, &blend_dest_alpha_);
      glGetIntegerv(GL_VIEWPORT, viewport_);
      glGetBooleanv(GL_SCISSOR_TEST, &scissor_test_);
      glGetIntegerv(GL_SCISSOR_BOX, scissor_box_);
      break;
  }

  glGetIntegerv(GL_PACK_ALIGNMENT, &pack_alignment_);
  glGetIntegerv(GL_UNPACK_ALIGNMENT, &unpack_alignment_);

  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(vertex_attrib_); ++i) {
    glGetVertexAttribiv(
        i, GL_VERTEX_ATTRIB_ARRAY_ENABLED, &vertex_attrib_[i].enabled);
    glGetVertexAttribiv(
        i, GL_VERTEX_ATTRIB_ARRAY_SIZE, &vertex_attrib_[i].size);
    glGetVertexAttribiv(
        i, GL_VERTEX_ATTRIB_ARRAY_TYPE, &vertex_attrib_[i].type);
    glGetVertexAttribiv(
        i, GL_VERTEX_ATTRIB_ARRAY_NORMALIZED, &vertex_attrib_[i].normalized);
    glGetVertexAttribiv(
        i, GL_VERTEX_ATTRIB_ARRAY_STRIDE, &vertex_attrib_[i].stride);
    glGetVertexAttribPointerv(
        i, GL_VERTEX_ATTRIB_ARRAY_POINTER, &vertex_attrib_[i].pointer);
  }

  glGetBooleanv(GL_DEPTH_TEST, &depth_test_);
  glGetBooleanv(GL_CULL_FACE, &cull_face_);
  glGetIntegerv(GL_CULL_FACE_MODE, &cull_face_mode_);
  glGetBooleanv(GL_COLOR_WRITEMASK, color_mask_);
  glGetIntegerv(GL_CURRENT_PROGRAM, &current_program_);
  glGetFloatv(GL_COLOR_CLEAR_VALUE, color_clear_);
  glGetFloatv(GL_DEPTH_CLEAR_VALUE, &depth_clear_);
  glGetIntegerv(GL_DEPTH_FUNC, &depth_func_);
  glGetBooleanv(GL_DEPTH_WRITEMASK, &depth_mask_);
  glGetFloatv(GL_DEPTH_RANGE, depth_rage_);
  glGetIntegerv(GL_FRONT_FACE, &front_face_);
  glGetIntegerv(GL_GENERATE_MIPMAP_HINT, &hint_generate_mipmap_);
  glGetFloatv(GL_LINE_WIDTH, &line_width_);
  glGetFloatv(GL_POLYGON_OFFSET_FACTOR, &polygon_offset_factor_);
  glGetFloatv(GL_POLYGON_OFFSET_UNITS, &polygon_offset_units_);
  glGetFloatv(GL_SAMPLE_COVERAGE_VALUE, &sample_coverage_value_);
  glGetBooleanv(GL_SAMPLE_COVERAGE_INVERT, &sample_coverage_invert_);

  glGetBooleanv(GL_DITHER, &enable_dither_);
  glGetBooleanv(GL_POLYGON_OFFSET_FILL, &enable_polygon_offset_fill_);
  glGetBooleanv(GL_SAMPLE_ALPHA_TO_COVERAGE, &enable_sample_alpha_to_coverage_);
  glGetBooleanv(GL_SAMPLE_COVERAGE, &enable_sample_coverage_);

  glGetBooleanv(GL_STENCIL_TEST, &stencil_test_);
  glGetIntegerv(GL_STENCIL_FUNC, &stencil_func_);
  glGetIntegerv(GL_STENCIL_VALUE_MASK, &stencil_mask_);
  glGetIntegerv(GL_STENCIL_REF, &stencil_ref_);

  glGetIntegerv(GL_FRAMEBUFFER_BINDING_EXT, &framebuffer_binding_ext_);

  if (!g_gl_max_texture_units) {
    glGetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, &g_gl_max_texture_units);
    DCHECK_GT(g_gl_max_texture_units, 0);
  }

  glGetIntegerv(GL_ACTIVE_TEXTURE, &active_texture_);

  texture_bindings_.resize(g_gl_max_texture_units);
  for (int ii = 0; ii < g_gl_max_texture_units; ++ii) {
    glActiveTexture(GL_TEXTURE0 + ii);
    TextureBindings& bindings = texture_bindings_[ii];
    glGetIntegerv(GL_TEXTURE_BINDING_2D, &bindings.texture_2d);
    glGetIntegerv(GL_TEXTURE_BINDING_CUBE_MAP, &bindings.texture_cube_map);
    glGetIntegerv(GL_TEXTURE_BINDING_EXTERNAL_OES,
                  &bindings.texture_external_oes);
  }
}

