import abc
import logging
import threading
from enum import IntEnum
from functools import wraps

import psutil
import torch

from sglang.srt.mem_cache.memory_pool import KVCache, MHATokenToKVPool, MLATokenToKVPool
from sglang.srt.utils import is_npu

_is_npu = is_npu()
if not _is_npu:
    from sgl_kernel.kvcacheio import (
        transfer_kv_all_layer,
        transfer_kv_all_layer_lf_pf,
        transfer_kv_all_layer_mla,
        transfer_kv_all_layer_mla_lf_pf,
        transfer_kv_direct,
        transfer_kv_per_layer,
        transfer_kv_per_layer_mla,
        transfer_kv_per_layer_mla_pf_lf,
        transfer_kv_per_layer_pf_lf,
    )

logger = logging.getLogger(__name__)


class MemoryStateInt(IntEnum):
    IDLE = 0
    RESERVED = 1
    PROTECTED = 2
    SYNCED = 3
    BACKUP = 4


def synchronized(debug_only=False):
    def _decorator(func):
        @wraps(func)
        def wrapper(self, *args, **kwargs):
            if (not debug_only) or self.debug:
                with self.lock:
                    return func(self, *args, **kwargs)
            else:
                return True

        return wrapper

    return _decorator


class HostKVCache(abc.ABC):

    def __init__(
        self,
        device_pool: KVCache,
        host_to_device_ratio: float,
        host_size: int,
        page_size: int,
        layout: str,
        pin_memory: bool,
        device: str,
    ):
        self.device_pool = device_pool
        self.page_size = page_size
        self.layout = layout
        self.pin_memory = pin_memory
        self.device = device

        self.dtype = device_pool.store_dtype
        self.size_per_token = self.get_size_per_token()
        if host_size > 0:
            self.size = int(host_size * 1e9 // self.size_per_token)
        else:
            self.size = int(device_pool.size * host_to_device_ratio)
        # Align the host memory pool size to the page size
        self.size = self.size - (self.size % self.page_size)
        self.start_layer = device_pool.start_layer
        self.end_layer = device_pool.end_layer

        assert (
            self.size > device_pool.size
        ), "The host memory should be larger than the device memory with the current protocol"

        # Verify there is enough available host memory.
        host_mem = psutil.virtual_memory()
        requested_bytes = self.size * self.size_per_token
        # preserve at least 10GB for other usage
        ten_gb = 10 * (1024**3)
        available_bytes = host_mem.available - ten_gb
        if requested_bytes > available_bytes:
            raise ValueError(
                f"Not enough host memory available. Requesting "
                f"{requested_bytes / 1e9:.2f} GB but only have "
                f"{available_bytes / 1e9:.2f} GB free. Please reduce the "
                f"size of the hierarchical cache."
            )
        else:
            logger.info(
                f"Allocating {requested_bytes / 1e9:.2f} GB host memory for hierarchical KV cache."
            )

        self.kv_buffer = self.init_kv_buffer()

        # A lock for synchronized operations on memory allocation and state transitions.
        self.lock = threading.RLock()
        self.debug = logger.isEnabledFor(logging.DEBUG)
        self.clear()

    @abc.abstractmethod
    def get_size_per_token(self):
        raise NotImplementedError()

    @abc.abstractmethod
    def init_kv_buffer(self):
        raise NotImplementedError()

    @abc.abstractmethod
    def load_to_device_per_layer(
        self, device_pool, host_indices, device_indices, layer_id, io_backend
    ) -> None:
        """
        Load KV data from the host memory pool to the device memory pool for a specific layer.
        """
        raise NotImplementedError()

    @abc.abstractmethod
    def backup_from_device_all_layer(
        self, device_pool, host_indices, device_indices, io_backend
    ) -> None:
        """
        Backup KV data from the device memory pool to the host memory pool for all layers.
        """
        raise NotImplementedError()

    @abc.abstractmethod
    def get_flat_data_page(self, index) -> torch.Tensor:
        """
        Get a flat data page from the host memory pool.
        """
        raise NotImplementedError()

