/*
 * Ut Video decoder
 * Copyright (c) 2011 Konstantin Shishkov
 *
 * This file is part of Libav.
 *
 * Libav 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.
 *
 * Libav 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 Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * Ut Video decoder
 */

#include <stdlib.h>

#include "libavutil/intreadwrite.h"
#include "avcodec.h"
#include "bytestream.h"
#include "get_bits.h"
#include "dsputil.h"

enum {
    PRED_NONE = 0,
    PRED_LEFT,
    PRED_GRADIENT,
    PRED_MEDIAN,
};

typedef struct UtvideoContext {
    AVCodecContext *avctx;
    AVFrame pic;
    DSPContext dsp;

    uint32_t frame_info_size, flags, frame_info;
    int planes;
    int slices;
    int compression;
    int interlaced;
    int frame_pred;

    uint8_t *slice_bits;
    int slice_bits_size;
} UtvideoContext;

typedef struct HuffEntry {
    uint8_t sym;
    uint8_t len;
} HuffEntry;

static int huff_cmp(const void *a, const void *b)
{
    const HuffEntry *aa = a, *bb = b;
    return (aa->len - bb->len)*256 + aa->sym - bb->sym;
}

static int build_huff(const uint8_t *src, VLC *vlc, int *fsym)
{
    int i;
    HuffEntry he[256];
    int last;
    uint32_t codes[256];
    uint8_t bits[256];
    uint8_t syms[256];
    uint32_t code;

    *fsym = -1;
    for (i = 0; i < 256; i++) {
        he[i].sym = i;
        he[i].len = *src++;
    }
    qsort(he, 256, sizeof(*he), huff_cmp);

    if (!he[0].len) {
        *fsym = he[0].sym;
        return 0;
    }
    if (he[0].len > 32)
        return -1;

    last = 255;
    while (he[last].len == 255 && last)
        last--;

    code = 1;
    for (i = last; i >= 0; i--) {
        codes[i] = code >> (32 - he[i].len);
        bits[i]  = he[i].len;
        syms[i]  = he[i].sym;
        code += 0x80000000u >> (he[i].len - 1);
    }

    return init_vlc_sparse(vlc, FFMIN(he[last].len, 9), last + 1,
                           bits,  sizeof(*bits),  sizeof(*bits),
                           codes, sizeof(*codes), sizeof(*codes),
                           syms,  sizeof(*syms),  sizeof(*syms), 0);
}

static int decode_plane(UtvideoContext *c, int plane_no,
                        uint8_t *dst, int step, int stride,
                        int width, int height,
                        const uint8_t *src, int src_size, int use_pred)
{
    int i, j, slice, pix;
    int sstart, send;
    VLC vlc;
    GetBitContext gb;
    int prev, fsym;
    const int cmask = ~(!plane_no && c->avctx->pix_fmt == PIX_FMT_YUV420P);

    if (build_huff(src, &vlc, &fsym)) {
        av_log(c->avctx, AV_LOG_ERROR, "Cannot build Huffman codes\n");
        return AVERROR_INVALIDDATA;
    }
    if (fsym >= 0) { // build_huff reported a symbol to fill slices with
        send = 0;
        for (slice = 0; slice < c->slices; slice++) {
            uint8_t *dest;

            sstart = send;
            send   = (height * (slice + 1) / c->slices) & cmask;
            dest   = dst + sstart * stride;

            prev = 0x80;
            for (j = sstart; j < send; j++) {
                for (i = 0; i < width * step; i += step) {
                    pix = fsym;
                    if (use_pred) {
                        prev += pix;
                        pix   = prev;
                    }
                    dest[i] = pix;
                }
                dest += stride;
            }
        }
        return 0;
    }

    src      += 256;
    src_size -= 256;

    send = 0;
    for (slice = 0; slice < c->slices; slice++) {
        uint8_t *dest;
        int slice_data_start, slice_data_end, slice_size;

        sstart = send;
        send   = (height * (slice + 1) / c->slices) & cmask;
        dest   = dst + sstart * stride;

