/*
 *  Aethyra
 *  Copyright (C) 2004  The Mana World Development Team
 *
 *  This file is part of Aethyra based on original code
 *  from The Mana World.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <SDL_image.h>

#include "dye.h"
#include "image.h"

#include "../log.h"
#include "../position.h"

#ifdef USE_OPENGL
bool Image::mUseOpenGL = false;
int Image::mTextureType = 0;
int Image::mTextureSize = 0;
#endif

Image::Image(SDL_Surface *image):
#ifdef USE_OPENGL
    mGLImage(0),
#endif
    mImage(image),
    mAlpha(1.0f)
{
    mBounds.x = 0;
    mBounds.y = 0;
    mBounds.w = mImage->w;
    mBounds.h = mImage->h;
}

#ifdef USE_OPENGL
Image::Image(GLuint glimage, int width, int height, int texWidth, int texHeight):
    mGLImage(glimage),
    mTexWidth(texWidth),
    mTexHeight(texHeight),
    mImage(0),
    mAlpha(1.0)
{
    mBounds.x = 0;
    mBounds.y = 0;
    mBounds.w = width;
    mBounds.h = height;
}
#endif

Image::~Image()
{
    unload();
}

Resource *Image::load(void *buffer, unsigned bufferSize)
{
    // Load the raw file data from the buffer in an RWops structure
    SDL_RWops *rw = SDL_RWFromMem(buffer, bufferSize);
    SDL_Surface *tmpImage = IMG_Load_RW(rw, 1);

    if (!tmpImage)
    {
        logger->log("Error, image load failed: %s", IMG_GetError());
        return NULL;
    }

    Image *image = load(tmpImage);

    SDL_FreeSurface(tmpImage);
    return image;
}

Resource *Image::load(void *buffer, unsigned bufferSize, Dye const &dye)
{
    SDL_RWops *rw = SDL_RWFromMem(buffer, bufferSize);
    SDL_Surface *tmpImage = IMG_Load_RW(rw, 1);

    if (!tmpImage)
    {
        logger->log("Error, image load failed: %s", IMG_GetError());
        return NULL;
    }

    SDL_PixelFormat rgba;
    rgba.palette = NULL;
    rgba.BitsPerPixel = 32;
    rgba.BytesPerPixel = 4;
    rgba.Rmask = 0xFF000000; rgba.Rloss = 0; rgba.Rshift = 24;
    rgba.Gmask = 0x00FF0000; rgba.Gloss = 0; rgba.Gshift = 16;
    rgba.Bmask = 0x0000FF00; rgba.Bloss = 0; rgba.Bshift = 8;
    rgba.Amask = 0x000000FF; rgba.Aloss = 0; rgba.Ashift = 0;
    rgba.colorkey = 0;
    rgba.alpha = 255;

    SDL_Surface *surf = SDL_ConvertSurface(tmpImage, &rgba, SDL_SWSURFACE);
    SDL_FreeSurface(tmpImage);

    Uint32 *pixels = static_cast< Uint32 * >(surf->pixels);
    for (Uint32 *p_end = pixels + surf->w * surf->h; pixels != p_end; ++pixels)
    {
        int alpha = *pixels & 255;
        if (!alpha) continue;
        int v[3];
        v[0] = (*pixels >> 24) & 255;
        v[1] = (*pixels >> 16) & 255;
        v[2] = (*pixels >> 8 ) & 255;
        dye.update(v);
        *pixels = (v[0] << 24) | (v[1] << 16) | (v[2] << 8) | alpha;
    }

    Image *image = load(surf);
    SDL_FreeSurface(surf);
    return image;
}

Image *Image::load(SDL_Surface *tmpImage)
{
#ifdef USE_OPENGL
    if (mUseOpenGL)
    {
        // Flush current error flag.
        glGetError();

        int width = tmpImage->w;
        int height = tmpImage->h;
        int realWidth = powerOfTwo(width);
        int realHeight = powerOfTwo(height);

        if (realWidth < width || realHeight < height)
        {
            logger->log("Warning: image too large, cropping to %dx%d texture!",
                    tmpImage->w, tmpImage->h);
        }

        // Make sure the alpha channel is not used, but copied to destination
        SDL_SetAlpha(tmpImage, 0, SDL_ALPHA_OPAQUE);

        // Determine 32-bit masks based on byte order
        Uint32 rmask, gmask, bmask, amask;
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
        rmask = 0xff000000;
        gmask = 0x00ff0000;
        bmask = 0x0000ff00;
        amask = 0x000000ff;
#else
        rmask = 0x000000ff;
        gmask = 0x0000ff00;
        bmask = 0x00ff0000;
        amask = 0xff000000;
#endif

