/*
  * Apple Pixlet decoder
  * Copyright (c) 2016 Paul B Mahol
  *
  * 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 <stdint.h>
 
 #include "libavutil/imgutils.h"
 #include "libavutil/intmath.h"
 #include "libavutil/opt.h"
 
 #include "avcodec.h"
 #include "bytestream.h"
 #include "get_bits.h"
 #include "unary.h"
 #include "internal.h"
 #include "thread.h"
 
 #define NB_LEVELS 4
 
 #define H 0
 #define V 1
 
 typedef struct SubBand {
     unsigned width, height;
     unsigned size;
     unsigned x, y;
 } SubBand;
 
 typedef struct PixletContext {
     AVClass *class;
 
     GetByteContext gb;
     GetBitContext gbit;
 
     int levels;
     int depth;
     int h, w;
 
     int16_t *filter[2];
     int16_t *prediction;

     int64_t scaling[4][2][NB_LEVELS];

     SubBand band[4][NB_LEVELS * 3 + 1];
 } PixletContext;
 
 static int init_decoder(AVCodecContext *avctx)
 {
     PixletContext *ctx = avctx->priv_data;
     int i, plane;
 
     ctx->filter[0]  = av_malloc_array(ctx->h, sizeof(int16_t));
     ctx->filter[1]  = av_malloc_array(FFMAX(ctx->h, ctx->w) + 16, sizeof(int16_t));
     ctx->prediction = av_malloc_array((ctx->w >> NB_LEVELS), sizeof(int16_t));
     if (!ctx->filter[0] || !ctx->filter[1] || !ctx->prediction)
         return AVERROR(ENOMEM);
 
     for (plane = 0; plane < 3; plane++) {
         unsigned shift = plane > 0;
         unsigned w = ctx->w >> shift;
         unsigned h = ctx->h >> shift;
 
         ctx->band[plane][0].width  = w >> NB_LEVELS;
         ctx->band[plane][0].height = h >> NB_LEVELS;
         ctx->band[plane][0].size = (w >> NB_LEVELS) * (h >> NB_LEVELS);
 
         for (i = 0; i < NB_LEVELS * 3; i++) {
             unsigned scale = ctx->levels - (i / 3);
 
             ctx->band[plane][i + 1].width  = w >> scale;
             ctx->band[plane][i + 1].height = h >> scale;
             ctx->band[plane][i + 1].size = (w >> scale) * (h >> scale);
 
             ctx->band[plane][i + 1].x = (w >> scale) * (((i + 1) % 3) != 2);
             ctx->band[plane][i + 1].y = (h >> scale) * (((i + 1) % 3) != 1);
         }
     }
 
     return 0;
 }
 
 static void free_buffers(AVCodecContext *avctx)
 {
     PixletContext *ctx = avctx->priv_data;
 
     av_freep(&ctx->filter[0]);
     av_freep(&ctx->filter[1]);
     av_freep(&ctx->prediction);
 }
 
 static av_cold int pixlet_close(AVCodecContext *avctx)
 {
     PixletContext *ctx = avctx->priv_data;
     free_buffers(avctx);
     ctx->w = 0;
     ctx->h = 0;
     return 0;
 }
 
 static av_cold int pixlet_init(AVCodecContext *avctx)
 {
     avctx->pix_fmt = AV_PIX_FMT_YUV420P16;
     avctx->color_range = AVCOL_RANGE_JPEG;
     return 0;
 }
 
 static int read_low_coeffs(AVCodecContext *avctx, int16_t *dst, int size, int width, ptrdiff_t stride)
 {
     PixletContext *ctx = avctx->priv_data;
     GetBitContext *b = &ctx->gbit;
     unsigned cnt1, nbits, k, j = 0, i = 0;
     int64_t value, state = 3;
     int rlen, escape, flag = 0;
 
     while (i < size) {
         nbits = FFMIN(ff_clz((state >> 8) + 3) ^ 0x1F, 14);
 