        // slice offset and size validation was done earlier
        slice_data_start = slice ? AV_RL32(src + slice * 4 - 4) : 0;
        slice_data_end   = AV_RL32(src + slice * 4);
        slice_size       = slice_data_end - slice_data_start;

        if (!slice_size) {
            for (j = sstart; j < send; j++) {
                for (i = 0; i < width * step; i += step)
                    dest[i] = 0x80;
                dest += stride;
            }
            continue;
        }

        memcpy(c->slice_bits, src + slice_data_start + c->slices * 4, slice_size);
        memset(c->slice_bits + slice_size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
        c->dsp.bswap_buf((uint32_t*)c->slice_bits, (uint32_t*)c->slice_bits,
                         (slice_data_end - slice_data_start + 3) >> 2);
        init_get_bits(&gb, c->slice_bits, slice_size * 8);

        prev = 0x80;
        for (j = sstart; j < send; j++) {
            for (i = 0; i < width * step; i += step) {
                if (get_bits_left(&gb) <= 0) {
                    av_log(c->avctx, AV_LOG_ERROR, "Slice decoding ran out of bits\n");
                    goto fail;
                }
                pix = get_vlc2(&gb, vlc.table, vlc.bits, 4);
                if (pix < 0) {
                    av_log(c->avctx, AV_LOG_ERROR, "Decoding error\n");
                    goto fail;
                }
                if (use_pred) {
                    prev += pix;
                    pix   = prev;
                }
                dest[i] = pix;
            }
            dest += stride;
        }
        if (get_bits_left(&gb) > 32)
            av_log(c->avctx, AV_LOG_WARNING, "%d bits left after decoding slice\n",
                   get_bits_left(&gb));
    }

    free_vlc(&vlc);

    return 0;
fail:
    free_vlc(&vlc);
    return AVERROR_INVALIDDATA;
}

static const int rgb_order[4] = { 1, 2, 0, 3 };

static void restore_rgb_planes(uint8_t *src, int step, int stride, int width, int height)
{
    int i, j;
    uint8_t r, g, b;

    for (j = 0; j < height; j++) {
        for (i = 0; i < width * step; i += step) {
            r = src[i];
            g = src[i + 1];
            b = src[i + 2];
            src[i]     = r + g - 0x80;
            src[i + 2] = b + g - 0x80;
        }
        src += stride;
    }
}

static void restore_median(uint8_t *src, int step, int stride,
                           int width, int height, int slices, int rmode)
{
    int i, j, slice;
    int A, B, C;
    uint8_t *bsrc;
    int slice_start, slice_height;
    const int cmask = ~rmode;

    for (slice = 0; slice < slices; slice++) {
        slice_start = ((slice * height) / slices) & cmask;
        slice_height = ((((slice + 1) * height) / slices) & cmask) - slice_start;

        bsrc = src + slice_start * stride;

        // first line - left neighbour prediction
        bsrc[0] += 0x80;
        A = bsrc[0];
        for (i = step; i < width * step; i += step) {
            bsrc[i] += A;
            A = bsrc[i];
        }
        bsrc += stride;
        if (slice_height == 1)
            continue;
        // second line - first element has top predition, the rest uses median
        C = bsrc[-stride];
        bsrc[0] += C;
        A = bsrc[0];
        for (i = step; i < width * step; i += step) {
            B = bsrc[i - stride];
            bsrc[i] += mid_pred(A, B, (uint8_t)(A + B - C));
            C = B;
            A = bsrc[i];
        }
        bsrc += stride;
        // the rest of lines use continuous median prediction
        for (j = 2; j < slice_height; j++) {
            for (i = 0; i < width * step; i += step) {
                B = bsrc[i - stride];
                bsrc[i] += mid_pred(A, B, (uint8_t)(A + B - C));
                C = B;
                A = bsrc[i];
            }
            bsrc += stride;
        }
    }
}

static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    const uint8_t *buf_end = buf + buf_size;
    UtvideoContext *c = avctx->priv_data;
    const uint8_t *ptr;
    int i, j;
    const uint8_t *plane_start[5];
    int plane_size, max_slice_size = 0, slice_start, slice_end, slice_size;
    int ret;

