/*
  * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
  * Copyright (c) 2013 Paul B Mahol
  *
  * 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
  */
 

 #include "libavutil/avassert.h"

 #include "libavutil/eval.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/pixdesc.h"
 #include "libavutil/opt.h"
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
 #include "video.h"
 
 #define SUB_PIXEL_BITS  8
 #define SUB_PIXELS      (1 << SUB_PIXEL_BITS)
 #define COEFF_BITS      11
 
 #define LINEAR 0
 #define CUBIC  1
 
 typedef struct PerspectiveContext {
     const AVClass *class;
     char *expr_str[4][2];
     double ref[4][2];
     int32_t (*pv)[2];
     int32_t coeff[SUB_PIXELS][4];
     int interpolation;
     int linesize[4];
     int height[4];
     int hsub, vsub;
     int nb_planes;

     int sense;

     int eval_mode;

     int (*perspective)(AVFilterContext *ctx,
                        void *arg, int job, int nb_jobs);

 } PerspectiveContext;
 
 #define OFFSET(x) offsetof(PerspectiveContext, x)
 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 

 enum PERSPECTIVESense {
     PERSPECTIVE_SENSE_SOURCE      = 0, ///< coordinates give locations in source of corners of destination.
     PERSPECTIVE_SENSE_DESTINATION = 1, ///< coordinates give locations in destination of corners of source.
 };
 

 enum EvalMode {
     EVAL_MODE_INIT,
     EVAL_MODE_FRAME,
     EVAL_MODE_NB
 };
 

 static const AVOption perspective_options[] = {
     { "x0", "set top left x coordinate",     OFFSET(expr_str[0][0]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },
     { "y0", "set top left y coordinate",     OFFSET(expr_str[0][1]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },
     { "x1", "set top right x coordinate",    OFFSET(expr_str[1][0]), AV_OPT_TYPE_STRING, {.str="W"}, 0, 0, FLAGS },
     { "y1", "set top right y coordinate",    OFFSET(expr_str[1][1]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },
     { "x2", "set bottom left x coordinate",  OFFSET(expr_str[2][0]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },
     { "y2", "set bottom left y coordinate",  OFFSET(expr_str[2][1]), AV_OPT_TYPE_STRING, {.str="H"}, 0, 0, FLAGS },
     { "x3", "set bottom right x coordinate", OFFSET(expr_str[3][0]), AV_OPT_TYPE_STRING, {.str="W"}, 0, 0, FLAGS },
     { "y3", "set bottom right y coordinate", OFFSET(expr_str[3][1]), AV_OPT_TYPE_STRING, {.str="H"}, 0, 0, FLAGS },
     { "interpolation", "set interpolation", OFFSET(interpolation), AV_OPT_TYPE_INT, {.i64=LINEAR}, 0, 1, FLAGS, "interpolation" },
     {      "linear", "", 0, AV_OPT_TYPE_CONST, {.i64=LINEAR}, 0, 0, FLAGS, "interpolation" },
     {       "cubic", "", 0, AV_OPT_TYPE_CONST, {.i64=CUBIC},  0, 0, FLAGS, "interpolation" },

     { "sense",   "specify the sense of the coordinates", OFFSET(sense), AV_OPT_TYPE_INT, {.i64=PERSPECTIVE_SENSE_SOURCE}, 0, 1, FLAGS, "sense"},
     {       "source", "specify locations in source to send to corners in destination",
                 0, AV_OPT_TYPE_CONST, {.i64=PERSPECTIVE_SENSE_SOURCE}, 0, 0, FLAGS, "sense"},
     {       "destination", "specify locations in destination to send corners of source",
                 0, AV_OPT_TYPE_CONST, {.i64=PERSPECTIVE_SENSE_DESTINATION}, 0, 0, FLAGS, "sense"},

     { "eval", "specify when to evaluate expressions", OFFSET(eval_mode), AV_OPT_TYPE_INT, {.i64 = EVAL_MODE_INIT}, 0, EVAL_MODE_NB-1, FLAGS, "eval" },
          { "init",  "eval expressions once during initialization", 0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_INIT},  .flags = FLAGS, .unit = "eval" },
          { "frame", "eval expressions per-frame",                  0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_FRAME}, .flags = FLAGS, .unit = "eval" },