         cnt1 = get_unary(b, 0, 8);
         if (cnt1 < 8) {
             value = show_bits(b, nbits);
             if (value <= 1) {
                 skip_bits(b, nbits - 1);
                 escape = ((1 << nbits) - 1) * cnt1;
             } else {
                 skip_bits(b, nbits);
                 escape = value + ((1 << nbits) - 1) * cnt1 - 1;
             }
         } else {
             escape = get_bits(b, 16);
         }
 
         value = -((escape + flag) & 1) | 1;
         dst[j++] = value * ((escape + flag + 1) >> 1);
         i++;
         if (j == width) {
             j = 0;
             dst += stride;
         }
         state = 120 * (escape + flag) + state - (120 * state >> 8);
         flag = 0;
 

         if (state * 4ULL > 0xFF || i >= size)

             continue;
 
         nbits = ((state + 8) >> 5) + (state ? ff_clz(state) : 32) - 24;
         escape = av_mod_uintp2(16383, nbits);
         cnt1 = get_unary(b, 0, 8);
         if (cnt1 > 7) {
             rlen = get_bits(b, 16);
         } else {
             value = show_bits(b, nbits);
             if (value > 1) {
                 skip_bits(b, nbits);
                 rlen = value + escape * cnt1 - 1;
             } else {
                 skip_bits(b, nbits - 1);
                 rlen = escape * cnt1;
             }
         }
 

         if (rlen > size - i)

             return AVERROR_INVALIDDATA;
         i += rlen;
 
         for (k = 0; k < rlen; k++) {
             dst[j++] = 0;
             if (j == width) {
                 j = 0;
                 dst += stride;
             }
         }
 
         state = 0;
         flag = rlen < 0xFFFF ? 1 : 0;
     }
 
     align_get_bits(b);
     return get_bits_count(b) >> 3;
 }
 
 static int read_high_coeffs(AVCodecContext *avctx, uint8_t *src, int16_t *dst, int size,
                             int c, int a, int d,
                             int width, ptrdiff_t stride)
 {
     PixletContext *ctx = avctx->priv_data;
     GetBitContext *b = &ctx->gbit;
     unsigned cnt1, shbits, rlen, nbits, length, i = 0, j = 0, k;
     int ret, escape, pfx, value, yflag, xflag, flag = 0;
     int64_t state = 3, tmp;
 
     if ((ret = init_get_bits8(b, src, bytestream2_get_bytes_left(&ctx->gb))) < 0)
       return ret;
 

     if (a ^ (a >> 31)) {
         nbits = 33 - ff_clz(a ^ (a >> 31));

         if (nbits > 16)
             return AVERROR_INVALIDDATA;
     } else {
         nbits = 1;
     }
 
     length = 25 - nbits;
 
     while (i < size) {
         if (state >> 8 != -3) {
             value = ff_clz((state >> 8) + 3) ^ 0x1F;
         } else {
             value = -1;
         }
 
         cnt1 = get_unary(b, 0, length);
 
         if (cnt1 >= length) {
             cnt1 = get_bits(b, nbits);
         } else {
             pfx = 14 + ((((uint64_t)(value - 14)) >> 32) & (value - 14));

             if (pfx < 1 || pfx > 25)
                 return AVERROR_INVALIDDATA;

             cnt1 *= (1 << pfx) - 1;
             shbits = show_bits(b, pfx);
             if (shbits <= 1) {
                 skip_bits(b, pfx - 1);
             } else {
                 skip_bits(b, pfx);
                 cnt1 += shbits - 1;
             }
         }
 
         xflag = flag + cnt1;
         yflag = xflag;
 
         if (flag + cnt1 == 0) {
             value = 0;
         } else {
             xflag &= 1u;

             tmp = (int64_t)c * ((yflag + 1) >> 1) + (c >> 1);

             value = xflag + (tmp ^ -xflag);
         }
 
         i++;
         dst[j++] = value;
         if (j == width) {
             j = 0;
             dst += stride;
         }

         state += (int64_t)d * (uint64_t)yflag - ((int64_t)(d * (uint64_t)state) >> 8);

 
         flag = 0;
 

         if ((uint64_t)state > 0xFF / 4 || i >= size)

             continue;
 
