/*

 * Microsoft Screen 4 (aka Microsoft Expression Encoder Screen) decoder

 * Copyright (c) 2012 Konstantin Shishkov

 *

 * 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

 */

/**

 * @file

 * Microsoft Screen 4 (aka Microsoft Titanium Screen 2,

 * aka Microsoft Expression Encoder Screen) decoder

 */

#include "libavutil/mem.h"

#include "libavutil/thread.h"

#include "libavutil/imgutils.h"

#include "avcodec.h"

#include "bytestream.h"

#include "codec_internal.h"

#include "decode.h"

#include "get_bits.h"

#include "jpegtables.h"

#include "mss34dsp.h"

#include "unary.h"

#define HEADER_SIZE 8

enum FrameType {

    INTRA_FRAME = 0,

    INTER_FRAME,

    SKIP_FRAME

};

enum BlockType {

    SKIP_BLOCK = 0,

    DCT_BLOCK,

    IMAGE_BLOCK,

};

enum CachePos {

    LEFT = 0,

    TOP_LEFT,

    TOP,

};

static const uint8_t mss4_dc_vlc_lens[2][16] = {

    { 0, 1, 5, 1, 1, 1, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0 },

    { 0, 3, 1, 1, 1, 1, 1, 1, 1, 2, 0, 0, 0, 0, 0, 0 }

};

static const uint8_t vec_len_syms[2][4] = {

    { 4, 2, 3, 1 },

    { 4, 1, 2, 3 }

};

static const uint8_t mss4_vec_entry_vlc_lens[2][16] = {

    { 0, 2, 2, 3, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },

    { 0, 1, 5, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }

};

static const uint8_t mss4_vec_entry_vlc_syms[2][9] = {

    { 0, 7, 6, 5, 8, 4, 3, 1, 2 },

    { 0, 2, 3, 4, 5, 6, 7, 1, 8 }

};

#define MAX_ENTRIES  162

typedef struct MSS4Context {

    AVFrame    *pic;

    int        block[64];

    uint8_t    imgbuf[3][16 * 16];

    int        quality;

    uint16_t   quant_mat[2][64];

    int        *prev_dc[3];

    ptrdiff_t  dc_stride[3];

    int        dc_cache[4][4];

    int        prev_vec[3][4];

} MSS4Context;

static VLC dc_vlc[2], ac_vlc[2];

static VLC vec_entry_vlc[2];

static av_cold void mss4_init_vlc(VLC *vlc, unsigned *offset,

                                  const uint8_t *lens, const uint8_t *syms)

{

    static VLCElem vlc_buf[2146];

    uint8_t  bits[MAX_ENTRIES];

    int i, j;

    int idx = 0;

    for (i = 0; i < 16; i++) {

        for (j = 0; j < lens[i]; j++) {

            bits[idx]  = i + 1;

            idx++;

        }

    }

    vlc->table           = &vlc_buf[*offset];

    vlc->table_allocated = FF_ARRAY_ELEMS(vlc_buf) - *offset;

    ff_vlc_init_from_lengths(vlc, FFMIN(bits[idx - 1], 9), idx,

                             bits, 1, syms, 1, 1,

                             0, VLC_INIT_STATIC_OVERLONG, NULL);

    *offset += vlc->table_size;

}

static av_cold void mss4_init_vlcs(void)

{

    for (unsigned i = 0, offset = 0; i < 2; i++) {

        mss4_init_vlc(&dc_vlc[i], &offset, mss4_dc_vlc_lens[i], NULL);

        mss4_init_vlc(&ac_vlc[i], &offset,

                      i ? ff_mjpeg_bits_ac_chrominance + 1

                        : ff_mjpeg_bits_ac_luminance   + 1,

                      i ? ff_mjpeg_val_ac_chrominance

                        : ff_mjpeg_val_ac_luminance);

        mss4_init_vlc(&vec_entry_vlc[i], &offset, mss4_vec_entry_vlc_lens[i],

                      mss4_vec_entry_vlc_syms[i]);

    }

}

/* This function returns values in the range

 * (-range + 1; -range/2] U [range/2; range - 1)

 * i.e.