     { NULL }
 };
 
 AVFILTER_DEFINE_CLASS(perspective);
 
 static int query_formats(AVFilterContext *ctx)
 {
     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA420P,
         AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ422P,AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ411P,
         AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,
         AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRAP, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE
     };
 

     AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
     if (!fmts_list)
         return AVERROR(ENOMEM);
     return ff_set_common_formats(ctx, fmts_list);

 }
 
 static inline double get_coeff(double d)
 {
     double coeff, A = -0.60;
 
     d = fabs(d);
 
     if (d < 1.0)
         coeff = (1.0 - (A + 3.0) * d * d + (A + 2.0) * d * d * d);
     else if (d < 2.0)
         coeff = (-4.0 * A + 8.0 * A * d - 5.0 * A * d * d + A * d * d * d);
     else
         coeff = 0.0;
 
     return coeff;
 }
 

 static const char *const var_names[] = {   "W",   "H",   "in",   "on",        NULL };
 enum                                   { VAR_W, VAR_H, VAR_IN, VAR_ON, VAR_VARS_NB };

 static int calc_persp_luts(AVFilterContext *ctx, AVFilterLink *inlink)

 {

     PerspectiveContext *s = ctx->priv;
     AVFilterLink *outlink = ctx->outputs[0];
     double (*ref)[2]      = s->ref;
 
     double values[VAR_VARS_NB] = { [VAR_W] = inlink->w, [VAR_H] = inlink->h,

                                    [VAR_IN] = inlink->frame_count_out + 1,
                                    [VAR_ON] = outlink->frame_count_in + 1 };

     const int h = values[VAR_H];
     const int w = values[VAR_W];

     double x0, x1, x2, x3, x4, x5, x6, x7, x8, q;
     double t0, t1, t2, t3;

     int x, y, i, j, ret;
 
     for (i = 0; i < 4; i++) {
         for (j = 0; j < 2; j++) {
             if (!s->expr_str[i][j])
                 return AVERROR(EINVAL);
             ret = av_expr_parse_and_eval(&s->ref[i][j], s->expr_str[i][j],
                                          var_names, &values[0],
                                          NULL, NULL, NULL, NULL,
                                          0, 0, ctx);
             if (ret < 0)
                 return ret;
         }
     }
 

     switch (s->sense) {
     case PERSPECTIVE_SENSE_SOURCE:
         x6 = ((ref[0][0] - ref[1][0] - ref[2][0] + ref[3][0]) *
               (ref[2][1] - ref[3][1]) -
              ( ref[0][1] - ref[1][1] - ref[2][1] + ref[3][1]) *
               (ref[2][0] - ref[3][0])) * h;
         x7 = ((ref[0][1] - ref[1][1] - ref[2][1] + ref[3][1]) *
               (ref[1][0] - ref[3][0]) -
              ( ref[0][0] - ref[1][0] - ref[2][0] + ref[3][0]) *
               (ref[1][1] - ref[3][1])) * w;
         q =  ( ref[1][0] - ref[3][0]) * (ref[2][1] - ref[3][1]) -
              ( ref[2][0] - ref[3][0]) * (ref[1][1] - ref[3][1]);
 
         x0 = q * (ref[1][0] - ref[0][0]) * h + x6 * ref[1][0];
         x1 = q * (ref[2][0] - ref[0][0]) * w + x7 * ref[2][0];
         x2 = q *  ref[0][0] * w * h;
         x3 = q * (ref[1][1] - ref[0][1]) * h + x6 * ref[1][1];
         x4 = q * (ref[2][1] - ref[0][1]) * w + x7 * ref[2][1];
         x5 = q *  ref[0][1] * w * h;
         x8 = q * w * h;
         break;
     case PERSPECTIVE_SENSE_DESTINATION:
         t0 = ref[0][0] * (ref[3][1] - ref[1][1]) +
              ref[1][0] * (ref[0][1] - ref[3][1]) +
              ref[3][0] * (ref[1][1] - ref[0][1]);
         t1 = ref[1][0] * (ref[2][1] - ref[3][1]) +
              ref[2][0] * (ref[3][1] - ref[1][1]) +
              ref[3][0] * (ref[1][1] - ref[2][1]);
         t2 = ref[0][0] * (ref[3][1] - ref[2][1]) +
              ref[2][0] * (ref[0][1] - ref[3][1]) +
              ref[3][0] * (ref[2][1] - ref[0][1]);
         t3 = ref[0][0] * (ref[1][1] - ref[2][1]) +
              ref[1][0] * (ref[2][1] - ref[0][1]) +
              ref[2][0] * (ref[0][1] - ref[1][1]);
 
