/*
  * Copyright (c) 2015 Timo Rothenpieler <timo@rothenpieler.org>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "libavutil/opt.h"
 #include "libavutil/imgutils.h"
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
 #include "video.h"
 
 typedef struct ColorkeyContext {
     const AVClass *class;
 
     /* color offsets rgba */
     int co[4];
 
     uint8_t colorkey_rgba[4];
     float similarity;
     float blend;
 } ColorkeyContext;
 
 static uint8_t do_colorkey_pixel(ColorkeyContext *ctx, uint8_t r, uint8_t g, uint8_t b)
 {
     int dr = (int)r - ctx->colorkey_rgba[0];
     int dg = (int)g - ctx->colorkey_rgba[1];
     int db = (int)b - ctx->colorkey_rgba[2];
 
     double diff = sqrt((dr * dr + dg * dg + db * db) / (255.0 * 255.0));
 
     if (ctx->blend > 0.0001) {
         return av_clipd((diff - ctx->similarity) / ctx->blend, 0.0, 1.0) * 255.0;
     } else {
         return (diff > ctx->similarity) ? 255 : 0;
     }
 }
 
 static int do_colorkey_slice(AVFilterContext *avctx, void *arg, int jobnr, int nb_jobs)
 {
     AVFrame *frame = arg;
 
     const int slice_start = (frame->height * jobnr) / nb_jobs;
     const int slice_end = (frame->height * (jobnr + 1)) / nb_jobs;
 
     ColorkeyContext *ctx = avctx->priv;
 
     int o, x, y;
 
     for (y = slice_start; y < slice_end; ++y) {
         for (x = 0; x < frame->width; ++x) {
             o = frame->linesize[0] * y + x * 4;
 
             frame->data[0][o + ctx->co[3]] =
                 do_colorkey_pixel(ctx,
                                   frame->data[0][o + ctx->co[0]],
                                   frame->data[0][o + ctx->co[1]],
                                   frame->data[0][o + ctx->co[2]]);
         }
     }
 
     return 0;
 }
 
 static int filter_frame(AVFilterLink *link, AVFrame *frame)
 {
     AVFilterContext *avctx = link->dst;
     int res;
 
     if (res = av_frame_make_writable(frame))
         return res;
 

     if (res = avctx->internal->execute(avctx, do_colorkey_slice, frame, NULL, FFMIN(frame->height, ff_filter_get_nb_threads(avctx))))

         return res;
 
     return ff_filter_frame(avctx->outputs[0], frame);
 }
 
 static av_cold int config_output(AVFilterLink *outlink)
 {
     AVFilterContext *avctx = outlink->src;
     ColorkeyContext *ctx = avctx->priv;
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(outlink->format);
     int i;
 
     outlink->w = avctx->inputs[0]->w;
     outlink->h = avctx->inputs[0]->h;
     outlink->time_base = avctx->inputs[0]->time_base;
 
     for (i = 0; i < 4; ++i)

         ctx->co[i] = desc->comp[i].offset;

 
     return 0;
 }
 
 static av_cold int query_formats(AVFilterContext *avctx)
 {
     static const enum AVPixelFormat pixel_fmts[] = {
         AV_PIX_FMT_ARGB,
         AV_PIX_FMT_RGBA,
         AV_PIX_FMT_ABGR,
         AV_PIX_FMT_BGRA,
         AV_PIX_FMT_NONE
     };
 
     AVFilterFormats *formats = NULL;
 
     formats = ff_make_format_list(pixel_fmts);
     if (!formats)
         return AVERROR(ENOMEM);
 
     return ff_set_common_formats(avctx, formats);
 }
 
 static const AVFilterPad colorkey_inputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
     },
     { NULL }
 };
 
 static const AVFilterPad colorkey_outputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,
         .config_props  = config_output,
     },
     { NULL }
 };
 
 #define OFFSET(x) offsetof(ColorkeyContext, x)
 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 
 static const AVOption colorkey_options[] = {
     { "color", "set the colorkey key color", OFFSET(colorkey_rgba), AV_OPT_TYPE_COLOR, { .str = "black" }, CHAR_MIN, CHAR_MAX, FLAGS },
     { "similarity", "set the colorkey similarity value", OFFSET(similarity), AV_OPT_TYPE_FLOAT, { .dbl = 0.01 }, 0.01, 1.0, FLAGS },
     { "blend", "set the colorkey key blend value", OFFSET(blend), AV_OPT_TYPE_FLOAT, { .dbl = 0.0 }, 0.0, 1.0, FLAGS },
     { NULL }
 };
 
 AVFILTER_DEFINE_CLASS(colorkey);
 
 AVFilter ff_vf_colorkey = {
     .name          = "colorkey",

     .description   = NULL_IF_CONFIG_SMALL("Turns a certain color into transparency. Operates on RGB colors."),

     .priv_size     = sizeof(ColorkeyContext),
     .priv_class    = &colorkey_class,
     .query_formats = query_formats,
     .inputs        = colorkey_inputs,
     .outputs       = colorkey_outputs,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
 };