/*
 * This file is part of mpv.
 *
 * mpv 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.
 *
 * mpv 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 mpv.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <pthread.h>

#include "config.h"

#include <libavcodec/avcodec.h>

#include <libavutil/hwcontext.h>
#include <libavutil/hwcontext_d3d11va.h>

#if HAVE_D3D9_HWACCEL
#include <libavutil/hwcontext_dxva2.h>
#endif

#include "lavc.h"
#include "common/common.h"
#include "common/av_common.h"
#include "video/fmt-conversion.h"
#include "video/mp_image.h"
#include "video/mp_image_pool.h"
#include "osdep/windows_utils.h"

#include "d3d.h"

HMODULE d3d11_dll, d3d9_dll, dxva2_dll;
PFN_D3D11_CREATE_DEVICE d3d11_D3D11CreateDevice;

static pthread_once_t d3d_load_once = PTHREAD_ONCE_INIT;

#if !HAVE_UWP
static void d3d_do_load(void)
{
    d3d11_dll = LoadLibrary(L"d3d11.dll");
    d3d9_dll  = LoadLibrary(L"d3d9.dll");
    dxva2_dll = LoadLibrary(L"dxva2.dll");

    if (d3d11_dll) {
        d3d11_D3D11CreateDevice =
            (void *)GetProcAddress(d3d11_dll, "D3D11CreateDevice");
    }
}
#else
static void d3d_do_load(void)
{

    d3d11_D3D11CreateDevice = D3D11CreateDevice;
}
#endif

void d3d_load_dlls(void)
{
    pthread_once(&d3d_load_once, d3d_do_load);
}

// Test if Direct3D11 can be used by us. Basically, this prevents trying to use
// D3D11 on Win7, and then failing somewhere in the process.
bool d3d11_check_decoding(ID3D11Device *dev)
{
    HRESULT hr;
    // We assume that NV12 is always supported, if hw decoding is supported at
    // all.
    UINT supported = 0;
    hr = ID3D11Device_CheckFormatSupport(dev, DXGI_FORMAT_NV12, &supported);
    return !FAILED(hr) && (supported & D3D11_BIND_DECODER);
}

void d3d_hwframes_refine(struct lavc_ctx *ctx, AVBufferRef *hw_frames_ctx)
{
    AVHWFramesContext *fctx = (void *)hw_frames_ctx->data;

    int alignment = 16;
    switch (ctx->avctx->codec_id) {
        // decoding MPEG-2 requires additional alignment on some Intel GPUs, but it
        // causes issues for H.264 on certain AMD GPUs.....
    case AV_CODEC_ID_MPEG2VIDEO:
        alignment = 32;
        break;
        // the HEVC DXVA2 spec asks for 128 pixel aligned surfaces to ensure
        // all coding features have enough room to work with
    case AV_CODEC_ID_HEVC:
        alignment = 128;
        break;
    }
    fctx->width  = FFALIGN(fctx->width,  alignment);
    fctx->height = FFALIGN(fctx->height, alignment);

#if HAVE_D3D9_HWACCEL
    if (fctx->format == AV_PIX_FMT_DXVA2_VLD) {
        AVDXVA2FramesContext *hwctx = fctx->hwctx;

        hwctx->surface_type = DXVA2_VideoDecoderRenderTarget;
    }
#endif

    if (fctx->format == AV_PIX_FMT_D3D11) {
        AVD3D11VAFramesContext *hwctx = fctx->hwctx;

        hwctx->BindFlags |= D3D11_BIND_DECODER;

        // According to hwcontex_d3d11va.h, yuv420p means DXGI_FORMAT_420_OPAQUE,
        // which has no shader support.
        if (fctx->sw_format != AV_PIX_FMT_YUV420P)
            hwctx->BindFlags |= D3D11_BIND_SHADER_RESOURCE;
    }
}

AVBufferRef *d3d11_wrap_device_ref(ID3D11Device *device)
{
    AVBufferRef *device_ref = av_hwdevice_ctx_alloc(AV_HWDEVICE_TYPE_D3D11VA);
    if (!device_ref)
        return NULL;

    AVHWDeviceContext *ctx = (void *)device_ref->data;
    AVD3D11VADeviceContext *hwctx = ctx->hwctx;

    ID3D11Device_AddRef(device);
    hwctx->device = device;

    if (av_hwdevice_ctx_init(device_ref) < 0)
        av_buffer_unref(&device_ref);

    return device_ref;
}

static void d3d11_complete_image_params(struct AVHWFramesContext *hw_frames,
                                        struct mp_image_params *p)
{
    // According to hwcontex_d3d11va.h, this means DXGI_FORMAT_420_OPAQUE.
    p->hw_flags = hw_frames->sw_format == AV_PIX_FMT_YUV420P
                ? MP_IMAGE_HW_FLAG_OPAQUE : 0;
}

const struct hwcontext_fns hwcontext_fns_d3d11 = {
    .av_hwdevice_type = AV_HWDEVICE_TYPE_D3D11VA,
    .complete_image_params = d3d11_complete_image_params,
};