#include "gl_calls.h"

const char *DefaultVertexShaderSource = "#version 330 core\n"
"layout (location = 0) in vec3 aPos;\n"
"layout (location = 1) in vec2 aTexCoord;\n"
"out vec2 TexCoord;\n"
"uniform int VertexMode;\n"
"uniform vec3 CompDimensions;\n"
"void main()\n"
"{\n"
" if (VertexMode == 0) {\n"
"   gl_Position = vec4(aPos, 1.0);\n"
"} else {\n"
"   gl_Position = vec4(vec2(aPos.x / CompDimensions.x, aPos.y / CompDimensions.y) * 2 - 1.0f, 0.0f, 1.0);\n"
"}\n"
" TexCoord = aTexCoord;\n"
"}\0";
const char *DefaultFragmentShaderSource = "#version 330 core\n"
"out vec4 FragColor;\n"
"in vec2 TexCoord;\n"
"uniform sampler2D Texture;\n"
"uniform int FragmentMode;\n"
"void main()\n"
"{\n"
"vec4 Col = texture(Texture, TexCoord);\n"
" if (FragmentMode == 0) {\n"
"   FragColor = Col;\n"
"} else {\n"
"   FragColor = vec4(vec3(1.0f), Col.a);\n"
"}\n"
"}\0";

static void GL_InitDefaultShader() {
    DefaultVertexShader = glCreateShader(GL_VERTEX_SHADER);

    glShaderSource(DefaultVertexShader, 1, &DefaultVertexShaderSource, NULL);
    glCompileShader(DefaultVertexShader);

    int success;
    char infoLog[512];
    glGetShaderiv(DefaultVertexShader, GL_COMPILE_STATUS, &success);

    if(!success)
    {
        glGetShaderInfoLog(DefaultVertexShader, 512, NULL, infoLog);
        printf("Vertex shader fail:\n %s", infoLog);
    }

    uint32 DefaultFragmentShader = glCreateShader(GL_FRAGMENT_SHADER);

    glShaderSource(DefaultFragmentShader, 1, &DefaultFragmentShaderSource, NULL);
    glCompileShader(DefaultFragmentShader);

    glGetShaderiv(DefaultFragmentShader, GL_COMPILE_STATUS, &success);

    if(!success)
    {
        glGetShaderInfoLog(DefaultFragmentShader, 512, NULL, infoLog);
        printf("Fragment shader fail:\n %s", infoLog);
    }

    // Shader programs link both types of shaders together.
    DefaultShaderProgram = glCreateProgram();

    glAttachShader(DefaultShaderProgram, DefaultVertexShader);
    glAttachShader(DefaultShaderProgram, DefaultFragmentShader);
    glLinkProgram(DefaultShaderProgram);

    glGetProgramiv(DefaultShaderProgram, GL_LINK_STATUS, &success);
    if(!success) {
        glGetProgramInfoLog(DefaultShaderProgram, 512, NULL, infoLog);
        printf("Shader linkage fail:\n %s", infoLog);
    }

    // Default vertex shader is still needed to link to other effects.
    glDeleteShader(DefaultFragmentShader);
}

static void GL_InitDefaultVerts() {

    unsigned int GLIndices[] = {
        0, 1, 3,
        1, 2, 3
    };

    // Indices!
    glGenVertexArrays(1, &DefaultVerts.VertexArrayObject);

    glGenBuffers(1, &DefaultVerts.ElementBufferObject);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, DefaultVerts.ElementBufferObject);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(GLIndices), GLIndices,
                 GL_STATIC_DRAW);
    glGenBuffers(1, &DefaultVerts.VertexBufferObject);

    // Our vertices need to be stored in this buffer.
    glBindBuffer(GL_ARRAY_BUFFER, DefaultVerts.VertexBufferObject);
    glBufferData(GL_ARRAY_BUFFER, sizeof(GL_DefaultVertices), GL_DefaultVertices, GL_STATIC_DRAW);

    // position attribute
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    // texture coordinate (note the last parameter's offset)
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);
}

void
GL_GenAndBindTexture(GLuint *GLTexture, int Width, int Height, int BytesPerPixel, void *BufferAddress)
{
    glGenTextures(1, GLTexture);
    glBindTexture(GL_TEXTURE_2D, *GLTexture);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    int ByteFlag = (BytesPerPixel == 4) ? GL_RGBA : GL_RGBA16;
    int ByteFlag2 = (BytesPerPixel == 4) ? GL_UNSIGNED_BYTE : GL_UNSIGNED_SHORT;
    glTexImage2D(GL_TEXTURE_2D, 0, ByteFlag, Width, Height, 0, GL_RGBA, ByteFlag2, BufferAddress);
}

static void
GL_BindDefaultVertexArrays()
{
    glBindVertexArray(DefaultVerts.VertexArrayObject);
    // Switch to main buffer
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, DefaultVerts.ElementBufferObject);
    glBindBuffer(GL_ARRAY_BUFFER, DefaultVerts.VertexBufferObject);
    glBufferData(GL_ARRAY_BUFFER, sizeof(GL_DefaultVertices), GL_DefaultVertices, GL_STATIC_DRAW);
    // position attribute
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    // texture coordinate (note the last parameter's offset)
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);

