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/*

 * Copyright (c) 1990 James Ashton - Sydney University

 * Copyright (c) 2012 Stefano Sabatini

 *

 * 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

 * X-Face decoder, based on libcompface, by James Ashton.

 */

#include "libavutil/pixdesc.h"

#include "avcodec.h"

#include "bytestream.h"

#include "internal.h"

#include "xface.h"

static int pop_integer(BigInt *b, const ProbRange *pranges)

{

    uint8_t r;

    int i;

    /* extract the last byte into r, and shift right b by 8 bits */

    ff_big_div(b, 0, &r);

    i = 0;

    while (r < pranges->offset || r >= pranges->range + pranges->offset) {

        pranges++;

        i++;

    }

    ff_big_mul(b, pranges->range);

    ff_big_add(b, r - pranges->offset);

    return i;

}

static void pop_greys(BigInt *b, char *bitmap, int w, int h)

{

    if (w > 3) {

        w /= 2;

        h /= 2;

        pop_greys(b, bitmap,                       w, h);

        pop_greys(b, bitmap + w,                   w, h);

        pop_greys(b, bitmap + XFACE_WIDTH * h,     w, h);

        pop_greys(b, bitmap + XFACE_WIDTH * h + w, w, h);

    } else {

        w = pop_integer(b, ff_xface_probranges_2x2);

        if (w & 1) bitmap[0]               = 1;

        if (w & 2) bitmap[1]               = 1;

        if (w & 4) bitmap[XFACE_WIDTH]     = 1;

        if (w & 8) bitmap[XFACE_WIDTH + 1] = 1;

    }

}

static void decode_block(BigInt *b, char *bitmap, int w, int h, int level)

{

    switch (pop_integer(b, &ff_xface_probranges_per_level[level][0])) {

    case XFACE_COLOR_WHITE:

        return;

    case XFACE_COLOR_BLACK:

        pop_greys(b, bitmap, w, h);

        return;

    default:

        w /= 2;

        h /= 2;

        level++;

        decode_block(b, bitmap,                       w, h, level);

        decode_block(b, bitmap + w,                   w, h, level);

        decode_block(b, bitmap + h * XFACE_WIDTH,     w, h, level);

        decode_block(b, bitmap + w + h * XFACE_WIDTH, w, h, level);

        return;

    }

}

typedef struct XFaceContext {

    uint8_t bitmap[XFACE_PIXELS]; ///< image used internally for decoding

} XFaceContext;

static av_cold int xface_decode_init(AVCodecContext *avctx)

{

    if (avctx->width || avctx->height) {

        if (avctx->width != XFACE_WIDTH || avctx->height != XFACE_HEIGHT) {

            av_log(avctx, AV_LOG_ERROR,

                   "Size value %dx%d not supported, only accepts a size of %dx%d\n",

                   avctx->width, avctx->height, XFACE_WIDTH, XFACE_HEIGHT);

            return AVERROR(EINVAL);

        }

    }

    avctx->width   = XFACE_WIDTH;

    avctx->height  = XFACE_HEIGHT;

    avctx->pix_fmt = AV_PIX_FMT_MONOWHITE;

    return 0;

}

static int xface_decode_frame(AVCodecContext *avctx,

                              void *data, int *got_frame,

                              AVPacket *avpkt)

{

    XFaceContext *xface = avctx->priv_data;

    int ret, i, j, k;

    uint8_t byte;

    BigInt b = {0};

    char *buf;

    int64_t c;

    AVFrame *frame = data;

    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)

        return ret;

    for (i = 0, k = 0; avpkt->data[i] && i < avpkt->size; i++) {

        c = avpkt->data[i];

        /* ignore invalid digits */

        if (c < XFACE_FIRST_PRINT || c > XFACE_LAST_PRINT)

            continue;

        if (++k > XFACE_MAX_DIGITS) {

            av_log(avctx, AV_LOG_WARNING,

                   "Buffer is longer than expected, truncating at byte %d\n", i);

            break;

        }

        ff_big_mul(&b, XFACE_PRINTS);

        ff_big_add(&b, c - XFACE_FIRST_PRINT);

    }

    /* decode image and put it in bitmap */

    memset(xface->bitmap, 0, XFACE_PIXELS);

    buf = xface->bitmap;

    decode_block(&b, buf,                         16, 16, 0);

    decode_block(&b, buf + 16,                    16, 16, 0);

    decode_block(&b, buf + 32,                    16, 16, 0);

    decode_block(&b, buf + XFACE_WIDTH * 16,      16, 16, 0);

    decode_block(&b, buf + XFACE_WIDTH * 16 + 16, 16, 16, 0);

    decode_block(&b, buf + XFACE_WIDTH * 16 + 32, 16, 16, 0);

    decode_block(&b, buf + XFACE_WIDTH * 32     , 16, 16, 0);

    decode_block(&b, buf + XFACE_WIDTH * 32 + 16, 16, 16, 0);

    decode_block(&b, buf + XFACE_WIDTH * 32 + 32, 16, 16, 0);

    ff_xface_generate_face(xface->bitmap, xface->bitmap);

    /* convert image from 1=black 0=white bitmap to MONOWHITE */

    buf = frame->data[0];

    for (i = 0, j = 0, k = 0, byte = 0; i < XFACE_PIXELS; i++) {

        byte += xface->bitmap[i];

        if (k == 7) {

            buf[j++] = byte;

            byte = k = 0;

        } else {

            k++;

            byte <<= 1;

        }

        if (j == XFACE_WIDTH/8) {

            j = 0;

            buf += frame->linesize[0];

        }

    }

    *got_frame = 1;

    return avpkt->size;

}

AVCodec ff_xface_decoder = {

    .name           = "xface",

    .long_name      = NULL_IF_CONFIG_SMALL("X-face image"),

    .type           = AVMEDIA_TYPE_VIDEO,

    .id             = AV_CODEC_ID_XFACE,

    .priv_data_size = sizeof(XFaceContext),

    .init           = xface_decode_init,

    .decode         = xface_decode_frame,

    .pix_fmts       = (const enum AVPixelFormat[]) { AV_PIX_FMT_MONOWHITE, AV_PIX_FMT_NONE },

};