import ctypes
import logging
import os
import random
import socket
import time
import unittest
from typing import Any, List, Optional, Union

import ray
import torch
import torch.distributed as dist
from torch.distributed import ProcessGroup
from vllm import _custom_ops as vllm_ops

from sglang.srt.distributed.device_communicators.cuda_wrapper import CudaRTLibrary

logger = logging.getLogger(__name__)


def get_open_port() -> int:
    # try ipv4
    try:
        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
            s.bind(("127.0.0.1", 0))
            return s.getsockname()[1]
    except OSError:
        # try ipv6
        with socket.socket(socket.AF_INET6, socket.SOCK_STREAM) as s:
            s.bind(("127.0.0.1", 0))
            return s.getsockname()[1]


def multi_process_parallel(
    world_size: int,
    cls: Any,
    test_target: Any,
) -> None:
    # Using ray helps debugging the error when it failed
    # as compared to multiprocessing.
    # NOTE: We need to set working_dir for distributed tests,
    # otherwise we may get import errors on ray workers
    ray.init(log_to_driver=True)

    distributed_init_port = get_open_port()
    refs = []
    for rank in range(world_size):
        refs.append(test_target.remote(cls, world_size, rank, distributed_init_port))
    ray.get(refs)

    ray.shutdown()


class TestCustomAllReduce(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        random.seed(42)
        cls.test_sizes = [512, 4096, 32768, 262144, 524288, 1048576, 2097152]
        cls.world_sizes = [2, 4, 8]

    @staticmethod
    def create_shared_buffer(
        size_in_bytes: int, group: Optional[ProcessGroup] = None
    ) -> List[int]:
        """
        Creates a shared buffer and returns a list of pointers
        representing the buffer on all processes in the group.
        """
        lib = CudaRTLibrary()
        pointer = lib.cudaMalloc(size_in_bytes)
        handle = lib.cudaIpcGetMemHandle(pointer)
        world_size = dist.get_world_size(group=group)
        rank = dist.get_rank(group=group)
        handles = [None] * world_size
        dist.all_gather_object(handles, handle, group=group)

        pointers: List[int] = []
        for i, h in enumerate(handles):
            if i == rank:
                pointers.append(pointer.value)  # type: ignore
            else:
                pointers.append(lib.cudaIpcOpenMemHandle(h).value)  # type: ignore

        return pointers

    @staticmethod
    def free_shared_buffer(
        pointers: List[int], group: Optional[ProcessGroup] = None
    ) -> None:
        rank = dist.get_rank(group=group)
        lib = CudaRTLibrary()
        lib.cudaFree(ctypes.c_void_p(pointers[rank]))

    def test_correctness(self):
        for world_size in self.world_sizes:
            if world_size > torch.cuda.device_count():
                continue
            multi_process_parallel(world_size, self, self.correctness)

    def test_performance(self):
        for world_size in self.world_sizes:
            if world_size > torch.cuda.device_count():
                continue
            multi_process_parallel(world_size, self, self.performance)

    def init_custom_allreduce(self, rank, world_size, group):
        import sgl_kernel

        buffer_max_size = 8 * 1024 * 1024
        barrier_max_size = 8 * (24 + 2) * 8

        self.buffer_ptrs = self.create_shared_buffer(buffer_max_size, group=group)
        self.barrier_in_ptrs = self.create_shared_buffer(barrier_max_size, group=group)
        self.barrier_out_ptrs = self.create_shared_buffer(barrier_max_size, group=group)

        self.custom_ptr = sgl_kernel.ops.init_custom_reduce(
            rank,
            world_size,
            self.buffer_ptrs,
            self.barrier_in_ptrs,
            self.barrier_out_ptrs,
        )

    def custom_allreduce(self, inp, out):
        import sgl_kernel

        sgl_kernel.ops.custom_reduce(self.custom_ptr, inp, out)

    def free_custom_allreduce(self, group):
        import sgl_kernel

        self.free_shared_buffer(self.buffer_ptrs, group)
        self.free_shared_buffer(self.barrier_in_ptrs, group)
        self.free_shared_buffer(self.barrier_out_ptrs, group)
        sgl_kernel.ops.custom_dispose(self.custom_ptr)

