# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
"""Utility functions for vLLM config dataclasses."""

import ast
import enum
import hashlib
import inspect
import json
import pathlib
import textwrap
from collections.abc import Callable, Mapping, Sequence, Set
from dataclasses import MISSING, Field, field, fields, is_dataclass
from itertools import pairwise
from typing import TYPE_CHECKING, Any, Protocol, TypeVar, cast

import torch
from pydantic import ConfigDict
from pydantic.dataclasses import dataclass
from pydantic.fields import Field as PydanticField
from pydantic.fields import FieldInfo
from typing_extensions import dataclass_transform, runtime_checkable

from vllm.logger import init_logger

logger = init_logger(__name__)

if TYPE_CHECKING:
    from _typeshed import DataclassInstance
else:
    DataclassInstance = Any

ConfigType = type[DataclassInstance]
ConfigT = TypeVar("ConfigT", bound=DataclassInstance)


@dataclass_transform(field_specifiers=(PydanticField,))
def config(
    cls: type[ConfigT] | None = None,
    *,
    config: ConfigDict | None = None,
    **kwargs: Any,
) -> type[ConfigT] | Callable[[type[ConfigT]], type[ConfigT]]:
    """Decorator to create a pydantic dataclass with default config. The default config
    for the dataclass forbids extra fields.

    All config classes in vLLM should use this decorator.

    Args:
        cls: The class to decorate
        config: The pydantic ConfigDict to use. If provided, it will be merged with
            the default config.
        **kwargs: Additional arguments to pass to pydantic.dataclass."""
    # Extra fields are forbidden by default
    merged_config = ConfigDict(extra="forbid")
    if config is not None:
        merged_config.update(config)

    def decorator(cls):
        return dataclass(cls, config=merged_config, **kwargs)

    # Called with arguments: @config(config=...)
    if cls is None:
        return decorator
    # Called without arguments: @config
    return decorator(cls)


def get_field(cls: ConfigType, name: str) -> Field:
    """Get the default factory field of a dataclass by name. Used for getting
    default factory fields in `EngineArgs`."""
    if not is_dataclass(cls):
        raise TypeError("The given class is not a dataclass.")
    try:
        named_field = next(f for f in fields(cls) if f.name == name)
    except StopIteration as e:
        raise ValueError(f"Field '{name}' not found in {cls.__name__}.") from e

    # The arguments to copy to the new field
    default = named_field.default
    default_factory = named_field.default_factory
    init = named_field.init

    # Handle pydantic.Field
    if isinstance(default, FieldInfo):
        if default.init is not None:
            init = default.init
        if default.default_factory is not None:
            default_factory = cast(Callable[[], Any], default.default_factory)
            default = MISSING
        else:
            default = default.default

    if default is MISSING and default_factory is MISSING:
        logger.warning_once(
            "%s.%s has no default or default factory.", cls.__name__, name
        )
    return field(default=default, default_factory=default_factory, init=init)


def is_init_field(cls: ConfigType, name: str) -> bool:
    return get_field(cls, name).init


def replace(dataclass_instance: ConfigT, /, **kwargs) -> ConfigT:
    """Like [`dataclasses.replace`](https://docs.python.org/3/library/dataclasses.html#dataclasses.replace),
    but compatible with Pydantic dataclasses which use `pydantic.fields.Field` instead
    of `dataclasses.field`"""
    cls = type(dataclass_instance)
    dataclass_dict = dataclass_instance.__dict__
    dataclass_dict = {k: v for k, v in dataclass_dict.items() if is_init_field(cls, k)}
    dataclass_dict.update(kwargs)
    return cls(**dataclass_dict)


def getattr_iter(
    object: object,
    names: Sequence[str],
    default: Any | None = None,
    default_factory: Callable[[], Any] | None = None,
    warn: bool = False,
) -> Any:
    """
    A helper function that retrieves an attribute from an object which may
    have multiple possible names. This is useful when fetching attributes from
    arbitrary `transformers.PretrainedConfig` instances.

