/*
  * Copyright (c) 2012 Steven Robertson
  *
  * 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
  */
 
 /**
  * @file
  * copy an alpha component from another video's luma
  */
 
 #include <string.h>
 
 #include "libavutil/pixfmt.h"
 #include "avfilter.h"
 #include "bufferqueue.h"
 #include "drawutils.h"
 #include "formats.h"
 #include "internal.h"
 #include "video.h"
 
 enum { Y, U, V, A };
 
 typedef struct {
     int frame_requested;
     int is_packed_rgb;
     uint8_t rgba_map[4];
     struct FFBufQueue queue_main;
     struct FFBufQueue queue_alpha;
 } AlphaMergeContext;
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     AlphaMergeContext *merge = ctx->priv;
     ff_bufqueue_discard_all(&merge->queue_main);
     ff_bufqueue_discard_all(&merge->queue_alpha);
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     enum PixelFormat main_fmts[] = {
         PIX_FMT_YUVA444P, PIX_FMT_YUVA422P, PIX_FMT_YUVA420P,
         PIX_FMT_RGBA, PIX_FMT_BGRA, PIX_FMT_ARGB, PIX_FMT_ABGR,
         PIX_FMT_NONE
     };
     enum PixelFormat alpha_fmts[] = { PIX_FMT_GRAY8, PIX_FMT_NONE };
     AVFilterFormats *main_formats = ff_make_format_list(main_fmts);
     AVFilterFormats *alpha_formats = ff_make_format_list(alpha_fmts);
     ff_formats_ref(main_formats, &ctx->inputs[0]->out_formats);
     ff_formats_ref(alpha_formats, &ctx->inputs[1]->out_formats);
     ff_formats_ref(main_formats, &ctx->outputs[0]->in_formats);
     return 0;
 }
 
 static int config_input_main(AVFilterLink *inlink)
 {
     AlphaMergeContext *merge = inlink->dst->priv;
     merge->is_packed_rgb =
         ff_fill_rgba_map(merge->rgba_map, inlink->format) >= 0;
     return 0;
 }
 
 static int config_output(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     AVFilterLink *mainlink = ctx->inputs[0];
     AVFilterLink *alphalink = ctx->inputs[1];
     if (mainlink->w != alphalink->w || mainlink->h != alphalink->h) {
         av_log(ctx, AV_LOG_ERROR,
                "Input frame sizes do not match (%dx%d vs %dx%d).\n",
                mainlink->w, mainlink->h,
                alphalink->w, alphalink->h);
         return AVERROR(EINVAL);
     }
 
     outlink->w = mainlink->w;
     outlink->h = mainlink->h;
     outlink->time_base = mainlink->time_base;
     outlink->sample_aspect_ratio = mainlink->sample_aspect_ratio;
     outlink->frame_rate = mainlink->frame_rate;
     return 0;
 }
 

 static int start_frame(AVFilterLink *inlink, AVFilterBufferRef *picref) {return 0;}
 static int draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir) {return 0;}

 
 static void draw_frame(AVFilterContext *ctx,
                        AVFilterBufferRef *main_buf,
                        AVFilterBufferRef *alpha_buf)
 {
     AlphaMergeContext *merge = ctx->priv;
     int h = main_buf->video->h;
 
     if (merge->is_packed_rgb) {
         int x, y;
         uint8_t *pin, *pout;
         for (y = 0; y < h; y++) {
             pin = alpha_buf->data[0] + y * alpha_buf->linesize[0];
             pout = main_buf->data[0] + y * main_buf->linesize[0] + merge->rgba_map[A];
             for (x = 0; x < main_buf->video->w; x++) {
                 *pout = *pin;
                 pin += 1;
                 pout += 4;
             }
         }
     } else {
         int y;
         const int main_linesize = main_buf->linesize[A];
         const int alpha_linesize = alpha_buf->linesize[Y];
         for (y = 0; y < h && y < alpha_buf->video->h; y++) {
             memcpy(main_buf->data[A] + y * main_linesize,
                    alpha_buf->data[Y] + y * alpha_linesize,
                    FFMIN(main_linesize, alpha_linesize));
         }
     }
     ff_draw_slice(ctx->outputs[0], 0, h, 1);
 }
 

 static int end_frame(AVFilterLink *inlink)

 {
     AVFilterContext *ctx = inlink->dst;
     AlphaMergeContext *merge = ctx->priv;
 
     int is_alpha = (inlink == ctx->inputs[1]);
     struct FFBufQueue *queue =
         (is_alpha ? &merge->queue_alpha : &merge->queue_main);
     ff_bufqueue_add(ctx, queue, inlink->cur_buf);
     inlink->cur_buf = NULL;
 
     while (1) {
         AVFilterBufferRef *main_buf, *alpha_buf;
 
         if (!ff_bufqueue_peek(&merge->queue_main, 0) ||
             !ff_bufqueue_peek(&merge->queue_alpha, 0)) break;
 
         main_buf = ff_bufqueue_get(&merge->queue_main);
         alpha_buf = ff_bufqueue_get(&merge->queue_alpha);
 
         ctx->outputs[0]->out_buf = main_buf;
         ff_start_frame(ctx->outputs[0], avfilter_ref_buffer(main_buf, ~0));
         merge->frame_requested = 0;
         draw_frame(ctx, main_buf, alpha_buf);
         ff_end_frame(ctx->outputs[0]);
         avfilter_unref_buffer(alpha_buf);
     }

     return 0;

 }
 
 static int request_frame(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     AlphaMergeContext *merge = ctx->priv;
     int in, ret;
 
     merge->frame_requested = 1;
     while (merge->frame_requested) {

         in = ff_bufqueue_peek(&merge->queue_main, 0) ? 1 : 0;

         ret = ff_request_frame(ctx->inputs[in]);
         if (ret < 0)
             return ret;
     }
     return 0;
 }
 
 AVFilter avfilter_vf_alphamerge = {
     .name           = "alphamerge",
     .description    = NULL_IF_CONFIG_SMALL("Copy the luma value of the second "
                       "input into the alpha channel of the first input."),
     .uninit         = uninit,
     .priv_size      = sizeof(AlphaMergeContext),
     .query_formats  = query_formats,
 
     .inputs    = (const AVFilterPad[]) {
         { .name             = "main",
           .type             = AVMEDIA_TYPE_VIDEO,
           .config_props     = config_input_main,
           .get_video_buffer = ff_null_get_video_buffer,
           .start_frame      = start_frame,
           .draw_slice       = draw_slice,
           .end_frame        = end_frame,

           .min_perms        = AV_PERM_READ | AV_PERM_WRITE | AV_PERM_PRESERVE },

         { .name             = "alpha",
           .type             = AVMEDIA_TYPE_VIDEO,
           .start_frame      = start_frame,
           .draw_slice       = draw_slice,
           .end_frame        = end_frame,

           .min_perms        = AV_PERM_READ | AV_PERM_PRESERVE },

         { .name = NULL }
     },
     .outputs   = (const AVFilterPad[]) {
       { .name               = "default",
         .type               = AVMEDIA_TYPE_VIDEO,
         .config_props       = config_output,
         .request_frame      = request_frame },
       { .name = NULL }
     },
 };