/*
 * Copyright (c) 2022 Mohamed Khaled <Mohamed_Khaled_Kamal@outlook.com>
 *
 * 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 <float.h>
#include <stdio.h>
#include <string.h>

#include "libavutil/avstring.h"
#include "libavutil/common.h"
#include "libavutil/hwcontext.h"
#include "libavutil/hwcontext_cuda_internal.h"
#include "libavutil/cuda_check.h"
#include "libavutil/internal.h"
#include "libavutil/opt.h"
#include "libavutil/pixdesc.h"

#include "avfilter.h"
#include "formats.h"
#include "internal.h"
#include "video.h"

#include "cuda/load_helper.h"

static const enum AVPixelFormat supported_formats[] = {
    AV_PIX_FMT_YUV420P,
    AV_PIX_FMT_NV12,
    AV_PIX_FMT_YUV444P
};

#define DIV_UP(a, b) ( ((a) + (b) - 1) / (b) )
#define BLOCKX 32
#define BLOCKY 16

#define CHECK_CU(x) FF_CUDA_CHECK_DL(ctx, s->hwctx->internal->cuda_dl, x)


typedef struct CUDABilateralContext {
    const AVClass *class;
    AVCUDADeviceContext *hwctx;

    enum AVPixelFormat in_fmt, out_fmt;
    const AVPixFmtDescriptor *in_desc, *out_desc;
    int in_planes, out_planes;
    int in_plane_depths[4];
    int in_plane_channels[4];

    int   window_size;
    float sigmaS;
    float sigmaR;

    AVBufferRef *frames_ctx;
    AVFrame     *frame;
    AVFrame *tmp_frame;

    CUcontext   cu_ctx;
    CUmodule    cu_module;
    CUfunction  cu_func;
    CUfunction  cu_func_uv;
    CUstream    cu_stream;
} CUDABilateralContext;

static av_cold int cudabilateral_init(AVFilterContext *ctx)
{
    CUDABilateralContext *s = ctx->priv;

    s->frame = av_frame_alloc();
    if (!s->frame)
        return AVERROR(ENOMEM);

    s->tmp_frame = av_frame_alloc();
    if (!s->tmp_frame)
        return AVERROR(ENOMEM);

    return 0;
}

static av_cold void cudabilateral_uninit(AVFilterContext *ctx)
{
    CUDABilateralContext *s = ctx->priv;

    if (s->hwctx && s->cu_module) {
        CudaFunctions *cu = s->hwctx->internal->cuda_dl;
        CUcontext bilateral;

        CHECK_CU(cu->cuCtxPushCurrent(s->hwctx->cuda_ctx));
        CHECK_CU(cu->cuModuleUnload(s->cu_module));
        s->cu_module = NULL;
        CHECK_CU(cu->cuCtxPopCurrent(&bilateral));
    }

    av_frame_free(&s->frame);
    av_buffer_unref(&s->frames_ctx);
    av_frame_free(&s->tmp_frame);
}

static av_cold int init_hwframe_ctx(CUDABilateralContext *s, AVBufferRef *device_ctx, int width, int height)
{
    AVBufferRef *out_ref = NULL;
    AVHWFramesContext *out_ctx;
    int ret;

    out_ref = av_hwframe_ctx_alloc(device_ctx);
    if (!out_ref)
        return AVERROR(ENOMEM);
    out_ctx = (AVHWFramesContext*)out_ref->data;

    out_ctx->format    = AV_PIX_FMT_CUDA;
    out_ctx->sw_format = s->out_fmt;
    out_ctx->width     = width;
    out_ctx->height    = height;

    ret = av_hwframe_ctx_init(out_ref);
    if (ret < 0)
        goto fail;

    av_frame_unref(s->frame);
    ret = av_hwframe_get_buffer(out_ref, s->frame, 0);
    if (ret < 0)
        goto fail;

    av_buffer_unref(&s->frames_ctx);
    s->frames_ctx = out_ref;

    return 0;
fail:
    av_buffer_unref(&out_ref);
    return ret;
}

static int format_is_supported(enum AVPixelFormat fmt)
{
    int i;

    for (i = 0; i < FF_ARRAY_ELEMS(supported_formats); i++)
        if (supported_formats[i] == fmt)
            return 1;
    return 0;
}

static av_cold void set_format_info(AVFilterContext *ctx, enum AVPixelFormat in_format, enum AVPixelFormat out_format)
{
    CUDABilateralContext *s = ctx->priv;
    int i, p, d;

    s->in_fmt = in_format;
    s->out_fmt = out_format;

    s->in_desc  = av_pix_fmt_desc_get(s->in_fmt);
    s->out_desc = av_pix_fmt_desc_get(s->out_fmt);
    s->in_planes  = av_pix_fmt_count_planes(s->in_fmt);
    s->out_planes = av_pix_fmt_count_planes(s->out_fmt);

