import hashlib
import logging
import os
from abc import ABC, abstractmethod
from dataclasses import dataclass
from enum import Enum
from typing import Any, List, Optional, Set

import torch

from sglang.srt.environ import envs
from sglang.srt.mem_cache.memory_pool_host import HostKVCache

logger = logging.getLogger(__name__)


def get_hash_str(token_ids: List[int], prior_hash: str = None) -> str:
    hasher = hashlib.sha256()

    if prior_hash:
        hasher.update(bytes.fromhex(prior_hash))

    for t in token_ids:
        if isinstance(t, tuple):
            # EAGLE bigram mode: hash both elements to uniquely identify the bigram
            for elem in t:
                hasher.update(elem.to_bytes(4, byteorder="little", signed=False))
        else:
            # Regular mode: single integer token
            hasher.update(t.to_bytes(4, byteorder="little", signed=False))

    return hasher.hexdigest()


def hash_str_to_int64(hash_str: str) -> int:
    """Convert SHA256 hex string to signed 64-bit integer for events.

    Takes first 16 hex characters (64 bits) and converts to signed int64 range.
    """
    # Take first 16 hex chars to get 64-bit value
    uint64_val = int(hash_str[:16], 16)
    # Convert to signed int64 range [-2^63, 2^63-1]
    if uint64_val >= 2**63:
        return uint64_val - 2**64
    return uint64_val


@dataclass
class HiCacheStorageConfig:
    tp_rank: int
    tp_size: int
    pp_rank: int
    pp_size: int
    is_mla_model: bool
    enable_storage_metrics: bool
    is_page_first_layout: bool
    model_name: Optional[str]
    tp_lcm_size: Optional[int] = None
    should_split_heads: bool = False
    extra_config: Optional[dict] = None


@dataclass
class HiCacheStorageExtraInfo:
    prefix_keys: Optional[List[str]] = (None,)
    extra_info: Optional[dict] = None


class PoolName(str, Enum):
    """Well-known pool names used as PoolTransfer/PoolEntry identifiers."""

    KV = "kv"
    MAMBA = "mamba"


class PoolHitPolicy(str, Enum):
    """Hit policy for batch_exists_v2 per-pool prefix matching.

    ALL_PAGES      : every page in [0, kv_hit) must exist (default).
    TRAILING_PAGES : only the last N pages must exist (e.g. Mamba/SWA states).
    """

    ALL_PAGES = "all_pages"
    TRAILING_PAGES = "trailing_pages"


@dataclass
class PoolTransfer:
    """Unified per-pool transfer descriptor for batch v2 interface.

    device<->host path : host_indices + device_indices
    host<->storage path: host_indices + keys
    """

    name: PoolName
    host_indices: Optional[torch.Tensor] = None
    device_indices: Optional[torch.Tensor] = None
    keys: Optional[List[str]] = None
    hit_policy: PoolHitPolicy = PoolHitPolicy.ALL_PAGES


@dataclass
class PoolTransferResult:
    """Tracks how many pages were successfully processed per pool."""

    kv_hit_pages: int
    extra_pool_hit_pages: dict[str, int]

    @classmethod
    def empty(cls) -> "PoolTransferResult":
        return cls(0, {})

    def update_kv_hit_pages(self, kv_hit_pages: int) -> None:
        """Accumulate kv_hit_pages across batches (max = last successful batch)."""
        self.kv_hit_pages = max(self.kv_hit_pages, kv_hit_pages)

    def update_extra_pool_hit_pages(self, results: dict[str, List[bool]]) -> None:
        """Record actual load/write success counts per extra pool."""
        self.extra_pool_hit_pages.update(
            {name: sum(rs) for name, rs in results.items()}
        )


class HiCacheStorage(ABC):
    """
    HiCacheStorage is a class that provides a generic key-value interface for storing and retrieving KV cache.
    It abstracts the underlying storage mechanism, allowing different implementations to be used.
    """

    # todo, the page size of storage backend does not have to be the same as the same as host memory pool
    def register_mem_pool_host(self, mem_pool_host: HostKVCache):
        self.mem_pool_host = mem_pool_host

    def register_mem_host_pool_v2(self, host_pool: HostKVCache, host_pool_name):
        if not hasattr(self, "registered_pools"):
            self.registered_pools = {}
        self.registered_pools[host_pool_name] = host_pool

    def batch_exists_v2(
        self,
        keys: List[str],
        pool_transfers: Optional[List[PoolTransfer]] = None,
        extra_info: Optional[HiCacheStorageExtraInfo] = None,
    ) -> PoolTransferResult:
        """Check which cache pages exist in storage, respecting per-pool hit policies.

