/*
 * 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
 * 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 'cuvid' decoder (aka NvDecode).
 *
 * For now, cuvid/NvDecode will always return images in NV12 format, even
 * when decoding 10bit streams (there is some hardware dithering going on).
 */

#include "cuda_dynamic.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"

struct priv_owner {
    struct mp_hwdec_ctx hwctx;
    CUcontext display_ctx;
    CUcontext decode_ctx;
};

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

    CUcontext display_ctx;
};

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

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

    if (err == CUDA_SUCCESS)
        return 0;

    cuGetErrorName(err, &err_name);
    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;
    unsigned int device_count;
    int ret = 0;
    struct priv_owner *p = hw->priv;

    if (!ra_is_gl(hw->ra))
        return -1;

    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;
    }

    bool loaded = cuda_load();
    if (!loaded) {
        MP_VERBOSE(hw, "Failed to load CUDA symbols\n");
        return -1;
    }

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

    // Allocate display context
    ret = CHECK_CU(cuGLGetDevices(&device_count, &display_dev, 1,
                                  CU_GL_DEVICE_LIST_ALL));
    if (ret < 0)
        goto error;

    ret = CHECK_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(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(cuCtxPopCurrent(&dummy));
            if (ret < 0)
                goto error;

            ret = CHECK_CU(cuCtxCreate(&p->decode_ctx, CU_CTX_SCHED_BLOCKING_SYNC,
                                       decode_dev));
            if (ret < 0)
                goto error;
        }
    }

    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(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(cuCtxPopCurrent(&dummy));

    return -1;
}

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

    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(cuCtxDestroy(p->decode_ctx));

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

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

static int mapper_init(struct ra_hwdec_mapper *mapper)
{
    struct priv_owner *p_owner = mapper->owner->priv;
    struct priv *p = mapper->priv;
    CUcontext dummy;
    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(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;
        }

        GLuint texture;
        GLenum target;
        ra_gl_get_raw_tex(mapper->ra, mapper->tex[n], &texture, &target);

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

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

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

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

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

    return ret;
}

static void mapper_uninit(struct ra_hwdec_mapper *mapper)
{
    struct priv *p = mapper->priv;
    CUcontext dummy;

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

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

    for (int n = 0; n < p->layout.num_planes; n++) {
        CUDA_MEMCPY2D cpy = {
            .srcMemoryType = CU_MEMORYTYPE_DEVICE,
            .dstMemoryType = CU_MEMORYTYPE_ARRAY,
            .srcDevice     = (CUdeviceptr)mapper->src->planes[n],
            .srcPitch      = mapper->src->stride[n],
            .srcY          = 0,
            .dstArray      = p->cu_array[n],
            .WidthInBytes  = mp_image_plane_w(&p->layout, n) *
                             mapper->tex[n]->params.format->pixel_size,
            .Height        = mp_image_plane_h(&p->layout, n),
        };
        ret = CHECK_CU(cuMemcpy2D(&cpy));
        if (ret < 0)
            goto error;
    }


 error:
   eret = CHECK_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,
    },
};