/*
  * Chronomaster DFA Video Decoder
  * Copyright (c) 2011 Konstantin Shishkov
  * based on work by Vladimir "VAG" Gneushev
  *

  * 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 "libavutil/intreadwrite.h"
 #include "bytestream.h"
 #include "libavutil/lzo.h" // for av_memcpy_backptr
 
 typedef struct DfaContext {
     AVFrame pic;
 
     uint32_t pal[256];
     uint8_t *frame_buf;
 } DfaContext;
 
 static av_cold int dfa_decode_init(AVCodecContext *avctx)
 {
     DfaContext *s = avctx->priv_data;
 
     avctx->pix_fmt = PIX_FMT_PAL8;
 
     s->frame_buf = av_mallocz(avctx->width * avctx->height + AV_LZO_OUTPUT_PADDING);
     if (!s->frame_buf)
         return AVERROR(ENOMEM);
 
     return 0;
 }
 
 static int decode_copy(uint8_t *frame, int width, int height,
                        const uint8_t *src, const uint8_t *src_end)
 {
     const int size = width * height;
 
     if (src_end - src < size)
         return -1;
     bytestream_get_buffer(&src, frame, size);
     return 0;
 }
 
 static int decode_tsw1(uint8_t *frame, int width, int height,
                        const uint8_t *src, const uint8_t *src_end)
 {
     const uint8_t *frame_start = frame;
     const uint8_t *frame_end   = frame + width * height;
     int mask = 0x10000, bitbuf = 0;

     int v, count, segments;
     unsigned offset;

 
     segments = bytestream_get_le32(&src);

     offset   = bytestream_get_le32(&src);
     if (frame_end - frame <= offset)

         return -1;

     frame += offset;

     while (segments--) {
         if (mask == 0x10000) {
             if (src >= src_end)
                 return -1;
             bitbuf = bytestream_get_le16(&src);
             mask = 1;
         }
         if (src_end - src < 2 || frame_end - frame < 2)
             return -1;
         if (bitbuf & mask) {
             v = bytestream_get_le16(&src);
             offset = (v & 0x1FFF) << 1;
             count = ((v >> 13) + 2) << 1;

             if (frame - frame_start < offset || frame_end - frame < count)

                 return -1;
             av_memcpy_backptr(frame, offset, count);
             frame += count;
         } else {
             *frame++ = *src++;
             *frame++ = *src++;
         }
         mask <<= 1;
     }
 
     return 0;
 }
 
 static int decode_dsw1(uint8_t *frame, int width, int height,
                        const uint8_t *src, const uint8_t *src_end)
 {
     const uint8_t *frame_start = frame;
     const uint8_t *frame_end   = frame + width * height;
     int mask = 0x10000, bitbuf = 0;
     int v, offset, count, segments;
 
     segments = bytestream_get_le16(&src);
     while (segments--) {
         if (mask == 0x10000) {
             if (src >= src_end)
                 return -1;
             bitbuf = bytestream_get_le16(&src);
             mask = 1;
         }
         if (src_end - src < 2 || frame_end - frame < 2)
             return -1;
         if (bitbuf & mask) {
             v = bytestream_get_le16(&src);
             offset = (v & 0x1FFF) << 1;
             count = ((v >> 13) + 2) << 1;

             if (frame - frame_start < offset || frame_end - frame < count)

                 return -1;
             // can't use av_memcpy_backptr() since it can overwrite following pixels
             for (v = 0; v < count; v++)
                 frame[v] = frame[v - offset];
             frame += count;
         } else if (bitbuf & (mask << 1)) {
             frame += bytestream_get_le16(&src);
         } else {
             *frame++ = *src++;
             *frame++ = *src++;
         }
         mask <<= 2;
     }
 
     return 0;
 }
 
 static int decode_dds1(uint8_t *frame, int width, int height,
                        const uint8_t *src, const uint8_t *src_end)
 {
     const uint8_t *frame_start = frame;
     const uint8_t *frame_end   = frame + width * height;
     int mask = 0x10000, bitbuf = 0;
     int i, v, offset, count, segments;
 