         pfx = ((state + 8) >> 5) + (state ? ff_clz(state): 32) - 24;
         escape = av_mod_uintp2(16383, pfx);
         cnt1 = get_unary(b, 0, 8);
         if (cnt1 < 8) {

             if (pfx < 1 || pfx > 25)
                 return AVERROR_INVALIDDATA;

             value = show_bits(b, pfx);
             if (value > 1) {
                 skip_bits(b, pfx);
                 rlen = value + escape * cnt1 - 1;
             } else {
                 skip_bits(b, pfx - 1);
                 rlen = escape * cnt1;
             }
         } else {
             if (get_bits1(b))
                 value = get_bits(b, 16);
             else
                 value = get_bits(b, 8);
 
             rlen = value + 8 * escape;
         }
 
         if (rlen > 0xFFFF || i + rlen > size)
             return AVERROR_INVALIDDATA;
         i += rlen;
 
         for (k = 0; k < rlen; k++) {
             dst[j++] = 0;
             if (j == width) {
                 j = 0;
                 dst += stride;
             }
         }
 
         state = 0;
         flag = rlen < 0xFFFF ? 1 : 0;
     }
 
     align_get_bits(b);
     return get_bits_count(b) >> 3;
 }
 
 static int read_highpass(AVCodecContext *avctx, uint8_t *ptr, int plane, AVFrame *frame)
 {
     PixletContext *ctx = avctx->priv_data;
     ptrdiff_t stride = frame->linesize[plane] / 2;
     int i, ret;
 
     for (i = 0; i < ctx->levels * 3; i++) {
         int32_t a = bytestream2_get_be32(&ctx->gb);
         int32_t b = bytestream2_get_be32(&ctx->gb);
         int32_t c = bytestream2_get_be32(&ctx->gb);
         int32_t d = bytestream2_get_be32(&ctx->gb);
         int16_t *dest = (int16_t *)frame->data[plane] + ctx->band[plane][i + 1].x +
                                                stride * ctx->band[plane][i + 1].y;
         unsigned size = ctx->band[plane][i + 1].size;
         uint32_t magic;
 
         magic = bytestream2_get_be32(&ctx->gb);
         if (magic != 0xDEADBEEF) {

             av_log(avctx, AV_LOG_ERROR, "wrong magic number: 0x%08"PRIX32
                    " for plane %d, band %d\n", magic, plane, i);

             return AVERROR_INVALIDDATA;
         }
 

         if (a == INT32_MIN)
             return AVERROR_INVALIDDATA;
 

         ret = read_high_coeffs(avctx, ptr + bytestream2_tell(&ctx->gb), dest, size,
                                c, (b >= FFABS(a)) ? b : a, d,
                                ctx->band[plane][i + 1].width, stride);
         if (ret < 0) {
             av_log(avctx, AV_LOG_ERROR, "error in highpass coefficients for plane %d, band %d\n", plane, i);
             return ret;
         }
         bytestream2_skip(&ctx->gb, ret);
     }
 
     return 0;
 }
 
 static void lowpass_prediction(int16_t *dst, int16_t *pred, int width, int height, ptrdiff_t stride)
 {

     int16_t val;

     int i, j;
 
     memset(pred, 0, width * sizeof(*pred));
 
     for (i = 0; i < height; i++) {

         val    = pred[0] + dst[0];
         dst[0] = pred[0] = val;
         for (j = 1; j < width; j++) {
             val     = pred[j] + dst[j];
             dst[j]  = pred[j] = val;
             dst[j] += dst[j-1];

         }
         dst += stride;
     }
 }
 

 static void filterfn(int16_t *dest, int16_t *tmp, unsigned size, int64_t scale)

