/*
 * Copyright (c) 2016 Philip Langdale <philipl@overt.org>
 *
 * 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/>.
 */

/*
 * This hwdec implements an optimized output path using CUDA->OpenGL
 * or CUDA->Vulkan interop for frame data that is stored in CUDA
 * device memory. Although it is not explicit in the code here, the
 * only practical way to get data in this form is from the
 * nvdec/cuvid decoder.
 */

#include <unistd.h>

#include <ffnvcodec/dynlink_loader.h>
#include <libavutil/hwcontext.h>
#include <libavutil/hwcontext_cuda.h>

#include "video/out/gpu/hwdec.h"
#include "formats.h"
#include "options/m_config.h"
#include "ra_gl.h"
#include "video/out/vulkan/formats.h"
#include "video/out/vulkan/ra_vk.h"
#include "video/out/vulkan/utils.h"

#if HAVE_WIN32_DESKTOP
#include <versionhelpers.h>
#endif

struct priv_owner {
    struct mp_hwdec_ctx hwctx;
    CudaFunctions *cu;
    CUcontext display_ctx;
    CUcontext decode_ctx;

    bool is_gl;
    bool is_vk;
};

struct ext_buf {
#if HAVE_WIN32_DESKTOP
    HANDLE handle;
#else
    int fd;
#endif
    CUexternalMemory mem;
    CUdeviceptr buf;
};

struct priv {
    struct mp_image layout;
    CUgraphicsResource cu_res[4];
    CUarray cu_array[4];

    CUcontext display_ctx;

    struct ra_buf_params buf_params[4];
    struct ra_buf_pool buf_pool[4];
};

static int check_cu(struct ra_hwdec *hw, CUresult err, const char *func)
{
    const char *err_name;
    const char *err_string;

    struct priv_owner *p = hw->priv;

    MP_TRACE(hw, "Calling %s\n", func);

    if (err == CUDA_SUCCESS)
        return 0;

    p->cu->cuGetErrorName(err, &err_name);
    p->cu->cuGetErrorString(err, &err_string);

    MP_ERR(hw, "%s failed", func);
    if (err_name && err_string)
        MP_ERR(hw, " -> %s: %s", err_name, err_string);
    MP_ERR(hw, "\n");

    return -1;
}

#define CHECK_CU(x) check_cu(hw, (x), #x)

static int cuda_init(struct ra_hwdec *hw)
{
    CUdevice display_dev;
    AVBufferRef *hw_device_ctx = NULL;
    CUcontext dummy;
    int ret = 0;
    struct priv_owner *p = hw->priv;
    CudaFunctions *cu;

#if HAVE_GL
    p->is_gl = ra_is_gl(hw->ra);
    if (p->is_gl) {
        GL *gl = ra_gl_get(hw->ra);
        if (gl->version < 210 && gl->es < 300) {
            MP_VERBOSE(hw, "need OpenGL >= 2.1 or OpenGL-ES >= 3.0\n");
            return -1;
        }
    }
#endif

#if HAVE_VULKAN
    p->is_vk = ra_vk_get(hw->ra) != NULL;
    if (p->is_vk) {
        if (!ra_vk_get(hw->ra)->has_ext_external_memory_export) {
            MP_ERR(hw, "CUDA hwdec with Vulkan requires the %s extension\n",
                   MP_VK_EXTERNAL_MEMORY_EXPORT_EXTENSION_NAME);
            return -1;
        }
    }
#endif

    ret = cuda_load_functions(&p->cu, NULL);
    if (ret != 0) {
        MP_VERBOSE(hw, "Failed to load CUDA symbols\n");
        return -1;
    }
    cu = p->cu;

    if (p->is_vk && !cu->cuImportExternalMemory) {
        MP_ERR(hw, "CUDA hwdec with Vulkan requires driver version 410.48 or newer.\n");
        return -1;
    }

    ret = CHECK_CU(cu->cuInit(0));
    if (ret < 0)
        goto error;

    // Allocate display context
    if (p->is_gl) {
        unsigned int device_count;
        ret = CHECK_CU(cu->cuGLGetDevices(&device_count, &display_dev, 1,
                                          CU_GL_DEVICE_LIST_ALL));
        if (ret < 0)
            goto error;

        ret = CHECK_CU(cu->cuCtxCreate(&p->display_ctx, CU_CTX_SCHED_BLOCKING_SYNC,
                                       display_dev));
        if (ret < 0)
            goto error;

        p->decode_ctx = p->display_ctx;

        int decode_dev_idx = -1;
        mp_read_option_raw(hw->global, "cuda-decode-device", &m_option_type_choice,
                           &decode_dev_idx);

        if (decode_dev_idx > -1) {
            CUdevice decode_dev;
            ret = CHECK_CU(cu->cuDeviceGet(&decode_dev, decode_dev_idx));
            if (ret < 0)
                goto error;

            if (decode_dev != display_dev) {
                MP_INFO(hw, "Using separate decoder and display devices\n");

