/*
  * Copyright (c) 2014-2015 Michael Niedermayer <michaelni@gmx.at>
  *
  * 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.
  */
 
 /**
  * @todo switch to dualinput
  */
 
 #include "libavutil/avassert.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/opt.h"
 #include "internal.h"
 
 #include "lavfutils.h"
 
 #define MAX_MIPMAPS 5
 
 typedef struct FOCContext {
     AVClass *class;
     float threshold;
     int mipmaps;
     int xmin, ymin, xmax, ymax;
     char *obj_filename;
     int last_x, last_y;
     AVFrame *obj_frame;
     AVFrame *needle_frame[MAX_MIPMAPS];
     AVFrame *haystack_frame[MAX_MIPMAPS];
 } FOCContext;
 
 #define OFFSET(x) offsetof(FOCContext, x)
 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM

 static const AVOption find_rect_options[] = {

     { "object", "object bitmap filename", OFFSET(obj_filename), AV_OPT_TYPE_STRING, {.str = NULL}, .flags = FLAGS },
     { "threshold", "set threshold", OFFSET(threshold), AV_OPT_TYPE_FLOAT, {.dbl = 0.5}, 0, 1.0, FLAGS },
     { "mipmaps", "set mipmaps", OFFSET(mipmaps), AV_OPT_TYPE_INT, {.i64 = 3}, 1, MAX_MIPMAPS, FLAGS },
     { "xmin", "", OFFSET(xmin), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, FLAGS },
     { "ymin", "", OFFSET(ymin), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, FLAGS },
     { "xmax", "", OFFSET(xmax), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, FLAGS },
     { "ymax", "", OFFSET(ymax), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, FLAGS },
     { NULL }
 };
 

 AVFILTER_DEFINE_CLASS(find_rect);

 
 static int query_formats(AVFilterContext *ctx)
 {
     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_YUV420P,
         AV_PIX_FMT_YUVJ420P,
         AV_PIX_FMT_NONE
     };
 
     return ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
 }
 
 static AVFrame *downscale(AVFrame *in)
 {
     int x, y;
     AVFrame *frame = av_frame_alloc();
     uint8_t *src, *dst;
     if (!frame)
         return NULL;
 
     frame->format = in->format;
     frame->width  = (in->width + 1) / 2;
     frame->height = (in->height+ 1) / 2;
 
     if (av_frame_get_buffer(frame, 32) < 0) {
         av_frame_free(&frame);
         return NULL;
     }
     src = in   ->data[0];
     dst = frame->data[0];
 
     for(y = 0; y < frame->height; y++) {
         for(x = 0; x < frame->width; x++) {
             dst[x] = (  src[2*x+0]
                       + src[2*x+1]
                       + src[2*x+0 + in->linesize[0]]
                       + src[2*x+1 + in->linesize[0]]
                       + 2) >> 2;
         }
         src += 2*in->linesize[0];
         dst += frame->linesize[0];
     }
     return frame;
 }
 
 static float compare(const AVFrame *haystack, const AVFrame *obj, int offx, int offy)
 {
     int x,y;
     int o_sum_v = 0;
     int h_sum_v = 0;
     int64_t oo_sum_v = 0;
     int64_t hh_sum_v = 0;
     int64_t oh_sum_v = 0;
     float c;
     int n = obj->height * obj->width;
     const uint8_t *odat = obj     ->data[0];
     const uint8_t *hdat = haystack->data[0] + offx + offy * haystack->linesize[0];
     int64_t o_sigma, h_sigma;
 
     for(y = 0; y < obj->height; y++) {
         for(x = 0; x < obj->width; x++) {
             int o_v = odat[x];
             int h_v = hdat[x];
             o_sum_v += o_v;
             h_sum_v += h_v;
             oo_sum_v += o_v * o_v;
             hh_sum_v += h_v * h_v;
             oh_sum_v += o_v * h_v;
         }
         odat += obj->linesize[0];
         hdat += haystack->linesize[0];
     }
     o_sigma = n*oo_sum_v - o_sum_v*(int64_t)o_sum_v;
     h_sigma = n*hh_sum_v - h_sum_v*(int64_t)h_sum_v;
 
     if (o_sigma == 0 || h_sigma == 0)
         return 1.0;
 
     c = (n*oh_sum_v - o_sum_v*(int64_t)h_sum_v) / (sqrt(o_sigma)*sqrt(h_sigma));
 
     return 1 - fabs(c);
 }
 
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     FOCContext *foc = ctx->priv;
 
     if (foc->xmax <= 0)
         foc->xmax = inlink->w - foc->obj_frame->width;
     if (foc->ymax <= 0)
         foc->ymax = inlink->h - foc->obj_frame->height;
 
     return 0;
 }
 
 static float search(FOCContext *foc, int pass, int maxpass, int xmin, int xmax, int ymin, int ymax, int *best_x, int *best_y, float best_score)
 {
     int x, y;
 
