/*
  * Copyright (C) 2006 Michael Niedermayer <michaelni@gmx.at>
  * Copyright (C) 2012 Clément Bœsch <ubitux@gmail.com>
  *
  * This file is part of FFmpeg.
  *

  * FFmpeg 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
  * (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 General Public License for more details.

  *

  * You should have received a copy of the GNU 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.

  */
 
 /**
  * @file
  * Generic equation change filter
  * Originally written by Michael Niedermayer for the MPlayer project, and
  * ported by Clément Bœsch for FFmpeg.
  */
 
 #include "libavutil/avstring.h"
 #include "libavutil/eval.h"
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 #include "internal.h"
 
 typedef struct {
     const AVClass *class;
     AVExpr *e[3];               ///< expressions for each plane
     char *expr_str[3];          ///< expression strings for each plane
     int framenum;               ///< frame counter
     AVFilterBufferRef *picref;  ///< current input buffer
     int hsub, vsub;             ///< chroma subsampling
 } GEQContext;
 
 #define OFFSET(x) offsetof(GEQContext, x)
 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 
 static const AVOption geq_options[] = {
     { "lum_expr",   "set luminance expression",   OFFSET(expr_str),                   AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "cb_expr",    "set chroma blue expression", OFFSET(expr_str) +   sizeof(char*), AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "cr_expr",    "set chroma red expression",  OFFSET(expr_str) + 2*sizeof(char*), AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
     {NULL},
 };
 
 AVFILTER_DEFINE_CLASS(geq);
 
 static inline double getpix(void *priv, double x, double y, int plane)
 {
     int xi, yi;
     GEQContext *geq = priv;
     AVFilterBufferRef *picref = geq->picref;
     const uint8_t *src = picref->data[plane];
     const int linesize = picref->linesize[plane];
     const int w = picref->video->w >> (plane ? geq->hsub : 0);
     const int h = picref->video->h >> (plane ? geq->vsub : 0);
 
     xi = x = av_clipf(x, 0, w - 2);
     yi = y = av_clipf(y, 0, h - 2);
 
     x -= xi;
     y -= yi;
 
     return (1-y)*((1-x)*src[xi +  yi    * linesize] + x*src[xi + 1 +  yi    * linesize])
           +   y *((1-x)*src[xi + (yi+1) * linesize] + x*src[xi + 1 + (yi+1) * linesize]);
 }
 
 //TODO: cubic interpolate
 //TODO: keep the last few frames
 static double lum(void *priv, double x, double y) { return getpix(priv, x, y, 0); }
 static double  cb(void *priv, double x, double y) { return getpix(priv, x, y, 1); }
 static double  cr(void *priv, double x, double y) { return getpix(priv, x, y, 2); }
 

 static const char *const var_names[] = {   "X",   "Y",   "W",   "H",   "N",   "SW",   "SH",   "T",        NULL };
 enum                                   { VAR_X, VAR_Y, VAR_W, VAR_H, VAR_N, VAR_SW, VAR_SH, VAR_T, VAR_VARS_NB };

 
 static av_cold int geq_init(AVFilterContext *ctx, const char *args)
 {
     GEQContext *geq = ctx->priv;
     int plane, ret = 0;
     static const char *shorthand[] = { "lum_expr", "cb_expr", "cr_expr", NULL };
 
     geq->class = &geq_class;
     av_opt_set_defaults(geq);
 
     if ((ret = av_opt_set_from_string(geq, args, shorthand, "=", ":")) < 0)
         return ret;
 
     if (!geq->expr_str[0]) {
         av_log(ctx, AV_LOG_ERROR, "Luminance expression is mandatory\n");
         ret = AVERROR(EINVAL);
         goto end;
     }
 
     if (!geq->expr_str[1] && !geq->expr_str[2]) {
         /* No chroma at all: fallback on luma */
         geq->expr_str[1] = av_strdup(geq->expr_str[0]);
         geq->expr_str[2] = av_strdup(geq->expr_str[0]);
     } else {
         /* One chroma unspecified, fallback on the other */
         if (!geq->expr_str[1]) geq->expr_str[1] = av_strdup(geq->expr_str[2]);
         if (!geq->expr_str[2]) geq->expr_str[2] = av_strdup(geq->expr_str[1]);
     }
 
