/*
 * HEVC common code
 *
 * 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 <string.h>

#include "config.h"

#include "libavutil/intreadwrite.h"
#include "libavutil/mem.h"

#include "hevc.h"

/* FIXME: This is adapted from ff_h264_decode_nal, avoiding duplication
 * between these functions would be nice. */
int ff_hevc_extract_rbsp(HEVCContext *s, const uint8_t *src, int length,
                         HEVCNAL *nal)
{
    int i, si, di;
    uint8_t *dst;

    if (s)
        nal->skipped_bytes = 0;
#define STARTCODE_TEST                                                  \
        if (i + 2 < length && src[i + 1] == 0 && src[i + 2] <= 3) {     \
            if (src[i + 2] != 3) {                                      \
                /* startcode, so we must be past the end */             \
                length = i;                                             \
            }                                                           \
            break;                                                      \
        }
#if HAVE_FAST_UNALIGNED
#define FIND_FIRST_ZERO                                                 \
        if (i > 0 && !src[i])                                           \
            i--;                                                        \
        while (src[i])                                                  \
            i++
#if HAVE_FAST_64BIT
    for (i = 0; i + 1 < length; i += 9) {
        if (!((~AV_RN64A(src + i) &
               (AV_RN64A(src + i) - 0x0100010001000101ULL)) &
              0x8000800080008080ULL))
            continue;
        FIND_FIRST_ZERO;
        STARTCODE_TEST;
        i -= 7;
    }
#else
    for (i = 0; i + 1 < length; i += 5) {
        if (!((~AV_RN32A(src + i) &
               (AV_RN32A(src + i) - 0x01000101U)) &
              0x80008080U))
            continue;
        FIND_FIRST_ZERO;
        STARTCODE_TEST;
        i -= 3;
    }
#endif /* HAVE_FAST_64BIT */
#else
    for (i = 0; i + 1 < length; i += 2) {
        if (src[i])
            continue;
        if (i > 0 && src[i - 1] == 0)
            i--;
        STARTCODE_TEST;
    }
#endif /* HAVE_FAST_UNALIGNED */

    if (i >= length - 1) { // no escaped 0
        nal->data     =
        nal->raw_data = src;
        nal->size     =
        nal->raw_size = length;
        return length;
    }

    av_fast_malloc(&nal->rbsp_buffer, &nal->rbsp_buffer_size,
                   length + FF_INPUT_BUFFER_PADDING_SIZE);
    if (!nal->rbsp_buffer)
        return AVERROR(ENOMEM);

    dst = nal->rbsp_buffer;

    memcpy(dst, src, i);
    si = di = i;
    while (si + 2 < length) {
        // remove escapes (very rare 1:2^22)
        if (src[si + 2] > 3) {
            dst[di++] = src[si++];
            dst[di++] = src[si++];
        } else if (src[si] == 0 && src[si + 1] == 0) {
            if (src[si + 2] == 3) { // escape
                dst[di++] = 0;
                dst[di++] = 0;
                si       += 3;

                if (s) {
                        nal->skipped_bytes++;
                        if (s->skipped_bytes_pos_size < nal->skipped_bytes) {
                        s->skipped_bytes_pos_size *= 2;
                        av_reallocp_array(&s->skipped_bytes_pos,
                                s->skipped_bytes_pos_size,
                                sizeof(*s->skipped_bytes_pos));
                        if (!s->skipped_bytes_pos)
                                return AVERROR(ENOMEM);
                        }
                        if (s->skipped_bytes_pos)
                        s->skipped_bytes_pos[nal->skipped_bytes-1] = di - 1;
                }
                continue;
            } else // next start code
                goto nsc;
        }

        dst[di++] = src[si++];
    }
    while (si < length)
        dst[di++] = src[si++];

nsc:
    memset(dst + di, 0, FF_INPUT_BUFFER_PADDING_SIZE);

    nal->data = dst;
    nal->size = di;
    nal->raw_data = src;
    nal->raw_size = si;
    return si;
}