    @abc.abstractmethod
    def get_dummy_flat_data_page(self) -> torch.Tensor:
        """
        Get a dummy flat data page from the host memory pool.
        This is used for prefetching or initializing empty pages.
        """
        raise NotImplementedError()

    @abc.abstractmethod
    def set_from_flat_data_page(self, index: int, data_page: torch.Tensor) -> None:
        """
        Set a flat data page to the host memory pool.
        """
        raise NotImplementedError()

    @synchronized()
    def clear(self):
        # Initialize memory states and tracking structures.
        self.mem_state = torch.zeros(
            (self.size,), dtype=torch.uint8, device=self.device
        )
        self.free_slots = torch.arange(self.size, dtype=torch.int64)

    def available_size(self):
        return len(self.free_slots)

    @synchronized()
    def alloc(self, need_size: int) -> torch.Tensor:
        assert (
            need_size % self.page_size == 0
        ), "The requested size should be a multiple of the page size."
        if need_size > self.available_size():
            return None

        select_index = self.free_slots[:need_size]
        self.free_slots = self.free_slots[need_size:]

        if self.debug:
            self.mem_state[select_index] = MemoryStateInt.RESERVED

        return select_index

    @synchronized()
    def free(self, indices: torch.Tensor) -> int:
        self.free_slots = torch.cat([self.free_slots, indices])
        if self.debug:
            self.mem_state[indices] = MemoryStateInt.IDLE
        return len(indices)

    @synchronized(debug_only=True)
    def get_state(self, indices: torch.Tensor) -> MemoryStateInt:
        assert len(indices) > 0, "The indices should not be empty"
        states = self.mem_state[indices]
        assert (
            states == states[0]
        ).all(), "The memory slots should have the same state {}".format(states)
        return MemoryStateInt(states[0].item())

    @synchronized(debug_only=True)
    def is_reserved(self, indices: torch.Tensor) -> bool:
        return self.get_state(indices) == MemoryStateInt.RESERVED

    @synchronized(debug_only=True)
    def is_protected(self, indices: torch.Tensor) -> bool:
        return self.get_state(indices) == MemoryStateInt.PROTECTED

    @synchronized(debug_only=True)
    def is_synced(self, indices: torch.Tensor) -> bool:
        return self.get_state(indices) == MemoryStateInt.SYNCED

    @synchronized(debug_only=True)
    def is_backup(self, indices: torch.Tensor) -> bool:
        return self.get_state(indices) == MemoryStateInt.BACKUP

    @synchronized(debug_only=True)
    def update_backup(self, indices: torch.Tensor):
        if not self.is_synced(indices):
            raise ValueError(
                f"The host memory slots should be in SYNCED state before turning into BACKUP. "
                f"Current state: {self.get_state(indices)}"
            )
        self.mem_state[indices] = MemoryStateInt.BACKUP

    @synchronized(debug_only=True)
    def update_prefetch(self, indices: torch.Tensor):
        if not self.is_reserved(indices):
            raise ValueError(
                f"The host memory slots should be in RESERVED state before turning into BACKUP. "
                f"Current state: {self.get_state(indices)}"
            )
        self.mem_state[indices] = MemoryStateInt.BACKUP

    @synchronized(debug_only=True)
    def update_synced(self, indices: torch.Tensor):
        self.mem_state[indices] = MemoryStateInt.SYNCED

    @synchronized(debug_only=True)
    def protect_write(self, indices: torch.Tensor):
        if not self.is_reserved(indices):
            raise ValueError(
                f"The host memory slots should be RESERVED before write operations. "
                f"Current state: {self.get_state(indices)}"
            )
        self.mem_state[indices] = MemoryStateInt.PROTECTED

    @synchronized(debug_only=True)
    def protect_load(self, indices: torch.Tensor):
        if not self.is_backup(indices):
            raise ValueError(
                f"The host memory slots should be in BACKUP state before load operations. "
                f"Current state: {self.get_state(indices)}"
            )
        self.mem_state[indices] = MemoryStateInt.PROTECTED

