/*

 * Gryphon's Anim Compressor decoder

 * Copyright (c) 2019 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 "libavutil/attributes.h"

#include "libavutil/internal.h"

#include "libavutil/intreadwrite.h"

#include "avcodec.h"

#include "bytestream.h"

#include "codec_internal.h"

#include "decode.h"

typedef struct ARBCContext {

    GetByteContext gb;

    AVFrame *prev_frame;

} ARBCContext;

static int fill_tile4(AVCodecContext *avctx, int color, AVFrame *frame)

{

    ARBCContext *s = avctx->priv_data;

    GetByteContext *gb = &s->gb;

    int nb_tiles = bytestream2_get_le16(gb);

    int h = avctx->height - 1;

    int pixels_overwritten = 0;

    if ((avctx->width / 4 + 1) * (avctx->height / 4 + 1) < nb_tiles)

        return 0;

    for (int i = 0; i < nb_tiles; i++) {

        int y = bytestream2_get_byte(gb);

        int x = bytestream2_get_byte(gb);

        uint16_t mask = bytestream2_get_le16(gb);

        int start_y = y * 4, start_x = x * 4;

        int end_y = start_y + 4, end_x = start_x + 4;

        for (int j = start_y; j < end_y; j++) {

            for (int k = start_x; k < end_x; k++) {

                if (mask & 0x8000) {

                    if (j >= avctx->height || k >= avctx->width) {

                        mask = mask << 1;

                        continue;

                    }

                    AV_WB24(&frame->data[0][frame->linesize[0] * (h - j) + 3 * k], color);

                    pixels_overwritten ++;

                }

                mask = mask << 1;

            }

        }

    }

    return pixels_overwritten;

}

static int fill_tileX(AVCodecContext *avctx, int tile_width, int tile_height,

                       int color, AVFrame *frame)

{

    ARBCContext *s = avctx->priv_data;

    GetByteContext *gb = &s->gb;

    const int step_h = tile_height / 4;

    const int step_w = tile_width / 4;

    int nb_tiles = bytestream2_get_le16(gb);

    int h = avctx->height - 1;

    int pixels_overwritten = 0;

    if ((avctx->width / tile_width + 1) * (avctx->height / tile_height + 1) < nb_tiles)

        return 0;

    for (int i = 0; i < nb_tiles; i++) {

        int y = bytestream2_get_byte(gb);

        int x = bytestream2_get_byte(gb);

        uint16_t mask = bytestream2_get_le16(gb);

        int start_y = y * tile_height, start_x = x * tile_width;

        int end_y = start_y + tile_height, end_x = start_x + tile_width;

        if (start_x >= avctx->width || start_y >= avctx->height)

            continue;

        for (int j = start_y; j < end_y; j += step_h) {

            for (int k = start_x; k < end_x; k += step_w) {

                if (mask & 0x8000U) {

                    for (int m = 0; m < step_h; m++) {

                        for (int n = 0; n < step_w; n++) {

                            if (j + m >= avctx->height || k + n >= avctx->width)

                                continue;

                            AV_WB24(&frame->data[0][frame->linesize[0] * (h - (j + m)) + 3 * (k + n)], color);

                        }

                    }

                    pixels_overwritten += FFMIN(step_h, avctx->height - j) * FFMIN(step_w, avctx->width - k);

                }

                mask = mask << 1;

            }

        }

    }

    return pixels_overwritten;

}

static int decode_frame(AVCodecContext *avctx, AVFrame *frame,

                        int *got_frame, AVPacket *avpkt)

{

    ARBCContext *s = avctx->priv_data;

    int ret, nb_segments;

    int prev_pixels = avctx->width * avctx->height;

    if (avpkt->size < 10)

        return AVERROR_INVALIDDATA;

    bytestream2_init(&s->gb, avpkt->data, avpkt->size);

    bytestream2_skip(&s->gb, 8);

    nb_segments = bytestream2_get_le16(&s->gb);

    if (nb_segments == 0)

        return avpkt->size;

    if (7 * nb_segments > bytestream2_get_bytes_left(&s->gb))

        return AVERROR_INVALIDDATA;

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

        return ret;

    if (s->prev_frame->data[0]) {

        ret = av_frame_copy(frame, s->prev_frame);

        if (ret < 0)

            return ret;

    }

    for (int i = 0; i < nb_segments; i++) {

        int resolution_flag;

        int fill;

        if (bytestream2_get_bytes_left(&s->gb) <= 0)

            return AVERROR_INVALIDDATA;

        fill = bytestream2_get_byte(&s->gb) << 16;

        bytestream2_skip(&s->gb, 1);

        fill |= bytestream2_get_byte(&s->gb) << 8;

        bytestream2_skip(&s->gb, 1);

        fill |= bytestream2_get_byte(&s->gb) << 0;

        bytestream2_skip(&s->gb, 1);

        resolution_flag = bytestream2_get_byte(&s->gb);

        if (resolution_flag & 0x10)

            prev_pixels -= fill_tileX(avctx, 1024, 1024, fill, frame);

        if (resolution_flag & 0x08)

            prev_pixels -= fill_tileX(avctx, 256, 256, fill, frame);

        if (resolution_flag & 0x04)

            prev_pixels -= fill_tileX(avctx, 64, 64, fill, frame);

        if (resolution_flag & 0x02)

            prev_pixels -= fill_tileX(avctx, 16, 16, fill, frame);

        if (resolution_flag & 0x01)

            prev_pixels -= fill_tile4(avctx, fill, frame);

    }

    if ((ret = av_frame_replace(s->prev_frame, frame)) < 0)

        return ret;

    frame->pict_type = prev_pixels <= 0 ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;

    if (prev_pixels <= 0)

        frame->flags |= AV_FRAME_FLAG_KEY;

    else

        frame->flags &= ~AV_FRAME_FLAG_KEY;

    *got_frame = 1;

    return avpkt->size;

}

static av_cold int decode_init(AVCodecContext *avctx)

{

    ARBCContext *s = avctx->priv_data;

    avctx->pix_fmt = AV_PIX_FMT_RGB24;

    s->prev_frame = av_frame_alloc();

    if (!s->prev_frame)

        return AVERROR(ENOMEM);

    return 0;

}

static av_cold void decode_flush(AVCodecContext *avctx)

{

    ARBCContext *s = avctx->priv_data;

    av_frame_unref(s->prev_frame);

}

static av_cold int decode_close(AVCodecContext *avctx)

{

    ARBCContext *s = avctx->priv_data;

    av_frame_free(&s->prev_frame);

    return 0;

}

const FFCodec ff_arbc_decoder = {

    .p.name         = "arbc",

    CODEC_LONG_NAME("Gryphon's Anim Compressor"),

    .p.type         = AVMEDIA_TYPE_VIDEO,

    .p.id           = AV_CODEC_ID_ARBC,

    .priv_data_size = sizeof(ARBCContext),

    .init           = decode_init,

    FF_CODEC_DECODE_CB(decode_frame),

    .flush          = decode_flush,

    .close          = decode_close,

    .p.capabilities = AV_CODEC_CAP_DR1,

    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,

};