from __future__ import annotations

import asyncio
import dataclasses
import logging
import queue
import socket
import struct
import threading
import uuid
from collections import defaultdict
from functools import cache
from typing import Dict, List, Optional, Set, Tuple, TypeAlias, Union

import numpy as np
import numpy.typing as npt
import requests
import zmq
from aiohttp import web

from sglang.srt.disaggregation.base.conn import BaseKVSender, KVArgs, KVPoll
from sglang.srt.disaggregation.common.conn import (
    CommonKVBootstrapServer,
    CommonKVManager,
    CommonKVReceiver,
)
from sglang.srt.disaggregation.utils import (
    DisaggregationMode,
    group_concurrent_contiguous,
)
from sglang.srt.server_args import ServerArgs
from sglang.srt.utils import get_local_ip_by_remote

logger = logging.getLogger(__name__)

NixlEngineInfo: TypeAlias = Dict[str, Union[str, int]]

GUARD = "NixlMsgGuard".encode("ascii")


@dataclasses.dataclass
class TransferInfo:
    room: int
    endpoint: str
    dst_port: int
    agent_metadata: bytes
    agent_name: str
    dst_kv_ptrs: list[int]
    dst_kv_indices: npt.NDArray[np.int64]
    dst_aux_ptrs: list[int]
    dst_aux_index: int
    dst_gpu_id: int
    required_dst_info_num: int

    def is_dummy(self):
        return self.dst_kv_indices.size == 0

    @classmethod
    def from_zmq(cls, msg: List[bytes]):
        return cls(
            room=int(msg[0].decode("ascii")),
            endpoint=msg[1].decode("ascii"),
            dst_port=int(msg[2].decode("ascii")),
            agent_metadata=msg[3],
            agent_name=msg[4].decode("ascii"),
            dst_kv_ptrs=list(struct.unpack(f"{len(msg[5])//8}Q", msg[5])),
            dst_kv_indices=np.frombuffer(msg[6], dtype=np.int64),
            dst_aux_ptrs=list(struct.unpack(f"{len(msg[7])//8}Q", msg[7])),
            dst_aux_index=int(msg[8].decode("ascii")),
            dst_gpu_id=int(msg[9].decode("ascii")),
            required_dst_info_num=int(msg[10].decode("ascii")),
        )


@dataclasses.dataclass
class TransferStatus:
    """Used by KV Receiver to know when a transfer is done."""

    # KV chunk IDs that have been received.
    received_kvs: Set[int] = dataclasses.field(default_factory=set)
    # Number of kv chunks to expect, will know this after last chunk is received.
    num_kvs_expected: Optional[int] = None
    # Whether aux data has been received.
    received_aux: bool = False

    def is_done(self):
        if self.num_kvs_expected is None:
            return False
        return self.num_kvs_expected == len(self.received_kvs) and self.received_aux


class NixlKVManager(CommonKVManager):
    def __init__(
        self,
        args: KVArgs,
        disaggregation_mode: DisaggregationMode,
        server_args: ServerArgs,
        is_mla_backend: Optional[bool] = False,
    ):
        super().__init__(args, disaggregation_mode, server_args, is_mla_backend)
        try:
            from nixl._api import nixl_agent
        except ImportError as e:
            raise ImportError(
                "Please install NIXL by following the instructions at "
                "https://github.com/ai-dynamo/nixl/blob/main/README.md "
                "to run SGLang with NixlTransferEngine."
            ) from e
        self.agent = nixl_agent(str(uuid.uuid4()))
        self.server_socket = zmq.Context().socket(zmq.PULL)
        self.register_buffer_to_engine()

        if self.disaggregation_mode == DisaggregationMode.PREFILL:
            self.request_status = {}
            self.transfer_infos: Dict[int, TransferInfo] = {}
            self.peer_names: Dict[str, str] = {}
            self._start_bootstrap_thread()
        elif self.disaggregation_mode == DisaggregationMode.DECODE:
            self.transfer_statuses: Dict[int, TransferStatus] = defaultdict(
                TransferStatus
            )
        else:
            raise ValueError(
                f"Unsupported DisaggregationMode: {self.disaggregation_mode}"
            )

    def check_status(self, bootstrap_room: int):
        return self.request_status[bootstrap_room]

    def update_status(self, bootstrap_room: int, status: KVPoll):
        if bootstrap_room not in self.request_status:
            self.request_status[bootstrap_room] = status
        else:
            # NOTE: The prefill engine could recv bootstrapping first
            self.request_status[bootstrap_room] = max(
                self.request_status[bootstrap_room], status
            )