    @synchronized(debug_only=True)
    def complete_io(self, indices: torch.Tensor):
        if not self.is_protected(indices):
            raise ValueError(
                f"The host memory slots should be PROTECTED during I/O operations. "
                f"Current state: {self.get_state(indices)}"
            )
        self.mem_state[indices] = MemoryStateInt.SYNCED


class MHATokenToKVPoolHost(HostKVCache):
    device_pool: MHATokenToKVPool

    def __init__(
        self,
        device_pool: MHATokenToKVPool,
        host_to_device_ratio: float,
        host_size: int,
        page_size: int,
        layout: str,
        pin_memory: bool = True,
        device: str = "cpu",
    ):
        super().__init__(
            device_pool,
            host_to_device_ratio,
            host_size,
            page_size,
            layout,
            pin_memory,
            device,
        )
        self.k_data_refs = [self.k_buffer[i] for i in range(self.layer_num)]
        self.v_data_refs = [self.v_buffer[i] for i in range(self.layer_num)]
        self.k_data_ptrs = torch.tensor(
            [x.data_ptr() for x in self.k_data_refs],
            dtype=torch.uint64,
            device=self.device_pool.device,
        )
        self.v_data_ptrs = torch.tensor(
            [x.data_ptr() for x in self.v_data_refs],
            dtype=torch.uint64,
            device=self.device_pool.device,
        )

    def get_size_per_token(self):
        self.head_num = self.device_pool.head_num
        self.head_dim = self.device_pool.head_dim
        self.layer_num = self.device_pool.layer_num

        return self.head_dim * self.head_num * self.layer_num * self.dtype.itemsize * 2

    def get_ksize_per_token(self):
        return self.get_size_per_token() // 2

    def init_kv_buffer(self):
        if self.layout == "layer_first":
            dims = (2, self.layer_num, self.size, self.head_num, self.head_dim)
        elif self.layout == "page_first":
            dims = (2, self.size, self.layer_num, self.head_num, self.head_dim)
        else:
            raise ValueError(f"Unsupported layout: {self.layout}")
        self.token_stride_size = self.head_num * self.head_dim * self.dtype.itemsize
        self.layout_dim = self.token_stride_size * self.layer_num
        return torch.empty(
            dims,
            dtype=self.dtype,
            device=self.device,
            pin_memory=self.pin_memory,
        )

    @property
    def k_buffer(self):
        return self.kv_buffer[0]

    @property
    def v_buffer(self):
        return self.kv_buffer[1]

    def load_to_device_per_layer(
        self,
        device_pool,
        host_indices,
        device_indices,
        layer_id,
        io_backend,
    ):
        if io_backend == "kernel":
            if self.layout == "layer_first":
                transfer_kv_per_layer(
                    src_k=self.k_buffer[layer_id],
                    dst_k=device_pool.k_buffer[layer_id],
                    src_v=self.v_buffer[layer_id],
                    dst_v=device_pool.v_buffer[layer_id],
                    src_indices=host_indices,
                    dst_indices=device_indices,
                    item_size=self.token_stride_size,
                )
            elif self.layout == "page_first":
                transfer_kv_per_layer_pf_lf(
                    src_k=self.k_buffer,
                    dst_k=device_pool.k_buffer[layer_id],
                    src_v=self.v_buffer,
                    dst_v=device_pool.v_buffer[layer_id],
                    src_indices=host_indices,
                    dst_indices=device_indices,
                    layer_id=layer_id,
                    item_size=self.token_stride_size,
                    src_layout_dim=self.layout_dim,
                )
            else:
                raise ValueError(f"Unsupported layout: {self.layout}")
        elif io_backend == "direct":
            assert (
                self.layout == "layer_first"
            ), f"Direct IO backend only supports layer_first layout."
            transfer_kv_direct(
                src_layers=[self.k_buffer[layer_id], self.v_buffer[layer_id]],
                dst_layers=[
                    device_pool.k_buffer[layer_id],
                    device_pool.v_buffer[layer_id],
                ],
                src_indices=host_indices,
                dst_indices=device_indices,
                page_size=self.page_size,
            )
        else:
            raise ValueError(f"Unsupported IO backend: {io_backend}")

