/*
 * MIT License
 *
 * Copyright (c) 2016-2017 Patrick Rudolph <siro@das-labor.org>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:

 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
*/
/*
 * ==============================================================
 *
 *                              API
 *
 * ===============================================================
 */

 /* Adapted from nulear_rawfb.h for use with SDL_Surface by Martijn Versteegh*/
#ifndef NK_SDLSURFACE_H_
#define NK_SDLSURFACE_H_

#include <SDL.h>
#include <SDL_surface.h>

struct sdlsurface_context *nk_sdlsurface_init(SDL_Surface *fb, float fontSize);
void                  nk_sdlsurface_render(const struct sdlsurface_context *sdlsurface, const struct nk_color clear, const unsigned char enable_clear);
void                  nk_sdlsurface_shutdown(struct sdlsurface_context *sdlsurface);

#endif
/*
 * ==============================================================
 *
 *                          IMPLEMENTATION
 *
 * ===============================================================
 */
#ifdef NK_SDLSURFACE_IMPLEMENTATION
struct sdlsurface_context {
    struct nk_context ctx;
    struct nk_rect scissors;
    struct SDL_Surface *fb;
    struct SDL_Surface *font_tex;
    struct nk_font_atlas atlas;
};

#ifndef MIN
#define MIN(a,b) ((a) < (b) ? (a) : (b))
#endif
#ifndef MAX
#define MAX(a,b) ((a) < (b) ? (b) : (a))
#endif

static unsigned int
nk_sdlsurface_color2int(const struct nk_color c, const SDL_PixelFormat *format)
{
    return SDL_MapRGBA(format, c.r, c.g, c.b, c.a);
}

static struct nk_color
nk_sdlsurface_int2color(const unsigned int i, const SDL_PixelFormat *format)
{
    struct nk_color col = {0,0,0,0};

    SDL_GetRGBA(i, format, &col.r, &col.g, &col.b, &col.a);

    return col;
}

static void
nk_sdlsurface_ctx_setpixel(const struct sdlsurface_context *sdlsurface,
    const short x0, const short y0, const struct nk_color col)
{
    unsigned int c = nk_sdlsurface_color2int(col, sdlsurface->fb->format);
    unsigned char *pixels = sdlsurface->fb->pixels;

    pixels += y0 * sdlsurface->fb->pitch;

    if (y0 < sdlsurface->scissors.h && y0 >= sdlsurface->scissors.y &&
        x0 >= sdlsurface->scissors.x && x0 < sdlsurface->scissors.w) {

        if (sdlsurface->fb->format->BytesPerPixel == 4) {
            *((Uint32 *)pixels + x0) = c;
        } else if (sdlsurface->fb->format->BytesPerPixel == 2) {
            *((Uint16 *)pixels + x0) = c;
        } else {
            *((Uint8 *)pixels + x0) = c;
        }
    }
}

static void
nk_sdlsurface_line_horizontal(const struct sdlsurface_context *sdlsurface,
    const short x0, const short y, const short x1, const struct nk_color col)
{
    /* This function is called the most. Try to optimize it a bit...
     * It does not check for scissors or image borders.
     * The caller has to make sure it does no exceed bounds. */
    unsigned int i, n;
    unsigned char c[16 * 4];
    unsigned char *pixels = sdlsurface->fb->pixels;
    unsigned int bpp = sdlsurface->fb->format->BytesPerPixel;

    pixels += (y * sdlsurface->fb->pitch) + (x0 * bpp);

    n = (x1 - x0) * bpp;
    if (bpp == 4) {
        for (i = 0; i < sizeof(c) / bpp; i++)
            ((Uint32 *)c)[i] = nk_sdlsurface_color2int(col, sdlsurface->fb->format);
    } else if (bpp == 2) {
        for (i = 0; i < sizeof(c) / bpp; i++)
            ((Uint16 *)c)[i] = nk_sdlsurface_color2int(col, sdlsurface->fb->format);
    } else {
        for (i = 0; i < sizeof(c) / bpp; i++)
            ((Uint8 *)c)[i] = nk_sdlsurface_color2int(col, sdlsurface->fb->format);
    }

    while (n > sizeof(c)) {
        memcpy((void*)pixels, c, sizeof(c));
        n -= sizeof(c); pixels += sizeof(c);
    } for (i = 0; i < n; i++)
        pixels[i] = c[i];
}

static void
nk_sdlsurface_img_setpixel(const struct SDL_Surface *img,
    const int x0, const int y0, const struct nk_color col)
{
    unsigned int c = nk_sdlsurface_color2int(col, img->format);
    unsigned char *ptr;
    NK_ASSERT(img);
    if (y0 < img->h && y0 >= 0 && x0 >= 0 && x0 < img->w) {
        ptr = (unsigned char *)img->pixels + (img->pitch * y0);

        if (img->format == NK_FONT_ATLAS_ALPHA8) {
            ptr[x0] = col.a;
        } else if (img->format->BytesPerPixel == 4) {
            ((Uint32 *)ptr)[x0] = c;
        } else if (img->format->BytesPerPixel == 2) {
            ((Uint16 *)ptr)[x0] = c;
        } else {
            ((Uint8 *)ptr)[x0] = c;
        }
    }
}

static struct nk_color
nk_sdlsurface_img_getpixel(const struct SDL_Surface *img, const int x0, const int y0)
{
    struct nk_color col = {0, 0, 0, 0};
    unsigned char *ptr;
    unsigned int pixel;
    NK_ASSERT(img);
    if (y0 < img->h && y0 >= 0 && x0 >= 0 && x0 < img->w) {
        ptr = (unsigned char *)img->pixels + (img->pitch * y0);