        SDL_Surface *oldImage = tmpImage;
        tmpImage = SDL_CreateRGBSurface(SDL_SWSURFACE, realWidth, realHeight,
            32, rmask, gmask, bmask, amask);

        if (!tmpImage)
        {
            logger->log("Error, image convert failed: out of memory");
            return NULL;
        }

        SDL_BlitSurface(oldImage, NULL, tmpImage, NULL);

        GLuint texture;
        glGenTextures(1, &texture);
        glBindTexture(mTextureType, texture);

        if (SDL_MUSTLOCK(tmpImage))
            SDL_LockSurface(tmpImage);

        glTexImage2D(
                mTextureType, 0, 4,
                tmpImage->w, tmpImage->h,
                0, GL_RGBA, GL_UNSIGNED_BYTE,
                tmpImage->pixels);

        glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
        glTexParameteri(mTextureType, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameteri(mTextureType, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

        if (SDL_MUSTLOCK(tmpImage)) {
            SDL_UnlockSurface(tmpImage);
        }

        SDL_FreeSurface(tmpImage);

        GLenum error = glGetError();
        if (error)
        {
            std::string errmsg = "Unknown error";
            switch (error)
            {
                case GL_INVALID_ENUM:
                    errmsg = "GL_INVALID_ENUM";
                    break;
                case GL_INVALID_VALUE:
                    errmsg = "GL_INVALID_VALUE";
                    break;
                case GL_INVALID_OPERATION:
                    errmsg = "GL_INVALID_OPERATION";
                    break;
                case GL_STACK_OVERFLOW:
                    errmsg = "GL_STACK_OVERFLOW";
                    break;
                case GL_STACK_UNDERFLOW:
                    errmsg = "GL_STACK_UNDERFLOW";
                    break;
                case GL_OUT_OF_MEMORY:
                    errmsg = "GL_OUT_OF_MEMORY";
                    break;
            }
            logger->log("Error: Image GL import failed: %s", errmsg.c_str());
            return NULL;
        }

        return new Image(texture, width, height, realWidth, realHeight);
    }
#endif

    bool hasAlpha = false;

    if (tmpImage->format->BitsPerPixel == 32)
    {
        // Figure out whether the image uses its alpha layer
        for (int i = 0; i < tmpImage->w * tmpImage->h; ++i)
        {
            Uint8 r, g, b, a;
            SDL_GetRGBA(
                    ((Uint32*) tmpImage->pixels)[i],
                    tmpImage->format,
                    &r, &g, &b, &a);

            if (a != 255)
            {
                hasAlpha = true;
                break;
            }
        }
    }

    SDL_Surface *image;

    // Convert the surface to the current display format
    if (hasAlpha)
        image = SDL_DisplayFormatAlpha(tmpImage);
    else
        image = SDL_DisplayFormat(tmpImage);

    if (!image)
    {
        logger->log("Error: Image convert failed.");
        return NULL;
    }

    return new Image(image);
}

void Image::unload()
{
    mLoaded = false;

    if (mImage)
    {
        // Free the image surface.
        SDL_FreeSurface(mImage);
        mImage = NULL;
    }

#ifdef USE_OPENGL
    if (mGLImage)
    {
        glDeleteTextures(1, &mGLImage);
        mGLImage = 0;
    }
#endif
}

Image *Image::getSubImage(int x, int y, int width, int height)
{
    // Create a new clipped sub-image
#ifdef USE_OPENGL
    if (mUseOpenGL)
        return new SubImage(this, mGLImage, x, y, width, height,
                            mTexWidth, mTexHeight);
#endif

    return new SubImage(this, mImage, x, y, width, height);
}

void Image::setAlpha(float a)
{
    if (mAlpha == a)
        return;

    mAlpha = a;

    if (mImage)
    {
        // Set the alpha value this image is drawn at
        SDL_SetAlpha(mImage, SDL_SRCALPHA, (int) (255 * mAlpha));
    }
}

Image* Image::merge(Image* image, const Position& pos)
{
    SDL_Surface* surface = new SDL_Surface(*(image->mImage));

    Uint32 surface_pix, cur_pix;
    Uint8 r, g, b, a, p_r, p_g, p_b, p_a;
    double f_a, f_ca, f_pa;
    SDL_PixelFormat *current_fmt = mImage->format;
    SDL_PixelFormat *surface_fmt = surface->format;
    int current_offset, surface_offset;
    Position offset(0, 0);