    def backup_from_device_all_layer(
        self, device_pool, host_indices, device_indices, io_backend
    ):
        if io_backend == "kernel":
            if self.layout == "layer_first":
                transfer_kv_all_layer(
                    src_k_layers=device_pool.k_data_ptrs,
                    dst_k_layers=self.k_data_ptrs,
                    src_v_layers=device_pool.v_data_ptrs,
                    dst_v_layers=self.v_data_ptrs,
                    src_indices=device_indices,
                    dst_indices=host_indices,
                    item_size=self.token_stride_size,
                    num_layers=self.layer_num,
                )
            elif self.layout == "page_first":
                transfer_kv_all_layer_lf_pf(
                    src_k_layers=device_pool.k_data_ptrs,
                    dst_k=self.k_buffer,
                    src_v_layers=device_pool.v_data_ptrs,
                    dst_v=self.v_buffer,
                    src_indices=device_indices,
                    dst_indices=host_indices,
                    item_size=self.token_stride_size,
                    dst_layout_dim=self.layout_dim,
                    num_layers=self.layer_num,
                )
            else:
                raise ValueError(f"Unsupported layout: {self.layout}")
        elif io_backend == "direct":
            assert (
                self.layout == "layer_first"
            ), f"Direct IO backend only supports layer_first layout."
            transfer_kv_direct(
                src_layers=device_pool.k_buffer + device_pool.v_buffer,
                dst_layers=self.k_data_refs + self.v_data_refs,
                src_indices=device_indices,
                dst_indices=host_indices,
                page_size=self.page_size,
            )
        else:
            raise ValueError(f"Unsupported IO backend: {io_backend}")

    def get_flat_data_page(self, index) -> torch.Tensor:
        if self.layout == "layer_first":
            return self.kv_buffer[:, :, index : index + self.page_size, :, :].flatten()
        elif self.layout == "page_first":
            return self.kv_buffer[:, index : index + self.page_size, :, :, :].flatten()
        else:
            raise ValueError(f"Unsupported layout: {self.layout}")

    def get_dummy_flat_data_page(self) -> torch.Tensor:
        return torch.zeros(
            (2, self.layer_num, self.page_size, self.head_num, self.head_dim),
            dtype=self.dtype,
            device=self.device,
            pin_memory=self.pin_memory,
        ).flatten()

    def set_from_flat_data_page(self, index: int, data_page: torch.Tensor) -> None:
        if self.layout == "layer_first":
            self.kv_buffer[:, :, index : index + self.page_size, :, :] = (
                data_page.reshape(
                    2,
                    self.layer_num,
                    self.page_size,
                    self.head_num,
                    self.head_dim,
                )
            )
        elif self.layout == "page_first":
            self.kv_buffer[:, index : index + self.page_size, :, :, :] = (
                data_page.reshape(
                    2, self.page_size, self.layer_num, self.head_num, self.head_dim
                )
            )
        else:
            raise ValueError(f"Unsupported layout: {self.layout}")

    def get_buffer_meta(self, keys, indices):
        ptr_list = []
        key_list = []
        kv_buffer_data_ptr = self.kv_buffer.data_ptr()
        v_offset = (
            self.layer_num
            * self.size
            * self.head_num
            * self.head_dim
            * self.dtype.itemsize
        )
        for index in range(0, len(indices), self.page_size):
            k_ptr = (
                kv_buffer_data_ptr
                + indices[index]
                * self.layer_num
                * self.head_num
                * self.head_dim
                * self.dtype.itemsize
            )
            v_ptr = k_ptr + v_offset
            ptr_list.append(k_ptr)
            ptr_list.append(v_ptr)
            key_ = keys[index // self.page_size]
            key_list.append(f"{key_}_k")
            key_list.append(f"{key_}_v")
        element_size = (
            self.layer_num
            * self.dtype.itemsize
            * self.page_size
            * self.head_num
            * self.head_dim
        )
        element_size_list = [element_size] * len(key_list)
        return key_list, ptr_list, element_size_list