    def register_buffer_to_engine(self):
        kv_addrs = []
        for kv_data_ptr, kv_data_len in zip(
            self.kv_args.kv_data_ptrs, self.kv_args.kv_data_lens
        ):
            kv_addrs.append((kv_data_ptr, kv_data_len, self.kv_args.gpu_id, ""))
        self.kv_descs = self.agent.register_memory(kv_addrs, "VRAM", is_sorted=True)
        logger.debug(f"Register kv tensors, len(kv_addr)= {len(kv_addrs)}")
        if not self.kv_descs:
            raise Exception("NIXL memory registration failed for kv tensors")
        aux_addrs = []
        for aux_data_ptr, aux_data_len in zip(
            self.kv_args.aux_data_ptrs, self.kv_args.aux_data_lens
        ):
            aux_addrs.append((aux_data_ptr, aux_data_len, 0, ""))
        self.aux_descs = self.agent.register_memory(aux_addrs, "DRAM", is_sorted=True)
        logger.debug(f"Register aux tensors, len(aux_addrs)= {len(aux_addrs)}")
        if not self.aux_descs:
            raise Exception("NIXL memory registration failed for aux tensors")

    def _add_remote(self, agent_name: str, agent_metadata: bytes):
        if agent_name not in self.peer_names:
            self.peer_names[agent_name] = self.agent.add_remote_agent(agent_metadata)
        return self.peer_names[agent_name]

    def send_kvcache(
        self,
        peer_name: str,
        prefill_kv_indices: npt.NDArray[np.int64],
        dst_kv_ptrs: list[int],
        dst_kv_indices: npt.NDArray[np.int64],
        dst_gpu_id: int,
        notif: str,
    ):
        # group by indices
        prefill_kv_blocks, dst_kv_blocks = group_concurrent_contiguous(
            prefill_kv_indices, dst_kv_indices
        )

        logger.debug(f"sending kvcache to {peer_name} with notif {notif}")
        # Make descs
        num_layers = len(self.kv_args.kv_data_ptrs)
        src_addrs = []
        dst_addrs = []
        for layer_id in range(num_layers):
            src_ptr = self.kv_args.kv_data_ptrs[layer_id]
            dst_ptr = dst_kv_ptrs[layer_id]
            item_len = self.kv_args.kv_item_lens[layer_id]

            for prefill_index, decode_index in zip(prefill_kv_blocks, dst_kv_blocks):
                src_addr = src_ptr + int(prefill_index[0]) * item_len
                dst_addr = dst_ptr + int(decode_index[0]) * item_len
                length = item_len * len(prefill_index)
                src_addrs.append((src_addr, length, self.kv_args.gpu_id))
                dst_addrs.append((dst_addr, length, dst_gpu_id))

        logger.debug(
            f"len(src_addrs): before group: {len(prefill_kv_indices)}, after group: {len(src_addrs)}"
        )
        src_descs = self.agent.get_xfer_descs(src_addrs, "VRAM", is_sorted=True)
        dst_descs = self.agent.get_xfer_descs(dst_addrs, "VRAM", is_sorted=True)
        # Transfer data
        xfer_handle = self.agent.initialize_xfer(
            "WRITE",
            src_descs,
            dst_descs,
            peer_name,
            notif.encode("ascii"),  # type: ignore
        )
        if not xfer_handle:
            raise Exception("KVSender failed to create transfer")
        state = self.agent.transfer(xfer_handle)
        if state == "ERR":
            raise Exception("KVSender failed to post transfer")
        return xfer_handle

    def send_aux(
        self,
        peer_name: str,
        prefill_aux_index: int,
        dst_aux_ptrs: list[int],
        dst_aux_index: int,
        notif: str,
    ):
        # Make descs
        aux_item_len = self.kv_args.aux_item_lens[0]
        prefill_aux_addr = (
            self.kv_args.aux_data_ptrs[0] + prefill_aux_index * aux_item_len
        )
        decode_aux_addr = dst_aux_ptrs[0] + dst_aux_index * aux_item_len
        src_addrs = [(prefill_aux_addr, aux_item_len, 0)]
        dst_addrs = [(decode_aux_addr, aux_item_len, 0)]
        src_descs = self.agent.get_xfer_descs(src_addrs, "DRAM", is_sorted=True)
        dst_descs = self.agent.get_xfer_descs(dst_addrs, "DRAM", is_sorted=True)
        # Transfer data
        xfer_handle = self.agent.initialize_xfer(
            "WRITE",
            src_descs,
            dst_descs,
            peer_name,
            notif.encode("ascii"),  # type: ignore
        )
        if not xfer_handle:
            raise Exception("KVSender failed to create transfer")
        state = self.agent.transfer(xfer_handle)
        if state == "ERR":
            raise Exception("KVSender failed to post transfer")
        return xfer_handle