        if (img->format == NK_FONT_ATLAS_ALPHA8) {
            col.a = ptr[x0];
            col.b = col.g = col.r = 0xff;
        } else if (img->format->BytesPerPixel == 4) {
            pixel = ((Uint32 *)ptr)[x0];
            col = nk_sdlsurface_int2color(pixel, img->format);
        } else if (img->format->BytesPerPixel == 2) {
            pixel = ((Uint16 *)ptr)[x0];
            col = nk_sdlsurface_int2color(pixel, img->format);
        } else {
            pixel = ((Uint8 *)ptr)[x0];
            col = nk_sdlsurface_int2color(pixel, img->format);
        }
    } return col;
}
static void
nk_sdlsurface_img_blendpixel(const struct SDL_Surface *img,
    const int x0, const int y0, struct nk_color col)
{
    struct nk_color col2;
    unsigned char inv_a;
    if (col.a == 0)
        return;

    inv_a = 0xff - col.a;
    col2 = nk_sdlsurface_img_getpixel(img, x0, y0);
    col.r = (col.r * col.a + col2.r * inv_a) >> 8;
    col.g = (col.g * col.a + col2.g * inv_a) >> 8;
    col.b = (col.b * col.a + col2.b * inv_a) >> 8;
    nk_sdlsurface_img_setpixel(img, x0, y0, col);
}

static void
nk_sdlsurface_scissor(struct sdlsurface_context *sdlsurface,
                 const float x,
                 const float y,
                 const float w,
                 const float h)
{
    sdlsurface->scissors.x = MIN(MAX(x, 0), sdlsurface->fb->w);
    sdlsurface->scissors.y = MIN(MAX(y, 0), sdlsurface->fb->h);
    sdlsurface->scissors.w = MIN(MAX(w + x, 0), sdlsurface->fb->w);
    sdlsurface->scissors.h = MIN(MAX(h + y, 0), sdlsurface->fb->h);
}

static void
nk_sdlsurface_stroke_line(const struct sdlsurface_context *sdlsurface,
    short x0, short y0, short x1, short y1,
    const unsigned int line_thickness, const struct nk_color col)
{
    short tmp;
    int dy, dx, stepx, stepy;

    NK_UNUSED(line_thickness);

    dy = y1 - y0;
    dx = x1 - x0;

    /* fast path */
    if (dy == 0) {
        if (dx == 0 || y0 >= sdlsurface->scissors.h || y0 < sdlsurface->scissors.y)
            return;

        if (dx < 0) {
            /* swap x0 and x1 */
            tmp = x1;
            x1 = x0;
            x0 = tmp;
        }
        x1 = MIN(sdlsurface->scissors.w, x1);
        x0 = MIN(sdlsurface->scissors.w, x0);
        x1 = MAX(sdlsurface->scissors.x, x1);
        x0 = MAX(sdlsurface->scissors.x, x0);
        nk_sdlsurface_line_horizontal(sdlsurface, x0, y0, x1, col);
        return;
    }
    if (dy < 0) {
        dy = -dy;
        stepy = -1;
    } else stepy = 1;

    if (dx < 0) {
        dx = -dx;
        stepx = -1;
    } else stepx = 1;

    dy <<= 1;
    dx <<= 1;

    nk_sdlsurface_ctx_setpixel(sdlsurface, x0, y0, col);
    if (dx > dy) {
        int fraction = dy - (dx >> 1);
        while (x0 != x1) {
            if (fraction >= 0) {
                y0 += stepy;
                fraction -= dx;
            }
            x0 += stepx;
            fraction += dy;
            nk_sdlsurface_ctx_setpixel(sdlsurface, x0, y0, col);
        }
    } else {
        int fraction = dx - (dy >> 1);
        while (y0 != y1) {
            if (fraction >= 0) {
                x0 += stepx;
                fraction -= dy;
            }
            y0 += stepy;
            fraction += dx;
            nk_sdlsurface_ctx_setpixel(sdlsurface, x0, y0, col);
        }
    }
}

static void
nk_sdlsurface_fill_polygon(const struct sdlsurface_context *sdlsurface,
    const struct nk_vec2i *pnts, int count, const struct nk_color col)
{
    int i = 0;
    #define MAX_POINTS 64
    int left = 10000, top = 10000, bottom = 0, right = 0;
    int nodes, nodeX[MAX_POINTS], pixelX, pixelY, j, swap ;

    if (count == 0) return;
    if (count > MAX_POINTS)
        count = MAX_POINTS;

    /* Get polygon dimensions */
    for (i = 0; i < count; i++) {
        if (left > pnts[i].x)
            left = pnts[i].x;
        if (right < pnts[i].x)
            right = pnts[i].x;
        if (top > pnts[i].y)
            top = pnts[i].y;
        if (bottom < pnts[i].y)
            bottom = pnts[i].y;
    } bottom++; right++;

    /* Polygon scanline algorithm released under public-domain by Darel Rex Finley, 2007 */
    /*  Loop through the rows of the image. */
    for (pixelY = top; pixelY < bottom; pixelY ++) {
        nodes = 0; /*  Build a list of nodes. */
        j = count - 1;
        for (i = 0; i < count; i++) {
            if (((pnts[i].y < pixelY) && (pnts[j].y >= pixelY)) ||
                ((pnts[j].y < pixelY) && (pnts[i].y >= pixelY))) {
                nodeX[nodes++]= (int)((float)pnts[i].x
                     + ((float)pixelY - (float)pnts[i].y) / ((float)pnts[j].y - (float)pnts[i].y)
                     * ((float)pnts[j].x - (float)pnts[i].x));
            } j = i;
        }

