// Copyright 2011 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 "cc/program_binding.h"

#include "base/debug/trace_event.h"
#include "cc/geometry_binding.h"
#include "cc/gl_renderer.h" // For the GLC() macro.
#include "third_party/WebKit/Source/Platform/chromium/public/WebGraphicsContext3D.h"
#include "third_party/khronos/GLES2/gl2.h"

using WebKit::WebGraphicsContext3D;

namespace cc {

ProgramBindingBase::ProgramBindingBase()
    : m_program(0)
    , m_vertexShaderId(0)
    , m_fragmentShaderId(0)
    , m_initialized(false)
{
}

ProgramBindingBase::~ProgramBindingBase()
{
    // If you hit these asserts, you initialized but forgot to call cleanup().
    DCHECK(!m_program);
    DCHECK(!m_vertexShaderId);
    DCHECK(!m_fragmentShaderId);
    DCHECK(!m_initialized);
}

void ProgramBindingBase::init(WebGraphicsContext3D* context, const std::string& vertexShader, const std::string& fragmentShader)
{
    TRACE_EVENT0("cc", "ProgramBindingBase::init");
    m_vertexShaderId = loadShader(context, GL_VERTEX_SHADER, vertexShader);
    if (!m_vertexShaderId) {
        if (!IsContextLost(context))
            LOG(ERROR) << "Failed to create vertex shader";
        return;
    }

    m_fragmentShaderId = loadShader(context, GL_FRAGMENT_SHADER, fragmentShader);
    if (!m_fragmentShaderId) {
        GLC(context, context->deleteShader(m_vertexShaderId));
        m_vertexShaderId = 0;
        if (!IsContextLost(context))
            LOG(ERROR) << "Failed to create fragment shader";
        return;
    }

    m_program = createShaderProgram(context, m_vertexShaderId, m_fragmentShaderId);
    DCHECK(m_program || IsContextLost(context));
}

void ProgramBindingBase::link(WebGraphicsContext3D* context)
{
    GLC(context, context->linkProgram(m_program));
    cleanupShaders(context);
#ifndef NDEBUG
    int linked = 0;
    GLC(context, context->getProgramiv(m_program, GL_LINK_STATUS, &linked));
    if (!linked) {
        if (!IsContextLost(context))
            LOG(ERROR) << "Failed to link shader program";
        GLC(context, context->deleteProgram(m_program));
    }
#endif
}

void ProgramBindingBase::cleanup(WebGraphicsContext3D* context)
{
    m_initialized = false;
    if (!m_program)
        return;

    DCHECK(context);
    GLC(context, context->deleteProgram(m_program));
    m_program = 0;

    cleanupShaders(context);
}

unsigned ProgramBindingBase::loadShader(WebGraphicsContext3D* context, unsigned type, const std::string& shaderSource)
{
    unsigned shader = context->createShader(type);
    if (!shader)
        return 0;
    GLC(context, context->shaderSource(shader, shaderSource.data()));
    GLC(context, context->compileShader(shader));
#ifndef NDEBUG
    int compiled = 0;
    GLC(context, context->getShaderiv(shader, GL_COMPILE_STATUS, &compiled));
    if (!compiled) {
        GLC(context, context->deleteShader(shader));
        return 0;
    }
#endif
    return shader;
}

unsigned ProgramBindingBase::createShaderProgram(WebGraphicsContext3D* context, unsigned vertexShader, unsigned fragmentShader)
{
    unsigned programObject = context->createProgram();
    if (!programObject) {
        if (!IsContextLost(context))
            LOG(ERROR) << "Failed to create shader program";
        return 0;
    }

    GLC(context, context->attachShader(programObject, vertexShader));
    GLC(context, context->attachShader(programObject, fragmentShader));

    // Bind the common attrib locations.
    GLC(context, context->bindAttribLocation(programObject, GeometryBinding::positionAttribLocation(), "a_position"));
    GLC(context, context->bindAttribLocation(programObject, GeometryBinding::texCoordAttribLocation(), "a_texCoord"));

    return programObject;
}

void ProgramBindingBase::cleanupShaders(WebGraphicsContext3D* context)
{
    if (m_vertexShaderId) {
        GLC(context, context->deleteShader(m_vertexShaderId));
        m_vertexShaderId = 0;
    }
    if (m_fragmentShaderId) {
        GLC(context, context->deleteShader(m_fragmentShaderId));
        m_fragmentShaderId = 0;
    }
}

bool ProgramBindingBase::IsContextLost(WebGraphicsContext3D* context) {
    return (context->getGraphicsResetStatusARB() != GL_NO_ERROR);
}

}  // namespace cc