    def add_transfer_request(
        self,
        bootstrap_room: int,
        kv_indices: npt.NDArray[np.int64],
        index_slice: slice,
        is_last: bool,
        chunk_id: int,
        aux_index: Optional[int] = None,
    ):
        assert self.disaggregation_mode == DisaggregationMode.PREFILL
        assert not is_last or (is_last and aux_index is not None)

        reqs_to_be_processed = self.transfer_infos[bootstrap_room].values()
        handles = []
        for req in reqs_to_be_processed:
            assert bootstrap_room == req.room
            if req.is_dummy():
                continue

            peer_name = self._add_remote(req.agent_name, req.agent_metadata)
            chunked_dst_kv_indice = req.dst_kv_indices[index_slice]
            assert len(chunked_dst_kv_indice) == len(kv_indices)

            notif = "_".join([str(req.room), "kv", str(chunk_id), str(int(is_last))])
            kv_xfer_handle = self.send_kvcache(
                peer_name,
                kv_indices,
                req.dst_kv_ptrs,
                chunked_dst_kv_indice,
                req.dst_gpu_id,
                notif,
            )
            handles.append(kv_xfer_handle)
            # Only the last chunk we need to send the aux data.
            if is_last:
                assert aux_index is not None
                aux_xfer_handle = self.send_aux(
                    peer_name,
                    aux_index,
                    req.dst_aux_ptrs,
                    req.dst_aux_index,
                    str(req.room) + "_aux",
                )
                handles.append(aux_xfer_handle)
        return handles

    def update_transfer_status(self):
        # Process notifications from received transfers.
        notif_map = self.agent.get_new_notifs()
        for peer_name, messages in notif_map.items():
            # We could also check that self.bootstrap_info['agent_name'] matches
            # the message sender. But the bootstrap room alone should be
            # sufficient to map the status.
            for msg in messages:
                components = msg.decode("ascii").split("_")
                room = int(components[0])
                if components[1] == "kv":
                    chunk_id = int(components[2])
                    is_last = bool(int(components[3]))
                    self.transfer_statuses[room].received_kvs.add(chunk_id)
                    if is_last:
                        self.transfer_statuses[room].num_kvs_expected = chunk_id + 1
                elif components[1] == "aux":
                    self.transfer_statuses[room].received_aux = True

    def check_transfer_done(self, room: int):
        if room not in self.transfer_statuses:
            return False
        return self.transfer_statuses[room].is_done()

    def _start_bootstrap_thread(self):
        self.server_socket.bind(f"tcp://{get_local_ip_by_remote()}:{self.rank_port}")

        def bootstrap_thread():
            """This thread recvs transfer info from the decode engine"""
            while True:
                waiting_req_bytes = self.server_socket.recv_multipart()
                logger.debug(
                    f"Received multipart with total byte size {sum(len(x) for x in waiting_req_bytes)}"
                )
                assert (
                    waiting_req_bytes[0] == GUARD
                ), f"First message should be {GUARD}. Foreign traffic?"
                waiting_req_bytes = waiting_req_bytes[1:]
                room = waiting_req_bytes[0].decode("ascii")

                required_dst_info_num = int(waiting_req_bytes[10].decode("ascii"))
                room = int(room)
                agent_name = waiting_req_bytes[4].decode("ascii")
                if room not in self.transfer_infos:
                    self.transfer_infos[room] = {}
                self.transfer_infos[room][agent_name] = TransferInfo.from_zmq(
                    waiting_req_bytes
                )

                logger.debug(f"got info {room=} {agent_name=} {required_dst_info_num=}")
                if len(self.transfer_infos[room]) == required_dst_info_num:
                    logger.debug(f"{room=} is bootstrapped")
                    self.update_status(room, KVPoll.WaitingForInput)

        threading.Thread(target=bootstrap_thread).start()


class NixlKVSender(BaseKVSender):