        /*  Sort the nodes, via a simple “Bubble” sort. */
        i = 0;
        while (i < nodes - 1) {
            if (nodeX[i] > nodeX[i+1]) {
                swap = nodeX[i];
                nodeX[i] = nodeX[i+1];
                nodeX[i+1] = swap;
                if (i) i--;
            } else i++;
        }
        /*  Fill the pixels between node pairs. */
        for (i = 0; i < nodes; i += 2) {
            if (nodeX[i+0] >= right) break;
            if (nodeX[i+1] > left) {
                if (nodeX[i+0] < left) nodeX[i+0] = left ;
                if (nodeX[i+1] > right) nodeX[i+1] = right;
                for (pixelX = nodeX[i]; pixelX < nodeX[i + 1]; pixelX++)
                    nk_sdlsurface_ctx_setpixel(sdlsurface, pixelX, pixelY, col);
            }
        }
    }
    #undef MAX_POINTS
}

static void
nk_sdlsurface_stroke_arc(const struct sdlsurface_context *sdlsurface,
    short x0, short y0, short w, short h, const short s,
    const short line_thickness, const struct nk_color col)
{
    /* Bresenham's ellipses - modified to draw one quarter */
    const int a2 = (w * w) / 4;
    const int b2 = (h * h) / 4;
    const int fa2 = 4 * a2, fb2 = 4 * b2;
    int x, y, sigma;

    NK_UNUSED(line_thickness);

    if (s != 0 && s != 90 && s != 180 && s != 270) return;
    if (w < 1 || h < 1) return;

    /* Convert upper left to center */
    h = (h + 1) / 2;
    w = (w + 1) / 2;
    x0 += w; y0 += h;

    /* First half */
    for (x = 0, y = h, sigma = 2*b2+a2*(1-2*h); b2*x <= a2*y; x++) {
        if (s == 180)
            nk_sdlsurface_ctx_setpixel(sdlsurface, x0 + x, y0 + y, col);
        else if (s == 270)
            nk_sdlsurface_ctx_setpixel(sdlsurface, x0 - x, y0 + y, col);
        else if (s == 0)
            nk_sdlsurface_ctx_setpixel(sdlsurface, x0 + x, y0 - y, col);
        else if (s == 90)
            nk_sdlsurface_ctx_setpixel(sdlsurface, x0 - x, y0 - y, col);
        if (sigma >= 0) {
            sigma += fa2 * (1 - y);
            y--;
        } sigma += b2 * ((4 * x) + 6);
    }

    /* Second half */
    for (x = w, y = 0, sigma = 2*a2+b2*(1-2*w); a2*y <= b2*x; y++) {
        if (s == 180)
            nk_sdlsurface_ctx_setpixel(sdlsurface, x0 + x, y0 + y, col);
        else if (s == 270)
            nk_sdlsurface_ctx_setpixel(sdlsurface, x0 - x, y0 + y, col);
        else if (s == 0)
            nk_sdlsurface_ctx_setpixel(sdlsurface, x0 + x, y0 - y, col);
        else if (s == 90)
            nk_sdlsurface_ctx_setpixel(sdlsurface, x0 - x, y0 - y, col);
        if (sigma >= 0) {
            sigma += fb2 * (1 - x);
            x--;
        } sigma += a2 * ((4 * y) + 6);
    }
}

static void
nk_sdlsurface_fill_arc(const struct sdlsurface_context *sdlsurface, short x0, short y0,
    short w, short h, const short s, const struct nk_color col)
{
    /* Bresenham's ellipses - modified to fill one quarter */
    const int a2 = (w * w) / 4;
    const int b2 = (h * h) / 4;
    const int fa2 = 4 * a2, fb2 = 4 * b2;
    int x, y, sigma;
    struct nk_vec2i pnts[3];
    if (w < 1 || h < 1) return;
    if (s != 0 && s != 90 && s != 180 && s != 270)
        return;

    /* Convert upper left to center */
    h = (h + 1) / 2;
    w = (w + 1) / 2;
    x0 += w;
    y0 += h;

    pnts[0].x = x0;
    pnts[0].y = y0;
    pnts[2].x = x0;
    pnts[2].y = y0;

    /* First half */
    for (x = 0, y = h, sigma = 2*b2+a2*(1-2*h); b2*x <= a2*y; x++) {
        if (s == 180) {
            pnts[1].x = x0 + x; pnts[1].y = y0 + y;
        } else if (s == 270) {
            pnts[1].x = x0 - x; pnts[1].y = y0 + y;
        } else if (s == 0) {
            pnts[1].x = x0 + x; pnts[1].y = y0 - y;
        } else if (s == 90) {
            pnts[1].x = x0 - x; pnts[1].y = y0 - y;
        }
        nk_sdlsurface_fill_polygon(sdlsurface, pnts, 3, col);
        pnts[2] = pnts[1];
        if (sigma >= 0) {
            sigma += fa2 * (1 - y);
            y--;
        } sigma += b2 * ((4 * x) + 6);
    }

    /* Second half */
    for (x = w, y = 0, sigma = 2*a2+b2*(1-2*w); a2*y <= b2*x; y++) {
        if (s == 180) {
            pnts[1].x = x0 + x; pnts[1].y = y0 + y;
        } else if (s == 270) {
            pnts[1].x = x0 - x; pnts[1].y = y0 + y;
        } else if (s == 0) {
            pnts[1].x = x0 + x; pnts[1].y = y0 - y;
        } else if (s == 90) {
            pnts[1].x = x0 - x; pnts[1].y = y0 - y;
        }
        nk_sdlsurface_fill_polygon(sdlsurface, pnts, 3, col);
        pnts[2] = pnts[1];
        if (sigma >= 0) {
            sigma += fb2 * (1 - x);
            x--;
        } sigma += a2 * ((4 * y) + 6);
    }
}