    def get_buffer_with_hash(self, keys, indices):
        assert self.layout == "page_first"
        assert len(keys) == (len(indices) // self.page_size)

        key_list = []
        buf_list = []

        for key, i in zip(keys, range(0, len(indices), self.page_size)):
            key_list.append(f"{key}-k")
            buf_list.append(self.k_buffer[i : i + self.page_size])
            key_list.append(f"{key}-v")
            buf_list.append(self.v_buffer[i : i + self.page_size])

        return key_list, buf_list


class MLATokenToKVPoolHost(HostKVCache):
    device_pool: MLATokenToKVPool

    def __init__(
        self,
        device_pool: MLATokenToKVPool,
        host_to_device_ratio: float,
        host_size: int,
        page_size: int,
        layout: str,
        pin_memory: bool = True,
        device: str = "cpu",
    ):
        super().__init__(
            device_pool,
            host_to_device_ratio,
            host_size,
            page_size,
            layout,
            pin_memory,
            device,
        )
        self.data_refs = [self.kv_buffer[i] for i in range(self.layer_num)]
        self.data_ptrs = torch.tensor(
            [x.data_ptr() for x in self.data_refs],
            dtype=torch.uint64,
            device=self.device_pool.device,
        )

    def get_size_per_token(self):
        self.kv_lora_rank = self.device_pool.kv_lora_rank
        self.qk_rope_head_dim = self.device_pool.qk_rope_head_dim
        self.layer_num = self.device_pool.layer_num

        return (
            (self.kv_lora_rank + self.qk_rope_head_dim)
            * 1
            * self.dtype.itemsize
            * self.layer_num
        )

    def get_ksize_per_token(self):
        return self.get_size_per_token()

    def init_kv_buffer(self):
        if self.layout == "layer_first":
            dims = (
                self.layer_num,
                self.size,
                1,
                self.kv_lora_rank + self.qk_rope_head_dim,
            )
        elif self.layout == "page_first":
            dims = (
                self.size,
                self.layer_num,
                1,
                self.kv_lora_rank + self.qk_rope_head_dim,
            )
        else:
            raise ValueError(f"Unsupported layout: {self.layout}")
        self.token_stride_size = (
            self.kv_lora_rank + self.qk_rope_head_dim
        ) * self.dtype.itemsize
        self.layout_dim = self.token_stride_size * self.layer_num

        return torch.empty(
            dims,
            dtype=self.dtype,
            device=self.device,
            pin_memory=self.pin_memory,
        )

    def load_to_device_per_layer(
        self, device_pool, host_indices, device_indices, layer_id, io_backend
    ):
        if io_backend == "kernel":
            if self.layout == "layer_first":
                transfer_kv_per_layer_mla(
                    src=self.kv_buffer[layer_id],
                    dst=device_pool.kv_buffer[layer_id],
                    src_indices=host_indices,
                    dst_indices=device_indices,
                    item_size=self.token_stride_size,
                )
            elif self.layout == "page_first":
                transfer_kv_per_layer_mla_pf_lf(
                    src=self.kv_buffer,
                    dst=device_pool.kv_buffer[layer_id],
                    src_indices=host_indices,
                    dst_indices=device_indices,
                    layer_id=layer_id,
                    item_size=self.token_stride_size,
                    src_layout_dim=self.layout_dim,
                )
            else:
                raise ValueError(f"Unsupported layout: {self.layout}")
        elif io_backend == "direct":
            assert (
                self.layout == "layer_first"
            ), f"Direct IO backend only supports layer_first layout."
            transfer_kv_direct(
                src_layers=[self.kv_buffer[layer_id]],
                dst_layers=[device_pool.kv_buffer[layer_id]],
                src_indices=host_indices,
                dst_indices=device_indices,
                page_size=self.page_size,
            )