         x0 = t0 * t1 * w * (ref[2][1] - ref[0][1]);
         x1 = t0 * t1 * w * (ref[0][0] - ref[2][0]);
         x2 = t0 * t1 * w * (ref[0][1] * ref[2][0] - ref[0][0] * ref[2][1]);
         x3 = t1 * t2 * h * (ref[1][1] - ref[0][1]);
         x4 = t1 * t2 * h * (ref[0][0] - ref[1][0]);
         x5 = t1 * t2 * h * (ref[0][1] * ref[1][0] - ref[0][0] * ref[1][1]);
         x6 = t1 * t2 * (ref[1][1] - ref[0][1]) +
              t0 * t3 * (ref[2][1] - ref[3][1]);
         x7 = t1 * t2 * (ref[0][0] - ref[1][0]) +
              t0 * t3 * (ref[3][0] - ref[2][0]);
         x8 = t1 * t2 * (ref[0][1] * ref[1][0] - ref[0][0] * ref[1][1]) +
              t0 * t3 * (ref[2][0] * ref[3][1] - ref[2][1] * ref[3][0]);
         break;

     default:
         av_assert0(0);

     }

 
     for (y = 0; y < h; y++){
         for (x = 0; x < w; x++){
             int u, v;
 

             u =      lrint(SUB_PIXELS * (x0 * x + x1 * y + x2) /
                                         (x6 * x + x7 * y + x8));
             v =      lrint(SUB_PIXELS * (x3 * x + x4 * y + x5) /
                                         (x6 * x + x7 * y + x8));

 
             s->pv[x + y * w][0] = u;
             s->pv[x + y * w][1] = v;
         }
     }
 

     return 0;
 }
 
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     PerspectiveContext *s = ctx->priv;
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
     int h = inlink->h;
     int w = inlink->w;
     int i, j, ret;
     s->hsub = desc->log2_chroma_w;
     s->vsub = desc->log2_chroma_h;
     s->nb_planes = av_pix_fmt_count_planes(inlink->format);
     if ((ret = av_image_fill_linesizes(s->linesize, inlink->format, inlink->w)) < 0)
         return ret;
 
     s->height[1] = s->height[2] = AV_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);
     s->height[0] = s->height[3] = inlink->h;
 
     s->pv = av_realloc_f(s->pv, w * h, 2 * sizeof(*s->pv));
     if (!s->pv)
         return AVERROR(ENOMEM);
 
     if (s->eval_mode == EVAL_MODE_INIT) {
         if ((ret = calc_persp_luts(ctx, inlink)) < 0) {
             return ret;
         }
     }
 

     for (i = 0; i < SUB_PIXELS; i++){
         double d = i / (double)SUB_PIXELS;
         double temp[4];
         double sum = 0;
 
         for (j = 0; j < 4; j++)
             temp[j] = get_coeff(j - d - 1);
 
         for (j = 0; j < 4; j++)
             sum += temp[j];
 
         for (j = 0; j < 4; j++)

             s->coeff[i][j] = lrint((1 << COEFF_BITS) * temp[j] / sum);

     }
 
     return 0;
 }
 

 typedef struct ThreadData {
     uint8_t *dst;
     int dst_linesize;
     uint8_t *src;
     int src_linesize;
     int w, h;
     int hsub, vsub;
 } ThreadData;
 
 static int resample_cubic(AVFilterContext *ctx, void *arg,
                           int job, int nb_jobs)