 * nbits = 0 -> 0

 * nbits = 1 -> -1, 1

 * nbits = 2 -> -3, -2, 2, 3

 */

static av_always_inline int get_coeff_bits(GetBitContext *gb, int nbits)

{

    int val;

    if (!nbits)

        return 0;

    val = get_bits(gb, nbits);

    if (val < (1 << (nbits - 1)))

        val -= (1 << nbits) - 1;

    return val;

}

static inline int get_coeff(GetBitContext *gb, const VLC *vlc,

                            int nb_bits, int max_depth)

{

    int val = get_vlc2(gb, vlc->table, nb_bits, max_depth);

    return get_coeff_bits(gb, val);

}

static int mss4_decode_dct(GetBitContext *gb, VLC *dc_vlc, VLC *ac_vlc,

                           int *block, int *dc_cache,

                           int bx, int by, uint16_t *quant_mat)

{

    int skip, val, pos = 1, zz_pos, dc;

    memset(block, 0, sizeof(*block) * 64);

    dc = get_coeff(gb, dc_vlc, dc_vlc->bits, 2);

    // DC prediction is the same as in MSS3

    if (by) {

        if (bx) {

            int l, tl, t;

            l  = dc_cache[LEFT];

            tl = dc_cache[TOP_LEFT];

            t  = dc_cache[TOP];

            if (FFABS(t - tl) <= FFABS(l - tl))

                dc += l;

            else

                dc += t;

        } else {

            dc += dc_cache[TOP];

        }

    } else if (bx) {

        dc += dc_cache[LEFT];

    }

    dc_cache[LEFT] = dc;

    block[0]       = dc * quant_mat[0];

    while (pos < 64) {

        val = get_vlc2(gb, ac_vlc->table, 9, 2);

        if (!val)

            return 0;

        if (val == -1)

            return -1;

        if (val == 0xF0) {

            pos += 16;

            continue;

        }

        skip = val >> 4;

        val  = get_coeff_bits(gb, val & 0xF);

        pos += skip;

        if (pos >= 64)

            return -1;

        zz_pos = ff_zigzag_direct[pos];

        block[zz_pos] = val * quant_mat[zz_pos];

        pos++;

    }

    return pos == 64 ? 0 : -1;

}

static int mss4_decode_dct_block(MSS4Context *c, GetBitContext *gb,

                                 uint8_t *dst[3], int mb_x, int mb_y)

{

    int i, j, k, ret;

    uint8_t *out = dst[0];

    for (j = 0; j < 2; j++) {

        for (i = 0; i < 2; i++) {

            int xpos = mb_x * 2 + i;

            c->dc_cache[j][TOP_LEFT] = c->dc_cache[j][TOP];

            c->dc_cache[j][TOP]      = c->prev_dc[0][mb_x * 2 + i];

            ret = mss4_decode_dct(gb, &dc_vlc[0], &ac_vlc[0], c->block,

                                  c->dc_cache[j],

                                  xpos, mb_y * 2 + j, c->quant_mat[0]);

            if (ret)

                return ret;

            c->prev_dc[0][mb_x * 2 + i] = c->dc_cache[j][LEFT];

            ff_mss34_dct_put(out + xpos * 8, c->pic->linesize[0],

                             c->block);

        }

        out += 8 * c->pic->linesize[0];

    }

    for (i = 1; i < 3; i++) {

        c->dc_cache[i + 1][TOP_LEFT] = c->dc_cache[i + 1][TOP];

        c->dc_cache[i + 1][TOP]      = c->prev_dc[i][mb_x];

        ret = mss4_decode_dct(gb, &dc_vlc[1], &ac_vlc[1],

                              c->block, c->dc_cache[i + 1], mb_x, mb_y,

                              c->quant_mat[1]);

        if (ret)

            return ret;

        c->prev_dc[i][mb_x] = c->dc_cache[i + 1][LEFT];

        ff_mss34_dct_put(c->imgbuf[i], 8, c->block);

        out = dst[i] + mb_x * 16;

        // Since the DCT block is coded as YUV420 and the whole frame as YUV444,

        // we need to scale chroma.

        for (j = 0; j < 16; j++) {

            for (k = 0; k < 8; k++)

                AV_WN16A(out + k * 2, c->imgbuf[i][k + (j & ~1) * 4] * 0x101);

            out += c->pic->linesize[i];

        }

    }

    return 0;

}

static void read_vec_pos(GetBitContext *gb, int *vec_pos, int *sel_flag,

                         int *sel_len, int *prev)

