/*
  ==============================================================================

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2020 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

OpenGLShaderProgram::OpenGLShaderProgram (const OpenGLContext& c) noexcept  : context (c)
{
}

OpenGLShaderProgram::~OpenGLShaderProgram() noexcept
{
    release();
}

GLuint OpenGLShaderProgram::getProgramID() const noexcept
{
    if (programID == 0)
    {
        // This method should only be called when the current thread has an active OpenGL context.
        jassert (OpenGLHelpers::isContextActive());

        programID = context.extensions.glCreateProgram();
    }

    return programID;
}

void OpenGLShaderProgram::release() noexcept
{
    if (programID != 0)
    {
        context.extensions.glDeleteProgram (programID);
        programID = 0;
    }
}

double OpenGLShaderProgram::getLanguageVersion()
{
    return String::fromUTF8 ((const char*) glGetString (GL_SHADING_LANGUAGE_VERSION))
            .retainCharacters("1234567890.").getDoubleValue();
}

bool OpenGLShaderProgram::addShader (const String& code, GLenum type)
{
    GLuint shaderID = context.extensions.glCreateShader (type);

    const GLchar* c = code.toRawUTF8();
    context.extensions.glShaderSource (shaderID, 1, &c, nullptr);

    context.extensions.glCompileShader (shaderID);

    GLint status = GL_FALSE;
    context.extensions.glGetShaderiv (shaderID, GL_COMPILE_STATUS, &status);

    if (status == GL_FALSE)
    {
        GLchar infoLog [16384];
        GLsizei infoLogLength = 0;
        context.extensions.glGetShaderInfoLog (shaderID, sizeof (infoLog), &infoLogLength, infoLog);
        errorLog = String (infoLog, (size_t) infoLogLength);

       #if JUCE_DEBUG && ! JUCE_DONT_ASSERT_ON_GLSL_COMPILE_ERROR
        // Your GLSL code contained compile errors!
        // Hopefully this compile log should help to explain what went wrong.
        DBG (errorLog);
        jassertfalse;
       #endif

        return false;
    }

    context.extensions.glAttachShader (getProgramID(), shaderID);
    context.extensions.glDeleteShader (shaderID);
    JUCE_CHECK_OPENGL_ERROR
    return true;
}

bool OpenGLShaderProgram::addVertexShader (const String& code)    { return addShader (code, GL_VERTEX_SHADER); }
bool OpenGLShaderProgram::addFragmentShader (const String& code)  { return addShader (code, GL_FRAGMENT_SHADER); }

bool OpenGLShaderProgram::link() noexcept
{
    // This method can only be used when the current thread has an active OpenGL context.
    jassert (OpenGLHelpers::isContextActive());

    GLuint progID = getProgramID();

    context.extensions.glLinkProgram (progID);

    GLint status = GL_FALSE;
    context.extensions.glGetProgramiv (progID, GL_LINK_STATUS, &status);

    if (status == GL_FALSE)
    {
        GLchar infoLog [16384];
        GLsizei infoLogLength = 0;
        context.extensions.glGetProgramInfoLog (progID, sizeof (infoLog), &infoLogLength, infoLog);
        errorLog = String (infoLog, (size_t) infoLogLength);

       #if JUCE_DEBUG && ! JUCE_DONT_ASSERT_ON_GLSL_COMPILE_ERROR
        // Your GLSL code contained link errors!
        // Hopefully this compile log should help to explain what went wrong.
        DBG (errorLog);
        jassertfalse;
       #endif
    }

    JUCE_CHECK_OPENGL_ERROR
    return status != GL_FALSE;
}

void OpenGLShaderProgram::use() const noexcept
{
    // The shader program must have been successfully linked when this method is called!
    jassert (programID != 0);

    context.extensions.glUseProgram (programID);
}

GLint OpenGLShaderProgram::getUniformIDFromName (const char* uniformName) const noexcept
{
    // The shader program must be active when this method is called!
    jassert (programID != 0);

    return (GLint) context.extensions.glGetUniformLocation (programID, uniformName);
}

