/*
  * Copyright (c) 1990 James Ashton - Sydney University
  * Copyright (c) 2012 Stefano Sabatini
  *
  * 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
  * X-Face decoder, based on libcompface, by James Ashton.
  */
 
 #include "libavutil/pixdesc.h"
 #include "avcodec.h"
 #include "bytestream.h"

 #include "internal.h"

 #include "xface.h"
 
 static int pop_integer(BigInt *b, const ProbRange *pranges)
 {
     uint8_t r;
     int i;
 
     /* extract the last byte into r, and shift right b by 8 bits */
     ff_big_div(b, 0, &r);
 
     i = 0;
     while (r < pranges->offset || r >= pranges->range + pranges->offset) {
         pranges++;
         i++;
     }
     ff_big_mul(b, pranges->range);
     ff_big_add(b, r - pranges->offset);
     return i;
 }
 
 static void pop_greys(BigInt *b, char *bitmap, int w, int h)
 {
     if (w > 3) {
         w /= 2;
         h /= 2;
         pop_greys(b, bitmap,                       w, h);
         pop_greys(b, bitmap + w,                   w, h);
         pop_greys(b, bitmap + XFACE_WIDTH * h,     w, h);
         pop_greys(b, bitmap + XFACE_WIDTH * h + w, w, h);
     } else {
         w = pop_integer(b, ff_xface_probranges_2x2);
         if (w & 1) bitmap[0]               = 1;
         if (w & 2) bitmap[1]               = 1;
         if (w & 4) bitmap[XFACE_WIDTH]     = 1;
         if (w & 8) bitmap[XFACE_WIDTH + 1] = 1;
     }
 }
 
 static void decode_block(BigInt *b, char *bitmap, int w, int h, int level)
 {
     switch (pop_integer(b, &ff_xface_probranges_per_level[level][0])) {
     case XFACE_COLOR_WHITE:
         return;
     case XFACE_COLOR_BLACK:
         pop_greys(b, bitmap, w, h);
         return;
     default:
         w /= 2;
         h /= 2;
         level++;
         decode_block(b, bitmap,                       w, h, level);
         decode_block(b, bitmap + w,                   w, h, level);
         decode_block(b, bitmap + h * XFACE_WIDTH,     w, h, level);
         decode_block(b, bitmap + w + h * XFACE_WIDTH, w, h, level);
         return;
     }
 }
 
 typedef struct XFaceContext {
     uint8_t bitmap[XFACE_PIXELS]; ///< image used internally for decoding
 } XFaceContext;
 
 static av_cold int xface_decode_init(AVCodecContext *avctx)
 {
     if (avctx->width || avctx->height) {
         if (avctx->width != XFACE_WIDTH || avctx->height != XFACE_HEIGHT) {
             av_log(avctx, AV_LOG_ERROR,
                    "Size value %dx%d not supported, only accepts a size of %dx%d\n",
                    avctx->width, avctx->height, XFACE_WIDTH, XFACE_HEIGHT);
             return AVERROR(EINVAL);
         }
     }
 
     avctx->width   = XFACE_WIDTH;
     avctx->height  = XFACE_HEIGHT;
     avctx->pix_fmt = AV_PIX_FMT_MONOWHITE;
 
     return 0;
 }
 
 static int xface_decode_frame(AVCodecContext *avctx,

                               void *data, int *got_frame,

                               AVPacket *avpkt)
 {
     XFaceContext *xface = avctx->priv_data;
     int ret, i, j, k;
     uint8_t byte;
     BigInt b = {0};
     char *buf;
     int64_t c;

     AVFrame *frame = data;

     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)

         return ret;
 
     for (i = 0, k = 0; avpkt->data[i] && i < avpkt->size; i++) {
         c = avpkt->data[i];
 
         /* ignore invalid digits */
         if (c < XFACE_FIRST_PRINT || c > XFACE_LAST_PRINT)
             continue;
 
         if (++k > XFACE_MAX_DIGITS) {
             av_log(avctx, AV_LOG_WARNING,
                    "Buffer is longer than expected, truncating at byte %d\n", i);
             break;
         }
         ff_big_mul(&b, XFACE_PRINTS);
         ff_big_add(&b, c - XFACE_FIRST_PRINT);
     }
 
     /* decode image and put it in bitmap */
     memset(xface->bitmap, 0, XFACE_PIXELS);
     buf = xface->bitmap;
     decode_block(&b, buf,                         16, 16, 0);
     decode_block(&b, buf + 16,                    16, 16, 0);
     decode_block(&b, buf + 32,                    16, 16, 0);
     decode_block(&b, buf + XFACE_WIDTH * 16,      16, 16, 0);
     decode_block(&b, buf + XFACE_WIDTH * 16 + 16, 16, 16, 0);
     decode_block(&b, buf + XFACE_WIDTH * 16 + 32, 16, 16, 0);
     decode_block(&b, buf + XFACE_WIDTH * 32     , 16, 16, 0);
     decode_block(&b, buf + XFACE_WIDTH * 32 + 16, 16, 16, 0);
     decode_block(&b, buf + XFACE_WIDTH * 32 + 32, 16, 16, 0);
 
     ff_xface_generate_face(xface->bitmap, xface->bitmap);
 
     /* convert image from 1=black 0=white bitmap to MONOWHITE */

     buf = frame->data[0];

     for (i = 0, j = 0, k = 0, byte = 0; i < XFACE_PIXELS; i++) {
         byte += xface->bitmap[i];
         if (k == 7) {
             buf[j++] = byte;
             byte = k = 0;
         } else {
             k++;
             byte <<= 1;
         }
         if (j == XFACE_WIDTH/8) {
             j = 0;

             buf += frame->linesize[0];

         }
     }
 

     *got_frame = 1;

 
     return avpkt->size;
 }
 
 AVCodec ff_xface_decoder = {
     .name           = "xface",

     .long_name      = NULL_IF_CONFIG_SMALL("X-face image"),

     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_XFACE,
     .priv_data_size = sizeof(XFaceContext),
     .init           = xface_decode_init,
     .decode         = xface_decode_frame,
     .pix_fmts       = (const enum AVPixelFormat[]) { AV_PIX_FMT_MONOWHITE, AV_PIX_FMT_NONE },
 };