        Longest-prefix semantics
        Extra-pool hit policies (``PoolTransfer.hit_policy``)
        ------------------------------------------------------
        Each ``PoolTransfer`` in ``pool_transfers`` describes a secondary
        cache pool (e.g. Mamba SSM states) that must be co-present with the
        KV pages.  The final ``final_pages`` is the minimum across all pools,
        so a missing auxiliary page shrinks the usable prefix.

        - ``"all_pages"`` (default):  every page in [0, kv_hit) must exist
          for this pool.  Used for pools that are required for every token
          in the prefix (e.g. DeepSeek DSA pool).

        - ``"trailing_pages"``:  only the *last* ``len(transfer.keys)`` pages
          of the KV prefix need to exist.  Used for pools whose data covers
          only the tail of a prefix (e.g. Mamba/SWA Pool).

        Returns
        -------
        PoolTransferResult
            ``kv_hit_pages`` = length of the usable KV prefix.
            ``extra_pool_hit_pages`` maps each pool name to the number of pages
            that were found.
        """
        raise NotImplementedError()

    def batch_get_v2(
        self,
        transfers: List[PoolTransfer],
        extra_info: Optional["HiCacheStorageExtraInfo"] = None,
    ) -> dict[str, List[bool]]:
        """Read data from storage into host memory for each PoolTransfer.

        Returns a dict mapping pool name to a per-entry success list.
        """
        raise NotImplementedError()

    def batch_set_v2(
        self,
        transfers: List[PoolTransfer],
        extra_info: Optional["HiCacheStorageExtraInfo"] = None,
    ) -> dict[str, List[bool]]:
        """Write data from host memory to storage for each PoolTransfer.

        Returns a dict mapping pool name to a per-entry success list.
        """
        raise NotImplementedError()

    def batch_get_v1(
        self,
        keys: List[str],
        host_indices: torch.Tensor,
        extra_info: Optional[HiCacheStorageExtraInfo] = None,
    ) -> List[bool]:
        """
        Retrieve values for multiple keys.
        Returns a list of booleans indicating success for each key.
        """
        pass

    def batch_set_v1(
        self,
        keys: List[str],
        host_indices: torch.Tensor,
        extra_info: Optional[HiCacheStorageExtraInfo] = None,
    ) -> List[bool]:
        """
        Store multiple key-value pairs.
        Returns a list of booleans indicating success for each key.
        """
        pass

    @abstractmethod
    def get(
        self,
        key: str,
        target_location: Optional[Any] = None,
        target_sizes: Optional[Any] = None,
    ) -> torch.Tensor | None:
        """
        Retrieve the value associated with the given key.
        Returns None if the key does not exist.
        """
        pass

    # TODO: Deprecate
    @abstractmethod
    def batch_get(
        self,
        keys: List[str],
        target_locations: Optional[Any] = None,
        target_sizes: Optional[Any] = None,
    ) -> List[torch.Tensor | None] | int:
        """
        Retrieve values for multiple keys.
        Returns a list of tensors or None for each key.
        """
        pass

    @abstractmethod
    def set(
        self,
        key: str,
        value: Optional[Any] = None,
        target_location: Optional[Any] = None,
        target_sizes: Optional[Any] = None,
    ) -> bool:
        """
        Store the value associated with the given key.
        Returns True if the operation was successful, False otherwise.
        """
        pass

    # TODO: Deprecate
    @abstractmethod
    def batch_set(
        self,
        keys: List[str],
        values: Optional[Any] = None,
        target_locations: Optional[Any] = None,
        target_sizes: Optional[Any] = None,
    ) -> bool:
        """
        Store multiple key-value pairs.
        Returns True if all operations were successful, False otherwise.
        """
        pass

    @abstractmethod
    def exists(self, key: str) -> bool:
        """
        Check if the key exists in the storage.
        Returns True if the key exists, False otherwise.
        """
        pass