    SDL_LockSurface(surface);
    SDL_LockSurface(mImage);
    // for each pixel lines of a source image
    for (offset.x = (pos.x > 0 ? 0 : -pos.x); offset.x < image->getWidth() &&
                     pos.x + offset.x < getWidth(); offset.x++)
    {
        for (offset.y = (pos.y > 0 ? 0 : -pos.y); offset.y < image->getHeight()
                        && pos.y + offset.y < getHeight(); offset.y++)
        {
            // Computing offset on both images
            current_offset = (pos.y + offset.y) * getWidth() + pos.x + offset.x;
            surface_offset = offset.y * surface->w + offset.x;

            // Retrieving a pixel to merge
            surface_pix = ((Uint32*) surface->pixels)[surface_offset];
            cur_pix = ((Uint32*) mImage->pixels)[current_offset];

            // Retreiving each channel of the pixel using pixel format
            r = (Uint8)(((surface_pix & surface_fmt->Rmask) >> 
                          surface_fmt->Rshift) << surface_fmt->Rloss);
            g = (Uint8)(((surface_pix & surface_fmt->Gmask) >>
                          surface_fmt->Gshift) << surface_fmt->Gloss);
            b = (Uint8)(((surface_pix & surface_fmt->Bmask) >>
                          surface_fmt->Bshift) << surface_fmt->Bloss);
            a = (Uint8)(((surface_pix & surface_fmt->Amask) >>
                          surface_fmt->Ashift) << surface_fmt->Aloss);

            // Retreiving previous alpha value
            p_a = (Uint8)(((cur_pix & current_fmt->Amask) >>
                            current_fmt->Ashift) << current_fmt->Aloss);

            // new pixel with no alpha or nothing on previous pixel
            if (a == SDL_ALPHA_OPAQUE || (p_a == 0 && a > 0))
                ((Uint32 *)(surface->pixels))[current_offset] = 
                    SDL_MapRGBA(current_fmt, r, g, b, a);
            else if (a > 0) 
            { // alpha is lower => merge color with previous value
                f_a = (double) a / 255.0;
                f_ca = 1.0 - f_a;
                f_pa = (double) p_a / 255.0;
                p_r = (Uint8)(((cur_pix & current_fmt->Rmask) >> 
                                current_fmt->Rshift) << current_fmt->Rloss);
                p_g = (Uint8)(((cur_pix & current_fmt->Gmask) >>
                                current_fmt->Gshift) << current_fmt->Gloss);
                p_b = (Uint8)(((cur_pix & current_fmt->Bmask) >>
                                current_fmt->Bshift) << current_fmt->Bloss);
                r = (Uint8)((double) p_r * f_ca * f_pa + (double)r * f_a);
                g = (Uint8)((double) p_g * f_ca * f_pa + (double)g * f_a);
                b = (Uint8)((double) p_b * f_ca * f_pa + (double)b * f_a);
                a = (a > p_a ? a : p_a);
               ((Uint32 *)(surface->pixels))[current_offset] =
                   SDL_MapRGBA(current_fmt, r, g, b, a);
            }
        }
    }
    SDL_UnlockSurface(surface);
    SDL_UnlockSurface(mImage);

    Image* newImage = new Image(surface);

    return newImage;
}

float Image::getAlpha()
{
    return mAlpha;
}

#ifdef USE_OPENGL
void Image::setLoadAsOpenGL(bool useOpenGL)
{
    Image::mUseOpenGL = useOpenGL;
}

int Image::powerOfTwo(int input)
{
    int value;
    if (mTextureType == GL_TEXTURE_2D)
    {
        value = 1;
        while (value < input && value < mTextureSize)
        {
            value <<= 1;
        }
    }
    else
    {
        value = input;
    }
    return value >= mTextureSize ? mTextureSize : value;
}
#endif

//============================================================================
// SubImage Class
//============================================================================

SubImage::SubImage(Image *parent, SDL_Surface *image,
        int x, int y, int width, int height):
    Image(image),
    mParent(parent)
{
    mParent->incRef();

    // Set up the rectangle.
    mBounds.x = x;
    mBounds.y = y;
    mBounds.w = width;
    mBounds.h = height;
}

#ifdef USE_OPENGL
SubImage::SubImage(Image *parent, GLuint image,
                   int x, int y, int width, int height,
                   int texWidth, int texHeight):
    Image(image, width, height, texWidth, texHeight),
    mParent(parent)
{
    mParent->incRef();

    // Set up the rectangle.
    mBounds.x = x;
    mBounds.y = y;
    mBounds.w = width;
    mBounds.h = height;
}
#endif

SubImage::~SubImage()
{
    // Avoid destruction of the image
    mImage = 0;
#ifdef USE_OPENGL
    mGLImage = 0;
#endif
    mParent->decRef();
}

Image *SubImage::getSubImage(int x, int y, int w, int h)
{
    return mParent->getSubImage(mBounds.x + x, mBounds.y + y, w, h);
}