/*

 * DivX (XSUB) subtitle encoder

 * Copyright (c) 2005 DivX, Inc.

 * Copyright (c) 2009 Bjorn Axelsson

 *

 * 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 "bytestream.h"

#include "codec_internal.h"

#include "put_bits.h"

/**

 * Number of pixels to pad left and right.

 *

 * The official encoder pads the subtitles with two pixels on either side,

 * but until we find out why, we won't do it (we will pad to have width

 * divisible by 2 though).

 */

#define PADDING 0

#define PADDING_COLOR 0

/**

 * Encode a single color run. At most 16 bits will be used.

 * @param len   length of the run, values > 255 mean "until end of line", may not be < 0.

 * @param color color to encode, only the lowest two bits are used and all others must be 0.

 */

static void put_xsub_rle(PutBitContext *pb, int len, int color)

{

    if (len <= 255)

        put_bits(pb, 2 + ((ff_log2_tab[len] >> 1) << 2), len);

    else

        put_bits(pb, 14, 0);

    put_bits(pb, 2, color);

}

/**

 * Encode a 4-color bitmap with XSUB rle.

 *

 * The encoded bitmap may be wider than the source bitmap due to padding.

 */

static int xsub_encode_rle(PutBitContext *pb, const uint8_t *bitmap,

                           int linesize, int w, int h)

{

    int x0, x1, y, len, color = PADDING_COLOR;

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

        x0 = 0;

        while (x0 < w) {

            // Make sure we have enough room for at least one run and padding

            if (put_bytes_left(pb, 1) < 7)

                return AVERROR_BUFFER_TOO_SMALL;

            x1 = x0;

            color = bitmap[x1++] & 3;

            while (x1 < w && (bitmap[x1] & 3) == color)

                x1++;

            len = x1 - x0;

            if (PADDING && x0 == 0) {

                if (color == PADDING_COLOR) {

                    len += PADDING;

                    x0  -= PADDING;

                } else

                    put_xsub_rle(pb, PADDING, PADDING_COLOR);

            }

            // Run can't be longer than 255, unless it is the rest of a row

            if (x1 == w && color == PADDING_COLOR) {

                len += PADDING + (w&1);

            } else

                len = FFMIN(len, 255);

            put_xsub_rle(pb, len, color);

            x0 += len;

        }

        if (color != PADDING_COLOR && (PADDING + (w&1)))

            put_xsub_rle(pb, PADDING + (w&1), PADDING_COLOR);

        align_put_bits(pb);

        bitmap += linesize;

    }

    return 0;

}

static int make_tc(uint64_t ms, int *tc)

{

    static const int tc_divs[3] = { 1000, 60, 60 };

    int i;

    for (i=0; i<3; i++) {

        tc[i] = ms % tc_divs[i];

        ms /= tc_divs[i];

    }

    tc[3] = ms;

    return ms > 99;

}

static int xsub_encode(AVCodecContext *avctx, unsigned char *buf,

                       int bufsize, const AVSubtitle *h)

{

    uint64_t startTime = h->pts / 1000; // FIXME: need better solution...

    uint64_t endTime = startTime + h->end_display_time - h->start_display_time;

    int start_tc[4], end_tc[4];

    uint8_t *hdr = buf + 27; // Point behind the timestamp

    uint8_t *rlelenptr;

    uint16_t width, height;

    int i;

    PutBitContext pb;

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

        av_log(avctx, AV_LOG_ERROR, "Buffer too small for XSUB header.\n");

        return AVERROR_BUFFER_TOO_SMALL;

    }

    // TODO: support multiple rects

    if (h->num_rects != 1)

        av_log(avctx, AV_LOG_WARNING, "Only single rects supported (%d in subtitle.)\n", h->num_rects);

    // TODO: render text-based subtitles into bitmaps

    if (!h->rects[0]->data[0] || !h->rects[0]->data[1]) {

        av_log(avctx, AV_LOG_WARNING, "No subtitle bitmap available.\n");

        return AVERROR(EINVAL);