    def backup_from_device_all_layer(
        self, device_pool, host_indices, device_indices, io_backend
    ):
        if io_backend == "kernel":
            if self.layout == "layer_first":
                transfer_kv_all_layer_mla(
                    src_layers=device_pool.data_ptrs,
                    dst_layers=self.data_ptrs,
                    src_indices=device_indices,
                    dst_indices=host_indices,
                    item_size=self.token_stride_size,
                    num_layers=self.layer_num,
                )
            elif self.layout == "page_first":
                transfer_kv_all_layer_mla_lf_pf(
                    src_layers=device_pool.data_ptrs,
                    dst=self.kv_buffer,
                    src_indices=device_indices,
                    dst_indices=host_indices,
                    item_size=self.token_stride_size,
                    dst_layout_dim=self.layout_dim,
                    num_layers=self.layer_num,
                )
            else:
                raise ValueError(f"Unsupported layout: {self.layout}")
        elif io_backend == "direct":
            assert (
                self.layout == "layer_first"
            ), f"Direct IO backend only supports layer_first layout."
            transfer_kv_direct(
                src_layers=device_pool.kv_buffer,
                dst_layers=self.data_refs,
                src_indices=device_indices,
                dst_indices=host_indices,
                page_size=self.page_size,
            )
        else:
            raise ValueError(f"Unsupported IO backend: {io_backend}")

    def get_flat_data_page(self, index) -> torch.Tensor:
        if self.layout == "layer_first":
            return self.kv_buffer[:, index : index + self.page_size, :, :].flatten()
        elif self.layout == "page_first":
            return self.kv_buffer[index : index + self.page_size, :, :, :].flatten()
        else:
            raise ValueError(f"Unsupported layout: {self.layout}")

    def get_dummy_flat_data_page(self) -> torch.Tensor:
        return torch.zeros(
            (
                self.layer_num,
                self.page_size,
                1,
                self.kv_lora_rank + self.qk_rope_head_dim,
            ),
            dtype=self.dtype,
            device=self.device,
            pin_memory=self.pin_memory,
        ).flatten()

    def set_from_flat_data_page(self, index: int, data_page: torch.Tensor) -> None:
        if self.layout == "layer_first":
            self.kv_buffer[:, index : index + self.page_size, :, :] = data_page.reshape(
                self.layer_num,
                self.page_size,
                1,
                self.kv_lora_rank + self.qk_rope_head_dim,
            )
        elif self.layout == "page_first":
            self.kv_buffer[index : index + self.page_size, :, :, :] = data_page.reshape(
                self.page_size,
                self.layer_num,
                1,
                self.kv_lora_rank + self.qk_rope_head_dim,
            )
        else:
            raise ValueError(f"Unsupported layout: {self.layout}")

    def get_buffer_meta(self, keys, indices):
        ptr_list = []
        key_list = []
        kv_buffer_data_ptr = self.kv_buffer.data_ptr()
        for index in range(0, len(indices), self.page_size):
            k_ptr = (
                kv_buffer_data_ptr
                + indices[index]
                * self.layer_num
                * (self.kv_lora_rank + self.qk_rope_head_dim)
                * self.dtype.itemsize
            )
            ptr_list.append(k_ptr)
            key_ = keys[index // self.page_size]
            key_list.append(f"{key_}_k")
        element_size = (
            self.layer_num
            * self.dtype.itemsize
            * self.page_size
            * (self.kv_lora_rank + self.qk_rope_head_dim)
        )
        element_size_list = [element_size] * len(key_list)
        return key_list, ptr_list, element_size_list

    def get_buffer_with_hash(self, keys, indices):
        assert self.layout == "page_first"
        assert len(keys) == (len(indices) // self.page_size)

        buf_list = []

        for i in range(0, len(indices), self.page_size):
            buf_list.append(self.kv_buffer[i : i + self.page_size])

        return keys, buf_list