static void
nk_sdlsurface_stroke_rect(const struct sdlsurface_context *sdlsurface,
    const short x, const short y, const short w, const short h,
    const short r, const short line_thickness, const struct nk_color col)
{
    if (r == 0) {
        nk_sdlsurface_stroke_line(sdlsurface, x, y, x + w, y, line_thickness, col);
        nk_sdlsurface_stroke_line(sdlsurface, x, y + h, x + w, y + h, line_thickness, col);
        nk_sdlsurface_stroke_line(sdlsurface, x, y, x, y + h, line_thickness, col);
        nk_sdlsurface_stroke_line(sdlsurface, x + w, y, x + w, y + h, line_thickness, col);
    } else {
        const short xc = x + r;
        const short yc = y + r;
        const short wc = (short)(w - 2 * r);
        const short hc = (short)(h - 2 * r);

        nk_sdlsurface_stroke_line(sdlsurface, xc, y, xc + wc, y, line_thickness, col);
        nk_sdlsurface_stroke_line(sdlsurface, x + w, yc, x + w, yc + hc, line_thickness, col);
        nk_sdlsurface_stroke_line(sdlsurface, xc, y + h, xc + wc, y + h, line_thickness, col);
        nk_sdlsurface_stroke_line(sdlsurface, x, yc, x, yc + hc, line_thickness, col);

        nk_sdlsurface_stroke_arc(sdlsurface, xc + wc - r, y,
                (unsigned)r*2, (unsigned)r*2, 0 , line_thickness, col);
        nk_sdlsurface_stroke_arc(sdlsurface, x, y,
                (unsigned)r*2, (unsigned)r*2, 90 , line_thickness, col);
        nk_sdlsurface_stroke_arc(sdlsurface, x, yc + hc - r,
                (unsigned)r*2, (unsigned)r*2, 270 , line_thickness, col);
        nk_sdlsurface_stroke_arc(sdlsurface, xc + wc - r, yc + hc - r,
                (unsigned)r*2, (unsigned)r*2, 180 , line_thickness, col);
    }
}

static void
nk_sdlsurface_fill_rect(const struct sdlsurface_context *sdlsurface,
    const short x, const short y, const short w, const short h,
    const short r, const struct nk_color col)
{
    int i;
    if (r == 0) {
        for (i = 0; i < h; i++)
            nk_sdlsurface_stroke_line(sdlsurface, x, y + i, x + w, y + i, 1, col);
    } else {
        const short xc = x + r;
        const short yc = y + r;
        const short wc = (short)(w - 2 * r);
        const short hc = (short)(h - 2 * r);

        struct nk_vec2i pnts[12];
        pnts[0].x = x;
        pnts[0].y = yc;
        pnts[1].x = xc;
        pnts[1].y = yc;
        pnts[2].x = xc;
        pnts[2].y = y;

        pnts[3].x = xc + wc;
        pnts[3].y = y;
        pnts[4].x = xc + wc;
        pnts[4].y = yc;
        pnts[5].x = x + w;
        pnts[5].y = yc;

        pnts[6].x = x + w;
        pnts[6].y = yc + hc;
        pnts[7].x = xc + wc;
        pnts[7].y = yc + hc;
        pnts[8].x = xc + wc;
        pnts[8].y = y + h;

        pnts[9].x = xc;
        pnts[9].y = y + h;
        pnts[10].x = xc;
        pnts[10].y = yc + hc;
        pnts[11].x = x;
        pnts[11].y = yc + hc;

        nk_sdlsurface_fill_polygon(sdlsurface, pnts, 12, col);

        nk_sdlsurface_fill_arc(sdlsurface, xc + wc - r, y,
                (unsigned)r*2, (unsigned)r*2, 0 , col);
        nk_sdlsurface_fill_arc(sdlsurface, x, y,
                (unsigned)r*2, (unsigned)r*2, 90 , col);
        nk_sdlsurface_fill_arc(sdlsurface, x, yc + hc - r,
                (unsigned)r*2, (unsigned)r*2, 270 , col);
        nk_sdlsurface_fill_arc(sdlsurface, xc + wc - r, yc + hc - r,
                (unsigned)r*2, (unsigned)r*2, 180 , col);
    }
}

NK_API void
nk_sdlsurface_draw_rect_multi_color(const struct sdlsurface_context *sdlsurface,
    const short x, const short y, const short w, const short h, struct nk_color tl,
    struct nk_color tr, struct nk_color br, struct nk_color bl)
{
    int i, j;
    struct nk_color *edge_buf;
    struct nk_color *edge_t;
    struct nk_color *edge_b;
    struct nk_color *edge_l;
    struct nk_color *edge_r;
    struct nk_color pixel;

    edge_buf = malloc(((2*w) + (2*h)) * sizeof(struct nk_color));
    if (edge_buf == NULL)
    return;

    edge_t = edge_buf;
    edge_b = edge_buf + w;
    edge_l = edge_buf + (w*2);
    edge_r = edge_buf + (w*2) + h;

    /* Top and bottom edge gradients */
    for (i=0; i<w; i++)
    {
    edge_t[i].r = (((((float)tr.r - tl.r)/(w-1))*i) + 0.5) + tl.r;
    edge_t[i].g = (((((float)tr.g - tl.g)/(w-1))*i) + 0.5) + tl.g;
    edge_t[i].b = (((((float)tr.b - tl.b)/(w-1))*i) + 0.5) + tl.b;
    edge_t[i].a = (((((float)tr.a - tl.a)/(w-1))*i) + 0.5) + tl.a;

    edge_b[i].r = (((((float)br.r - bl.r)/(w-1))*i) + 0.5) + bl.r;
    edge_b[i].g = (((((float)br.g - bl.g)/(w-1))*i) + 0.5) + bl.g;
    edge_b[i].b = (((((float)br.b - bl.b)/(w-1))*i) + 0.5) + bl.b;
    edge_b[i].a = (((((float)br.a - bl.a)/(w-1))*i) + 0.5) + bl.a;
    }