 {
     int16_t *low, *high, *ll, *lh, *hl, *hh;
     int hsize, i, j;

     int64_t value;

 
     hsize = size >> 1;
     low = tmp + 4;
     high = &low[hsize + 8];
 
     memcpy(low, dest, size);
     memcpy(high, dest + hsize, size);
 
     ll = &low[hsize];
     lh = &low[hsize];
     hl = &high[hsize];
     hh = hl;
     for (i = 4, j = 2; i; i--, j++, ll--, hh++, lh++, hl--) {
         low[i - 5]  = low[j - 1];
         lh[0]       = ll[-1];
         high[i - 5] = high[j - 2];
         hh[0]       = hl[-2];
     }
 
     for (i = 0; i < hsize; i++) {

         value = (int64_t) low [i + 1] * -INT64_C(325392907)  +
                 (int64_t) low [i + 0] *  INT64_C(3687786320) +
                 (int64_t) low [i - 1] * -INT64_C(325392907)  +
                 (int64_t) high[i + 0] *  INT64_C(1518500249) +
                 (int64_t) high[i - 1] *  INT64_C(1518500249);
         dest[i * 2] = av_clip_int16(((value >> 32) * scale) >> 32);

     }
 
     for (i = 0; i < hsize; i++) {

         value = (int64_t) low [i + 2] * -INT64_C(65078576)   +
                 (int64_t) low [i + 1] *  INT64_C(1583578880) +
                 (int64_t) low [i + 0] *  INT64_C(1583578880) +
                 (int64_t) low [i - 1] * -INT64_C(65078576)   +
                 (int64_t) high[i + 1] *  INT64_C(303700064)  +
                 (int64_t) high[i + 0] * -INT64_C(3644400640) +
                 (int64_t) high[i - 1] *  INT64_C(303700064);
         dest[i * 2 + 1] = av_clip_int16(((value >> 32) * scale) >> 32);

     }
 }
 
 static void reconstruction(AVCodecContext *avctx,
                            int16_t *dest, unsigned width, unsigned height, ptrdiff_t stride, int nb_levels,

                            int64_t *scaling_H, int64_t *scaling_V)

 {
     PixletContext *ctx = avctx->priv_data;
     unsigned scaled_width, scaled_height;

     int64_t scale_H, scale_V;

     int16_t *ptr, *tmp;
     int i, j, k;
 
     scaled_height = height >> nb_levels;
     scaled_width  = width  >> nb_levels;
     tmp = ctx->filter[0];
 
     for (i = 0; i < nb_levels; i++) {
         scaled_width  <<= 1;
         scaled_height <<= 1;
         scale_H = scaling_H[i];
         scale_V = scaling_V[i];
 
         ptr = dest;
         for (j = 0; j < scaled_height; j++) {

             filterfn(ptr, ctx->filter[1], scaled_width, scale_V);

             ptr += stride;
         }
 
         for (j = 0; j < scaled_width; j++) {
             ptr = dest + j;
             for (k = 0; k < scaled_height; k++) {
                 tmp[k] = *ptr;
                 ptr += stride;
             }
 

             filterfn(tmp, ctx->filter[1], scaled_height, scale_H);

 
             ptr = dest + j;
             for (k = 0; k < scaled_height; k++) {
                 *ptr = tmp[k];
                 ptr += stride;
             }
         }
     }
 }
 
 static void postprocess_luma(AVFrame *frame, int w, int h, int depth)
 {
     uint16_t *dsty = (uint16_t *)frame->data[0];
     int16_t *srcy  = (int16_t *)frame->data[0];
     ptrdiff_t stridey = frame->linesize[0] / 2;
     int i, j;
 
     for (j = 0; j < h; j++) {
         for (i = 0; i < w; i++) {

             if (srcy[i] <= 0)
                 dsty[i] = 0;
             else if (srcy[i] > ((1 << depth) - 1))
                 dsty[i] = 65535;
             else
                 dsty[i] = ((int64_t) srcy[i] * srcy[i] * 65535) /
                           ((1 << depth) - 1) / ((1 << depth) - 1);

         }
         dsty += stridey;
         srcy += stridey;
     }
 }
 
 static void postprocess_chroma(AVFrame *frame, int w, int h, int depth)
 {
     uint16_t *dstu = (uint16_t *)frame->data[1];
     uint16_t *dstv = (uint16_t *)frame->data[2];
     int16_t *srcu  = (int16_t *)frame->data[1];
     int16_t *srcv  = (int16_t *)frame->data[2];
     ptrdiff_t strideu = frame->linesize[1] / 2;
     ptrdiff_t stridev = frame->linesize[2] / 2;

     const unsigned add = 1 << (depth - 1);
     const unsigned shift = 16 - depth;

     int i, j;
 
     for (j = 0; j < h; j++) {
         for (i = 0; i < w; i++) {

             dstu[i] = av_clip_uintp2_c(add + srcu[i], depth) << shift;
             dstv[i] = av_clip_uintp2_c(add + srcv[i], depth) << shift;