void OpenGLShaderProgram::setUniform (const char* name, GLfloat n1) noexcept                                       { context.extensions.glUniform1f  (getUniformIDFromName (name), n1); }
void OpenGLShaderProgram::setUniform (const char* name, GLint n1) noexcept                                         { context.extensions.glUniform1i  (getUniformIDFromName (name), n1); }
void OpenGLShaderProgram::setUniform (const char* name, GLfloat n1, GLfloat n2) noexcept                           { context.extensions.glUniform2f  (getUniformIDFromName (name), n1, n2); }
void OpenGLShaderProgram::setUniform (const char* name, GLfloat n1, GLfloat n2, GLfloat n3) noexcept               { context.extensions.glUniform3f  (getUniformIDFromName (name), n1, n2, n3); }
void OpenGLShaderProgram::setUniform (const char* name, GLfloat n1, GLfloat n2, GLfloat n3, GLfloat n4) noexcept   { context.extensions.glUniform4f  (getUniformIDFromName (name), n1, n2, n3, n4); }
void OpenGLShaderProgram::setUniform (const char* name, GLint n1, GLint n2, GLint n3, GLint n4) noexcept           { context.extensions.glUniform4i  (getUniformIDFromName (name), n1, n2, n3, n4); }
void OpenGLShaderProgram::setUniform (const char* name, const GLfloat* values, GLsizei numValues) noexcept         { context.extensions.glUniform1fv (getUniformIDFromName (name), numValues, values); }
void OpenGLShaderProgram::setUniformMat2 (const char* name, const GLfloat* v, GLint num, GLboolean trns) noexcept  { context.extensions.glUniformMatrix2fv (getUniformIDFromName (name), num, trns, v); }
void OpenGLShaderProgram::setUniformMat3 (const char* name, const GLfloat* v, GLint num, GLboolean trns) noexcept  { context.extensions.glUniformMatrix3fv (getUniformIDFromName (name), num, trns, v); }
void OpenGLShaderProgram::setUniformMat4 (const char* name, const GLfloat* v, GLint num, GLboolean trns) noexcept  { context.extensions.glUniformMatrix4fv (getUniformIDFromName (name), num, trns, v); }

//==============================================================================
OpenGLShaderProgram::Attribute::Attribute (const OpenGLShaderProgram& program, const char* name)
    : attributeID ((GLuint) program.context.extensions.glGetAttribLocation (program.getProgramID(), name))
{
   #if JUCE_DEBUG && ! JUCE_DONT_ASSERT_ON_GLSL_COMPILE_ERROR
    jassert ((GLint) attributeID >= 0);
   #endif
}

//==============================================================================
OpenGLShaderProgram::Uniform::Uniform (const OpenGLShaderProgram& program, const char* const name)
    : uniformID (program.context.extensions.glGetUniformLocation (program.getProgramID(), name)), context (program.context)
{
   #if JUCE_DEBUG && ! JUCE_DONT_ASSERT_ON_GLSL_COMPILE_ERROR
    jassert (uniformID >= 0);
   #endif
}

void OpenGLShaderProgram::Uniform::set (GLfloat n1) const noexcept                                    { context.extensions.glUniform1f (uniformID, n1); }
void OpenGLShaderProgram::Uniform::set (GLint n1) const noexcept                                      { context.extensions.glUniform1i (uniformID, n1); }
void OpenGLShaderProgram::Uniform::set (GLfloat n1, GLfloat n2) const noexcept                        { context.extensions.glUniform2f (uniformID, n1, n2); }
void OpenGLShaderProgram::Uniform::set (GLfloat n1, GLfloat n2, GLfloat n3) const noexcept            { context.extensions.glUniform3f (uniformID, n1, n2, n3); }
void OpenGLShaderProgram::Uniform::set (GLfloat n1, GLfloat n2, GLfloat n3, GLfloat n4) const noexcept  { context.extensions.glUniform4f (uniformID, n1, n2, n3, n4); }
void OpenGLShaderProgram::Uniform::set (GLint n1, GLint n2, GLint n3, GLint n4) const noexcept        { context.extensions.glUniform4i (uniformID, n1, n2, n3, n4); }
void OpenGLShaderProgram::Uniform::set (const GLfloat* values, GLsizei numValues) const noexcept      { context.extensions.glUniform1fv (uniformID, numValues, values); }

void OpenGLShaderProgram::Uniform::setMatrix2 (const GLfloat* v, GLint num, GLboolean trns) const noexcept { context.extensions.glUniformMatrix2fv (uniformID, num, trns, v); }
void OpenGLShaderProgram::Uniform::setMatrix3 (const GLfloat* v, GLint num, GLboolean trns) const noexcept { context.extensions.glUniformMatrix3fv (uniformID, num, trns, v); }
void OpenGLShaderProgram::Uniform::setMatrix4 (const GLfloat* v, GLint num, GLboolean trns) const noexcept { context.extensions.glUniformMatrix4fv (uniformID, num, trns, v); }

} // namespace juce