     if (pass + 1 <= maxpass) {
         int sub_x, sub_y;
         search(foc, pass+1, maxpass, xmin>>1, (xmax+1)>>1, ymin>>1, (ymax+1)>>1, &sub_x, &sub_y, 1.0);
         xmin = FFMAX(xmin, 2*sub_x - 4);
         xmax = FFMIN(xmax, 2*sub_x + 4);
         ymin = FFMAX(ymin, 2*sub_y - 4);
         ymax = FFMIN(ymax, 2*sub_y + 4);
     }
 
     for (y = ymin; y <= ymax; y++) {
         for (x = xmin; x <= xmax; x++) {
             float score = compare(foc->haystack_frame[pass], foc->needle_frame[pass], x, y);
             av_assert0(score != 0);
             if (score < best_score) {
                 best_score = score;
                 *best_x = x;
                 *best_y = y;
             }
         }
     }
     return best_score;
 }
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
 {
     AVFilterContext *ctx = inlink->dst;
     FOCContext *foc = ctx->priv;
     float best_score;
     int best_x, best_y;
     int i;
 
     foc->haystack_frame[0] = av_frame_clone(in);
     for (i=1; i<foc->mipmaps; i++) {
         foc->haystack_frame[i] = downscale(foc->haystack_frame[i-1]);
     }
 
     best_score = search(foc, 0, 0,
                         FFMAX(foc->xmin, foc->last_x - 8),
                         FFMIN(foc->xmax, foc->last_x + 8),
                         FFMAX(foc->ymin, foc->last_y - 8),
                         FFMIN(foc->ymax, foc->last_y + 8),
                         &best_x, &best_y, 1.0);
 
     best_score = search(foc, 0, foc->mipmaps - 1, foc->xmin, foc->xmax, foc->ymin, foc->ymax,
                         &best_x, &best_y, best_score);
 
     for (i=0; i<MAX_MIPMAPS; i++) {
         av_frame_free(&foc->haystack_frame[i]);
     }
 
     if (best_score > foc->threshold) {
         return ff_filter_frame(ctx->outputs[0], in);
     }
 
     av_log(ctx, AV_LOG_DEBUG, "Found at %d %d score %f\n", best_x, best_y, best_score);
     foc->last_x = best_x;
     foc->last_y = best_y;
 
     av_frame_make_writable(in);
 
     av_dict_set_int(&in->metadata, "lavfi.rect.w", foc->obj_frame->width, 0);
     av_dict_set_int(&in->metadata, "lavfi.rect.h", foc->obj_frame->height, 0);
     av_dict_set_int(&in->metadata, "lavfi.rect.x", best_x, 0);
     av_dict_set_int(&in->metadata, "lavfi.rect.y", best_y, 0);
 
     return ff_filter_frame(ctx->outputs[0], in);
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     FOCContext *foc = ctx->priv;
     int i;
 
     for (i = 0; i < MAX_MIPMAPS; i++) {
         av_frame_free(&foc->needle_frame[i]);
         av_frame_free(&foc->haystack_frame[i]);
     }
 
     if (foc->obj_frame)
         av_freep(&foc->obj_frame->data[0]);
     av_frame_free(&foc->obj_frame);
 }
 
 static av_cold int init(AVFilterContext *ctx)
 {
     FOCContext *foc = ctx->priv;
     int ret, i;
 
     if (!foc->obj_filename) {
         av_log(ctx, AV_LOG_ERROR, "object filename not set\n");
         return AVERROR(EINVAL);
     }
 
     foc->obj_frame = av_frame_alloc();
     if (!foc->obj_frame)
         return AVERROR(ENOMEM);
 
     if ((ret = ff_load_image(foc->obj_frame->data, foc->obj_frame->linesize,
                              &foc->obj_frame->width, &foc->obj_frame->height,
                              &foc->obj_frame->format, foc->obj_filename, ctx)) < 0)
         return ret;
 
     if (foc->obj_frame->format != AV_PIX_FMT_GRAY8) {
         av_log(ctx, AV_LOG_ERROR, "object image is not a grayscale image\n");
         return AVERROR(EINVAL);
     }
 
     foc->needle_frame[0] = av_frame_clone(foc->obj_frame);
     for (i = 1; i < foc->mipmaps; i++) {
         foc->needle_frame[i] = downscale(foc->needle_frame[i-1]);
         if (!foc->needle_frame[i])
             return AVERROR(ENOMEM);
     }
 
     return 0;
 }
 
 static const AVFilterPad foc_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .config_props = config_input,
         .filter_frame = filter_frame,
     },
     { NULL }
 };
 
 static const AVFilterPad foc_outputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,
     },
     { NULL }
 };
 
 AVFilter ff_vf_find_rect = {
     .name            = "find_rect",

     .description     = NULL_IF_CONFIG_SMALL("Find a user specified object."),

     .priv_size       = sizeof(FOCContext),
     .init            = init,
     .uninit          = uninit,
     .query_formats   = query_formats,
     .inputs          = foc_inputs,
     .outputs         = foc_outputs,

     .priv_class      = &find_rect_class,

 };