    // find maximum step of each component of each plane
    // For our subset of formats, this should accurately tell us how many channels CUDA needs
    // i.e. 1 for Y plane, 2 for UV plane of NV12, 4 for single plane of RGB0 formats

    for (i = 0; i < s->in_desc->nb_components; i++) {
        d = (s->in_desc->comp[i].depth + 7) / 8;
        p = s->in_desc->comp[i].plane;
        s->in_plane_channels[p] = FFMAX(s->in_plane_channels[p], s->in_desc->comp[i].step / d);

        s->in_plane_depths[p] = s->in_desc->comp[i].depth;
    }
}

static av_cold int init_processing_chain(AVFilterContext *ctx, int width, int height)
{
    CUDABilateralContext *s = ctx->priv;
    AVHWFramesContext *in_frames_ctx;
    int ret;

    /* check that we have a hw context */
    if (!ctx->inputs[0]->hw_frames_ctx) {
        av_log(ctx, AV_LOG_ERROR, "No hw context provided on input\n");
        return AVERROR(EINVAL);
    }
    in_frames_ctx = (AVHWFramesContext*)ctx->inputs[0]->hw_frames_ctx->data;

    if (!format_is_supported(in_frames_ctx->sw_format)) {
        av_log(ctx, AV_LOG_ERROR, "Unsupported format: %s\n", av_get_pix_fmt_name(in_frames_ctx->sw_format));
        return AVERROR(ENOSYS);
    }

    set_format_info(ctx, in_frames_ctx->sw_format, in_frames_ctx->sw_format);

    ret = init_hwframe_ctx(s, in_frames_ctx->device_ref, width, height);
    if (ret < 0)
        return ret;

    ctx->outputs[0]->hw_frames_ctx = av_buffer_ref(s->frames_ctx);
    if (!ctx->outputs[0]->hw_frames_ctx)
        return AVERROR(ENOMEM);

    return 0;
}

static av_cold int cuda_bilateral_load_functions(AVFilterContext *ctx)
{
    CUDABilateralContext *s = ctx->priv;
    CUcontext bilateral, cuda_ctx = s->hwctx->cuda_ctx;
    CudaFunctions *cu = s->hwctx->internal->cuda_dl;
    int ret;

    extern const unsigned char ff_vf_bilateral_cuda_ptx_data[];
    extern const unsigned int ff_vf_bilateral_cuda_ptx_len;

    ret = CHECK_CU(cu->cuCtxPushCurrent(cuda_ctx));
    if (ret < 0)
        return ret;

    ret = ff_cuda_load_module(ctx, s->hwctx, &s->cu_module,
                              ff_vf_bilateral_cuda_ptx_data, ff_vf_bilateral_cuda_ptx_len);
    if (ret < 0)
        goto fail;

    ret = CHECK_CU(cu->cuModuleGetFunction(&s->cu_func, s->cu_module, "Process_uchar"));
    if (ret < 0) {
        av_log(ctx, AV_LOG_FATAL, "Failed loading Process_uchar\n");
        goto fail;
    }

    ret = CHECK_CU(cu->cuModuleGetFunction(&s->cu_func_uv, s->cu_module, "Process_uchar2"));
    if (ret < 0) {
        av_log(ctx, AV_LOG_FATAL, "Failed loading Process_uchar2\n");
        goto fail;
    }

fail:
    CHECK_CU(cu->cuCtxPopCurrent(&bilateral));

    return ret;
}

static av_cold int cuda_bilateral_config_props(AVFilterLink *outlink)
{
    AVFilterContext *ctx = outlink->src;
    AVFilterLink *inlink = outlink->src->inputs[0];
    CUDABilateralContext *s  = ctx->priv;
    AVHWFramesContext     *frames_ctx = (AVHWFramesContext*)inlink->hw_frames_ctx->data;
    AVCUDADeviceContext *device_hwctx = frames_ctx->device_ctx->hwctx;
    int ret;

    s->hwctx = device_hwctx;
    s->cu_stream = s->hwctx->stream;

    ret = init_processing_chain(ctx, inlink->w, inlink->h);
    if (ret < 0)
        return ret;

    outlink->sample_aspect_ratio = inlink->sample_aspect_ratio;