    /* Left and right edge gradients */
    for (i=0; i<h; i++)
    {
    edge_l[i].r = (((((float)bl.r - tl.r)/(h-1))*i) + 0.5) + tl.r;
    edge_l[i].g = (((((float)bl.g - tl.g)/(h-1))*i) + 0.5) + tl.g;
    edge_l[i].b = (((((float)bl.b - tl.b)/(h-1))*i) + 0.5) + tl.b;
    edge_l[i].a = (((((float)bl.a - tl.a)/(h-1))*i) + 0.5) + tl.a;

    edge_r[i].r = (((((float)br.r - tr.r)/(h-1))*i) + 0.5) + tr.r;
    edge_r[i].g = (((((float)br.g - tr.g)/(h-1))*i) + 0.5) + tr.g;
    edge_r[i].b = (((((float)br.b - tr.b)/(h-1))*i) + 0.5) + tr.b;
    edge_r[i].a = (((((float)br.a - tr.a)/(h-1))*i) + 0.5) + tr.a;
    }

    for (i=0; i<h; i++) {
    for (j=0; j<w; j++) {
        if (i==0) {
        nk_sdlsurface_img_blendpixel(sdlsurface->fb, x+j, y+i, edge_t[j]);
        } else if (i==h-1) {
        nk_sdlsurface_img_blendpixel(sdlsurface->fb, x+j, y+i, edge_b[j]);
        } else {
        if (j==0) {
            nk_sdlsurface_img_blendpixel(sdlsurface->fb, x+j, y+i, edge_l[i]);
        } else if (j==w-1) {
            nk_sdlsurface_img_blendpixel(sdlsurface->fb, x+j, y+i, edge_r[i]);
        } else {
            pixel.r = (((((float)edge_r[i].r - edge_l[i].r)/(w-1))*j) + 0.5) + edge_l[i].r;
            pixel.g = (((((float)edge_r[i].g - edge_l[i].g)/(w-1))*j) + 0.5) + edge_l[i].g;
            pixel.b = (((((float)edge_r[i].b - edge_l[i].b)/(w-1))*j) + 0.5) + edge_l[i].b;
            pixel.a = (((((float)edge_r[i].a - edge_l[i].a)/(w-1))*j) + 0.5) + edge_l[i].a;
            nk_sdlsurface_img_blendpixel(sdlsurface->fb, x+j, y+i, pixel);
        }
        }
    }
    }

    free(edge_buf);
}

static void
nk_sdlsurface_fill_triangle(const struct sdlsurface_context *sdlsurface,
    const short x0, const short y0, const short x1, const short y1,
    const short x2, const short y2, const struct nk_color col)
{
    struct nk_vec2i pnts[3];
    pnts[0].x = x0;
    pnts[0].y = y0;
    pnts[1].x = x1;
    pnts[1].y = y1;
    pnts[2].x = x2;
    pnts[2].y = y2;
    nk_sdlsurface_fill_polygon(sdlsurface, pnts, 3, col);
}

static void
nk_sdlsurface_stroke_triangle(const struct sdlsurface_context *sdlsurface,
    const short x0, const short y0, const short x1, const short y1,
    const short x2, const short y2, const unsigned short line_thickness,
    const struct nk_color col)
{
    nk_sdlsurface_stroke_line(sdlsurface, x0, y0, x1, y1, line_thickness, col);
    nk_sdlsurface_stroke_line(sdlsurface, x1, y1, x2, y2, line_thickness, col);
    nk_sdlsurface_stroke_line(sdlsurface, x2, y2, x0, y0, line_thickness, col);
}

static void
nk_sdlsurface_stroke_polygon(const struct sdlsurface_context *sdlsurface,
    const struct nk_vec2i *pnts, const int count,
    const unsigned short line_thickness, const struct nk_color col)
{
    int i;
    for (i = 1; i < count; ++i)
        nk_sdlsurface_stroke_line(sdlsurface, pnts[i-1].x, pnts[i-1].y, pnts[i].x,
                pnts[i].y, line_thickness, col);
    nk_sdlsurface_stroke_line(sdlsurface, pnts[count-1].x, pnts[count-1].y,
            pnts[0].x, pnts[0].y, line_thickness, col);
}

static void
nk_sdlsurface_stroke_polyline(const struct sdlsurface_context *sdlsurface,
    const struct nk_vec2i *pnts, const int count,
    const unsigned short line_thickness, const struct nk_color col)
{
    int i;
    for (i = 0; i < count-1; ++i)
        nk_sdlsurface_stroke_line(sdlsurface, pnts[i].x, pnts[i].y,
                 pnts[i+1].x, pnts[i+1].y, line_thickness, col);
}

static void
nk_sdlsurface_fill_circle(const struct sdlsurface_context *sdlsurface,
    short x0, short y0, short w, short h, const struct nk_color col)
{
    /* Bresenham's ellipses */
    const int a2 = (w * w) / 4;
    const int b2 = (h * h) / 4;
    const int fa2 = 4 * a2, fb2 = 4 * b2;
    int x, y, sigma;

    /* Convert upper left to center */
    h = (h + 1) / 2;
    w = (w + 1) / 2;
    x0 += w;
    y0 += h;