{

    int i, y_flag = 0;

    for (i = 2; i >= 0; i--) {

        if (!sel_flag[i]) {

            vec_pos[i] = 0;

            continue;

        }

        if ((!i && !y_flag) || get_bits1(gb)) {

            if (sel_len[i] > 0) {

                int pval = prev[i];

                vec_pos[i] = get_bits(gb, sel_len[i]);

                if (vec_pos[i] >= pval)

                    vec_pos[i]++;

            } else {

                vec_pos[i] = !prev[i];

            }

            y_flag = 1;

        } else {

            vec_pos[i] = prev[i];

        }

    }

}

static int get_value_cached(GetBitContext *gb, int vec_pos, uint8_t *vec,

                            int vec_size, int component, int shift, int *prev)

{

    if (vec_pos < vec_size)

        return vec[vec_pos];

    if (!get_bits1(gb))

        return prev[component];

    prev[component] = get_bits(gb, 8 - shift) << shift;

    return prev[component];

}

#define MKVAL(vals)  ((vals)[0] | ((vals)[1] << 3) | ((vals)[2] << 6))

/* Image mode - the hardest to comprehend MSS4 coding mode.

 *

 * In this mode all three 16x16 blocks are coded together with a method

 * remotely similar to the methods employed in MSS1-MSS3.

 * The idea is that every component has a vector of 1-4 most common symbols

 * and an escape mode for reading new value from the bitstream. Decoding

 * consists of retrieving pixel values from the vector or reading new ones

 * from the bitstream; depending on flags read from the bitstream, these vector

 * positions can be updated or reused from the state of the previous line

 * or previous pixel.

 */

static int mss4_decode_image_block(MSS4Context *ctx, GetBitContext *gb,

                                   uint8_t *picdst[3], int mb_x, int mb_y)

{

    uint8_t vec[3][4];

    int     vec_len[3];

    int     sel_len[3], sel_flag[3];

    int     i, j, k, mode, split;

    int     prev_vec1 = 0, prev_split = 0;

    int     vals[3] = { 0 };

    int     prev_pix[3] = { 0 };

    int     prev_mode[16] = { 0 };

    uint8_t *dst[3];

    const int val_shift = ctx->quality == 100 ? 0 : 2;

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

        dst[i] = ctx->imgbuf[i];

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

        vec_len[i] = vec_len_syms[!!i][get_unary(gb, 0, 3)];

        for (j = 0; j < vec_len[i]; j++) {

            vec[i][j]  = get_coeff(gb, &vec_entry_vlc[!!i], 5, 1);

            vec[i][j] += ctx->prev_vec[i][j];

            ctx->prev_vec[i][j] = vec[i][j];

        }

        sel_flag[i] = vec_len[i] > 1;

        sel_len[i]  = vec_len[i] > 2 ? vec_len[i] - 2 : 0;

    }

    for (j = 0; j < 16; j++) {

        if (get_bits1(gb)) {

            split = 0;

            if (get_bits1(gb)) {

                prev_mode[0] = 0;

                vals[0] = vals[1] = vals[2] = 0;

                mode = 2;

            } else {

                mode = get_bits1(gb);

                if (mode)

                    split = get_bits(gb, 4);

            }

            for (i = 0; i < 16; i++) {

                if (mode <= 1) {

                    vals[0] =  prev_mode[i]       & 7;

                    vals[1] = (prev_mode[i] >> 3) & 7;

                    vals[2] =  prev_mode[i] >> 6;

                    if (mode == 1 && i == split) {

                        read_vec_pos(gb, vals, sel_flag, sel_len, vals);

                    }

                } else if (mode == 2) {

                    if (get_bits1(gb))

                        read_vec_pos(gb, vals, sel_flag, sel_len, vals);

                }

                for (k = 0; k < 3; k++)

                    *dst[k]++ = get_value_cached(gb, vals[k], vec[k],

                                                 vec_len[k], k,

                                                 val_shift, prev_pix);

                prev_mode[i] = MKVAL(vals);

            }

        } else {

            if (get_bits1(gb)) {

                split = get_bits(gb, 4);

                if (split >= prev_split)

                    split++;

                prev_split = split;

            } else {

                split = prev_split;

            }

            if (split) {

                vals[0] =  prev_mode[0]       & 7;

                vals[1] = (prev_mode[0] >> 3) & 7;

                vals[2] =  prev_mode[0] >> 6;