    // the window_size makes more sense when it is odd, so add 1 if even
    s->window_size= (s->window_size%2) ? s->window_size : s->window_size+1;

    ret = cuda_bilateral_load_functions(ctx);
    if (ret < 0)
        return ret;

    return 0;
}

static int call_cuda_kernel(AVFilterContext *ctx, CUfunction func,
                            CUtexObject src_tex[3], AVFrame *out_frame,
                            int width, int height, int pitch,
                            int width_uv, int height_uv, int pitch_uv,
                            int window_size, float sigmaS, float sigmaR)
{
    CUDABilateralContext *s = ctx->priv;
    CudaFunctions *cu = s->hwctx->internal->cuda_dl;
    int ret;

    CUdeviceptr dst_devptr[3] = {
        (CUdeviceptr)out_frame->data[0], (CUdeviceptr)out_frame->data[1], (CUdeviceptr)out_frame->data[2]
    };

    void *args_uchar[] = {
        &src_tex[0], &src_tex[1], &src_tex[2],
        &dst_devptr[0], &dst_devptr[1], &dst_devptr[2],
        &width, &height, &pitch,
        &width_uv, &height_uv, &pitch_uv,
        &window_size, &sigmaS, &sigmaR
    };

    ret = CHECK_CU(cu->cuLaunchKernel(func,
                                      DIV_UP(width, BLOCKX), DIV_UP(height, BLOCKY), 1,
                                      BLOCKX, BLOCKY, 1, 0, s->cu_stream, args_uchar, NULL));
    if (ret < 0)
        return ret;

    return ret;
}

static int cuda_bilateral_process_internal(AVFilterContext *ctx,
                                      AVFrame *out, AVFrame *in)
{
    CUDABilateralContext *s = ctx->priv;
    CudaFunctions *cu = s->hwctx->internal->cuda_dl;
    CUcontext bilateral, cuda_ctx = s->hwctx->cuda_ctx;
    int i, ret;

    CUtexObject tex[3] = { 0, 0, 0 };

    ret = CHECK_CU(cu->cuCtxPushCurrent(cuda_ctx));
    if (ret < 0)
        return ret;

    for (i = 0; i < s->in_planes; i++) {
        CUDA_TEXTURE_DESC tex_desc = {
            .filterMode = CU_TR_FILTER_MODE_LINEAR,
            .flags = 0, // CU_TRSF_READ_AS_INTEGER to get raw ints instead of normalized floats from tex2D
        };

        CUDA_RESOURCE_DESC res_desc = {
            .resType = CU_RESOURCE_TYPE_PITCH2D,
            .res.pitch2D.format = CU_AD_FORMAT_UNSIGNED_INT8,
            .res.pitch2D.numChannels = s->in_plane_channels[i],
            .res.pitch2D.pitchInBytes = in->linesize[i],
            .res.pitch2D.devPtr = (CUdeviceptr)in->data[i],
        };

        if (i == 1 || i == 2) {
            res_desc.res.pitch2D.width = AV_CEIL_RSHIFT(in->width, s->in_desc->log2_chroma_w);
            res_desc.res.pitch2D.height = AV_CEIL_RSHIFT(in->height, s->in_desc->log2_chroma_h);
        } else {
            res_desc.res.pitch2D.width = in->width;
            res_desc.res.pitch2D.height = in->height;
        }

        ret = CHECK_CU(cu->cuTexObjectCreate(&tex[i], &res_desc, &tex_desc, NULL));
        if (ret < 0)
            goto exit;
    }

    ret = call_cuda_kernel(ctx, (s->in_plane_channels[1] > 1) ? s->cu_func_uv : s->cu_func,
                           tex, out,
                           out->width, out->height, out->linesize[0],
                           AV_CEIL_RSHIFT(out->width, s->out_desc->log2_chroma_w),
                           AV_CEIL_RSHIFT(out->height, s->out_desc->log2_chroma_h),
                           out->linesize[1] >> ((s->in_plane_channels[1] > 1) ? 1 : 0),
                           s->window_size, s->sigmaS, s->sigmaR);
    if (ret < 0)
        goto exit;

exit:
    for (i = 0; i < s->in_planes; i++)
        if (tex[i])
            CHECK_CU(cu->cuTexObjectDestroy(tex[i]));