    # TODO: Use a finer-grained return type (e.g., List[bool])
    def batch_exists(
        self, keys: List[str], extra_info: Optional[HiCacheStorageExtraInfo] = None
    ) -> int:
        """
        Check if the keys exist in the storage.
        return the number of consecutive existing keys from the start.
        Can be overridden by subclasses for more efficient implementation.
        """
        for i in range(len(keys)):
            if not self.exists(keys[i]):
                return i
        return len(keys)

    def clear(self) -> None:
        pass

    def get_stats(self):
        return None


class HiCacheFile(HiCacheStorage):

    def __init__(
        self, storage_config: HiCacheStorageConfig, file_path: str = "/tmp/hicache"
    ):
        self.file_path = envs.SGLANG_HICACHE_FILE_BACKEND_STORAGE_DIR.get() or file_path

        tp_rank, tp_size, pp_rank, pp_size, model_name, is_mla_model = (
            storage_config.tp_rank,
            storage_config.tp_size,
            storage_config.pp_rank,
            storage_config.pp_size,
            storage_config.model_name,
            storage_config.is_mla_model,
        )
        model_name = "-".join(model_name.split("/")) if model_name else ""
        enable_pp = pp_size > 1
        self.config_suffix = f"_{model_name}"
        if not is_mla_model:
            self.config_suffix += f"_{tp_rank}_{tp_size}"
        if enable_pp:
            self.config_suffix += f"_{pp_size}_{pp_rank}"
        if not os.path.exists(self.file_path) and tp_rank == 0:
            os.makedirs(self.file_path)
            logger.info(f"Created HiCacheFile storage directory at {self.file_path}")

    def _get_suffixed_key(self, key: str) -> str:
        return key + self.config_suffix

    def _get_component_key(self, key: str, component_name: Optional[str] = None) -> str:
        if component_name is None or component_name in ("__default__", PoolName.KV):
            return self._get_suffixed_key(key)
        return self._get_suffixed_key(f"{key}.{component_name}")

    def _get_component_path(
        self, key: str, component_name: Optional[str] = None
    ) -> str:
        return os.path.join(
            self.file_path, f"{self._get_component_key(key, component_name)}.bin"
        )

    def get(
        self,
        key: str,
        target_location: torch.Tensor,
        target_sizes: Optional[Any] = None,
    ) -> torch.Tensor | None:
        key = self._get_suffixed_key(key)
        tensor_path = os.path.join(self.file_path, f"{key}.bin")
        try:
            expected = target_location.numel() * target_location.element_size()
            with open(tensor_path, "rb", buffering=0) as f:
                buf = memoryview(target_location.view(torch.uint8).contiguous().numpy())
                if f.readinto(buf) != expected:
                    raise IOError(f"Short read for {key}")
            return target_location
        except FileNotFoundError:
            logger.warning(f"Failed to fetch {key} from HiCacheFile storage.")
            return None

    def batch_get(
        self,
        keys: List[str],
        target_locations: List[torch.Tensor],
        target_sizes: Optional[Any] = None,
    ) -> List[torch.Tensor | None]:
        return [
            self.get(key, target_location)
            for key, target_location in zip(
                keys, target_locations or [None] * len(keys)
            )
        ]

    def set(
        self,
        key: str,
        value: Optional[Any] = None,
        target_location: Optional[Any] = None,
        target_sizes: Optional[Any] = None,
    ) -> bool:
        if self.exists(key):
            logger.debug(f"Key {key} already exists. Skipped.")
            return True

        key = self._get_suffixed_key(key)
        tensor_path = os.path.join(self.file_path, f"{key}.bin")
        try:
            value.contiguous().view(dtype=torch.uint8).numpy().tofile(tensor_path)
            return True
        except Exception as e:
            logger.error(f"Failed to save tensor {key}: {e}")
            return False

    def batch_set(
        self,
        keys: List[str],
        values: Optional[Any] = None,
        target_locations: Optional[Any] = None,
        target_sizes: Optional[Any] = None,
    ) -> bool:
        for key, value in zip(keys, values):
            if not self.set(key, value):
                return False
        return True

    def exists(self, key: str) -> bool:
        key = self._get_suffixed_key(key)
        tensor_path = os.path.join(self.file_path, f"{key}.bin")
        return os.path.exists(tensor_path)

    def _collect_existing_component_keys(
        self,
        keys: List[str],
        pool_transfers: Optional[List[PoolTransfer]] = None,
    ) -> Set[str]:
        target_files = {f"{self._get_component_key(key)}.bin" for key in keys}
        for transfer in pool_transfers or []:
            for key in keys:
                target_files.add(f"{self._get_component_key(key, transfer.name)}.bin")

        existing_files = set()
        with os.scandir(self.file_path) as entries:
            for entry in entries:
                if entry.is_file() and entry.name in target_files:
                    existing_files.add(entry.name)
        return existing_files

    def batch_exists_v2(
        self,
        keys: List[str],
        pool_transfers: Optional[List[PoolTransfer]] = None,
        extra_info: Optional[HiCacheStorageExtraInfo] = None,
    ) -> PoolTransferResult:
        existing_files = self._collect_existing_component_keys(keys, pool_transfers)

        def has_component(page_idx: int, name: str) -> bool:
            return (
                f"{self._get_component_key(keys[page_idx], name)}.bin" in existing_files
            )