    /* First half */
    for (x = 0, y = h, sigma = 2*b2+a2*(1-2*h); b2*x <= a2*y; x++) {
        nk_sdlsurface_stroke_line(sdlsurface, x0 - x, y0 + y, x0 + x, y0 + y, 1, col);
        nk_sdlsurface_stroke_line(sdlsurface, x0 - x, y0 - y, x0 + x, y0 - y, 1, col);
        if (sigma >= 0) {
            sigma += fa2 * (1 - y);
            y--;
        } sigma += b2 * ((4 * x) + 6);
    }
    /* Second half */
    for (x = w, y = 0, sigma = 2*a2+b2*(1-2*w); a2*y <= b2*x; y++) {
        nk_sdlsurface_stroke_line(sdlsurface, x0 - x, y0 + y, x0 + x, y0 + y, 1, col);
        nk_sdlsurface_stroke_line(sdlsurface, x0 - x, y0 - y, x0 + x, y0 - y, 1, col);
        if (sigma >= 0) {
            sigma += fb2 * (1 - x);
            x--;
        } sigma += a2 * ((4 * y) + 6);
    }
}

static void
nk_sdlsurface_stroke_circle(const struct sdlsurface_context *sdlsurface,
    short x0, short y0, short w, short h, const short line_thickness,
    const struct nk_color col)
{
    /* Bresenham's ellipses */
    const int a2 = (w * w) / 4;
    const int b2 = (h * h) / 4;
    const int fa2 = 4 * a2, fb2 = 4 * b2;
    int x, y, sigma;

    NK_UNUSED(line_thickness);

    /* Convert upper left to center */
    h = (h + 1) / 2;
    w = (w + 1) / 2;
    x0 += w;
    y0 += h;

    /* First half */
    for (x = 0, y = h, sigma = 2*b2+a2*(1-2*h); b2*x <= a2*y; x++) {
        nk_sdlsurface_ctx_setpixel(sdlsurface, x0 + x, y0 + y, col);
        nk_sdlsurface_ctx_setpixel(sdlsurface, x0 - x, y0 + y, col);
        nk_sdlsurface_ctx_setpixel(sdlsurface, x0 + x, y0 - y, col);
        nk_sdlsurface_ctx_setpixel(sdlsurface, x0 - x, y0 - y, col);
        if (sigma >= 0) {
            sigma += fa2 * (1 - y);
            y--;
        } sigma += b2 * ((4 * x) + 6);
    }
    /* Second half */
    for (x = w, y = 0, sigma = 2*a2+b2*(1-2*w); a2*y <= b2*x; y++) {
        nk_sdlsurface_ctx_setpixel(sdlsurface, x0 + x, y0 + y, col);
        nk_sdlsurface_ctx_setpixel(sdlsurface, x0 - x, y0 + y, col);
        nk_sdlsurface_ctx_setpixel(sdlsurface, x0 + x, y0 - y, col);
        nk_sdlsurface_ctx_setpixel(sdlsurface, x0 - x, y0 - y, col);
        if (sigma >= 0) {
            sigma += fb2 * (1 - x);
            x--;
        } sigma += a2 * ((4 * y) + 6);
    }
}

static void
nk_sdlsurface_stroke_curve(const struct sdlsurface_context *sdlsurface,
    const struct nk_vec2i p1, const struct nk_vec2i p2,
    const struct nk_vec2i p3, const struct nk_vec2i p4,
    const unsigned int num_segments, const unsigned short line_thickness,
    const struct nk_color col)
{
    unsigned int i_step, segments;
    float t_step;
    struct nk_vec2i last = p1;

    segments = MAX(num_segments, 1);
    t_step = 1.0f/(float)segments;
    for (i_step = 1; i_step <= segments; ++i_step) {
        float t = t_step * (float)i_step;
        float u = 1.0f - t;
        float w1 = u*u*u;
        float w2 = 3*u*u*t;
        float w3 = 3*u*t*t;
        float w4 = t * t *t;
        float x = w1 * p1.x + w2 * p2.x + w3 * p3.x + w4 * p4.x;
        float y = w1 * p1.y + w2 * p2.y + w3 * p3.y + w4 * p4.y;
        nk_sdlsurface_stroke_line(sdlsurface, last.x, last.y,
                (short)x, (short)y, line_thickness,col);
        last.x = (short)x; last.y = (short)y;
    }
}

static void
nk_sdlsurface_clear(const struct sdlsurface_context *sdlsurface, const struct nk_color col)
{
    nk_sdlsurface_fill_rect(sdlsurface, 0, 0, sdlsurface->fb->w, sdlsurface->fb->h, 0, col);
}

struct sdlsurface_context*
nk_sdlsurface_init(SDL_Surface *fb, float fontSize)
{
    const void *tex;
    int texh, texw;
    struct sdlsurface_context *sdlsurface;

    assert((fb->format->format == SDL_PIXELFORMAT_ARGB8888)
               || (fb->format->format == SDL_PIXELFORMAT_RGBA8888));

    sdlsurface = malloc(sizeof(struct sdlsurface_context));
    if (!sdlsurface)
        return NULL;

    memset(sdlsurface, 0, sizeof(struct sdlsurface_context));

    sdlsurface->fb = fb;

    if (0 == nk_init_default(&sdlsurface->ctx, 0)) {
    free(sdlsurface);
    return NULL;
    }

    nk_font_atlas_init_default(&sdlsurface->atlas);
    nk_font_atlas_begin(&sdlsurface->atlas);
    sdlsurface->atlas.default_font = nk_font_atlas_add_default(&sdlsurface->atlas, fontSize, 0);
    tex = nk_font_atlas_bake(&sdlsurface->atlas, &texw, &texh, NK_FONT_ATLAS_RGBA32);
    if (!tex) {
    free(sdlsurface);
    return NULL;
    }

    sdlsurface->font_tex = SDL_CreateRGBSurface(0, texw, texh, 32, 0xff, 0xff00, 0xff0000, 0xff000000);

    memcpy(sdlsurface->font_tex->pixels, tex, texw * texh * 4);

    nk_font_atlas_end(&sdlsurface->atlas, nk_handle_ptr(NULL), NULL);
    if (sdlsurface->atlas.default_font)
        nk_style_set_font(&sdlsurface->ctx, &sdlsurface->atlas.default_font->handle);
    nk_style_load_all_cursors(&sdlsurface->ctx, sdlsurface->atlas.cursors);
    nk_sdlsurface_scissor(sdlsurface, 0, 0, sdlsurface->fb->w, sdlsurface->fb->h);

    return sdlsurface;
}

static void
nk_sdlsurface_stretch_image(const struct SDL_Surface *dst,
    const struct SDL_Surface *src, const struct nk_rect *dst_rect,
    const struct nk_rect *src_rect, const struct nk_rect *dst_scissors,
    const struct nk_color *fg)
{
    short i, j;
    struct nk_color col;
    float xinc = src_rect->w / dst_rect->w;
    float yinc = src_rect->h / dst_rect->h;
    float xoff = src_rect->x, yoff = src_rect->y;