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

    c->pic.reference = 3;
    c->pic.buffer_hints = FF_BUFFER_HINTS_VALID;
    if ((ret = avctx->get_buffer(avctx, &c->pic)) < 0) {
        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
        return ret;
    }

    /* parse plane structure to retrieve frame flags and validate slice offsets */
    ptr = buf;
    for (i = 0; i < c->planes; i++) {
        plane_start[i] = ptr;
        if (buf_end - ptr < 256 + 4 * c->slices) {
            av_log(avctx, AV_LOG_ERROR, "Insufficient data for a plane\n");
            return AVERROR_INVALIDDATA;
        }
        ptr += 256;
        slice_start = 0;
        slice_end   = 0;
        for (j = 0; j < c->slices; j++) {
            slice_end   = bytestream_get_le32(&ptr);
            slice_size  = slice_end - slice_start;
            if (slice_size < 0) {
                av_log(avctx, AV_LOG_ERROR, "Incorrect slice size\n");
                return AVERROR_INVALIDDATA;
            }
            slice_start = slice_end;
            max_slice_size = FFMAX(max_slice_size, slice_size);
        }
        plane_size = slice_end;
        if (buf_end - ptr < plane_size) {
            av_log(avctx, AV_LOG_ERROR, "Plane size is bigger than available data\n");
            return AVERROR_INVALIDDATA;
        }
        ptr += plane_size;
    }
    plane_start[c->planes] = ptr;
    if (buf_end - ptr < c->frame_info_size) {
        av_log(avctx, AV_LOG_ERROR, "Not enough data for frame information\n");
        return AVERROR_INVALIDDATA;
    }
    c->frame_info = AV_RL32(ptr);
    av_log(avctx, AV_LOG_DEBUG, "frame information flags %X\n", c->frame_info);

    c->frame_pred = (c->frame_info >> 8) & 3;

    if (c->frame_pred == PRED_GRADIENT) {
        av_log_ask_for_sample(avctx, "Frame uses gradient prediction\n");
        return AVERROR_PATCHWELCOME;
    }

    av_fast_malloc(&c->slice_bits, &c->slice_bits_size,
                   max_slice_size + FF_INPUT_BUFFER_PADDING_SIZE);

    if (!c->slice_bits) {
        av_log(avctx, AV_LOG_ERROR, "Cannot allocate temporary buffer\n");
        return AVERROR(ENOMEM);
    }

    switch (c->avctx->pix_fmt) {
    case PIX_FMT_RGB24:
    case PIX_FMT_RGBA:
        for (i = 0; i < c->planes; i++) {
            ret = decode_plane(c, i, c->pic.data[0] + rgb_order[i], c->planes,
                               c->pic.linesize[0], avctx->width, avctx->height,
                               plane_start[i], plane_start[i + 1] - plane_start[i],
                               c->frame_pred == PRED_LEFT);
            if (ret)
                return ret;
            if (c->frame_pred == PRED_MEDIAN)
                restore_median(c->pic.data[0] + rgb_order[i], c->planes,
                               c->pic.linesize[0], avctx->width, avctx->height,
                               c->slices, 0);
        }
        restore_rgb_planes(c->pic.data[0], c->planes, c->pic.linesize[0],
                           avctx->width, avctx->height);
        break;
    case PIX_FMT_YUV420P:
        for (i = 0; i < 3; i++) {
            ret = decode_plane(c, i, c->pic.data[i], 1,
                               c->pic.linesize[i], avctx->width >> !!i, avctx->height >> !!i,
                               plane_start[i], plane_start[i + 1] - plane_start[i],
                               c->frame_pred == PRED_LEFT);
            if (ret)
                return ret;
            if (c->frame_pred == PRED_MEDIAN)
                restore_median(c->pic.data[i], 1, c->pic.linesize[i],
                               avctx->width >> !!i, avctx->height >> !!i,
                               c->slices, !i);
        }
        break;
    case PIX_FMT_YUV422P:
        for (i = 0; i < 3; i++) {
            ret = decode_plane(c, i, c->pic.data[i], 1,
                               c->pic.linesize[i], avctx->width >> !!i, avctx->height,
                               plane_start[i], plane_start[i + 1] - plane_start[i],
                               c->frame_pred == PRED_LEFT);
            if (ret)
                return ret;
            if (c->frame_pred == PRED_MEDIAN)
                restore_median(c->pic.data[i], 1, c->pic.linesize[i],
                               avctx->width >> !!i, avctx->height, c->slices, 0);
        }
        break;
    }