     if (!geq->expr_str[1] || !geq->expr_str[2]) {
         ret = AVERROR(ENOMEM);
         goto end;
     }
 
     for (plane = 0; plane < 3; plane++) {
         static double (*p[])(void *, double, double) = { lum, cb, cr };
         static const char *const func2_names[]    = { "lum", "cb", "cr", "p", NULL };
         double (*func2[])(void *, double, double) = { lum, cb, cr, p[plane], NULL };
 
         ret = av_expr_parse(&geq->e[plane], geq->expr_str[plane], var_names,
                             NULL, NULL, func2_names, func2, 0, ctx);
         if (ret < 0)
             break;
     }
 
 end:
     return ret;
 }
 
 static int geq_query_formats(AVFilterContext *ctx)
 {
     static const enum PixelFormat pix_fmts[] = {
         AV_PIX_FMT_YUV444P,  AV_PIX_FMT_YUV422P,  AV_PIX_FMT_YUV420P,
         AV_PIX_FMT_YUV411P,  AV_PIX_FMT_YUV410P,  AV_PIX_FMT_YUV440P,
         AV_PIX_FMT_YUVA420P,
         AV_PIX_FMT_NONE
     };
     ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
     return 0;
 }
 
 static int geq_config_props(AVFilterLink *inlink)
 {
     GEQContext *geq = inlink->dst->priv;
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
 
     geq->hsub = desc->log2_chroma_w;
     geq->vsub = desc->log2_chroma_h;
     return 0;
 }
 

 static int geq_filter_frame(AVFilterLink *inlink, AVFilterBufferRef *in)

 {

     int plane;

     GEQContext *geq = inlink->dst->priv;
     AVFilterLink *outlink = inlink->dst->outputs[0];

     AVFilterBufferRef *out;

     double values[VAR_VARS_NB] = {
         [VAR_N] = geq->framenum++,

         [VAR_T] = in->pts == AV_NOPTS_VALUE ? NAN : in->pts * av_q2d(inlink->time_base),

     };
 

     geq->picref = in;
     out = ff_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
     if (!out) {
         avfilter_unref_bufferp(&in);
         return AVERROR(ENOMEM);
     }
     avfilter_copy_buffer_ref_props(out, in);

 
     for (plane = 0; plane < 3; plane++) {
         int x, y;

         uint8_t *dst = out->data[plane];
         const int linesize = out->linesize[plane];

         const int w = inlink->w >> (plane ? geq->hsub : 0);
         const int h = inlink->h >> (plane ? geq->vsub : 0);
 
         values[VAR_W]  = w;
         values[VAR_H]  = h;
         values[VAR_SW] = w / (double)inlink->w;
         values[VAR_SH] = h / (double)inlink->h;
 
         for (y = 0; y < h; y++) {
             values[VAR_Y] = y;
             for (x = 0; x < w; x++) {
                 values[VAR_X] = x;
                 dst[x] = av_expr_eval(geq->e[plane], values, geq);
             }
             dst += linesize;
         }
     }
 

     avfilter_unref_bufferp(&geq->picref);
     return ff_filter_frame(outlink, out);

 }
 
 static av_cold void geq_uninit(AVFilterContext *ctx)
 {
     int i;
     GEQContext *geq = ctx->priv;
 
     for (i = 0; i < FF_ARRAY_ELEMS(geq->e); i++)
         av_expr_free(geq->e[i]);
     av_opt_free(geq);
 }
 
 static const AVFilterPad geq_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .config_props = geq_config_props,

         .filter_frame = geq_filter_frame,

         .min_perms    = AV_PERM_READ,
     },
     { NULL }
 };
 
 static const AVFilterPad geq_outputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,
     },
     { NULL }
 };
 
 AVFilter avfilter_vf_geq = {
     .name          = "geq",
     .description   = NULL_IF_CONFIG_SMALL("Apply generic equation to each pixel."),
     .priv_size     = sizeof(GEQContext),
     .init          = geq_init,
     .uninit        = geq_uninit,
     .query_formats = geq_query_formats,
     .inputs        = geq_inputs,
     .outputs       = geq_outputs,
     .priv_class    = &geq_class,
 };