/*
 * Canopus Lossless Codec decoder
 *
 * Copyright (c) 2012 Derek Buitenhuis
 *
 * 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/intreadwrite.h"
#include "dsputil.h"
#include "get_bits.h"
#include "avcodec.h"

typedef struct CLLCContext {
    DSPContext dsp;
    AVCodecContext *avctx;

    uint8_t *swapped_buf;
    int      swapped_buf_size;
} CLLCContext;

static int read_code_table(CLLCContext *ctx, GetBitContext *gb, VLC *vlc)
{
    uint8_t symbols[256];
    uint8_t bits[256];
    uint16_t codes[256];
    int num_lens, num_codes, num_codes_sum, prefix;
    int i, j, count;

    prefix        = 0;
    count         = 0;
    num_codes_sum = 0;

    num_lens = get_bits(gb, 5);

    for (i = 0; i < num_lens; i++) {
        num_codes      = get_bits(gb, 9);
        num_codes_sum += num_codes;

        if (num_codes_sum > 256) {
            vlc->table = NULL;

            av_log(ctx->avctx, AV_LOG_ERROR,
                   "Too many VLCs (%d) to be read.\n", num_codes_sum);
            return AVERROR_INVALIDDATA;
        }

        for (j = 0; j < num_codes; j++) {
            symbols[count] = get_bits(gb, 8);
            bits[count]    = i + 1;
            codes[count]   = prefix++;

            count++;
        }

        prefix <<= 1;
    }

    return ff_init_vlc_sparse(vlc, 7, count, bits, 1, 1,
                              codes, 2, 2, symbols, 1, 1, 0);
}

static int read_line(CLLCContext *ctx, GetBitContext *gb, int *top_left,
                     VLC *vlc, uint8_t *outbuf)
{
    uint8_t *dst;
    int pred, code;
    int i;

    OPEN_READER(bits, gb);

    dst  = outbuf;
    pred = *top_left;

    /* Simultaneously read and restore the line */
    for (i = 0; i < ctx->avctx->width; i++) {
        UPDATE_CACHE(bits, gb);
        GET_VLC(code, bits, gb, vlc->table, 7, 2);

        pred  += code;
        dst[0] = pred;
        dst   += 3;
    }

    CLOSE_READER(bits, gb);

    /* Stash the first pixel */
    *top_left = dst[-3 * ctx->avctx->width];

    return 0;
}

static int decode_bgr24_frame(CLLCContext *ctx, GetBitContext *gb, AVFrame *pic)
{
    AVCodecContext *avctx = ctx->avctx;
    uint8_t *dst;
    int pred[3];
    int ret;
    int i, j;
    VLC vlc[3];

    pred[0] = 0x80;
    pred[1] = 0x80;
    pred[2] = 0x80;

    dst = pic->data[0];

    skip_bits(gb, 16);

    /* Read in code table for each plane */
    for (i = 0; i < 3; i++) {
        ret = read_code_table(ctx, gb, &vlc[i]);
        if (ret < 0) {
            for (j = 0; j <= i; j++)
                ff_free_vlc(&vlc[j]);

            av_log(ctx->avctx, AV_LOG_ERROR,
                   "Could not read code table %d.\n", i);
            return ret;
        }
    }

    /* Read in and restore every line */
    for (i = 0; i < avctx->height; i++) {
        for (j = 0; j < 3; j++)
            read_line(ctx, gb, &pred[j], &vlc[j], &dst[j]);

        dst += pic->linesize[0];
    }

    for (i = 0; i < 3; i++)
        ff_free_vlc(&vlc[i]);

    return 0;
}

static int cllc_decode_frame(AVCodecContext *avctx, void *data,
                             int *got_picture_ptr, AVPacket *avpkt)
{
    CLLCContext *ctx = avctx->priv_data;
    AVFrame *pic = avctx->coded_frame;
    uint8_t *src = avpkt->data;
    uint8_t *swapped_buf_new;
    uint32_t info_tag, info_offset;
    GetBitContext gb;
    int coding_type, ret;

    if (pic->data[0])
        avctx->release_buffer(avctx, pic);

    pic->reference = 0;