    In the case where the first name in `names` is the preferred name, and
    any other names are deprecated aliases, setting `warn=True` will log a
    warning when a deprecated name is used.
    """
    for i, name in enumerate(names):
        if hasattr(object, name):
            if warn and i > 0:
                logger.warning_once(
                    "%s contains a deprecated attribute name '%s'. "
                    "Please use the preferred attribute name '%s' instead.",
                    type(object).__name__,
                    name,
                    names[0],
                )
            return getattr(object, name)
    return default_factory() if default_factory is not None else default


def get_attr_docs(cls: type[Any]) -> dict[str, str]:
    """
    Get any docstrings placed after attribute assignments in a class body.

    https://davidism.com/mit-license/
    """

    cls_node = ast.parse(textwrap.dedent(inspect.getsource(cls))).body[0]

    if not isinstance(cls_node, ast.ClassDef):
        raise TypeError("Given object was not a class.")

    out = {}

    # Consider each pair of nodes.
    for a, b in pairwise(cls_node.body):
        # Must be an assignment then a constant string.
        if (
            not isinstance(a, (ast.Assign, ast.AnnAssign))
            or not isinstance(b, ast.Expr)
            or not isinstance(b.value, ast.Constant)
            or not isinstance(b.value.value, str)
        ):
            continue

        doc = inspect.cleandoc(b.value.value)

        # An assignment can have multiple targets (a = b = v), but an
        # annotated assignment only has one target.
        targets = a.targets if isinstance(a, ast.Assign) else [a.target]

        for target in targets:
            # Must be assigning to a plain name.
            if not isinstance(target, ast.Name):
                continue

            out[target.id] = doc

    return out


@runtime_checkable
class SupportsHash(Protocol):
    def compute_hash(self) -> str: ...


class SupportsMetricsInfo(Protocol):
    def metrics_info(self) -> dict[str, str]: ...


def update_config(config: ConfigT, overrides: dict[str, Any]) -> ConfigT:
    processed_overrides = {}
    for field_name, value in overrides.items():
        assert hasattr(config, field_name), (
            f"{type(config)} has no field `{field_name}`"
        )
        current_value = getattr(config, field_name)
        if is_dataclass(current_value) and not is_dataclass(value):
            assert isinstance(value, dict), (
                f"Overrides to {type(config)}.{field_name} must be a dict"
                f"  or {type(current_value)}, but got {type(value)}"
            )
            value = update_config(
                current_value,  # type: ignore[type-var]
                value,
            )
        processed_overrides[field_name] = value
    return replace(config, **processed_overrides)


def normalize_value(x):
    """Return a stable, JSON-serializable canonical form for hashing.
    Order: primitives, special types (Enum, callable, torch.dtype, Path), then
    generic containers (Mapping/Set/Sequence) with recursion.
    """
    # Fast path
    if x is None or isinstance(x, (bool, int, float, str)):
        return x

    # Enums: tag with FQN to avoid primitive collisions.
    # Ex: Enum(1) vs int(1) -> ("module.QualName", value).
    if isinstance(x, enum.Enum):
        enum_type = f"{x.__class__.__module__}.{x.__class__.__qualname__}"
        return (enum_type, normalize_value(x.value))

    # Classes (types) are accepted and canonicalized by their fully-qualified
    # name (module.qualname) for a stable identifier.
    # Instances are only accepted if they expose uuid(); otherwise they are
    # rejected to avoid under-hashing object state.

    # Callables: accept classes only; reject funcs/lambdas/methods.
    # Used by LogitsProcessor types and ModelConfig.hf_overrides.
    if isinstance(x, type):
        module = getattr(x, "__module__", "")
        qual = getattr(x, "__qualname__", getattr(x, "__name__", ""))
        return ".".join([p for p in (module, qual) if p]) or repr(x)

    # Prefer stable uuid identifiers for objects that provide them, even if
    # they are callable instances (e.g., InductorPass wrappers).
    if hasattr(x, "uuid") and callable(getattr(x, "uuid", None)):
        return x.uuid()

    if callable(x):
        raise TypeError("normalize_value: function or callable instance unsupported")