                // Pop the display context. We won't use it again during init()
                ret = CHECK_CU(cu->cuCtxPopCurrent(&dummy));
                if (ret < 0)
                    goto error;

                ret = CHECK_CU(cu->cuCtxCreate(&p->decode_ctx, CU_CTX_SCHED_BLOCKING_SYNC,
                                               decode_dev));
                if (ret < 0)
                    goto error;
            }
        }
    } else if (p->is_vk) {
#if HAVE_VULKAN
        uint8_t vk_uuid[VK_UUID_SIZE];
        struct mpvk_ctx *vk = ra_vk_get(hw->ra);

        mpvk_get_phys_device_uuid(vk, vk_uuid);

        int count;
        ret = CHECK_CU(cu->cuDeviceGetCount(&count));
        if (ret < 0)
            goto error;

        display_dev = -1;
        for (int i = 0; i < count; i++) {
            CUdevice dev;
            ret = CHECK_CU(cu->cuDeviceGet(&dev, i));
            if (ret < 0)
                continue;

            CUuuid uuid;
            ret = CHECK_CU(cu->cuDeviceGetUuid(&uuid, dev));
            if (ret < 0)
                continue;

            if (memcmp(vk_uuid, uuid.bytes, VK_UUID_SIZE) == 0) {
                display_dev = dev;
                break;
            }
        }

        if (display_dev == -1) {
            MP_ERR(hw, "Could not match Vulkan display device in CUDA.\n");
            goto error;
        }

        ret = CHECK_CU(cu->cuCtxCreate(&p->display_ctx, CU_CTX_SCHED_BLOCKING_SYNC,
                                       display_dev));
        if (ret < 0)
            goto error;

        p->decode_ctx = p->display_ctx;
#endif
    }

    hw_device_ctx = av_hwdevice_ctx_alloc(AV_HWDEVICE_TYPE_CUDA);
    if (!hw_device_ctx)
        goto error;

    AVHWDeviceContext *device_ctx = (void *)hw_device_ctx->data;

    AVCUDADeviceContext *device_hwctx = device_ctx->hwctx;
    device_hwctx->cuda_ctx = p->decode_ctx;

    ret = av_hwdevice_ctx_init(hw_device_ctx);
    if (ret < 0) {
        MP_ERR(hw, "av_hwdevice_ctx_init failed\n");
        goto error;
    }

    ret = CHECK_CU(cu->cuCtxPopCurrent(&dummy));
    if (ret < 0)
        goto error;

    p->hwctx = (struct mp_hwdec_ctx) {
        .driver_name = hw->driver->name,
        .av_device_ref = hw_device_ctx,
    };
    hwdec_devices_add(hw->devs, &p->hwctx);
    return 0;

 error:
    av_buffer_unref(&hw_device_ctx);
    CHECK_CU(cu->cuCtxPopCurrent(&dummy));

    return -1;
}

static void cuda_uninit(struct ra_hwdec *hw)
{
    struct priv_owner *p = hw->priv;
    CudaFunctions *cu = p->cu;

    hwdec_devices_remove(hw->devs, &p->hwctx);
    av_buffer_unref(&p->hwctx.av_device_ref);

    if (p->decode_ctx && p->decode_ctx != p->display_ctx)
        CHECK_CU(cu->cuCtxDestroy(p->decode_ctx));

    if (p->display_ctx)
        CHECK_CU(cu->cuCtxDestroy(p->display_ctx));

    cuda_free_functions(&p->cu);
}

#undef CHECK_CU
#define CHECK_CU(x) check_cu((mapper)->owner, (x), #x)

#if HAVE_VULKAN
static struct ra_buf *cuda_buf_pool_get(struct ra_hwdec_mapper *mapper, int n)
{
    struct priv_owner *p_owner = mapper->owner->priv;
    struct priv *p = mapper->priv;
    CudaFunctions *cu = p_owner->cu;
    int ret = 0;

    struct ra_buf_pool *pool = &p->buf_pool[n];
    struct ra_buf *buf = ra_buf_pool_get(mapper->ra, pool, &p->buf_params[n]);
    if (!buf) {
        goto error;
    }

    if (!ra_vk_buf_get_user_data(buf)) {
        struct ext_buf *ebuf = talloc_zero(NULL, struct ext_buf);
        struct vk_external_mem mem_info;

        bool success = ra_vk_buf_get_external_info(mapper->ra, buf, &mem_info);
        if (!success) {
            ret = -1;
            goto error;
        }