     segments = bytestream_get_le16(&src);
     while (segments--) {
         if (mask == 0x10000) {
             if (src >= src_end)
                 return -1;
             bitbuf = bytestream_get_le16(&src);
             mask = 1;
         }
         if (src_end - src < 2 || frame_end - frame < 2)
             return -1;
         if (bitbuf & mask) {
             v = bytestream_get_le16(&src);
             offset = (v & 0x1FFF) << 2;
             count = ((v >> 13) + 2) << 1;

             if (frame - frame_start < offset || frame_end - frame < count*2 + width)

                 return -1;
             for (i = 0; i < count; i++) {
                 frame[0] = frame[1] =
                 frame[width] = frame[width + 1] = frame[-offset];
 
                 frame += 2;
             }
         } else if (bitbuf & (mask << 1)) {
             frame += bytestream_get_le16(&src) * 2;
         } else {
             frame[0] = frame[1] =
             frame[width] = frame[width + 1] =  *src++;
             frame += 2;
             frame[0] = frame[1] =
             frame[width] = frame[width + 1] =  *src++;
             frame += 2;
         }
         mask <<= 2;
     }
 
     return 0;
 }
 
 static int decode_bdlt(uint8_t *frame, int width, int height,
                        const uint8_t *src, const uint8_t *src_end)
 {
     uint8_t *line_ptr;
     int count, lines, segments;
 
     count = bytestream_get_le16(&src);

     if (count >= height)

         return -1;
     frame += width * count;
     lines = bytestream_get_le16(&src);

     if (count + lines > height || src >= src_end)

         return -1;
 
     while (lines--) {
         line_ptr = frame;
         frame += width;
         segments = *src++;
         while (segments--) {
             if (src_end - src < 3)
                 return -1;

             if (frame - line_ptr <= *src)

                 return -1;

             line_ptr += *src++;

             count = (int8_t)*src++;
             if (count >= 0) {

                 if (frame - line_ptr < count || src_end - src < count)

                     return -1;
                 bytestream_get_buffer(&src, line_ptr, count);
             } else {
                 count = -count;

                 if (frame - line_ptr < count || src >= src_end)

                     return -1;
                 memset(line_ptr, *src++, count);
             }
             line_ptr += count;
         }
     }
 
     return 0;
 }
 
 static int decode_wdlt(uint8_t *frame, int width, int height,
                        const uint8_t *src, const uint8_t *src_end)
 {
     const uint8_t *frame_end   = frame + width * height;
     uint8_t *line_ptr;
     int count, i, v, lines, segments;
 
     lines = bytestream_get_le16(&src);

     if (lines > height || src >= src_end)

         return -1;
 
     while (lines--) {
         segments = bytestream_get_le16(&src);
         while ((segments & 0xC000) == 0xC000) {

             unsigned delta = -((int16_t)segments * width);
             if (frame_end - frame <= delta)

                 return -1;

             frame    += delta;

             segments = bytestream_get_le16(&src);
         }
         if (segments & 0x8000) {
             frame[width - 1] = segments & 0xFF;
             segments = bytestream_get_le16(&src);
         }
         line_ptr = frame;
         frame += width;
         while (segments--) {
             if (src_end - src < 2)
                 return -1;

             if (frame - line_ptr <= *src)

                 return -1;

             line_ptr += *src++;

             count = (int8_t)*src++;
             if (count >= 0) {

                 if (frame - line_ptr < count*2 || src_end - src < count*2)

                     return -1;
                 bytestream_get_buffer(&src, line_ptr, count*2);
                 line_ptr += count * 2;
             } else {
                 count = -count;

                 if (frame - line_ptr < count*2 || src_end - src < 2)

                     return -1;
                 v = bytestream_get_le16(&src);
                 for (i = 0; i < count; i++)
                     bytestream_put_le16(&line_ptr, v);
             }
         }
     }
 
     return 0;
 }
 
 static int decode_unk6(uint8_t *frame, int width, int height,
                        const uint8_t *src, const uint8_t *src_end)
 {
     return -1;
 }
 