         }
         dstu += strideu;
         dstv += stridev;
         srcu += strideu;
         srcv += stridev;
     }
 }
 
 static int decode_plane(AVCodecContext *avctx, int plane, AVPacket *avpkt, AVFrame *frame)
 {
     PixletContext *ctx = avctx->priv_data;
     ptrdiff_t stride = frame->linesize[plane] / 2;
     unsigned shift = plane > 0;
     int16_t *dst;
     int i, ret;
 
     for (i = ctx->levels - 1; i >= 0; i--) {

         int32_t h = sign_extend(bytestream2_get_be32(&ctx->gb), 32);
         int32_t v = sign_extend(bytestream2_get_be32(&ctx->gb), 32);
 
         if (!h || !v)
             return AVERROR_INVALIDDATA;
 

         ctx->scaling[plane][H][i] = (1000000ULL << 32) / h;
         ctx->scaling[plane][V][i] = (1000000ULL << 32) / v;

     }
 
     bytestream2_skip(&ctx->gb, 4);
 
     dst = (int16_t *)frame->data[plane];
     dst[0] = sign_extend(bytestream2_get_be16(&ctx->gb), 16);
 
     if ((ret = init_get_bits8(&ctx->gbit, avpkt->data + bytestream2_tell(&ctx->gb),
                               bytestream2_get_bytes_left(&ctx->gb))) < 0)
         return ret;
 
     ret = read_low_coeffs(avctx, dst + 1, ctx->band[plane][0].width - 1, ctx->band[plane][0].width - 1, 0);
     if (ret < 0) {
         av_log(avctx, AV_LOG_ERROR, "error in lowpass coefficients for plane %d, top row\n", plane);
         return ret;
     }
 
     ret = read_low_coeffs(avctx, dst + stride, ctx->band[plane][0].height - 1, 1, stride);
     if (ret < 0) {
         av_log(avctx, AV_LOG_ERROR, "error in lowpass coefficients for plane %d, left column\n", plane);
         return ret;
     }
 
     ret = read_low_coeffs(avctx, dst + stride + 1,
                           (ctx->band[plane][0].width - 1) * (ctx->band[plane][0].height - 1),
                           ctx->band[plane][0].width - 1, stride);
     if (ret < 0) {
         av_log(avctx, AV_LOG_ERROR, "error in lowpass coefficients for plane %d, rest\n", plane);
         return ret;
     }
 
     bytestream2_skip(&ctx->gb, ret);
     if (bytestream2_get_bytes_left(&ctx->gb) <= 0) {
         av_log(avctx, AV_LOG_ERROR, "no bytes left\n");
         return AVERROR_INVALIDDATA;
     }
 
     ret = read_highpass(avctx, avpkt->data, plane, frame);
     if (ret < 0)
         return ret;
 
     lowpass_prediction(dst, ctx->prediction,
                        ctx->band[plane][0].width, ctx->band[plane][0].height, stride);
 
     reconstruction(avctx, (int16_t *)frame->data[plane], ctx->w >> shift, ctx->h >> shift,
                    stride, NB_LEVELS, ctx->scaling[plane][H], ctx->scaling[plane][V]);
 
     return 0;
 }
 
 static int pixlet_decode_frame(AVCodecContext *avctx, void *data,
                                int *got_frame, AVPacket *avpkt)
 {
     PixletContext *ctx = avctx->priv_data;
     int i, w, h, width, height, ret, version;
     AVFrame *p = data;
     ThreadFrame frame = { .f = data };
     uint32_t pktsize;
 
     bytestream2_init(&ctx->gb, avpkt->data, avpkt->size);
 
     pktsize = bytestream2_get_be32(&ctx->gb);
     if (pktsize <= 44 || pktsize - 4 > bytestream2_get_bytes_left(&ctx->gb)) {