    def init_vllm_allreduce(self, rank, group):
        self.vllm_rank = rank
        self.vllm_max_size = 8 * 1024 * 1024
        self.vllm_meta_ptrs = self.create_shared_buffer(
            vllm_ops.meta_size() + self.vllm_max_size, group=group
        )
        self.vllm_buffer_ptrs = self.create_shared_buffer(
            self.vllm_max_size, group=group
        )
        self.vllm_rank_data = torch.empty(
            8 * 1024 * 1024, dtype=torch.uint8, device=torch.device(f"cuda:{rank}")
        )
        self.vllm_ptr = vllm_ops.init_custom_ar(
            self.vllm_meta_ptrs, self.vllm_rank_data, rank, True
        )
        vllm_ops.register_buffer(self.vllm_ptr, self.vllm_buffer_ptrs)

    def vllm_allreduce(self, inp, out):
        vllm_ops.all_reduce(
            self.vllm_ptr,
            inp,
            out,
            self.vllm_buffer_ptrs[self.vllm_rank],
            self.vllm_max_size,
        )

    def free_vllm_allreduce(self, group):
        vllm_ops.dispose(self.vllm_ptr)
        self.free_shared_buffer(self.vllm_meta_ptrs, group)
        self.free_shared_buffer(self.vllm_buffer_ptrs, group)

    @staticmethod
    def init_distributed_env(world_size, rank, distributed_init_port):
        del os.environ["CUDA_VISIBLE_DEVICES"]
        device = torch.device(f"cuda:{rank}")
        torch.cuda.set_device(device)
        ranks = [i for i in range(world_size)]
        distributed_init_method = f"tcp://localhost:{distributed_init_port}"
        dist.init_process_group(
            backend="nccl",
            init_method=distributed_init_method,
            rank=rank,
            world_size=world_size,
        )
        group = torch.distributed.new_group(ranks, backend="gloo")
        return group

    # compare result with torch.distributed
    @ray.remote(num_gpus=1, max_calls=1)
    def correctness(self, world_size, rank, distributed_init_port):
        group = self.init_distributed_env(world_size, rank, distributed_init_port)

        self.init_custom_allreduce(rank=rank, world_size=world_size, group=group)

        test_loop = 10
        for sz in self.test_sizes:
            for dtype in [torch.float32, torch.float16, torch.bfloat16]:
                for _ in range(test_loop):
                    inp1 = torch.randint(
                        1, 16, (sz,), dtype=dtype, device=torch.cuda.current_device()
                    )
                    out1 = torch.empty_like(inp1)
                    self.custom_allreduce(inp1, out1)

                    dist.all_reduce(inp1, group=group)
                    torch.testing.assert_close(out1, inp1)

        self.free_custom_allreduce(group)

    # compare performance with vllm
    @ray.remote(num_gpus=1, max_calls=1)
    def performance(self, world_size, rank, distributed_init_port):
        group = self.init_distributed_env(world_size, rank, distributed_init_port)

        self.init_vllm_allreduce(rank, group)
        self.init_custom_allreduce(rank=rank, world_size=world_size, group=group)

        for sz in self.test_sizes:
            inp1 = torch.randint(
                1, 16, (sz,), dtype=torch.float32, device=torch.cuda.current_device()
            )
            out1 = torch.empty_like(inp1)
            test_loop = 5000
            start = time.time()
            for _ in range(test_loop):
                self.custom_allreduce(inp1, out1)
            elapse_custom = time.time() - start

            start = time.time()
            for _ in range(test_loop):
                self.vllm_allreduce(inp1, out1)
            elapse_vllm = time.time() - start

            if rank == 0:
                logger.warning(
                    f"test_size = {sz}, world_size = {world_size}, "
                    f"vllm time = {elapse_vllm * 1000 / test_loop:.4f}ms,"
                    f"custom time = {elapse_custom * 1000 / test_loop:.4f}ms"
                )

        self.free_custom_allreduce(group)
        self.free_vllm_allreduce(group)


if __name__ == "__main__":
    unittest.main()