 static int decode_blck(uint8_t *frame, int width, int height,
                        const uint8_t *src, const uint8_t *src_end)
 {
     memset(frame, 0, width * height);
     return 0;
 }
 
 
 typedef int (*chunk_decoder)(uint8_t *frame, int width, int height,
                              const uint8_t *src, const uint8_t *src_end);
 
 static const chunk_decoder decoder[8] = {
     decode_copy, decode_tsw1, decode_bdlt, decode_wdlt,
     decode_unk6, decode_dsw1, decode_blck, decode_dds1,
 };
 
 static const char* chunk_name[8] = {
     "COPY", "TSW1", "BDLT", "WDLT", "????", "DSW1", "BLCK", "DDS1"
 };
 
 static int dfa_decode_frame(AVCodecContext *avctx,
                             void *data, int *data_size,
                             AVPacket *avpkt)
 {
     DfaContext *s = avctx->priv_data;
     const uint8_t *buf = avpkt->data;
     const uint8_t *buf_end = avpkt->data + avpkt->size;
     const uint8_t *tmp_buf;
     uint32_t chunk_type, chunk_size;
     uint8_t *dst;
     int ret;
     int i, pal_elems;
 
     if (s->pic.data[0])
         avctx->release_buffer(avctx, &s->pic);
 
     if ((ret = avctx->get_buffer(avctx, &s->pic))) {
         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
         return ret;
     }
 
     while (buf < buf_end) {
         chunk_size = AV_RL32(buf + 4);
         chunk_type = AV_RL32(buf + 8);
         buf += 12;
         if (buf_end - buf < chunk_size) {
             av_log(avctx, AV_LOG_ERROR, "Chunk size is too big (%d bytes)\n", chunk_size);
             return -1;
         }
         if (!chunk_type)
             break;
         if (chunk_type == 1) {
             pal_elems = FFMIN(chunk_size / 3, 256);
             tmp_buf = buf;
             for (i = 0; i < pal_elems; i++) {
                 s->pal[i] = bytestream_get_be24(&tmp_buf) << 2;

                 s->pal[i] |= 0xFF << 24 | (s->pal[i] >> 6) & 0x30303;

             }
             s->pic.palette_has_changed = 1;
         } else if (chunk_type <= 9) {
             if (decoder[chunk_type - 2](s->frame_buf, avctx->width, avctx->height,
                                         buf, buf + chunk_size)) {
                 av_log(avctx, AV_LOG_ERROR, "Error decoding %s chunk\n",
                        chunk_name[chunk_type - 2]);
                 return -1;
             }
         } else {
             av_log(avctx, AV_LOG_WARNING, "Ignoring unknown chunk type %d\n",
                    chunk_type);
         }
         buf += chunk_size;
     }
 
     buf = s->frame_buf;
     dst = s->pic.data[0];
     for (i = 0; i < avctx->height; i++) {
         memcpy(dst, buf, avctx->width);
         dst += s->pic.linesize[0];
         buf += avctx->width;
     }
     memcpy(s->pic.data[1], s->pal, sizeof(s->pal));
 
     *data_size = sizeof(AVFrame);
     *(AVFrame*)data = s->pic;
 
     return avpkt->size;
 }
 
 static av_cold int dfa_decode_end(AVCodecContext *avctx)
 {
     DfaContext *s = avctx->priv_data;
 
     if (s->pic.data[0])
         avctx->release_buffer(avctx, &s->pic);
 
     av_freep(&s->frame_buf);
 
     return 0;
 }
 
 AVCodec ff_dfa_decoder = {

     .name           = "dfa",
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = CODEC_ID_DFA,
     .priv_data_size = sizeof(DfaContext),
     .init           = dfa_decode_init,
     .close          = dfa_decode_end,
     .decode         = dfa_decode_frame,
     .capabilities   = CODEC_CAP_DR1,

     .long_name = NULL_IF_CONFIG_SMALL("Chronomaster DFA"),
 };