/*
  * Librsvg rasterization wrapper
  * Copyright (c) 2017 Rostislav Pehlivanov <atomnuker@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 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 "avcodec.h"
 #include "internal.h"
 #include "libavutil/opt.h"
 #include "librsvg-2.0/librsvg/rsvg.h"
 
 typedef struct LibRSVGContext {
     AVClass *class;
 
     int width;
     int height;
     int keep_ar;
 } LibRSVGContext;
 
 static int librsvg_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *pkt)
 {
     int ret;
     LibRSVGContext *s = avctx->priv_data;
     AVFrame *frame = data;
 
     RsvgHandle *handle;
     RsvgDimensionData unscaled_dimensions, dimensions;
     cairo_surface_t *image;
     cairo_t *crender = NULL;
     GError *error = NULL;
 
     *got_frame = 0;
 
     handle = rsvg_handle_new_from_data(pkt->data, pkt->size, &error);
     if (error) {
         av_log(avctx, AV_LOG_ERROR, "Error parsing svg!\n");
         g_error_free(error);
         return AVERROR_INVALIDDATA;
     }
 
     rsvg_handle_get_dimensions(handle, &dimensions);
     rsvg_handle_get_dimensions(handle, &unscaled_dimensions);
     dimensions.width  = s->width  ? s->width  : dimensions.width;
     dimensions.height = s->height ? s->height : dimensions.height;
     if (s->keep_ar && (s->width || s->height)) {
         double default_ar = unscaled_dimensions.width/(double)unscaled_dimensions.height;
         if (!s->width)
             dimensions.width  = lrintf(dimensions.height * default_ar);
         else
             dimensions.height = lrintf(dimensions.width  / default_ar);
     }
 
     if ((ret = ff_set_dimensions(avctx, dimensions.width, dimensions.height)))
         return ret;

     avctx->pix_fmt = AV_PIX_FMT_RGB32;

 
     if ((ret = ff_get_buffer(avctx, frame, 0)))
         return ret;
     frame->pict_type = AV_PICTURE_TYPE_I;
     frame->key_frame = 1;
 
     image = cairo_image_surface_create_for_data(frame->data[0], CAIRO_FORMAT_ARGB32,
                                                 frame->width, frame->height,
                                                 frame->linesize[0]);
     if (cairo_surface_status(image) != CAIRO_STATUS_SUCCESS)
         return AVERROR_INVALIDDATA;
 
     crender = cairo_create(image);
 

     cairo_save(crender);
     cairo_set_operator(crender, CAIRO_OPERATOR_CLEAR);
     cairo_paint(crender);
     cairo_restore(crender);

 
     cairo_scale(crender, dimensions.width / (double)unscaled_dimensions.width,
                 dimensions.height / (double)unscaled_dimensions.height);
 
     rsvg_handle_render_cairo(handle, crender);
 
     cairo_destroy(crender);
     cairo_surface_destroy(image);
     g_object_unref(handle);
 
     *got_frame = 1;
 
     return 0;
 }
 
 #define OFFSET(x) offsetof(LibRSVGContext, x)
 #define DEC (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_VIDEO_PARAM)
 static const AVOption options[] = {
     { "width", "Width to render to (0 for default)", OFFSET(width), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, DEC },
     { "height", "Height to render to (0 for default)", OFFSET(height), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, DEC },
     { "keep_ar", "Keep aspect ratio with custom width/height", OFFSET(keep_ar), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, DEC },
     { NULL },
 };
 
 static const AVClass librsvg_decoder_class = {
     .class_name = "Librsvg",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 
 AVCodec ff_librsvg_decoder = {
     .name           = "librsvg",
     .long_name      = NULL_IF_CONFIG_SMALL("Librsvg rasterizer"),
     .priv_class     = &librsvg_decoder_class,
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_SVG,
     .decode         = librsvg_decode_frame,
     .priv_data_size = sizeof(LibRSVGContext),
     .capabilities   = AV_CODEC_CAP_LOSSLESS | AV_CODEC_CAP_DR1,

     .wrapper_name    = "librsvg",

 };