 {

     PerspectiveContext *s = ctx->priv;
     ThreadData *td = arg;
     uint8_t *dst = td->dst;
     int dst_linesize = td->dst_linesize;
     uint8_t *src = td->src;
     int src_linesize = td->src_linesize;
     int w = td->w;
     int h = td->h;
     int hsub = td->hsub;
     int vsub = td->vsub;
     int start = (h * job) / nb_jobs;
     int end   = (h * (job+1)) / nb_jobs;

     const int linesize = s->linesize[0];
     int x, y;
 

     for (y = start; y < end; y++) {

         int sy = y << vsub;
         for (x = 0; x < w; x++) {
             int u, v, subU, subV, sum, sx;
 
             sx   = x << hsub;
             u    = s->pv[sx + sy * linesize][0] >> hsub;
             v    = s->pv[sx + sy * linesize][1] >> vsub;
             subU = u & (SUB_PIXELS - 1);
             subV = v & (SUB_PIXELS - 1);
             u  >>= SUB_PIXEL_BITS;
             v  >>= SUB_PIXEL_BITS;
 
             if (u > 0 && v > 0 && u < w - 2 && v < h - 2){
                 const int index = u + v*src_linesize;
                 const int a = s->coeff[subU][0];
                 const int b = s->coeff[subU][1];
                 const int c = s->coeff[subU][2];
                 const int d = s->coeff[subU][3];
 
                 sum = s->coeff[subV][0] * (a * src[index - 1 -     src_linesize] + b * src[index - 0 -     src_linesize]  +
                                       c *      src[index + 1 -     src_linesize] + d * src[index + 2 -     src_linesize]) +
                       s->coeff[subV][1] * (a * src[index - 1                   ] + b * src[index - 0                   ]  +
                                       c *      src[index + 1                   ] + d * src[index + 2                   ]) +
                       s->coeff[subV][2] * (a * src[index - 1 +     src_linesize] + b * src[index - 0 +     src_linesize]  +
                                       c *      src[index + 1 +     src_linesize] + d * src[index + 2 +     src_linesize]) +
                       s->coeff[subV][3] * (a * src[index - 1 + 2 * src_linesize] + b * src[index - 0 + 2 * src_linesize]  +
                                       c *      src[index + 1 + 2 * src_linesize] + d * src[index + 2 + 2 * src_linesize]);
             } else {
                 int dx, dy;
 
                 sum = 0;
 
                 for (dy = 0; dy < 4; dy++) {
                     int iy = v + dy - 1;
 
                     if (iy < 0)
                         iy = 0;
                     else if (iy >= h)
                         iy = h-1;
                     for (dx = 0; dx < 4; dx++) {
                         int ix = u + dx - 1;
 
                         if (ix < 0)
                             ix = 0;
                         else if (ix >= w)
                             ix = w - 1;
 
                         sum += s->coeff[subU][dx] * s->coeff[subV][dy] * src[ ix + iy * src_linesize];
                     }
                 }
             }
 
             sum = (sum + (1<<(COEFF_BITS * 2 - 1))) >> (COEFF_BITS * 2);

             sum = av_clip_uint8(sum);

             dst[x + y * dst_linesize] = sum;
         }
     }

     return 0;

 }
 

 static int resample_linear(AVFilterContext *ctx, void *arg,
                            int job, int nb_jobs)

 {

     PerspectiveContext *s = ctx->priv;
     ThreadData *td = arg;
     uint8_t *dst = td->dst;
     int dst_linesize = td->dst_linesize;
     uint8_t *src = td->src;
     int src_linesize = td->src_linesize;
     int w = td->w;
     int h = td->h;
     int hsub = td->hsub;
     int vsub = td->vsub;
     int start = (h * job) / nb_jobs;
     int end   = (h * (job+1)) / nb_jobs;

     const int linesize = s->linesize[0];
     int x, y;
 

     for (y = start; y < end; y++){

         int sy = y << vsub;
         for (x = 0; x < w; x++){
             int u, v, subU, subV, sum, sx, index, subUI, subVI;
 
             sx   = x << hsub;
             u    = s->pv[sx + sy * linesize][0] >> hsub;
             v    = s->pv[sx + sy * linesize][1] >> vsub;
             subU = u & (SUB_PIXELS - 1);
             subV = v & (SUB_PIXELS - 1);
             u  >>= SUB_PIXEL_BITS;
             v  >>= SUB_PIXEL_BITS;
 