    *data_size = sizeof(AVFrame);
    *(AVFrame*)data = c->pic;

    /* always report that the buffer was completely consumed */
    return buf_size;
}

static av_cold int decode_init(AVCodecContext *avctx)
{
    UtvideoContext * const c = avctx->priv_data;

    c->avctx = avctx;

    dsputil_init(&c->dsp, avctx);

    if (avctx->extradata_size < 16) {
        av_log(avctx, AV_LOG_ERROR, "Insufficient extradata size %d, should be at least 16\n",
               avctx->extradata_size);
        return AVERROR_INVALIDDATA;
    }

    av_log(avctx, AV_LOG_DEBUG, "Encoder version %d.%d.%d.%d\n",
           avctx->extradata[3], avctx->extradata[2],
           avctx->extradata[1], avctx->extradata[0]);
    av_log(avctx, AV_LOG_DEBUG, "Original format %X\n", AV_RB32(avctx->extradata + 4));
    c->frame_info_size = AV_RL32(avctx->extradata + 8);
    c->flags           = AV_RL32(avctx->extradata + 12);

    if (c->frame_info_size != 4)
        av_log_ask_for_sample(avctx, "Frame info is not 4 bytes\n");
    av_log(avctx, AV_LOG_DEBUG, "Encoding parameters %08X\n", c->flags);
    c->slices      = (c->flags >> 24) + 1;
    c->compression = c->flags & 1;
    c->interlaced  = c->flags & 0x800;

    c->slice_bits_size = 0;

    switch (avctx->codec_tag) {
    case MKTAG('U', 'L', 'R', 'G'):
        c->planes      = 3;
        avctx->pix_fmt = PIX_FMT_RGB24;
        break;
    case MKTAG('U', 'L', 'R', 'A'):
        c->planes      = 4;
        avctx->pix_fmt = PIX_FMT_RGBA;
        break;
    case MKTAG('U', 'L', 'Y', '0'):
        c->planes      = 3;
        avctx->pix_fmt = PIX_FMT_YUV420P;
        break;
    case MKTAG('U', 'L', 'Y', '2'):
        c->planes      = 3;
        avctx->pix_fmt = PIX_FMT_YUV422P;
        break;
    default:
        av_log(avctx, AV_LOG_ERROR, "Unknown Ut Video FOURCC provided (%08X)\n",
               avctx->codec_tag);
        return AVERROR_INVALIDDATA;
    }

    return 0;
}

static av_cold int decode_end(AVCodecContext *avctx)
{
    UtvideoContext * const c = avctx->priv_data;

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

    av_freep(&c->slice_bits);

    return 0;
}

AVCodec ff_utvideo_decoder = {
    .name           = "utvideo",
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = CODEC_ID_UTVIDEO,
    .priv_data_size = sizeof(UtvideoContext),
    .init           = decode_init,
    .close          = decode_end,
    .decode         = decode_frame,
    .capabilities   = CODEC_CAP_DR1,
    .long_name      = NULL_IF_CONFIG_SMALL("Ut Video"),
};

