from __future__ import annotations

import enum
import threading
from abc import abstractmethod
from typing import (
    Any,
    AsyncIterator,
    Callable,
    Dict,
    Iterator,
    List,
    Optional,
    Sequence,
    Tuple,
    Type,
    Union,
    cast,
)
from weakref import WeakValueDictionary

from langchain_core.pydantic_v1 import BaseModel
from langchain_core.runnables.base import Runnable, RunnableSerializable
from langchain_core.runnables.config import (
    RunnableConfig,
    ensure_config,
    get_config_list,
    get_executor_for_config,
)
from langchain_core.runnables.graph import Graph
from langchain_core.runnables.utils import (
    AnyConfigurableField,
    ConfigurableField,
    ConfigurableFieldMultiOption,
    ConfigurableFieldSingleOption,
    ConfigurableFieldSpec,
    Input,
    Output,
    gather_with_concurrency,
    get_unique_config_specs,
)


class DynamicRunnable(RunnableSerializable[Input, Output]):
    """A Serializable Runnable that can be dynamically configured."""

    default: RunnableSerializable[Input, Output]

    class Config:
        arbitrary_types_allowed = True

    @classmethod
    def is_lc_serializable(cls) -> bool:
        return True

    @classmethod
    def get_lc_namespace(cls) -> List[str]:
        """Get the namespace of the langchain object."""
        return ["langchain", "schema", "runnable"]

    @property
    def InputType(self) -> Type[Input]:
        return self.default.InputType

    @property
    def OutputType(self) -> Type[Output]:
        return self.default.OutputType

    def get_input_schema(
        self, config: Optional[RunnableConfig] = None
    ) -> Type[BaseModel]:
        runnable, config = self._prepare(config)
        return runnable.get_input_schema(config)

    def get_output_schema(
        self, config: Optional[RunnableConfig] = None
    ) -> Type[BaseModel]:
        runnable, config = self._prepare(config)
        return runnable.get_output_schema(config)

    def get_graph(self, config: Optional[RunnableConfig] = None) -> Graph:
        runnable, config = self._prepare(config)
        return runnable.get_graph(config)

    @abstractmethod
    def _prepare(
        self, config: Optional[RunnableConfig] = None
    ) -> Tuple[Runnable[Input, Output], RunnableConfig]:
        ...

    def invoke(
        self, input: Input, config: Optional[RunnableConfig] = None, **kwargs: Any
    ) -> Output:
        runnable, config = self._prepare(config)
        return runnable.invoke(input, config, **kwargs)

    async def ainvoke(
        self, input: Input, config: Optional[RunnableConfig] = None, **kwargs: Any
    ) -> Output:
        runnable, config = self._prepare(config)
        return await runnable.ainvoke(input, config, **kwargs)

    def batch(
        self,
        inputs: List[Input],
        config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
        *,
        return_exceptions: bool = False,
        **kwargs: Optional[Any],
    ) -> List[Output]:
        configs = get_config_list(config, len(inputs))
        prepared = [self._prepare(c) for c in configs]

        if all(p is self.default for p, _ in prepared):
            return self.default.batch(
                inputs,
                [c for _, c in prepared],
                return_exceptions=return_exceptions,
                **kwargs,
            )

        if not inputs:
            return []

        def invoke(
            prepared: Tuple[Runnable[Input, Output], RunnableConfig],
            input: Input,
        ) -> Union[Output, Exception]:
            bound, config = prepared
            if return_exceptions:
                try:
                    return bound.invoke(input, config, **kwargs)
                except Exception as e:
                    return e
            else:
                return bound.invoke(input, config, **kwargs)

        # If there's only one input, don't bother with the executor
        if len(inputs) == 1:
            return cast(List[Output], [invoke(prepared[0], inputs[0])])

        with get_executor_for_config(configs[0]) as executor:
            return cast(List[Output], list(executor.map(invoke, prepared, inputs)))

    async def abatch(
        self,
        inputs: List[Input],
        config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
        *,
        return_exceptions: bool = False,
        **kwargs: Optional[Any],
    ) -> List[Output]:
        configs = get_config_list(config, len(inputs))
        prepared = [self._prepare(c) for c in configs]

        if all(p is self.default for p, _ in prepared):
            return await self.default.abatch(
                inputs,
                [c for _, c in prepared],
                return_exceptions=return_exceptions,
                **kwargs,
            )

        if not inputs:
            return []

        async def ainvoke(
            prepared: Tuple[Runnable[Input, Output], RunnableConfig],
            input: Input,
        ) -> Union[Output, Exception]:
            bound, config = prepared
            if return_exceptions:
                try:
                    return await bound.ainvoke(input, config, **kwargs)
                except Exception as e:
                    return e
            else:
                return await bound.ainvoke(input, config, **kwargs)

        coros = map(ainvoke, prepared, inputs)
        return await gather_with_concurrency(configs[0].get("max_concurrency"), *coros)

    def stream(
        self,
        input: Input,
        config: Optional[RunnableConfig] = None,
        **kwargs: Optional[Any],
    ) -> Iterator[Output]:
        runnable, config = self._prepare(config)
        return runnable.stream(input, config, **kwargs)

    async def astream(
        self,
        input: Input,
        config: Optional[RunnableConfig] = None,
        **kwargs: Optional[Any],
    ) -> AsyncIterator[Output]:
        runnable, config = self._prepare(config)
        async for chunk in runnable.astream(input, config, **kwargs):
            yield chunk

    def transform(
        self,
        input: Iterator[Input],
        config: Optional[RunnableConfig] = None,
        **kwargs: Optional[Any],
    ) -> Iterator[Output]:
        runnable, config = self._prepare(config)
        return runnable.transform(input, config, **kwargs)

    async def atransform(
        self,
        input: AsyncIterator[Input],
        config: Optional[RunnableConfig] = None,
        **kwargs: Optional[Any],
    ) -> AsyncIterator[Output]:
        runnable, config = self._prepare(config)
        async for chunk in runnable.atransform(input, config, **kwargs):
            yield chunk


class RunnableConfigurableFields(DynamicRunnable[Input, Output]):
    """A Runnable that can be dynamically configured."""

