/*

 * QOI image format

 *

 * 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 "decode.h"

#include "thread.h"

#include "qoi.h"

static int qoi_decode_frame(AVCodecContext *avctx, AVFrame *p,

                            int *got_frame, AVPacket *avpkt)

{

    int width, height, channels, space, run = 0;

    uint8_t index[64][4] = { 0 };

    uint8_t px[4] = { 0, 0, 0, 255 };

    GetByteContext gb;

    uint8_t *dst;

    uint64_t len;

    int ret;

    if (avpkt->size < 20)

        return AVERROR_INVALIDDATA;

    bytestream2_init(&gb, avpkt->data, avpkt->size);

    bytestream2_skip(&gb, 4);

    width  = bytestream2_get_be32(&gb);

    height = bytestream2_get_be32(&gb);

    channels = bytestream2_get_byte(&gb);

    space = bytestream2_get_byte(&gb);

    switch (space) {

    case 0: break;

    case 1: avctx->color_trc = AVCOL_TRC_LINEAR; break;

    default: return AVERROR_INVALIDDATA;

    }

    if ((ret = ff_set_dimensions(avctx, width, height)) < 0)

        return ret;

    switch (channels) {

    case 3: avctx->pix_fmt = AV_PIX_FMT_RGB24; break;

    case 4: avctx->pix_fmt = AV_PIX_FMT_RGBA;  break;

    default: return AVERROR_INVALIDDATA;

    }

    if (avctx->skip_frame >= AVDISCARD_ALL)

        return avpkt->size;

    if ((ret = ff_thread_get_buffer(avctx, p, 0)) < 0)

        return ret;

    dst = p->data[0];

    len = width * height * channels;

    for (int n = 0, off_x = 0; n < len; n += channels, off_x++) {

        if (off_x >= width) {

            off_x = 0;

            dst += p->linesize[0];

        }

        if (run > 0) {

            run--;

        } else if (bytestream2_get_bytes_left(&gb) > 4) {

            int chunk = bytestream2_get_byteu(&gb);

            if (chunk == QOI_OP_RGB) {

                bytestream2_get_bufferu(&gb, px, 3);

            } else if (chunk == QOI_OP_RGBA) {

                bytestream2_get_bufferu(&gb, px, 4);

            } else if ((chunk & QOI_MASK_2) == QOI_OP_INDEX) {

                memcpy(px, index[chunk], 4);

            } else if ((chunk & QOI_MASK_2) == QOI_OP_DIFF) {

                px[0] += ((chunk >> 4) & 0x03) - 2;

                px[1] += ((chunk >> 2) & 0x03) - 2;

                px[2] += ( chunk       & 0x03) - 2;

            } else if ((chunk & QOI_MASK_2) == QOI_OP_LUMA) {

                int b2 = bytestream2_get_byteu(&gb);

                int vg = (chunk & 0x3f) - 32;

                px[0] += vg - 8 + ((b2 >> 4) & 0x0f);

                px[1] += vg;

                px[2] += vg - 8 +  (b2       & 0x0f);

            } else if ((chunk & QOI_MASK_2) == QOI_OP_RUN) {

                run = chunk & 0x3f;

            }

            memcpy(index[QOI_COLOR_HASH(px) & 63], px, 4);

        } else {

            break;

        }

        memcpy(&dst[off_x * channels], px, channels);

    }

    *got_frame   = 1;

    return avpkt->size;

}

const FFCodec ff_qoi_decoder = {

    .p.name         = "qoi",

    CODEC_LONG_NAME("QOI (Quite OK Image format) image"),

    .p.type         = AVMEDIA_TYPE_VIDEO,

    .p.id           = AV_CODEC_ID_QOI,

    .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,

    .caps_internal  = FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM,

    FF_CODEC_DECODE_CB(qoi_decode_frame),

};