/**
 * @return AVERROR_INVALIDDATA if the packet is not a valid NAL unit,
 * 0 if the unit should be skipped, 1 otherwise
 */
static int hls_nal_unit(HEVCNAL *nal, AVCodecContext *avctx)
{
    GetBitContext *gb = &nal->gb;
    int nuh_layer_id;

    if (get_bits1(gb) != 0)
        return AVERROR_INVALIDDATA;

    nal->type = get_bits(gb, 6);

    nuh_layer_id   = get_bits(gb, 6);
    nal->temporal_id = get_bits(gb, 3) - 1;
    if (nal->temporal_id < 0)
        return AVERROR_INVALIDDATA;

    av_log(avctx, AV_LOG_DEBUG,
           "nal_unit_type: %d, nuh_layer_id: %d, temporal_id: %d\n",
           nal->type, nuh_layer_id, nal->temporal_id);

    return nuh_layer_id == 0;
}


int ff_hevc_split_packet(HEVCContext *s, HEVCPacket *pkt, const uint8_t *buf, int length,
                         AVCodecContext *avctx, int is_nalff, int nal_length_size)
{
    int consumed, ret = 0;

    pkt->nb_nals = 0;
    while (length >= 4) {
        HEVCNAL *nal;
        int extract_length = 0;

        if (is_nalff) {
            int i;
            for (i = 0; i < nal_length_size; i++)
                extract_length = (extract_length << 8) | buf[i];
            buf    += nal_length_size;
            length -= nal_length_size;

            if (extract_length > length) {
                av_log(avctx, AV_LOG_ERROR, "Invalid NAL unit size.\n");
                return AVERROR_INVALIDDATA;
            }
        } else {
            /* search start code */
            while (buf[0] != 0 || buf[1] != 0 || buf[2] != 1) {
                ++buf;
                --length;
                if (length < 4) {
                    av_log(avctx, AV_LOG_ERROR, "No start code is found.\n");
                    return AVERROR_INVALIDDATA;
                }
            }

            buf           += 3;
            length        -= 3;
            extract_length = length;
        }

        if (pkt->nals_allocated < pkt->nb_nals + 1) {
            int new_size = pkt->nals_allocated + 1;
            void *tmp = av_realloc_array(pkt->nals, new_size, sizeof(*pkt->nals));

            if (!tmp)
                return AVERROR(ENOMEM);

            pkt->nals = tmp;
            memset(pkt->nals + pkt->nals_allocated, 0,
                   (new_size - pkt->nals_allocated) * sizeof(*pkt->nals));

            tmp = av_realloc_array(s->skipped_bytes_pos_size_nal, new_size, sizeof(*s->skipped_bytes_pos_size_nal));
            if (!tmp)
                return AVERROR(ENOMEM);
            s->skipped_bytes_pos_size_nal = tmp;

            tmp = av_realloc_array(s->skipped_bytes_pos_nal, new_size, sizeof(*s->skipped_bytes_pos_nal));
            if (!tmp)
                return AVERROR(ENOMEM);
            s->skipped_bytes_pos_nal = tmp;

            s->skipped_bytes_pos_size_nal[pkt->nals_allocated] = 1024; // initial buffer size
            s->skipped_bytes_pos_nal[pkt->nals_allocated] = av_malloc_array(s->skipped_bytes_pos_size_nal[pkt->nals_allocated], sizeof(*s->skipped_bytes_pos));
            if (!s->skipped_bytes_pos_nal[pkt->nals_allocated])
                return AVERROR(ENOMEM);

            pkt->nals_allocated = new_size;
        }
        s->skipped_bytes_pos_size = s->skipped_bytes_pos_size_nal[pkt->nb_nals];
        s->skipped_bytes_pos = s->skipped_bytes_pos_nal[pkt->nb_nals];
        nal = &pkt->nals[pkt->nb_nals];

        consumed = ff_hevc_extract_rbsp(s, buf, extract_length, nal);
        if (consumed < 0)
            return consumed;

        s->skipped_bytes_pos_size_nal[pkt->nb_nals] = s->skipped_bytes_pos_size;
        s->skipped_bytes_pos_nal[pkt->nb_nals++] = s->skipped_bytes_pos;

        ret = init_get_bits8(&nal->gb, nal->data, nal->size);
        if (ret < 0)
            return ret;

        ret = hls_nal_unit(nal, avctx);
        if (ret <= 0) {
            if (ret < 0) {
                av_log(avctx, AV_LOG_ERROR, "Invalid NAL unit %d, skipping.\n",
                       nal->type);
            }
            pkt->nb_nals--;
        }

        buf    += consumed;
        length -= consumed;
    }

    return 0;
}