#include "concat.cuh"

static __global__ void concat_f32_dim0(const float * x, const float * y, float * dst, const int ne0, const int ne00) {
    int nidx = threadIdx.x + blockIdx.x * blockDim.x;
    if (nidx >= ne0) {
        return;
    }

    int offset_dst =
        nidx +
        blockIdx.y * ne0 +
        blockIdx.z * ne0 * gridDim.y;

    if (nidx < ne00) { // src0
        int offset_src =
            nidx +
            blockIdx.y * ne00 +
            blockIdx.z * ne00 * gridDim.y;
        dst[offset_dst] = x[offset_src];
    } else {
        int offset_src =
            (nidx - ne00) +
            blockIdx.y * (ne0 - ne00) +
            blockIdx.z * (ne0 - ne00) * gridDim.y;
        dst[offset_dst] = y[offset_src];
    }
}

static __global__ void concat_f32_dim1(const float * x, const float * y, float * dst, const int ne0, const int ne01) {
    int nidx = threadIdx.x + blockIdx.x * blockDim.x;
    if (nidx >= ne0) {
        return;
    }

    int offset_dst =
        nidx +
        blockIdx.y * ne0 +
        blockIdx.z * ne0 * gridDim.y;

    if (blockIdx.y < ne01) { // src0
        int offset_src =
            nidx +
            blockIdx.y * ne0 +
            blockIdx.z * ne0 * ne01;
        dst[offset_dst] = x[offset_src];
    } else {
        int offset_src =
            nidx +
            (blockIdx.y - ne01) * ne0 +
            blockIdx.z * ne0 * (gridDim.y - ne01);
        dst[offset_dst] = y[offset_src];
    }
}

static __global__ void concat_f32_dim2(const float * x, const float * y, float * dst, const int ne0, const int ne02) {
    int nidx = threadIdx.x + blockIdx.x * blockDim.x;
    if (nidx >= ne0) {
        return;
    }

    int offset_dst =
        nidx +
        blockIdx.y * ne0 +
        blockIdx.z * ne0 * gridDim.y;

    if (blockIdx.z < ne02) { // src0
        int offset_src =
            nidx +
            blockIdx.y * ne0 +
            blockIdx.z * ne0 * gridDim.y;
        dst[offset_dst] = x[offset_src];
    } else {
        int offset_src =
            nidx +
            blockIdx.y * ne0 +
            (blockIdx.z - ne02) * ne0 *  gridDim.y;
        dst[offset_dst] = y[offset_src];
    }
}

static void concat_f32_cuda(const float * x, const float * y, float * dst, int ne00, int ne01, int ne02, int ne0, int ne1, int ne2, int dim, cudaStream_t stream) {
    int num_blocks = (ne0 + CUDA_CONCAT_BLOCK_SIZE - 1) / CUDA_CONCAT_BLOCK_SIZE;
    dim3 gridDim(num_blocks, ne1, ne2);
    if (dim == 0) {
        concat_f32_dim0<<<gridDim, CUDA_CONCAT_BLOCK_SIZE, 0, stream>>>(x, y, dst, ne0, ne00);
        return;
    }
    if (dim == 1) {
        concat_f32_dim1<<<gridDim, CUDA_CONCAT_BLOCK_SIZE, 0, stream>>>(x, y, dst, ne0, ne01);
        return;
    }
    concat_f32_dim2<<<gridDim, CUDA_CONCAT_BLOCK_SIZE, 0, stream>>>(x, y, dst, ne0, ne02);
}

void ggml_cuda_op_concat(ggml_backend_cuda_context & ctx, ggml_tensor * dst) {
    const ggml_tensor * src0 = dst->src[0];
    const ggml_tensor * src1 = dst->src[1];

    const float * src0_d = (const float *)src0->data;
    const float * src1_d = (const float *)src1->data;

    float * dst_d = (float *)dst->data;
    cudaStream_t stream = ctx.stream();

    const int32_t dim = ((int32_t *) dst->op_params)[0];

    GGML_ASSERT(ggml_is_contiguous(src0));
    GGML_ASSERT(ggml_is_contiguous(src1));

    GGML_ASSERT(src0->type == GGML_TYPE_F32);
    GGML_ASSERT(src1->type == GGML_TYPE_F32);
    GGML_ASSERT(dst->type == GGML_TYPE_F32);

    if (dim != 3) {
        for (int i3 = 0; i3 < dst->ne[3]; i3++) {
            concat_f32_cuda(
                    src0_d + i3 * (src0->nb[3] / 4),
                    src1_d + i3 * (src1->nb[3] / 4),
                     dst_d + i3 * ( dst->nb[3] / 4),
                    src0->ne[0], src0->ne[1], src0->ne[2],
                     dst->ne[0],  dst->ne[1],  dst->ne[2], dim, stream);
        }
    } else {
        const size_t size0 = ggml_nbytes(src0);
        const size_t size1 = ggml_nbytes(src1);

        CUDA_CHECK(cudaMemcpyAsync(dst_d,           src0_d, size0, cudaMemcpyDeviceToDevice, stream));
        CUDA_CHECK(cudaMemcpyAsync(dst_d + size0/4, src1_d, size1, cudaMemcpyDeviceToDevice, stream));
    }
}