    CHECK_CU(cu->cuCtxPopCurrent(&bilateral));

    return ret;
}

static int cuda_bilateral_process(AVFilterContext *ctx, AVFrame *out, AVFrame *in)
{
    CUDABilateralContext *s = ctx->priv;
    AVFrame *src = in;
    int ret;

    ret = cuda_bilateral_process_internal(ctx, s->frame, src);
    if (ret < 0)
        return ret;

    src = s->frame;
    ret = av_hwframe_get_buffer(src->hw_frames_ctx, s->tmp_frame, 0);
    if (ret < 0)
        return ret;

    av_frame_move_ref(out, s->frame);
    av_frame_move_ref(s->frame, s->tmp_frame);

    ret = av_frame_copy_props(out, in);
    if (ret < 0)
        return ret;

    return 0;
}

static int cuda_bilateral_filter_frame(AVFilterLink *link, AVFrame *in)
{
    AVFilterContext       *ctx = link->dst;
    CUDABilateralContext        *s = ctx->priv;
    AVFilterLink      *outlink = ctx->outputs[0];
    CudaFunctions          *cu = s->hwctx->internal->cuda_dl;

    AVFrame *out = NULL;
    CUcontext bilateral;
    int ret = 0;

    out = av_frame_alloc();
    if (!out) {
        ret = AVERROR(ENOMEM);
        goto fail;
    }

    ret = CHECK_CU(cu->cuCtxPushCurrent(s->hwctx->cuda_ctx));
    if (ret < 0)
        goto fail;

    ret = cuda_bilateral_process(ctx, out, in);

    CHECK_CU(cu->cuCtxPopCurrent(&bilateral));
    if (ret < 0)
        goto fail;

    av_frame_free(&in);
    return ff_filter_frame(outlink, out);
fail:
    av_frame_free(&in);
    av_frame_free(&out);
    return ret;
}

#define OFFSET(x) offsetof(CUDABilateralContext, x)
#define FLAGS (AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM)
static const AVOption options[] = {
    { "sigmaS",      "set spatial sigma",          OFFSET(sigmaS), AV_OPT_TYPE_FLOAT,    {.dbl=0.1}, 0.1, 512, FLAGS },
    { "sigmaR",      "set range sigma",            OFFSET(sigmaR), AV_OPT_TYPE_FLOAT,    {.dbl=0.1}, 0.1, 512, FLAGS },
    { "window_size", "set neighbours window_size", OFFSET(window_size), AV_OPT_TYPE_INT, {.i64=1},   1,   255, FLAGS },
    { NULL }
};

static const AVClass cuda_bilateral_class = {
    .class_name = "cudabilateral",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
};

static const AVFilterPad cuda_bilateral_inputs[] = {
    {
        .name        = "default",
        .type        = AVMEDIA_TYPE_VIDEO,
        .filter_frame = cuda_bilateral_filter_frame,
    },
};

static const AVFilterPad cuda_bilateral_outputs[] = {
    {
        .name         = "default",
        .type         = AVMEDIA_TYPE_VIDEO,
        .config_props = cuda_bilateral_config_props,
    },
};

const AVFilter ff_vf_bilateral_cuda = {
    .name        = "bilateral_cuda",
    .description = NULL_IF_CONFIG_SMALL("GPU accelerated bilateral filter"),

    .init          = cudabilateral_init,
    .uninit        = cudabilateral_uninit,

    .priv_size = sizeof(CUDABilateralContext),
    .priv_class = &cuda_bilateral_class,

    FILTER_INPUTS(cuda_bilateral_inputs),
    FILTER_OUTPUTS(cuda_bilateral_outputs),

    FILTER_SINGLE_PIXFMT(AV_PIX_FMT_CUDA),

    .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE,
};