#include <Gosu/Graphics.hpp>
#include <GosuImpl/Graphics/Texture.hpp>
#include <GosuImpl/Graphics/TexChunk.hpp>
#include <Gosu/Bitmap.hpp>
#include <Gosu/Platform.hpp>
#include <stdexcept>

namespace Gosu
{
    bool undocumentedRetrofication = false;
}

Gosu::Texture::Texture(unsigned size)
: allocator(size, size), num(0)
{
    // Create texture name.
    glGenTextures(1, &name);
    if (name == static_cast<GLuint>(-1))
        throw std::runtime_error("Couldn't create OpenGL texture");
   
    // Create empty texture.
    glBindTexture(GL_TEXTURE_2D, name);
#ifdef GOSU_IS_IPHONE
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, allocator.width(), allocator.height(), 0,
                 GL_RGBA, GL_UNSIGNED_BYTE, 0);
#else
    glTexImage2D(GL_TEXTURE_2D, 0, 4, allocator.width(), allocator.height(), 0,
                 GL_RGBA, GL_UNSIGNED_BYTE, 0);
#endif
    
    if (undocumentedRetrofication)
    {
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    }
    else
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    
#ifdef GOSU_IS_WIN
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
#else
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
#endif
}

Gosu::Texture::~Texture()
{
    glDeleteTextures(1, &name);
}

unsigned Gosu::Texture::size() const
{
    return allocator.width(); // == height
}

GLuint Gosu::Texture::texName() const
{
    return name;
}

std::auto_ptr<Gosu::TexChunk>
    Gosu::Texture::tryAlloc(Graphics& graphics, Transforms& transforms,
        DrawOpQueueStack& queues, boost::shared_ptr<Texture> ptr, const Bitmap& bmp, unsigned padding)
{
    std::auto_ptr<Gosu::TexChunk> result;
    
    boost::optional<BlockAllocator::Block> block = allocator.alloc(bmp.width(), bmp.height());
    if (!block)
        return result;
    
    result.reset(new TexChunk(graphics, transforms, queues, ptr, block->left + padding, block->top + padding,
                              block->width - 2 * padding, block->height - 2 * padding, padding));
    
    glBindTexture(GL_TEXTURE_2D, name);
    glTexSubImage2D(GL_TEXTURE_2D, 0, block->left, block->top, block->width, block->height,
                 Color::GL_FORMAT, GL_UNSIGNED_BYTE, bmp.data());

    num += 1;
    return result;
}

void Gosu::Texture::free(unsigned x, unsigned y)
{
    allocator.free(x, y);
    num -= 1;
}

Gosu::Bitmap Gosu::Texture::toBitmap(unsigned x, unsigned y, unsigned width, unsigned height) const
{
#ifdef GOSU_IS_IPHONE
    throw std::logic_error("Texture::toBitmap not supported on iOS");
#else
    Gosu::Bitmap fullTexture;
    fullTexture.resize(size(), size());
    glBindTexture(GL_TEXTURE_2D, name);
    glGetTexImage(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, fullTexture.data());
    Gosu::Bitmap bitmap;
    bitmap.resize(width, height);
    bitmap.insert(fullTexture, -int(x), -int(y));
    
    return bitmap;
#endif
}