    # Torch dtype: stringify (torch.float64 -> "torch.float64").
    # We rely on the string form here; dtype-bearing fields that need additional
    # disambiguation should encode that at the config layer.
    if isinstance(x, torch.dtype):
        return str(x)

    # Bytes
    if isinstance(x, (bytes, bytearray)):
        return x.hex()

    # Paths (canonicalize)
    if isinstance(x, pathlib.Path):
        try:
            return str(x.expanduser().resolve())
        except Exception:
            return str(x)

    # Dataclasses: represent as (FQN, sorted(field,value) tuple) for stability.
    if is_dataclass(x):
        type_fqn = f"{x.__class__.__module__}.{x.__class__.__qualname__}"
        items = tuple(
            (f.name, normalize_value(getattr(x, f.name)))
            for f in sorted(fields(x), key=lambda f: f.name)
        )
        return (type_fqn, items)

    # Containers (generic)
    if isinstance(x, Mapping):
        return tuple(sorted((str(k), normalize_value(v)) for k, v in x.items()))
    if isinstance(x, Set):
        return tuple(sorted(repr(normalize_value(v)) for v in x))
    if isinstance(x, Sequence) and not isinstance(x, (str, bytes, bytearray)):
        return tuple(normalize_value(v) for v in x)

    # PretrainedConfig
    if hasattr(x, "to_json_string") and callable(x.to_json_string):
        return x.to_json_string()

    # Unsupported type: e.g., modules, generators, open files, or objects
    # without a stable JSON/UUID representation. Hard-error to avoid
    # under-hashing.
    # If you hit this, either reshape your config to use supported primitives
    # and containers, or extend normalize_value to provide a stable encoding
    # (e.g., via uuid() or to_json_string()) for this type.
    raise TypeError(
        f"normalize_value: unsupported type '{type(x).__name__}'. "
        "Ensure config values use supported primitives/containers or add a "
        "stable representation for this type."
    )


def get_hash_factors(config: ConfigT, ignored_factors: set[str]) -> dict[str, object]:
    """Gets the factors used for hashing a config class.
    - Includes all dataclass fields not in `ignored_factors`.
    - Errors on non-normalizable values.
    """
    factors: dict[str, object] = {}
    for dc_field in fields(config):
        factor = dc_field.name
        if factor in ignored_factors:
            continue
        value = getattr(config, factor, None)
        try:
            factors[factor] = normalize_value(value)
        except TypeError as e:
            raise TypeError(
                f"get_hash_factors: unsupported type for key '{factor}' "
                f"({type(value).__name__})"
            ) from e
    return factors


def hash_factors(items: dict[str, object]) -> str:
    """Return a SHA-256 hex digest of the canonical items structure."""
    return hashlib.sha256(json.dumps(items, sort_keys=True).encode()).hexdigest()


@dataclass
class Range:
    """
    A range of numbers.
    Inclusive of start, inclusive of end.
    """

    start: int
    end: int

    def is_single_size(self) -> bool:
        return self.start == self.end

    def __contains__(self, size: int) -> bool:
        # Inclusive of start, inclusive of end
        return self.start <= size <= self.end

    def __eq__(self, other: object) -> bool:
        if not isinstance(other, Range):
            return False
        return self.start == other.start and self.end == other.end

    def __hash__(self) -> int:
        return hash((self.start, self.end))

    def __str__(self) -> str:
        return f"({self.start}, {self.end})"

    def __repr__(self) -> str:
        return self.__str__()


def handle_deprecated(
    config: ConfigT,
    old_name: str,
    new_name_or_names: str | list[str],
    removal_version: str,
) -> None:
    old_val = getattr(config, old_name)
    if old_val is None:
        return

    if isinstance(new_name_or_names, str):
        new_names = [new_name_or_names]
    else:
        new_names = new_name_or_names

    msg = (
        f"{old_name} is deprecated and will be removed in {removal_version}. "
        f"Use {', '.join(new_names)} instead."
    )
    logger.warning(msg)

    for new_name in new_names:
        setattr(config, new_name, old_val)