ScopedAppGLStateRestore::~ScopedAppGLStateRestore() {
  TRACE_EVENT0("android_webview", "AppGLStateRestore");
  MakeAppContextCurrent();

  glBindFramebufferEXT(GL_FRAMEBUFFER, framebuffer_binding_ext_);
  glBindBuffer(GL_ARRAY_BUFFER, vertex_array_buffer_binding_);
  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_array_buffer_binding_);

  for (int ii = 0; ii < g_gl_max_texture_units; ++ii) {
    glActiveTexture(GL_TEXTURE0 + ii);
    TextureBindings& bindings = texture_bindings_[ii];
    glBindTexture(GL_TEXTURE_2D, bindings.texture_2d);
    glBindTexture(GL_TEXTURE_CUBE_MAP, bindings.texture_cube_map);
    glBindTexture(GL_TEXTURE_EXTERNAL_OES, bindings.texture_external_oes);
  }
  glActiveTexture(active_texture_);

  glPixelStorei(GL_PACK_ALIGNMENT, pack_alignment_);
  glPixelStorei(GL_UNPACK_ALIGNMENT, unpack_alignment_);

  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(vertex_attrib_); ++i) {
    glVertexAttribPointer(i,
                          vertex_attrib_[i].size,
                          vertex_attrib_[i].type,
                          vertex_attrib_[i].normalized,
                          vertex_attrib_[i].stride,
                          vertex_attrib_[i].pointer);

    if (vertex_attrib_[i].enabled) {
      glEnableVertexAttribArray(i);
    } else {
      glDisableVertexAttribArray(i);
    }
  }

  GLEnableDisable(GL_DEPTH_TEST, depth_test_);

  GLEnableDisable(GL_CULL_FACE, cull_face_);
  glCullFace(cull_face_mode_);

  glColorMask(color_mask_[0], color_mask_[1], color_mask_[2], color_mask_[3]);

  glUseProgram(current_program_);

  glClearColor(
      color_clear_[0], color_clear_[1], color_clear_[2], color_clear_[3]);
  glClearDepth(depth_clear_);
  glDepthFunc(depth_func_);
  glDepthMask(depth_mask_);
  glDepthRange(depth_rage_[0], depth_rage_[1]);
  glFrontFace(front_face_);
  glHint(GL_GENERATE_MIPMAP_HINT, hint_generate_mipmap_);
  // TODO(boliu): GL_FRAGMENT_SHADER_DERIVATIVE_HINT_OES ??
  glLineWidth(line_width_);
  glPolygonOffset(polygon_offset_factor_, polygon_offset_units_);
  glSampleCoverage(sample_coverage_value_, sample_coverage_invert_);

  GLEnableDisable(GL_DITHER, enable_dither_);
  GLEnableDisable(GL_POLYGON_OFFSET_FILL, enable_polygon_offset_fill_);
  GLEnableDisable(GL_SAMPLE_ALPHA_TO_COVERAGE,
                  enable_sample_alpha_to_coverage_);
  GLEnableDisable(GL_SAMPLE_COVERAGE, enable_sample_coverage_);

  switch(mode_) {
    case MODE_DRAW:
      // No-op.
      break;
    case MODE_RESOURCE_MANAGEMENT:
      GLEnableDisable(GL_BLEND, blend_enabled_);
      glBlendFuncSeparate(
          blend_src_rgb_, blend_dest_rgb_, blend_src_alpha_, blend_dest_alpha_);

      glViewport(viewport_[0], viewport_[1], viewport_[2], viewport_[3]);

      GLEnableDisable(GL_SCISSOR_TEST, scissor_test_);

      glScissor(
          scissor_box_[0], scissor_box_[1], scissor_box_[2], scissor_box_[3]);
      break;
  }

  GLEnableDisable(GL_STENCIL_TEST, stencil_test_);
  glStencilFunc(stencil_func_, stencil_mask_, stencil_ref_);
}

}  // namespace android_webview