/*

 * Copyright (c) 2024 Michael Niedermayer <michael-ffmpeg@niedermayer.cc>

 *

 * 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 "config.h"

#include "libavutil/avassert.h"

#include "libavutil/avstring.h"

#include "libavutil/cpu.h"

#include "libavutil/imgutils.h"

#include "libavutil/intreadwrite.h"

#include "libavutil/mem.h"

#include "libavutil/opt.h"

#include "libavcodec/bytestream.h"

#include "libswscale/swscale.h"

int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);

static void error(const char *err)

{

    fprintf(stderr, "%s", err);

    exit(1);

}

static int alloc_plane(uint8_t *data[AV_VIDEO_MAX_PLANES], int stride[AV_VIDEO_MAX_PLANES], int w, int h, int format, int *hshift, int *vshift)

{

    size_t size[AV_VIDEO_MAX_PLANES];

    ptrdiff_t ptrdiff_stride[AV_VIDEO_MAX_PLANES];

    int ret = av_image_fill_linesizes(stride, format, w);

    if (ret < 0)

        return -1;

    av_assert0(AV_VIDEO_MAX_PLANES == 4); // Some of the libavutil API has 4 hardcoded so this has undefined behaviour if its not 4

    av_pix_fmt_get_chroma_sub_sample(format, hshift, vshift);

    for(int p=0; p<AV_VIDEO_MAX_PLANES; p++) {

        stride[p] =

        ptrdiff_stride[p] = FFALIGN(stride[p], 32);

    }

    ret = av_image_fill_plane_sizes(size, format, h, ptrdiff_stride);

    if (ret < 0)

        return ret;

    for(int p=0; p<AV_VIDEO_MAX_PLANES; p++) {

        if (size[p]) {

            data[p] = av_mallocz(size[p] + 32);

            if (!data[p])

                return -1;

        } else

            data[p] = NULL;

    }

    return 0;

}

static void free_plane(uint8_t *data[AV_VIDEO_MAX_PLANES])

{

    for(int p=0; p<AV_VIDEO_MAX_PLANES; p++)

        av_freep(&data[p]);

}

static void mapres(unsigned *r0, unsigned *r1) {

    double d = (double)(*r0*10ll - 9ll*UINT32_MAX) / UINT32_MAX;

    double a = exp(d) * 16384 / exp(1) ;

    int ai = (int)round(a);

    uint64_t maxb = 16384 / ai;

    *r0 = ai;

    *r1 = 1 + (*r1 * maxb) / UINT32_MAX;

}

int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {

    int srcW= 48, srcH = 48;

    int dstW= 48, dstH = 48;

    int srcHShift, srcVShift;

    int dstHShift, dstVShift;

    unsigned flags = 1;

    int srcStride[AV_VIDEO_MAX_PLANES] = {0};

    int dstStride[AV_VIDEO_MAX_PLANES] = {0};

    int ret;

    const uint8_t *end = data + size;

    enum AVPixelFormat srcFormat = AV_PIX_FMT_YUV420P;

    enum AVPixelFormat dstFormat = AV_PIX_FMT_YUV420P;

    uint8_t *src[AV_VIDEO_MAX_PLANES] = { 0 };

    uint8_t *dst[AV_VIDEO_MAX_PLANES] = { 0 };

    struct SwsContext *sws = NULL;

    const AVPixFmtDescriptor *desc_src, *desc_dst;

    if (size > 128) {

        GetByteContext gbc;

        int64_t flags64;

        size -= 128;

        bytestream2_init(&gbc, data + size, 128);

        srcW = bytestream2_get_le32(&gbc);

        srcH = bytestream2_get_le32(&gbc);

        dstW = bytestream2_get_le32(&gbc);

        dstH = bytestream2_get_le32(&gbc);

        mapres(&srcW, &srcH);

        mapres(&dstW, &dstH);

        flags = bytestream2_get_le32(&gbc);

        unsigned mask = flags & (SWS_POINT         |

                                SWS_AREA          |

                                SWS_BILINEAR      |

                                SWS_FAST_BILINEAR |

                                SWS_BICUBIC       |

                                SWS_X             |

                                SWS_GAUSS         |

                                SWS_LANCZOS       |

                                SWS_SINC          |

                                SWS_SPLINE        |

                                SWS_BICUBLIN);

        mask &= flags;

        if (mask && (mask & (mask -1)))

            return 0; // multiple scalers are set, not possible

        srcFormat = bytestream2_get_le32(&gbc) % AV_PIX_FMT_NB;

        dstFormat = bytestream2_get_le32(&gbc) % AV_PIX_FMT_NB;

        flags64 = bytestream2_get_le64(&gbc);

        if (flags64 & 0x10)

            av_force_cpu_flags(0);

        if (av_image_check_size(srcW, srcH, srcFormat, NULL) < 0)

            srcW = srcH = 23;

        if (av_image_check_size(dstW, dstH, dstFormat, NULL) < 0)

            dstW = dstH = 23;

        //TODO alphablend

    }

    desc_src = av_pix_fmt_desc_get(srcFormat);

    desc_dst = av_pix_fmt_desc_get(dstFormat);

    // fprintf(stderr, "%d x %d %s -> %d x %d %s\n", srcW, srcH, desc_src->name, dstW, dstH, desc_dst->name);

    ret = alloc_plane(src, srcStride, srcW, srcH, srcFormat, &srcHShift, &srcVShift);

    if (ret < 0)

        goto end;

    ret = alloc_plane(dst, dstStride, dstW, dstH, dstFormat, &dstHShift, &dstVShift);

    if (ret < 0)

        goto end;

    for(int p=0; p<AV_VIDEO_MAX_PLANES; p++) {

        int psize = srcStride[p] * AV_CEIL_RSHIFT(srcH, (p == 1 || p == 2) ? srcVShift : 0);

        if (psize > size)

            psize = size;

        if (psize) {

            memcpy(src[p], data, psize);

            data += psize;

            size -= psize;

        }

    }

    sws = sws_alloc_context();

    if (!sws)

        error("Failed sws allocation");

    av_opt_set_int(sws, "sws_flags",  flags, 0);

    av_opt_set_int(sws, "srcw",       srcW, 0);

    av_opt_set_int(sws, "srch",       srcH, 0);

    av_opt_set_int(sws, "dstw",       dstW, 0);

    av_opt_set_int(sws, "dsth",       dstH, 0);

    av_opt_set_int(sws, "src_format", srcFormat, 0);

    av_opt_set_int(sws, "dst_format", dstFormat, 0);

    av_opt_set(sws, "alphablend", "none", 0);

    ret = sws_init_context(sws, NULL, NULL);

    if (ret < 0)

        goto end;

    //TODO Slices

    sws_scale(sws, (const uint8_t * const*)src, srcStride, 0, srcH, dst, dstStride);

end:

    sws_freeContext(sws);

    free_plane(src);

    free_plane(dst);

    return 0;

}