/*
  * Copyright (c) 2017 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 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/avstring.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
 #include "framesync.h"
 #include "video.h"
 
 typedef struct MixContext {
     const AVClass *class;
     const AVPixFmtDescriptor *desc;
     char *weights_str;
     int nb_inputs;
     int duration;
     float *weights;
     float wfactor;
 
     int depth;
     int nb_planes;
     int linesize[4];
     int height[4];
 
     AVFrame **frames;
     FFFrameSync fs;
 } MixContext;
 
 static int query_formats(AVFilterContext *ctx)
 {
     AVFilterFormats *pix_fmts = NULL;
     int fmt, ret;
 
     for (fmt = 0; av_pix_fmt_desc_get(fmt); fmt++) {
         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(fmt);
         if (!(desc->flags & AV_PIX_FMT_FLAG_PAL ||
               desc->flags & AV_PIX_FMT_FLAG_HWACCEL ||
               desc->flags & AV_PIX_FMT_FLAG_BITSTREAM) &&
             (ret = ff_add_format(&pix_fmts, fmt)) < 0)
             return ret;
     }
 
     return ff_set_common_formats(ctx, pix_fmts);
 }
 
 static av_cold int init(AVFilterContext *ctx)
 {
     MixContext *s = ctx->priv;
     char *p, *arg, *saveptr = NULL;
     int i, ret;
 
     s->frames = av_calloc(s->nb_inputs, sizeof(*s->frames));
     if (!s->frames)
         return AVERROR(ENOMEM);
 
     s->weights = av_calloc(s->nb_inputs, sizeof(*s->weights));
     if (!s->weights)
         return AVERROR(ENOMEM);
 
     for (i = 0; i < s->nb_inputs; i++) {
         AVFilterPad pad = { 0 };
 
         pad.type = AVMEDIA_TYPE_VIDEO;
         pad.name = av_asprintf("input%d", i);
         if (!pad.name)
             return AVERROR(ENOMEM);
 
         if ((ret = ff_insert_inpad(ctx, i, &pad)) < 0) {
             av_freep(&pad.name);
             return ret;
         }
     }
 
     p = s->weights_str;
     for (i = 0; i < s->nb_inputs; i++) {
         if (!(arg = av_strtok(p, " ", &saveptr)))
             break;
 
         p = NULL;
         sscanf(arg, "%f", &s->weights[i]);
         s->wfactor += s->weights[i];
     }
     s->wfactor = 1 / s->wfactor;
 
     return 0;
 }
 
 static int process_frame(FFFrameSync *fs)
 {
     AVFilterContext *ctx = fs->parent;
     AVFilterLink *outlink = ctx->outputs[0];
     MixContext *s = fs->opaque;
     AVFrame **in = s->frames;
     AVFrame *out;
     int i, p, ret, x, y;
 
     for (i = 0; i < s->nb_inputs; i++) {
         if ((ret = ff_framesync_get_frame(&s->fs, i, &in[i], 0)) < 0)
             return ret;
     }
 
     out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
     if (!out)
         return AVERROR(ENOMEM);
     out->pts = av_rescale_q(s->fs.pts, s->fs.time_base, outlink->time_base);
 
     if (s->depth <= 8) {
         for (p = 0; p < s->nb_planes; p++) {
             uint8_t *dst = out->data[p];
 
             for (y = 0; y < s->height[p]; y++) {
                 for (x = 0; x < s->linesize[p]; x++) {
                     int val = 0;
 
                     for (i = 0; i < s->nb_inputs; i++) {
                         uint8_t src = in[i]->data[p][y * s->linesize[p] + x];
 
                         val += src * s->weights[i];
                     }
 
                     dst[x] = val * s->wfactor;
                 }
 
                 dst += out->linesize[p];
             }
         }
     } else {
         for (p = 0; p < s->nb_planes; p++) {
             uint16_t *dst = (uint16_t *)out->data[p];
 
             for (y = 0; y < s->height[p]; y++) {
                 for (x = 0; x < s->linesize[p]; x++) {
                     int val = 0;
 
                     for (i = 0; i < s->nb_inputs; i++) {
                         uint16_t src = AV_RN16(in[i]->data[p] + y * s->linesize[p] + x * 2);
 