        # Longest contiguous KV prefix present in storage.
        kv_pages = next(
            (
                i
                for i in range(len(keys))
                if f"{self._get_component_key(keys[i])}.bin" not in existing_files
            ),
            len(keys),
        )

        hit_count: dict[str, int] = {PoolName.KV: kv_pages} if kv_pages else {}
        final_pages = kv_pages

        for transfer in pool_transfers or []:
            if final_pages == 0:
                break
            name = transfer.name
            if transfer.hit_policy == PoolHitPolicy.ALL_PAGES:
                boundary = next(
                    (i for i in range(kv_pages) if not has_component(i, name)), kv_pages
                )
            else:  # trailing_pages
                trailing = max(1, len(transfer.keys) if transfer.keys else 1)
                boundary = 0
                for prefix_len in range(kv_pages, 0, -1):
                    if all(
                        has_component(i, name)
                        for i in range(max(0, prefix_len - trailing), prefix_len)
                    ):
                        boundary = prefix_len
                        break
            if boundary:
                hit_count[name] = boundary
            final_pages = min(final_pages, boundary)

        return PoolTransferResult(final_pages, hit_count)

    def _log_key(self, pool_name: str, key: str) -> str:
        return key if pool_name == PoolName.KV else f"{key}.{pool_name}"

    def _read_page(self, pool_name: str, key: str, host_pool, page_offset: int) -> bool:
        """Read one page from storage into host_pool at page_offset."""
        storage_key = self._log_key(pool_name, key)
        data_page = self.get(storage_key, host_pool.get_dummy_flat_data_page())
        if data_page is None:
            return False
        host_pool.set_from_flat_data_page(page_offset, data_page)
        return True

    def _write_page(
        self, pool_name: str, key: str, host_pool, page_offset: int
    ) -> bool:
        """Write one page from host_pool at page_offset to storage as raw bytes."""
        storage_key = self._log_key(pool_name, key)
        data_page = host_pool.get_data_page(page_offset, flat=True)
        return self.set(storage_key, data_page)

    def _batch_io_v2(self, transfers: List[PoolTransfer], op_fn):
        results: dict[str, List[bool]] = {}
        for transfer in transfers:
            host_pool = self.registered_pools[transfer.name]
            keys = transfer.keys or []
            page_size = getattr(host_pool, "page_size", 1) or 1
            expected = len(keys) * page_size
            host_indices = transfer.host_indices

            if host_indices is None or host_indices.numel() != expected:
                logger.error(
                    "%s indices length mismatch for %s: expected %s, got %s",
                    op_fn.__name__,
                    transfer.name,
                    expected,
                    host_indices.numel() if host_indices is not None else 0,
                )
                results[transfer.name] = [False] * len(keys)
                continue

            results[transfer.name] = [
                op_fn(transfer.name, key, host_pool, host_indices[i * page_size].item())
                for i, key in enumerate(keys)
            ]
        return results

    def batch_get_v2(
        self,
        transfers: List[PoolTransfer],
        extra_info: Optional["HiCacheStorageExtraInfo"] = None,
    ) -> dict[str, List[bool]]:
        return self._batch_io_v2(transfers, self._read_page)

    def batch_set_v2(
        self,
        transfers: List[PoolTransfer],
        extra_info: Optional["HiCacheStorageExtraInfo"] = None,
    ) -> dict[str, List[bool]]:
        return self._batch_io_v2(transfers, self._write_page)

    def clear(self) -> bool:
        try:
            for filename in os.listdir(self.file_path):
                file_path = os.path.join(self.file_path, filename)
                if os.path.isfile(file_path):
                    os.remove(file_path)
            logger.info("Cleared all entries in HiCacheFile storage.")
            return True
        except Exception as e:
            logger.error(f"Failed to clear HiCacheFile storage: {e}")
            return False