    /* Simple nearest filtering rescaling */
    /* TODO: use bilinear filter */
    for (j = 0; j < (short)dst_rect->h; j++) {
        for (i = 0; i < (short)dst_rect->w; i++) {
            if (dst_scissors) {
                if (i + (int)(dst_rect->x + 0.5f) < dst_scissors->x || i + (int)(dst_rect->x + 0.5f) >= dst_scissors->w)
                    continue;
                if (j + (int)(dst_rect->y + 0.5f) < dst_scissors->y || j + (int)(dst_rect->y + 0.5f) >= dst_scissors->h)
                    continue;
            }
            col = nk_sdlsurface_img_getpixel(src, (int)xoff, (int) yoff);
            if (col.r || col.g || col.b)
            {
                col.r = fg->r;
                col.g = fg->g;
                col.b = fg->b;
            }
            nk_sdlsurface_img_blendpixel(dst, i + (int)(dst_rect->x + 0.5f), j + (int)(dst_rect->y + 0.5f), col);
            xoff += xinc;
        }
        xoff = src_rect->x;
        yoff += yinc;
    }
}

static void
nk_sdlsurface_font_query_font_glyph(nk_handle handle, const float height,
    struct nk_user_font_glyph *glyph, const nk_rune codepoint,
    const nk_rune next_codepoint)
{
    float scale;
    const struct nk_font_glyph *g;
    struct nk_font *font;
    NK_ASSERT(glyph);
    NK_UNUSED(next_codepoint);

    font = (struct nk_font*)handle.ptr;
    NK_ASSERT(font);
    NK_ASSERT(font->glyphs);
    if (!font || !glyph)
        return;

    scale = height/font->info.height;
    g = nk_font_find_glyph(font, codepoint);
    glyph->width = (g->x1 - g->x0) * scale;
    glyph->height = (g->y1 - g->y0) * scale;
    glyph->offset = nk_vec2(g->x0 * scale, g->y0 * scale);
    glyph->xadvance = (g->xadvance * scale);
    glyph->uv[0] = nk_vec2(g->u0, g->v0);
    glyph->uv[1] = nk_vec2(g->u1, g->v1);
}

NK_API void
nk_sdlsurface_draw_text(const struct sdlsurface_context *sdlsurface,
    const struct nk_user_font *font, const struct nk_rect rect,
    const char *text, const int len, const float font_height,
    const struct nk_color fg)
{
    float x = 0;
    int text_len = 0;
    nk_rune unicode = 0;
    nk_rune next = 0;
    int glyph_len = 0;
    int next_glyph_len = 0;
    struct nk_user_font_glyph g;
    if (!len || !text) return;

    x = 0;
    glyph_len = nk_utf_decode(text, &unicode, len);
    if (!glyph_len) return;

    /* draw every glyph image */
    while (text_len < len && glyph_len) {
        struct nk_rect src_rect;
        struct nk_rect dst_rect;
        float char_width = 0;
        if (unicode == NK_UTF_INVALID) break;

        /* query currently drawn glyph information */
        next_glyph_len = nk_utf_decode(text + text_len + glyph_len, &next, (int)len - text_len);
        nk_sdlsurface_font_query_font_glyph(font->userdata, font_height, &g, unicode,
                    (next == NK_UTF_INVALID) ? '\0' : next);

        /* calculate and draw glyph drawing rectangle and image */
        char_width = g.xadvance;
        src_rect.x = g.uv[0].x * sdlsurface->font_tex->w;
        src_rect.y = g.uv[0].y * sdlsurface->font_tex->h;
        src_rect.w = g.uv[1].x * sdlsurface->font_tex->w - g.uv[0].x * sdlsurface->font_tex->w;
        src_rect.h = g.uv[1].y * sdlsurface->font_tex->h - g.uv[0].y * sdlsurface->font_tex->h;

        dst_rect.x = x + g.offset.x + rect.x;
        dst_rect.y = g.offset.y + rect.y;
        dst_rect.w = ceil(g.width);
        dst_rect.h = ceil(g.height);

        /* Use software rescaling to blit glyph from font_text to framebuffer */
        nk_sdlsurface_stretch_image(sdlsurface->fb, sdlsurface->font_tex, &dst_rect, &src_rect, &sdlsurface->scissors, &fg);

        /* offset next glyph */
        text_len += glyph_len;
        x += char_width;
        glyph_len = next_glyph_len;
        unicode = next;
    }
}

NK_API void
nk_sdlsurface_drawimage(const struct sdlsurface_context *sdlsurface,
    const int x, const int y, const int w, const int h,
    const struct nk_image *img, const struct nk_color *col)
{
    struct nk_rect src_rect;
    struct nk_rect dst_rect;

    src_rect.x = img->region[0];
    src_rect.y = img->region[1];
    src_rect.w = img->region[2];
    src_rect.h = img->region[3];

    dst_rect.x = x;
    dst_rect.y = y;
    dst_rect.w = w;
    dst_rect.h = h;
    nk_sdlsurface_stretch_image(sdlsurface->fb, sdlsurface->font_tex, &dst_rect, &src_rect, &sdlsurface->scissors, col);
}