                         val += src * s->weights[i];
                     }
 
                     dst[x] = val * s->wfactor;
                 }
 
                 dst += out->linesize[p] / 2;
             }
         }
     }
 
     return ff_filter_frame(outlink, out);
 }
 
 static int config_output(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     MixContext *s = ctx->priv;
     AVRational time_base = ctx->inputs[0]->time_base;
     AVRational frame_rate = ctx->inputs[0]->frame_rate;
     AVFilterLink *inlink = ctx->inputs[0];
     int height = ctx->inputs[0]->h;
     int width = ctx->inputs[0]->w;
     FFFrameSyncIn *in;
     int i, ret;
 
     for (i = 1; i < s->nb_inputs; i++) {
         if (ctx->inputs[i]->h != height || ctx->inputs[i]->w != width) {
             av_log(ctx, AV_LOG_ERROR, "Input %d size (%dx%d) does not match input %d size (%dx%d).\n", i, ctx->inputs[i]->w, ctx->inputs[i]->h, 0, width, height);
             return AVERROR(EINVAL);
         }
     }
 
     s->desc = av_pix_fmt_desc_get(outlink->format);
     if (!s->desc)
         return AVERROR_BUG;
     s->nb_planes = av_pix_fmt_count_planes(outlink->format);
     s->depth = s->desc->comp[0].depth;
 
     outlink->w          = width;
     outlink->h          = height;
     outlink->time_base  = time_base;
     outlink->frame_rate = frame_rate;
 
     if ((ret = ff_framesync_init(&s->fs, ctx, s->nb_inputs)) < 0)
         return ret;
 
     in = s->fs.in;
     s->fs.opaque = s;
     s->fs.on_event = process_frame;
 
     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, s->desc->log2_chroma_h);
     s->height[0] = s->height[3] = inlink->h;
 
     for (i = 0; i < s->nb_inputs; i++) {
         AVFilterLink *inlink = ctx->inputs[i];
 
         in[i].time_base = inlink->time_base;
         in[i].sync   = 1;
         in[i].before = EXT_STOP;
         in[i].after  = (s->duration == 1 || (s->duration == 2 && i == 0)) ? EXT_STOP : EXT_INFINITY;
     }
 
     return ff_framesync_configure(&s->fs);
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     MixContext *s = ctx->priv;
     int i;
 
     ff_framesync_uninit(&s->fs);
     av_freep(&s->frames);
     av_freep(&s->weights);
 
     for (i = 0; i < ctx->nb_inputs; i++)
         av_freep(&ctx->input_pads[i].name);
 }
 
 static int activate(AVFilterContext *ctx)
 {
     MixContext *s = ctx->priv;
     return ff_framesync_activate(&s->fs);
 }
 
 #define OFFSET(x) offsetof(MixContext, x)
 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM
 
 static const AVOption mix_options[] = {
     { "inputs", "set number of inputs", OFFSET(nb_inputs), AV_OPT_TYPE_INT, {.i64=2}, 2, INT_MAX, .flags = FLAGS },
     { "weights", "set weight for each input", OFFSET(weights_str), AV_OPT_TYPE_STRING, {.str="1 1"}, 0, 0, .flags = FLAGS },
     { "duration", "how to determine end of stream", OFFSET(duration), AV_OPT_TYPE_INT, {.i64=0}, 0, 2, .flags = FLAGS, "duration" },
         { "longest",  "Duration of longest input",  0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, FLAGS, "duration" },
         { "shortest", "Duration of shortest input", 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, FLAGS, "duration" },
         { "first",    "Duration of first input",    0, AV_OPT_TYPE_CONST, {.i64=2}, 0, 0, FLAGS, "duration" },
     { NULL },
 };
 
 static const AVFilterPad outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
         .config_props  = config_output,
     },
     { NULL }
 };
 
 AVFILTER_DEFINE_CLASS(mix);
 
 AVFilter ff_vf_mix = {
     .name          = "mix",
     .description   = NULL_IF_CONFIG_SMALL("Mix video inputs."),
     .priv_size     = sizeof(MixContext),
     .priv_class    = &mix_class,
     .query_formats = query_formats,
     .outputs       = outputs,
     .init          = init,
     .uninit        = uninit,
     .activate      = activate,
     .flags         = AVFILTER_FLAG_DYNAMIC_INPUTS,
 };