    }

    // TODO: color reduction, similar to dvdsub encoder

    if (h->rects[0]->nb_colors > 4)

        av_log(avctx, AV_LOG_WARNING, "No more than 4 subtitle colors supported (%d found.)\n", h->rects[0]->nb_colors);

    // TODO: Palette swapping if color zero is not transparent

    if (((uint32_t *)h->rects[0]->data[1])[0] & 0xff000000)

        av_log(avctx, AV_LOG_WARNING, "Color index 0 is not transparent. Transparency will be messed up.\n");

    if (make_tc(startTime, start_tc) || make_tc(endTime, end_tc)) {

        av_log(avctx, AV_LOG_WARNING, "Time code >= 100 hours.\n");

        return AVERROR(EINVAL);

    }

    snprintf(buf, 28,

        "[%02d:%02d:%02d.%03d-%02d:%02d:%02d.%03d]",

        start_tc[3], start_tc[2], start_tc[1], start_tc[0],

        end_tc[3],   end_tc[2],   end_tc[1],   end_tc[0]);

    // Width and height must probably be multiples of 2.

    // 2 pixels required on either side of subtitle.

    // Possibly due to limitations of hardware renderers.

    // TODO: check if the bitmap is already padded

    width  = FFALIGN(h->rects[0]->w, 2) + PADDING * 2;

    height = FFALIGN(h->rects[0]->h, 2);

    bytestream_put_le16(&hdr, width);

    bytestream_put_le16(&hdr, height);

    bytestream_put_le16(&hdr, h->rects[0]->x);

    bytestream_put_le16(&hdr, h->rects[0]->y);

    bytestream_put_le16(&hdr, h->rects[0]->x + width -1);

    bytestream_put_le16(&hdr, h->rects[0]->y + height -1);

    rlelenptr = hdr; // Will store length of first field here later.

    hdr+=2;

    // Palette

    for (i=0; i<4; i++)

        bytestream_put_be24(&hdr, ((uint32_t *)h->rects[0]->data[1])[i]);

    // Bitmap

    // RLE buffer. Reserve 2 bytes for possible padding after the last row.

    init_put_bits(&pb, hdr, bufsize - (hdr - buf) - 2);

    if (xsub_encode_rle(&pb, h->rects[0]->data[0],

                        h->rects[0]->linesize[0] * 2,

                        h->rects[0]->w, (h->rects[0]->h + 1) >> 1))

        return AVERROR_BUFFER_TOO_SMALL;

    bytestream_put_le16(&rlelenptr, put_bytes_count(&pb, 0)); // Length of first field

    if (xsub_encode_rle(&pb, h->rects[0]->data[0] + h->rects[0]->linesize[0],

                        h->rects[0]->linesize[0] * 2,

                        h->rects[0]->w, h->rects[0]->h >> 1))

        return AVERROR_BUFFER_TOO_SMALL;

    // Enforce total height to be a multiple of 2

    if (h->rects[0]->h & 1) {

        put_xsub_rle(&pb, h->rects[0]->w, PADDING_COLOR);

    }

    flush_put_bits(&pb);

    return hdr - buf + put_bytes_output(&pb);

}

static av_cold int xsub_encoder_init(AVCodecContext *avctx)

{

    if (!avctx->codec_tag)

        avctx->codec_tag = MKTAG('D','X','S','B');

    avctx->bits_per_coded_sample = 4;

    return 0;

}

const FFCodec ff_xsub_encoder = {

    .p.name     = "xsub",

    CODEC_LONG_NAME("DivX subtitles (XSUB)"),

    .p.type     = AVMEDIA_TYPE_SUBTITLE,

    .p.id       = AV_CODEC_ID_XSUB,

    .init       = xsub_encoder_init,

    FF_CODEC_ENCODE_SUB_CB(xsub_encode),

};