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

                    for (k = 0; k < split; k++) {

                        *dst[i]++ = get_value_cached(gb, vals[i], vec[i],

                                                     vec_len[i], i, val_shift,

                                                     prev_pix);

                        prev_mode[k] = MKVAL(vals);

                    }

                }

            }

            if (split != 16) {

                vals[0] =  prev_vec1       & 7;

                vals[1] = (prev_vec1 >> 3) & 7;

                vals[2] =  prev_vec1 >> 6;

                if (get_bits1(gb)) {

                    read_vec_pos(gb, vals, sel_flag, sel_len, vals);

                    prev_vec1 = MKVAL(vals);

                }

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

                    for (k = 0; k < 16 - split; k++) {

                        *dst[i]++ = get_value_cached(gb, vals[i], vec[i],

                                                     vec_len[i], i, val_shift,

                                                     prev_pix);

                        prev_mode[split + k] = MKVAL(vals);

                    }

                }

            }

        }

    }

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

        for (j = 0; j < 16; j++)

            memcpy(picdst[i] + mb_x * 16 + j * ctx->pic->linesize[i],

                   ctx->imgbuf[i] + j * 16, 16);

    return 0;

}

static inline void mss4_update_dc_cache(MSS4Context *c, int mb_x)

{

    int i;

    c->dc_cache[0][TOP]  = c->prev_dc[0][mb_x * 2 + 1];

    c->dc_cache[0][LEFT] = 0;

    c->dc_cache[1][TOP]  = 0;

    c->dc_cache[1][LEFT] = 0;

    for (i = 0; i < 2; i++)

        c->prev_dc[0][mb_x * 2 + i] = 0;

    for (i = 1; i < 3; i++) {

        c->dc_cache[i + 1][TOP]  = c->prev_dc[i][mb_x];

        c->dc_cache[i + 1][LEFT] = 0;

        c->prev_dc[i][mb_x]      = 0;

    }

}

static int mss4_decode_frame(AVCodecContext *avctx, AVFrame *rframe,

                             int *got_frame, AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    MSS4Context *c = avctx->priv_data;

    GetBitContext gb;

    GetByteContext bc;

    uint8_t *dst[3];

    int width, height, quality, frame_type;

    int x, y, i, mb_width, mb_height, blk_type;

    int ret;

    if (buf_size < HEADER_SIZE) {

        av_log(avctx, AV_LOG_ERROR,

               "Frame should have at least %d bytes, got %d instead\n",

               HEADER_SIZE, buf_size);

        return AVERROR_INVALIDDATA;

    }

    bytestream2_init(&bc, buf, buf_size);

    width      = bytestream2_get_be16(&bc);

    height     = bytestream2_get_be16(&bc);

    bytestream2_skip(&bc, 2);

    quality    = bytestream2_get_byte(&bc);

    frame_type = bytestream2_get_byte(&bc);

    if (width > avctx->width ||

        height != avctx->height) {

        av_log(avctx, AV_LOG_ERROR, "Invalid frame dimensions %dx%d\n",

               width, height);

        return AVERROR_INVALIDDATA;

    }

    if (av_image_check_size2(width, height, avctx->max_pixels, AV_PIX_FMT_NONE, 0, avctx) < 0)

        return AVERROR_INVALIDDATA;

    if (quality < 1 || quality > 100) {

        av_log(avctx, AV_LOG_ERROR, "Invalid quality setting %d\n", quality);

        return AVERROR_INVALIDDATA;

    }

    if ((frame_type & ~3) || frame_type == 3) {

        av_log(avctx, AV_LOG_ERROR, "Invalid frame type %d\n", frame_type);

        return AVERROR_INVALIDDATA;

    }

    if (frame_type != SKIP_FRAME && !bytestream2_get_bytes_left(&bc)) {

        av_log(avctx, AV_LOG_ERROR,

               "Empty frame found but it is not a skip frame.\n");

        return AVERROR_INVALIDDATA;