    /* Make sure our bswap16'd buffer is big enough */
    swapped_buf_new = av_fast_realloc(ctx->swapped_buf,
                                      &ctx->swapped_buf_size, avpkt->size);
    if (!swapped_buf_new) {
        av_log(avctx, AV_LOG_ERROR, "Could not realloc swapped buffer.\n");
        return AVERROR(ENOMEM);
    }
    ctx->swapped_buf = swapped_buf_new;

    /* Skip the INFO header if present */
    info_offset = 0;
    info_tag    = AV_RL32(src);
    if (info_tag == MKTAG('I', 'N', 'F', 'O')) {
        info_offset = AV_RL32(src + 4);
        if (info_offset > UINT32_MAX - 8 || info_offset + 8 > avpkt->size) {
            av_log(avctx, AV_LOG_ERROR,
                   "Invalid INFO header offset: 0x%08X is too large.\n",
                   info_offset);
            return AVERROR_INVALIDDATA;
        }

        info_offset += 8;
        src         += info_offset;

        av_log(avctx, AV_LOG_DEBUG, "Skipping INFO chunk.\n");
    }

    /* bswap16 the buffer since CLLC's bitreader works in 16-bit words */
    ctx->dsp.bswap16_buf((uint16_t *) ctx->swapped_buf, (uint16_t *) src,
                         (avpkt->size - info_offset) / 2);

    init_get_bits(&gb, ctx->swapped_buf, (avpkt->size - info_offset) * 8);

    /*
     * Read in coding type. The types are as follows:
     *
     * 0 - YUY2
     * 1 - BGR24 (Triples)
     * 2 - BGR24 (Quads)
     * 3 - BGRA
     */
    coding_type = (AV_RL32(src) >> 8) & 0xFF;
    av_log(avctx, AV_LOG_DEBUG, "Frame coding type: %d\n", coding_type);

    switch (coding_type) {
    case 1:
        avctx->pix_fmt             = PIX_FMT_RGB24;
        avctx->bits_per_raw_sample = 8;

        ret = avctx->get_buffer(avctx, pic);
        if (ret < 0) {
            av_log(avctx, AV_LOG_ERROR, "Could not allocate buffer.\n");
            return ret;
        }

        ret = decode_bgr24_frame(ctx, &gb, pic);
        if (ret < 0)
            return ret;

        break;
    default:
        av_log(avctx, AV_LOG_ERROR, "Unknown coding type: %d.\n", coding_type);
        return AVERROR_INVALIDDATA;
    }

    pic->key_frame = 1;
    pic->pict_type = AV_PICTURE_TYPE_I;

    *got_picture_ptr = 1;
    *(AVFrame *)data = *pic;

    return avpkt->size;
}

static av_cold int cllc_decode_close(AVCodecContext *avctx)
{
    CLLCContext *ctx = avctx->priv_data;

    if (avctx->coded_frame->data[0])
        avctx->release_buffer(avctx, avctx->coded_frame);

    av_freep(&avctx->coded_frame);
    av_freep(&ctx->swapped_buf);

    return 0;
}

static av_cold int cllc_decode_init(AVCodecContext *avctx)
{
    CLLCContext *ctx = avctx->priv_data;

    /* Initialize various context values */
    ctx->avctx            = avctx;
    ctx->swapped_buf      = NULL;
    ctx->swapped_buf_size = 0;

    ff_dsputil_init(&ctx->dsp, avctx);

    avctx->coded_frame = avcodec_alloc_frame();
    if (!avctx->coded_frame) {
        av_log(avctx, AV_LOG_ERROR, "Could not allocate frame.\n");
        return AVERROR(ENOMEM);
    }

    return 0;
}

AVCodec ff_cllc_decoder = {
    .name           = "cllc",
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_CLLC,
    .priv_data_size = sizeof(CLLCContext),
    .init           = cllc_decode_init,
    .decode         = cllc_decode_frame,
    .close          = cllc_decode_close,
    .capabilities   = CODEC_CAP_DR1,
    .long_name      = NULL_IF_CONFIG_SMALL("Canopus Lossless Codec"),
};