#if HAVE_WIN32_DESKTOP
        ebuf->handle = mem_info.mem_handle;
        MP_DBG(mapper, "vk_external_info[%d][%d]: %p %zu %zu\n", n, pool->index, ebuf->handle, mem_info.size, mem_info.offset);
#else
        ebuf->fd = mem_info.mem_fd;
        MP_DBG(mapper, "vk_external_info[%d][%d]: %d %zu %zu\n", n, pool->index, ebuf->fd, mem_info.size, mem_info.offset);
#endif

        CUDA_EXTERNAL_MEMORY_HANDLE_DESC ext_desc = {
#if HAVE_WIN32_DESKTOP
            .type = IsWindows8OrGreater()
                ? CU_EXTERNAL_MEMORY_HANDLE_TYPE_OPAQUE_WIN32
                : CU_EXTERNAL_MEMORY_HANDLE_TYPE_OPAQUE_WIN32_KMT,
            .handle.win32.handle = ebuf->handle,
#else
            .type = CU_EXTERNAL_MEMORY_HANDLE_TYPE_OPAQUE_FD,
            .handle.fd = ebuf->fd,
#endif
            .size = mem_info.mem_size,
            .flags = 0,
        };
        ret = CHECK_CU(cu->cuImportExternalMemory(&ebuf->mem, &ext_desc));
        if (ret < 0)
            goto error;

        CUDA_EXTERNAL_MEMORY_BUFFER_DESC buf_desc = {
            .offset = mem_info.offset,
            .size = mem_info.size,
            .flags = 0,
        };
        ret = CHECK_CU(cu->cuExternalMemoryGetMappedBuffer(&ebuf->buf, ebuf->mem, &buf_desc));
        if (ret < 0)
            goto error;

        ra_vk_buf_set_user_data(buf, ebuf);
    }
    return buf;

error:
    MP_ERR(mapper, "cuda_buf_pool_get failed\n");
    return NULL;
}

static void cuda_buf_pool_uninit(struct ra_hwdec_mapper *mapper, int n)
{
    struct priv_owner *p_owner = mapper->owner->priv;
    struct priv *p = mapper->priv;
    CudaFunctions *cu = p_owner->cu;

    struct ra_buf_pool *pool = &p->buf_pool[n];
    for (int i = 0; i < pool->num_buffers; i++) {
        struct ra_buf *buf = pool->buffers[i];
        struct ext_buf *ebuf = ra_vk_buf_get_user_data(buf);
        if (ebuf) {
            if (ebuf->mem > 0) {
                CHECK_CU(cu->cuDestroyExternalMemory(ebuf->mem));
#if HAVE_WIN32_DESKTOP
            }
            if (ebuf->handle) {
                // Handle must always be closed by us.
                CloseHandle(ebuf->handle);
            }
#else
            } else if (ebuf->fd > -1) {
                // fd should only be closed if external memory was not imported
                close(ebuf->fd);
            }
#endif
        }
        talloc_free(ebuf);
        ra_vk_buf_set_user_data(buf, NULL);
    }
    ra_buf_pool_uninit(mapper->ra, pool);
}
#endif // HAVE_VULKAN

static int mapper_init(struct ra_hwdec_mapper *mapper)
{
    struct priv_owner *p_owner = mapper->owner->priv;
    struct priv *p = mapper->priv;
    CUcontext dummy;
    CudaFunctions *cu = p_owner->cu;
    int ret = 0, eret = 0;

    p->display_ctx = p_owner->display_ctx;

    int imgfmt = mapper->src_params.hw_subfmt;
    mapper->dst_params = mapper->src_params;
    mapper->dst_params.imgfmt = imgfmt;
    mapper->dst_params.hw_subfmt = 0;

    mp_image_set_params(&p->layout, &mapper->dst_params);

    struct ra_imgfmt_desc desc;
    if (!ra_get_imgfmt_desc(mapper->ra, imgfmt, &desc)) {
        MP_ERR(mapper, "Unsupported format: %s\n", mp_imgfmt_to_name(imgfmt));
        return -1;
    }

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

    for (int n = 0; n < desc.num_planes; n++) {
        const struct ra_format *format = desc.planes[n];

        struct ra_tex_params params = {
            .dimensions = 2,
            .w = mp_image_plane_w(&p->layout, n),
            .h = mp_image_plane_h(&p->layout, n),
            .d = 1,
            .format = format,
            .render_src = true,
            .src_linear = format->linear_filter,
        };

        mapper->tex[n] = ra_tex_create(mapper->ra, &params);
        if (!mapper->tex[n]) {
            ret = -1;
            goto error;
        }

        if (p_owner->is_gl) {
#if HAVE_GL
            GLuint texture;
            GLenum target;
            ra_gl_get_raw_tex(mapper->ra, mapper->tex[n], &texture, &target);

            ret = CHECK_CU(cu->cuGraphicsGLRegisterImage(&p->cu_res[n], texture, target,
                                                         CU_GRAPHICS_REGISTER_FLAGS_WRITE_DISCARD));
            if (ret < 0)
                goto error;