    }

    mb_width  = FFALIGN(width,  16) >> 4;

    mb_height = FFALIGN(height, 16) >> 4;

    if (frame_type != SKIP_FRAME && 8*buf_size < 8*HEADER_SIZE + mb_width*mb_height)

        return AVERROR_INVALIDDATA;

    if ((ret = ff_reget_buffer(avctx, c->pic, 0)) < 0)

        return ret;

    if (frame_type == INTRA_FRAME)

        c->pic->flags |= AV_FRAME_FLAG_KEY;

    else

        c->pic->flags &= ~AV_FRAME_FLAG_KEY;

    c->pic->pict_type = (frame_type == INTRA_FRAME) ? AV_PICTURE_TYPE_I

                                                   : AV_PICTURE_TYPE_P;

    if (frame_type == SKIP_FRAME) {

        *got_frame      = 1;

        if ((ret = av_frame_ref(rframe, c->pic)) < 0)

            return ret;

        return buf_size;

    }

    if (c->quality != quality) {

        c->quality = quality;

        for (i = 0; i < 2; i++)

            ff_mss34_gen_quant_mat(c->quant_mat[i], quality, !i);

    }

    if ((ret = init_get_bits8(&gb, buf + HEADER_SIZE, buf_size - HEADER_SIZE)) < 0)

        return ret;

    dst[0] = c->pic->data[0];

    dst[1] = c->pic->data[1];

    dst[2] = c->pic->data[2];

    memset(c->prev_vec, 0, sizeof(c->prev_vec));

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

        memset(c->dc_cache, 0, sizeof(c->dc_cache));

        for (x = 0; x < mb_width; x++) {

            blk_type = decode012(&gb);

            switch (blk_type) {

            case DCT_BLOCK:

                if (mss4_decode_dct_block(c, &gb, dst, x, y) < 0) {

                    av_log(avctx, AV_LOG_ERROR,

                           "Error decoding DCT block %d,%d\n",

                           x, y);

                    return AVERROR_INVALIDDATA;

                }

                break;

            case IMAGE_BLOCK:

                if (mss4_decode_image_block(c, &gb, dst, x, y) < 0) {

                    av_log(avctx, AV_LOG_ERROR,

                           "Error decoding VQ block %d,%d\n",

                           x, y);

                    return AVERROR_INVALIDDATA;

                }

                break;

            case SKIP_BLOCK:

                if (frame_type == INTRA_FRAME) {

                    av_log(avctx, AV_LOG_ERROR, "Skip block in intra frame\n");

                    return AVERROR_INVALIDDATA;

                }

                break;

            }

            if (blk_type != DCT_BLOCK)

                mss4_update_dc_cache(c, x);

        }

        dst[0] += c->pic->linesize[0] * 16;

        dst[1] += c->pic->linesize[1] * 16;

        dst[2] += c->pic->linesize[2] * 16;

    }

    if ((ret = av_frame_ref(rframe, c->pic)) < 0)

        return ret;

    *got_frame      = 1;

    return buf_size;

}

static av_cold int mss4_decode_end(AVCodecContext *avctx)

{

    MSS4Context * const c = avctx->priv_data;

    int i;

    av_frame_free(&c->pic);

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

        av_freep(&c->prev_dc[i]);

    return 0;

}

static av_cold int mss4_decode_init(AVCodecContext *avctx)

{

    static AVOnce init_static_once = AV_ONCE_INIT;

    MSS4Context * const c = avctx->priv_data;

    int i;

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

        c->dc_stride[i] = FFALIGN(avctx->width, 16) >> (2 + !!i);

        c->prev_dc[i]   = av_malloc_array(c->dc_stride[i], sizeof(**c->prev_dc));

        if (!c->prev_dc[i]) {

            av_log(avctx, AV_LOG_ERROR, "Cannot allocate buffer\n");

            return AVERROR(ENOMEM);

        }

    }

    c->pic = av_frame_alloc();

    if (!c->pic)

        return AVERROR(ENOMEM);

    avctx->pix_fmt     = AV_PIX_FMT_YUV444P;

    ff_thread_once(&init_static_once, mss4_init_vlcs);

    return 0;

}

const FFCodec ff_mts2_decoder = {

    .p.name         = "mts2",

    CODEC_LONG_NAME("MS Expression Encoder Screen"),

    .p.type         = AVMEDIA_TYPE_VIDEO,

    .p.id           = AV_CODEC_ID_MTS2,

    .priv_data_size = sizeof(MSS4Context),

    .init           = mss4_decode_init,

    .close          = mss4_decode_end,

    FF_CODEC_DECODE_CB(mss4_decode_frame),

    .p.capabilities = AV_CODEC_CAP_DR1,

    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,

};