             index = u + v * src_linesize;
             subUI = SUB_PIXELS - subU;
             subVI = SUB_PIXELS - subV;
 
             if ((unsigned)u < (unsigned)(w - 1)){
                 if((unsigned)v < (unsigned)(h - 1)){
                     sum = subVI * (subUI * src[index] + subU * src[index + 1]) +
                           subV  * (subUI * src[index + src_linesize] + subU * src[index + src_linesize + 1]);
                     sum = (sum + (1 << (SUB_PIXEL_BITS * 2 - 1)))>> (SUB_PIXEL_BITS * 2);
                 } else {
                     if (v < 0)
                         v = 0;
                     else
                         v = h - 1;
                     index = u + v * src_linesize;
                     sum   = subUI * src[index] + subU * src[index + 1];
                     sum   = (sum + (1 << (SUB_PIXEL_BITS - 1))) >> SUB_PIXEL_BITS;
                 }
             } else {

                 if (u < 0)
                     u = 0;
                 else
                     u = w - 1;

                 if ((unsigned)v < (unsigned)(h - 1)){
                     index = u + v * src_linesize;
                     sum   = subVI * src[index] + subV * src[index + src_linesize];
                     sum   = (sum + (1 << (SUB_PIXEL_BITS - 1))) >> SUB_PIXEL_BITS;
                 } else {
                     if (v < 0)
                         v = 0;
                     else
                         v = h - 1;
                     index = u + v * src_linesize;
                     sum   = src[index];
                 }
             }
 

             sum = av_clip_uint8(sum);

             dst[x + y * dst_linesize] = sum;
         }
     }

     return 0;

 }
 
 static av_cold int init(AVFilterContext *ctx)
 {
     PerspectiveContext *s = ctx->priv;
 
     switch (s->interpolation) {
     case LINEAR: s->perspective = resample_linear; break;
     case CUBIC:  s->perspective = resample_cubic;  break;
     }
 
     return 0;
 }
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
 {
     AVFilterContext *ctx = inlink->dst;
     AVFilterLink *outlink = ctx->outputs[0];
     PerspectiveContext *s = ctx->priv;
     AVFrame *out;
     int plane;

     int ret;

 
     out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
     if (!out) {
         av_frame_free(&frame);
         return AVERROR(ENOMEM);
     }
     av_frame_copy_props(out, frame);
 

     if (s->eval_mode == EVAL_MODE_FRAME) {
         if ((ret = calc_persp_luts(ctx, inlink)) < 0) {

             av_frame_free(&out);

             return ret;
         }
     }
 

     for (plane = 0; plane < s->nb_planes; plane++) {
         int hsub = plane == 1 || plane == 2 ? s->hsub : 0;
         int vsub = plane == 1 || plane == 2 ? s->vsub : 0;

         ThreadData td = {.dst = out->data[plane],
                          .dst_linesize = out->linesize[plane],
                          .src = frame->data[plane],
                          .src_linesize = frame->linesize[plane],
                          .w = s->linesize[plane],
                          .h = s->height[plane],
                          .hsub = hsub,
                          .vsub = vsub };

         ctx->internal->execute(ctx, s->perspective, &td, NULL, FFMIN(td.h, ff_filter_get_nb_threads(ctx)));

     }
 
     av_frame_free(&frame);
     return ff_filter_frame(outlink, out);
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     PerspectiveContext *s = ctx->priv;
 
     av_freep(&s->pv);
 }
 
 static const AVFilterPad perspective_inputs[] = {
     {

         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
         .config_props = config_input,

     },
     { NULL }
 };
 
 static const AVFilterPad perspective_outputs[] = {
     {

         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,

     },
     { NULL }
 };
 

 AVFilter ff_vf_perspective = {

     .name          = "perspective",
     .description   = NULL_IF_CONFIG_SMALL("Correct the perspective of video."),
     .priv_size     = sizeof(PerspectiveContext),
     .init          = init,
     .uninit        = uninit,
     .query_formats = query_formats,
     .inputs        = perspective_inputs,
     .outputs       = perspective_outputs,
     .priv_class    = &perspective_class,

     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,

 };