         av_log(avctx, AV_LOG_ERROR, "Invalid packet size %"PRIu32"\n", pktsize);

         return AVERROR_INVALIDDATA;
     }
 
     version = bytestream2_get_le32(&ctx->gb);
     if (version != 1)
         avpriv_request_sample(avctx, "Version %d", version);
 
     bytestream2_skip(&ctx->gb, 4);
     if (bytestream2_get_be32(&ctx->gb) != 1)
         return AVERROR_INVALIDDATA;
     bytestream2_skip(&ctx->gb, 4);
 
     width  = bytestream2_get_be32(&ctx->gb);
     height = bytestream2_get_be32(&ctx->gb);
 

     if (    width > INT_MAX - (1U << (NB_LEVELS + 1))
         || height > INT_MAX - (1U << (NB_LEVELS + 1)))
         return AVERROR_INVALIDDATA;
 

     w = FFALIGN(width,  1 << (NB_LEVELS + 1));
     h = FFALIGN(height, 1 << (NB_LEVELS + 1));
 
     ctx->levels = bytestream2_get_be32(&ctx->gb);
     if (ctx->levels != NB_LEVELS)
         return AVERROR_INVALIDDATA;
     ctx->depth = bytestream2_get_be32(&ctx->gb);
     if (ctx->depth < 8 || ctx->depth > 15) {
         avpriv_request_sample(avctx, "Depth %d", ctx->depth);
         return AVERROR_INVALIDDATA;
     }
 
     ret = ff_set_dimensions(avctx, w, h);
     if (ret < 0)
         return ret;
     avctx->width  = width;
     avctx->height = height;
 
     if (ctx->w != w || ctx->h != h) {
         free_buffers(avctx);
         ctx->w = w;
         ctx->h = h;
 
         ret = init_decoder(avctx);
         if (ret < 0) {
             free_buffers(avctx);
             ctx->w = 0;
             ctx->h = 0;
             return ret;
         }
     }
 
     bytestream2_skip(&ctx->gb, 8);
 
     p->pict_type = AV_PICTURE_TYPE_I;
     p->key_frame = 1;
     p->color_range = AVCOL_RANGE_JPEG;
 
     ret = ff_thread_get_buffer(avctx, &frame, 0);
     if (ret < 0)
         return ret;
 
     for (i = 0; i < 3; i++) {
         ret = decode_plane(avctx, i, avpkt, frame.f);
         if (ret < 0)
             return ret;
         if (avctx->flags & AV_CODEC_FLAG_GRAY)
             break;
     }
 
     postprocess_luma(frame.f, ctx->w, ctx->h, ctx->depth);
     postprocess_chroma(frame.f, ctx->w >> 1, ctx->h >> 1, ctx->depth);
 
     *got_frame = 1;
 
     return pktsize;
 }
 
 #if HAVE_THREADS
 static int pixlet_init_thread_copy(AVCodecContext *avctx)
 {
     PixletContext *ctx = avctx->priv_data;
 
     ctx->filter[0] = NULL;
     ctx->filter[1] = NULL;
     ctx->prediction = NULL;
     ctx->w = ctx->h = 0;
 
     return 0;
 }
 #endif
 
 AVCodec ff_pixlet_decoder = {
     .name             = "pixlet",
     .long_name        = NULL_IF_CONFIG_SMALL("Apple Pixlet"),
     .type             = AVMEDIA_TYPE_VIDEO,
     .id               = AV_CODEC_ID_PIXLET,
     .init             = pixlet_init,
     .init_thread_copy = ONLY_IF_THREADS_ENABLED(pixlet_init_thread_copy),
     .close            = pixlet_close,
     .decode           = pixlet_decode_frame,
     .priv_data_size   = sizeof(PixletContext),
     .capabilities     = AV_CODEC_CAP_DR1 |
                         AV_CODEC_CAP_FRAME_THREADS,
     .caps_internal    = FF_CODEC_CAP_INIT_THREADSAFE |
                         FF_CODEC_CAP_INIT_CLEANUP,
 };