    def __init__(self, mgr: NixlKVManager, bootstrap_addr: str, bootstrap_room: int):
        self.kv_mgr = mgr
        self.bootstrap_room = bootstrap_room
        self.aux_index = None
        self.bootstrap_server_url = bootstrap_addr
        self.xfer_handles = []
        self.has_sent = False
        self.chunk_id = 0
        self.kv_mgr.update_status(self.bootstrap_room, KVPoll.Bootstrapping)
        # inner state
        self.curr_idx = 0

    def init(self, num_kv_indices: int, aux_index: Optional[int] = None):
        self.num_kv_indices = num_kv_indices
        self.aux_index = aux_index

    def send(
        self,
        kv_indices: npt.NDArray[np.int64],
    ):
        index_slice = slice(self.curr_idx, self.curr_idx + len(kv_indices))
        self.curr_idx += len(kv_indices)
        is_last = self.curr_idx == self.num_kv_indices

        new_xfer_handles = self.kv_mgr.add_transfer_request(
            self.bootstrap_room,
            kv_indices,
            index_slice,
            is_last,
            self.chunk_id,
            self.aux_index,
        )
        self.xfer_handles.extend(new_xfer_handles)
        self.chunk_id += 1
        if is_last:
            self.has_sent = True

    def poll(self) -> KVPoll:
        if not self.has_sent:
            return self.kv_mgr.check_status(self.bootstrap_room)
        states = [self.kv_mgr.agent.check_xfer_state(x) for x in self.xfer_handles]
        if all([x == "DONE" for x in states]):
            return KVPoll.Success  # type: ignore
        if any([x == "ERR" for x in states]):
            raise Exception("KVSender transfer encountered an error.")
        return KVPoll.WaitingForInput  # type: ignore

    def failure_exception(self):
        raise Exception("Fake KVSender Exception")


class NixlKVReceiver(CommonKVReceiver):
    def __init__(
        self,
        mgr: NixlKVManager,
        bootstrap_addr: str,
        bootstrap_room: Optional[int] = None,
        data_parallel_rank: Optional[int] = None,
    ):
        self.started_transfer = False
        super().__init__(mgr, bootstrap_addr, bootstrap_room, data_parallel_rank)

    def init(self, kv_indices: npt.NDArray[np.int64], aux_index: Optional[int] = None):
        for bootstrap_info in self.bootstrap_infos:
            self.prefill_server_url = (
                f"{bootstrap_info['rank_ip']}:{bootstrap_info['rank_port']}"
            )
            logger.debug(
                f"Fetched bootstrap info: {bootstrap_info} for engine rank: {self.kv_mgr.kv_args.engine_rank}"
            )
            is_dummy = bootstrap_info["is_dummy"]

            # TODO: send_kv_args earlier
            packed_kv_data_ptrs = b"".join(
                struct.pack("Q", ptr) for ptr in self.kv_mgr.kv_args.kv_data_ptrs
            )
            packed_aux_data_ptrs = b"".join(
                struct.pack("Q", ptr) for ptr in self.kv_mgr.kv_args.aux_data_ptrs
            )

            logger.debug(
                f"Sending to {self.prefill_server_url} with bootstrap room {self.bootstrap_room}"
            )
            sock, lock = self._connect("tcp://" + self.prefill_server_url)
            with lock:
                sock.send_multipart(
                    [
                        GUARD,
                        str(self.bootstrap_room).encode("ascii"),
                        get_local_ip_by_remote().encode("ascii"),
                        str(self.kv_mgr.rank_port).encode("ascii"),
                        self.kv_mgr.agent.get_agent_metadata(),
                        self.kv_mgr.agent.name.encode("ascii"),
                        packed_kv_data_ptrs,
                        kv_indices.tobytes() if not is_dummy else b"",
                        packed_aux_data_ptrs,
                        str(aux_index).encode("ascii"),
                        str(self.kv_mgr.kv_args.gpu_id).encode("ascii"),
                        str(self.required_dst_info_num).encode("ascii"),
                    ]
                )

        self.started_transfer = True

    def poll(self) -> KVPoll:
        if not self.started_transfer:
            return KVPoll.WaitingForInput  # type: ignore

        self.kv_mgr.update_transfer_status()

        if self.kv_mgr.check_transfer_done(self.bootstrap_room):  # type: ignore
            return KVPoll.Success  # type: ignore
        return KVPoll.WaitingForInput  # type: ignore

    def _register_kv_args(self):
        pass

    def failure_exception(self):
        raise Exception("Fake KVReceiver Exception")


class NixlKVBootstrapServer(CommonKVBootstrapServer):
    pass