}

void
GL_InitHWBuffer(gl_effect_layer *Test)
{
    glGenFramebuffers(1, &Test->FramebufferObject);
    glGenTextures(1, &Test->Texture);
    glGenRenderbuffers(1, &Test->Color_Renderbuffer);
    glGenRenderbuffers(1, &Test->Stencil_Renderbuffer);
    Test->Initialized = true;
}

void
GL_DeleteHWBuffer(gl_effect_layer *Test)
{
    glDeleteFramebuffers(1, &Test->FramebufferObject);
    glDeleteTextures(1, &Test->Texture);
    glDeleteRenderbuffers(1, &Test->Color_Renderbuffer);
    glDeleteRenderbuffers(1, &Test->Stencil_Renderbuffer);
    Test->Initialized = true;
}

void
GL_UpdateTexture(gl_effect_layer *Test, void *Data, uint16 Width, uint16 Height, uint16 BytesPerPixel, bool32 Multisample)
{
    glViewport(0, 0, Width, Height);

    if (!Test->Initialized) {
        GL_InitHWBuffer(Test);
    }

    GLenum Target = GL_TEXTURE_2D;
    if (Multisample)
        Target = GL_TEXTURE_2D_MULTISAMPLE;

    glBindTexture(Target, Test->Texture);

    int Depth = 0, StencilDepth = 0;
    if (BytesPerPixel == 4) {
        Depth = GL_RGBA8;
        StencilDepth = GL_STENCIL_INDEX8;
    } else if (BytesPerPixel == 8) {
        Depth = GL_RGBA16;
        StencilDepth = GL_STENCIL_INDEX16;
    }

    if (Multisample) {
        // glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, 4, GL_RGB, Width, Height, GL_TRUE);
        glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, 0);

        glBindRenderbuffer(GL_RENDERBUFFER, Test->Color_Renderbuffer);

        glRenderbufferStorageMultisample(GL_RENDERBUFFER, 4, Depth, Width, Height);

        glBindRenderbuffer(GL_RENDERBUFFER, (GLuint)Test->Stencil_Renderbuffer );
        glRenderbufferStorageMultisample(GL_RENDERBUFFER, 4, StencilDepth, Width, Height );
    } else {
        glTexParameteri(Target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameteri(Target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
        glTexParameteri(Target, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(Target, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        // glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, Width, Height, 0, GL_RGBA,
        //              GL_UNSIGNED_BYTE, Data);
        glBindTexture(GL_TEXTURE_2D, 0);

        glBindRenderbuffer(GL_RENDERBUFFER, Test->Color_Renderbuffer);
        glRenderbufferStorage(GL_RENDERBUFFER, Depth, Width, Height);

        glBindRenderbuffer(GL_RENDERBUFFER, (GLuint)Test->Stencil_Renderbuffer );
        glRenderbufferStorage(GL_RENDERBUFFER, StencilDepth, Width, Height );
    }

    glBindFramebuffer(GL_FRAMEBUFFER, Test->FramebufferObject);

    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, Test->Color_Renderbuffer);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, Test->Stencil_Renderbuffer);

    GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
    if (status != GL_FRAMEBUFFER_COMPLETE) {
        printf("incomplete framebuffer");
        Assert(0);
    }

    glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

static uint16
Effect_GL_InitShader(const char *FragmentShaderEffectSource)
{
    glShaderSource(DefaultVertexShader, 1, &DefaultVertexShaderSource, NULL);
    glCompileShader(DefaultVertexShader);

    int success;
    char infoLog[512];
    glGetShaderiv(DefaultVertexShader, GL_COMPILE_STATUS, &success);

    if(!success)
    {
        glGetShaderInfoLog(DefaultVertexShader, 512, NULL, infoLog);
        printf("Vertex shader fail:\n %s", infoLog);
    }

    uint32 FragmentShader = glCreateShader(GL_FRAGMENT_SHADER);

    glShaderSource(FragmentShader, 1, &FragmentShaderEffectSource, NULL);
    glCompileShader(FragmentShader);

    glGetShaderiv(FragmentShader, GL_COMPILE_STATUS, &success);

    if(!success)
    {
        glGetShaderInfoLog(FragmentShader, 512, NULL, infoLog);
        printf("Fragment shader fail:\n %s", infoLog);
    }

    uint16 ShaderProgram = glCreateProgram();

    glAttachShader(ShaderProgram, DefaultVertexShader);
    glAttachShader(ShaderProgram, FragmentShader);
    glLinkProgram(ShaderProgram);

    glGetProgramiv(ShaderProgram, GL_LINK_STATUS, &success);
    if(!success) {
        glGetProgramInfoLog(ShaderProgram, 512, NULL, infoLog);
        printf("Shader linkage fail:\n %s", infoLog);
    }

    glDeleteShader(FragmentShader);

    glUseProgram(ShaderProgram);

    return ShaderProgram;
}