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/*

 * XSUB subtitle decoder

 * Copyright (c) 2007 Reimar Döffinger

 *

 * 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 "libavutil/mathematics.h"

#include "libavutil/imgutils.h"

#include "avcodec.h"

#include "get_bits.h"

#include "bytestream.h"

static av_cold int decode_init(AVCodecContext *avctx) {

    avctx->pix_fmt = AV_PIX_FMT_PAL8;

    return 0;

}

static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 };

static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 };

static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) {

    int i;

    int64_t ms = 0;

    if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.')

        return AV_NOPTS_VALUE;

    for (i = 0; i < sizeof(tc_offsets); i++) {

        uint8_t c = buf[tc_offsets[i]] - '0';

        if (c > 9) return AV_NOPTS_VALUE;

        ms = (ms + c) * tc_muls[i];

    }

    return ms - packet_time;

}

static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,

                        AVPacket *avpkt) {

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    AVSubtitle *sub = data;

    const uint8_t *buf_end = buf + buf_size;

    uint8_t *bitmap;

    int w, h, x, y, i;

    int64_t packet_time = 0;

    GetBitContext gb;

    int has_alpha = avctx->codec_tag == MKTAG('D','X','S','A');

    // check that at least header fits

    if (buf_size < 27 + 7 * 2 + 4 * (3 + has_alpha)) {

        av_log(avctx, AV_LOG_ERROR, "coded frame size %d too small\n", buf_size);

        return -1;

    }

    // read start and end time

    if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') {

        av_log(avctx, AV_LOG_ERROR, "invalid time code\n");

        return -1;

    }

    if (avpkt->pts != AV_NOPTS_VALUE)

        packet_time = av_rescale_q(avpkt->pts, AV_TIME_BASE_Q, (AVRational){1, 1000});

    sub->start_display_time = parse_timecode(buf +  1, packet_time);

    sub->end_display_time   = parse_timecode(buf + 14, packet_time);

    buf += 27;

    // read header

    w = bytestream_get_le16(&buf);

    h = bytestream_get_le16(&buf);

    if (av_image_check_size(w, h, 0, avctx) < 0)

        return -1;

    x = bytestream_get_le16(&buf);

    y = bytestream_get_le16(&buf);

    // skip bottom right position, it gives no new information

    bytestream_get_le16(&buf);

    bytestream_get_le16(&buf);

    // The following value is supposed to indicate the start offset

    // (relative to the palette) of the data for the second field,

    // however there are files in which it has a bogus value and thus

    // we just ignore it

    bytestream_get_le16(&buf);

    // allocate sub and set values

    sub->rects =  av_mallocz(sizeof(*sub->rects));

    if (!sub->rects)

        return AVERROR(ENOMEM);

    sub->rects[0] = av_mallocz(sizeof(*sub->rects[0]));

    if (!sub->rects[0]) {

        av_freep(&sub->rects);

        return AVERROR(ENOMEM);

    }

    sub->rects[0]->x = x; sub->rects[0]->y = y;

    sub->rects[0]->w = w; sub->rects[0]->h = h;

    sub->rects[0]->type = SUBTITLE_BITMAP;

    sub->rects[0]->pict.linesize[0] = w;

    sub->rects[0]->pict.data[0] = av_malloc(w * h);

    sub->rects[0]->nb_colors = 4;

    sub->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);

    if (!sub->rects[0]->pict.data[0] || !sub->rects[0]->pict.data[1]) {

        av_freep(&sub->rects[0]->pict.data[1]);

        av_freep(&sub->rects[0]->pict.data[0]);

        av_freep(&sub->rects[0]);

        av_freep(&sub->rects);

        return AVERROR(ENOMEM);

    }

    sub->num_rects = 1;

    // read palette

    for (i = 0; i < sub->rects[0]->nb_colors; i++)

        ((uint32_t*)sub->rects[0]->pict.data[1])[i] = bytestream_get_be24(&buf);

    if (!has_alpha) {

        // make all except background (first entry) non-transparent

        for (i = 1; i < sub->rects[0]->nb_colors; i++)

            ((uint32_t *)sub->rects[0]->pict.data[1])[i] |= 0xff000000;

    } else {

        for (i = 0; i < sub->rects[0]->nb_colors; i++)

            ((uint32_t *)sub->rects[0]->pict.data[1])[i] |= *buf++ << 24;

    }

    // process RLE-compressed data

    init_get_bits(&gb, buf, (buf_end - buf) * 8);

    bitmap = sub->rects[0]->pict.data[0];

    for (y = 0; y < h; y++) {

        // interlaced: do odd lines

        if (y == (h + 1) / 2) bitmap = sub->rects[0]->pict.data[0] + w;

        for (x = 0; x < w; ) {

            int log2 = ff_log2_tab[show_bits(&gb, 8)];

            int run = get_bits(&gb, 14 - 4 * (log2 >> 1));

            int color = get_bits(&gb, 2);

            run = FFMIN(run, w - x);

            // run length 0 means till end of row

            if (!run) run = w - x;

            memset(bitmap, color, run);

            bitmap += run;

            x += run;

        }

        // interlaced, skip every second line

        bitmap += w;

        align_get_bits(&gb);

    }

    *data_size = 1;

    return buf_size;

}

AVCodec ff_xsub_decoder = {

    .name      = "xsub",

    .long_name = NULL_IF_CONFIG_SMALL("XSUB"),

    .type      = AVMEDIA_TYPE_SUBTITLE,

    .id        = AV_CODEC_ID_XSUB,

    .init      = decode_init,

    .decode    = decode_frame,

};