/*
  * Copyright (c) 2015 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 <tesseract/capi.h>
 
 #include "libavutil/opt.h"
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
 #include "video.h"
 
 typedef struct OCRContext {
     const AVClass *class;
 
     char *datapath;
     char *language;
     char *whitelist;
     char *blacklist;
 
     TessBaseAPI *tess;
 } OCRContext;
 
 #define OFFSET(x) offsetof(OCRContext, x)
 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 
 static const AVOption ocr_options[] = {
     { "datapath",  "set datapath",            OFFSET(datapath),  AV_OPT_TYPE_STRING, {.str=NULL},  0, 0, FLAGS },
     { "language",  "set language",            OFFSET(language),  AV_OPT_TYPE_STRING, {.str="eng"}, 0, 0, FLAGS },
     { "whitelist", "set character whitelist", OFFSET(whitelist), AV_OPT_TYPE_STRING, {.str="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.:;,-+_!?\"'[]{}()<>|/\\=*&%$#@!~"}, 0, 0, FLAGS },
     { "blacklist", "set character blacklist", OFFSET(blacklist), AV_OPT_TYPE_STRING, {.str=""},    0, 0, FLAGS },
     { NULL }
 };
 
 static av_cold int init(AVFilterContext *ctx)
 {
     OCRContext *s = ctx->priv;
 
     s->tess = TessBaseAPICreate();
     if (TessBaseAPIInit3(s->tess, s->datapath, s->language) == -1) {
         av_log(ctx, AV_LOG_ERROR, "failed to init tesseract\n");
         return AVERROR(EINVAL);
     }
 
     if (!TessBaseAPISetVariable(s->tess, "tessedit_char_whitelist", s->whitelist)) {
         av_log(ctx, AV_LOG_ERROR, "failed to set whitelist\n");
         return AVERROR(EINVAL);
     }
 
     if (!TessBaseAPISetVariable(s->tess, "tessedit_char_blacklist", s->blacklist)) {
         av_log(ctx, AV_LOG_ERROR, "failed to set blacklist\n");
         return AVERROR(EINVAL);
     }
 
     av_log(ctx, AV_LOG_DEBUG, "Tesseract version: %s\n", TessVersion());
 
     return 0;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_GRAY8,
         AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV411P,
         AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P,
         AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV444P,
         AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P,
         AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ444P,
         AV_PIX_FMT_YUVJ411P,
         AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA420P,
         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 int filter_frame(AVFilterLink *inlink, AVFrame *in)
 {

     AVDictionary **metadata = &in->metadata;

     AVFilterContext *ctx = inlink->dst;
     AVFilterLink *outlink = ctx->outputs[0];
     OCRContext *s = ctx->priv;
     char *result;

     int *confs;

 
     result = TessBaseAPIRect(s->tess, in->data[0], 1,
                              in->linesize[0], 0, 0, in->width, in->height);

     confs = TessBaseAPIAllWordConfidences(s->tess);

     av_dict_set(metadata, "lavfi.ocr.text", result, 0);

     for (int i = 0; confs[i] != -1; i++) {
         char number[256];
 
         snprintf(number, sizeof(number), "%d ", confs[i]);
         av_dict_set(metadata, "lavfi.ocr.confidence", number, AV_DICT_APPEND);
     }
 

     TessDeleteText(result);

     TessDeleteIntArray(confs);

 
     return ff_filter_frame(outlink, in);
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     OCRContext *s = ctx->priv;
 
     TessBaseAPIEnd(s->tess);
     TessBaseAPIDelete(s->tess);
 }
 
 AVFILTER_DEFINE_CLASS(ocr);
 
 static const AVFilterPad ocr_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
     },
     { NULL }
 };
 
 static const AVFilterPad ocr_outputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
     },
     { NULL }
 };
 
 AVFilter ff_vf_ocr = {
     .name          = "ocr",
     .description   = NULL_IF_CONFIG_SMALL("Optical Character Recognition."),
     .priv_size     = sizeof(OCRContext),
     .priv_class    = &ocr_class,
     .query_formats = query_formats,
     .init          = init,
     .uninit        = uninit,
     .inputs        = ocr_inputs,
     .outputs       = ocr_outputs,
 };