NK_API void
nk_sdlsurface_shutdown(struct sdlsurface_context *sdlsurface)
{
    if (sdlsurface) {
        SDL_FreeSurface(sdlsurface->font_tex);
        nk_free(&sdlsurface->ctx);
        memset(sdlsurface, 0, sizeof(struct sdlsurface_context));
        free(sdlsurface);
    }
}


NK_API void
nk_sdlsurface_render(const struct sdlsurface_context *sdlsurface,
                const struct nk_color clear,
                const unsigned char enable_clear)
{
    const struct nk_command *cmd;
    if (enable_clear)
        nk_sdlsurface_clear(sdlsurface, clear);

    nk_foreach(cmd, (struct nk_context*)&sdlsurface->ctx) {
        switch (cmd->type) {
        case NK_COMMAND_NOP: break;
        case NK_COMMAND_SCISSOR: {
            const struct nk_command_scissor *s =(const struct nk_command_scissor*)cmd;
            nk_sdlsurface_scissor((struct sdlsurface_context *)sdlsurface, s->x, s->y, s->w, s->h);
        } break;
        case NK_COMMAND_LINE: {
            const struct nk_command_line *l = (const struct nk_command_line *)cmd;
            nk_sdlsurface_stroke_line(sdlsurface, l->begin.x, l->begin.y, l->end.x,
                l->end.y, l->line_thickness, l->color);
        } break;
        case NK_COMMAND_RECT: {
            const struct nk_command_rect *r = (const struct nk_command_rect *)cmd;
            nk_sdlsurface_stroke_rect(sdlsurface, r->x, r->y, r->w, r->h,
                (unsigned short)r->rounding, r->line_thickness, r->color);
        } break;
        case NK_COMMAND_RECT_FILLED: {
            const struct nk_command_rect_filled *r = (const struct nk_command_rect_filled *)cmd;
            nk_sdlsurface_fill_rect(sdlsurface, r->x, r->y, r->w, r->h,
                (unsigned short)r->rounding, r->color);
        } break;
        case NK_COMMAND_CIRCLE: {
            const struct nk_command_circle *c = (const struct nk_command_circle *)cmd;
            nk_sdlsurface_stroke_circle(sdlsurface, c->x, c->y, c->w, c->h, c->line_thickness, c->color);
        } break;
        case NK_COMMAND_CIRCLE_FILLED: {
            const struct nk_command_circle_filled *c = (const struct nk_command_circle_filled *)cmd;
            nk_sdlsurface_fill_circle(sdlsurface, c->x, c->y, c->w, c->h, c->color);
        } break;
        case NK_COMMAND_TRIANGLE: {
            const struct nk_command_triangle*t = (const struct nk_command_triangle*)cmd;
            nk_sdlsurface_stroke_triangle(sdlsurface, t->a.x, t->a.y, t->b.x, t->b.y,
                t->c.x, t->c.y, t->line_thickness, t->color);
        } break;
        case NK_COMMAND_TRIANGLE_FILLED: {
            const struct nk_command_triangle_filled *t = (const struct nk_command_triangle_filled *)cmd;
            nk_sdlsurface_fill_triangle(sdlsurface, t->a.x, t->a.y, t->b.x, t->b.y,
                t->c.x, t->c.y, t->color);
        } break;
        case NK_COMMAND_POLYGON: {
            const struct nk_command_polygon *p =(const struct nk_command_polygon*)cmd;
            nk_sdlsurface_stroke_polygon(sdlsurface, p->points, p->point_count, p->line_thickness,p->color);
        } break;
        case NK_COMMAND_POLYGON_FILLED: {
            const struct nk_command_polygon_filled *p = (const struct nk_command_polygon_filled *)cmd;
            nk_sdlsurface_fill_polygon(sdlsurface, p->points, p->point_count, p->color);
        } break;
        case NK_COMMAND_POLYLINE: {
            const struct nk_command_polyline *p = (const struct nk_command_polyline *)cmd;
            nk_sdlsurface_stroke_polyline(sdlsurface, p->points, p->point_count, p->line_thickness, p->color);
        } break;
        case NK_COMMAND_TEXT: {
            const struct nk_command_text *t = (const struct nk_command_text*)cmd;
            nk_sdlsurface_draw_text(sdlsurface, t->font, nk_rect(t->x, t->y, t->w, t->h),
                t->string, t->length, t->height, t->foreground);
        } break;
        case NK_COMMAND_CURVE: {
            const struct nk_command_curve *q = (const struct nk_command_curve *)cmd;
            nk_sdlsurface_stroke_curve(sdlsurface, q->begin, q->ctrl[0], q->ctrl[1],
                q->end, 22, q->line_thickness, q->color);
        } break;
        case NK_COMMAND_RECT_MULTI_COLOR: {
        const struct nk_command_rect_multi_color *q = (const struct nk_command_rect_multi_color *)cmd;
        nk_sdlsurface_draw_rect_multi_color(sdlsurface, q->x, q->y, q->w, q->h, q->left, q->top, q->right, q->bottom);
    } break;
        case NK_COMMAND_IMAGE: {
            const struct nk_command_image *q = (const struct nk_command_image *)cmd;
            nk_sdlsurface_drawimage(sdlsurface, q->x, q->y, q->w, q->h, &q->img, &q->col);
        } break;
        case NK_COMMAND_ARC: {
            assert(0 && "NK_COMMAND_ARC not implemented\n");
        } break;
        case NK_COMMAND_ARC_FILLED: {
            assert(0 && "NK_COMMAND_ARC_FILLED not implemented\n");
        } break;
        default: break;
        }
    }
    nk_clear((struct nk_context*)&sdlsurface->ctx);
}
#endif