            ret = CHECK_CU(cu->cuGraphicsMapResources(1, &p->cu_res[n], 0));
            if (ret < 0)
                goto error;

            ret = CHECK_CU(cu->cuGraphicsSubResourceGetMappedArray(&p->cu_array[n], p->cu_res[n],
                                                                   0, 0));
            if (ret < 0)
                goto error;

            ret = CHECK_CU(cu->cuGraphicsUnmapResources(1, &p->cu_res[n], 0));
            if (ret < 0)
                goto error;
#endif
        } else if (p_owner->is_vk) {
            struct ra_buf_params buf_params = {
                .type = RA_BUF_TYPE_SHARED_MEMORY,
                .size = mp_image_plane_h(&p->layout, n) *
                        mp_image_plane_w(&p->layout, n) *
                        mapper->tex[n]->params.format->pixel_size,
            };
            p->buf_params[n] = buf_params;
        }
    }

 error:
    eret = CHECK_CU(cu->cuCtxPopCurrent(&dummy));
    if (eret < 0)
        return eret;

    return ret;
}

static void mapper_uninit(struct ra_hwdec_mapper *mapper)
{
    struct priv *p = mapper->priv;
    struct priv_owner *p_owner = mapper->owner->priv;
    CudaFunctions *cu = p_owner->cu;
    CUcontext dummy;

    // Don't bail if any CUDA calls fail. This is all best effort.
    CHECK_CU(cu->cuCtxPushCurrent(p->display_ctx));
    for (int n = 0; n < 4; n++) {
        if (p->cu_res[n] > 0)
            CHECK_CU(cu->cuGraphicsUnregisterResource(p->cu_res[n]));
        p->cu_res[n] = 0;
        ra_tex_free(mapper->ra, &mapper->tex[n]);

#if HAVE_VULKAN
        cuda_buf_pool_uninit(mapper, n);
#endif
    }
    CHECK_CU(cu->cuCtxPopCurrent(&dummy));
}

static void mapper_unmap(struct ra_hwdec_mapper *mapper)
{
}

static int mapper_map(struct ra_hwdec_mapper *mapper)
{
    struct priv *p = mapper->priv;
    struct priv_owner *p_owner = mapper->owner->priv;
    CudaFunctions *cu = p_owner->cu;
    CUcontext dummy;
    int ret = 0, eret = 0;
    bool is_gl = p_owner->is_gl;
    bool is_vk = p_owner->is_vk;

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

    for (int n = 0; n < p->layout.num_planes; n++) {
        struct ra_buf *buf = NULL;

        CUDA_MEMCPY2D cpy = {
            .srcMemoryType = CU_MEMORYTYPE_DEVICE,
            .srcDevice     = (CUdeviceptr)mapper->src->planes[n],
            .srcPitch      = mapper->src->stride[n],
            .srcY          = 0,
            .WidthInBytes  = mp_image_plane_w(&p->layout, n) *
                             mapper->tex[n]->params.format->pixel_size,
            .Height        = mp_image_plane_h(&p->layout, n),
        };

        if (is_gl) {
            cpy.dstMemoryType = CU_MEMORYTYPE_ARRAY;
            cpy.dstArray = p->cu_array[n];
        } else if (is_vk) {
#if HAVE_VULKAN
            buf = cuda_buf_pool_get(mapper, n);
            struct ext_buf *ebuf = ra_vk_buf_get_user_data(buf);

            cpy.dstMemoryType = CU_MEMORYTYPE_DEVICE;
            cpy.dstDevice = ebuf->buf;
            cpy.dstPitch  = mp_image_plane_w(&p->layout, n) *
                            mapper->tex[n]->params.format->pixel_size;
#endif
        }

        ret = CHECK_CU(cu->cuMemcpy2D(&cpy));
        if (ret < 0)
            goto error;

        if (is_vk) {
            struct ra_tex_upload_params params = {
                .tex = mapper->tex[n],
                .invalidate = true,
                .buf = buf,
            };
            mapper->ra->fns->tex_upload(mapper->ra, &params);
        }
    }

 error:
   eret = CHECK_CU(cu->cuCtxPopCurrent(&dummy));
   if (eret < 0)
       return eret;

   return ret;
}

const struct ra_hwdec_driver ra_hwdec_cuda = {
    .name = "cuda-nvdec",
    .imgfmts = {IMGFMT_CUDA, 0},
    .priv_size = sizeof(struct priv_owner),
    .init = cuda_init,
    .uninit = cuda_uninit,
    .mapper = &(const struct ra_hwdec_mapper_driver){
        .priv_size = sizeof(struct priv),
        .init = mapper_init,
        .uninit = mapper_uninit,
        .map = mapper_map,
        .unmap = mapper_unmap,
    },
};