    fields: Dict[str, AnyConfigurableField]

    @classmethod
    def get_lc_namespace(cls) -> List[str]:
        """Get the namespace of the langchain object."""
        return ["langchain", "schema", "runnable"]

    @property
    def config_specs(self) -> List[ConfigurableFieldSpec]:
        return get_unique_config_specs(
            [
                ConfigurableFieldSpec(
                    id=spec.id,
                    name=spec.name,
                    description=spec.description
                    or self.default.__fields__[field_name].field_info.description,
                    annotation=spec.annotation
                    or self.default.__fields__[field_name].annotation,
                    default=getattr(self.default, field_name),
                    is_shared=spec.is_shared,
                )
                if isinstance(spec, ConfigurableField)
                else make_options_spec(
                    spec, self.default.__fields__[field_name].field_info.description
                )
                for field_name, spec in self.fields.items()
            ]
            + list(self.default.config_specs)
        )

    def configurable_fields(
        self, **kwargs: AnyConfigurableField
    ) -> RunnableSerializable[Input, Output]:
        return self.default.configurable_fields(**{**self.fields, **kwargs})

    def _prepare(
        self, config: Optional[RunnableConfig] = None
    ) -> Tuple[Runnable[Input, Output], RunnableConfig]:
        config = ensure_config(config)
        specs_by_id = {spec.id: (key, spec) for key, spec in self.fields.items()}
        configurable_fields = {
            specs_by_id[k][0]: v
            for k, v in config.get("configurable", {}).items()
            if k in specs_by_id and isinstance(specs_by_id[k][1], ConfigurableField)
        }
        configurable_single_options = {
            k: v.options[(config.get("configurable", {}).get(v.id) or v.default)]
            for k, v in self.fields.items()
            if isinstance(v, ConfigurableFieldSingleOption)
        }
        configurable_multi_options = {
            k: [
                v.options[o]
                for o in config.get("configurable", {}).get(v.id, v.default)
            ]
            for k, v in self.fields.items()
            if isinstance(v, ConfigurableFieldMultiOption)
        }
        configurable = {
            **configurable_fields,
            **configurable_single_options,
            **configurable_multi_options,
        }

        if configurable:
            return (
                self.default.__class__(**{**self.default.__dict__, **configurable}),
                config,
            )
        else:
            return (self.default, config)


# Before Python 3.11 native StrEnum is not available
class StrEnum(str, enum.Enum):
    """A string enum."""

    pass


_enums_for_spec: WeakValueDictionary[
    Union[
        ConfigurableFieldSingleOption, ConfigurableFieldMultiOption, ConfigurableField
    ],
    Type[StrEnum],
] = WeakValueDictionary()

_enums_for_spec_lock = threading.Lock()


class RunnableConfigurableAlternatives(DynamicRunnable[Input, Output]):
    """A Runnable that can be dynamically configured."""

    which: ConfigurableField

    alternatives: Dict[
        str,
        Union[Runnable[Input, Output], Callable[[], Runnable[Input, Output]]],
    ]

    default_key: str = "default"
    """The enum value to use for the default option. Defaults to "default"."""

    prefix_keys: bool
    """Whether to prefix configurable fields of each alternative with a namespace
    of the form <which.id>==<alternative_key>, eg. a key named "temperature" used by 
    the alternative named "gpt3" becomes "model==gpt3/temperature"."""

    @classmethod
    def get_lc_namespace(cls) -> List[str]:
        """Get the namespace of the langchain object."""
        return ["langchain", "schema", "runnable"]

    @property
    def config_specs(self) -> List[ConfigurableFieldSpec]:
        with _enums_for_spec_lock:
            if which_enum := _enums_for_spec.get(self.which):
                pass
            else:
                which_enum = StrEnum(  # type: ignore[call-overload]
                    self.which.name or self.which.id,
                    (
                        (v, v)
                        for v in list(self.alternatives.keys()) + [self.default_key]
                    ),
                )
                _enums_for_spec[self.which] = cast(Type[StrEnum], which_enum)
        return get_unique_config_specs(
            # which alternative
            [
                ConfigurableFieldSpec(
                    id=self.which.id,
                    name=self.which.name,
                    description=self.which.description,
                    annotation=which_enum,
                    default=self.default_key,
                    is_shared=self.which.is_shared,
                ),
            ]
            # config specs of the default option
            + (
                [
                    prefix_config_spec(s, f"{self.which.id}=={self.default_key}")
                    for s in self.default.config_specs
                ]
                if self.prefix_keys
                else self.default.config_specs
            )
            # config specs of the alternatives
            + [
                prefix_config_spec(s, f"{self.which.id}=={alt_key}")
                if self.prefix_keys
                else s
                for alt_key, alt in self.alternatives.items()
                if isinstance(alt, RunnableSerializable)
                for s in alt.config_specs
            ]
        )

    def configurable_fields(
        self, **kwargs: AnyConfigurableField
    ) -> RunnableSerializable[Input, Output]:
        return self.__class__(
            which=self.which,
            default=self.default.configurable_fields(**kwargs),
            alternatives=self.alternatives,
        )

    def _prepare(
        self, config: Optional[RunnableConfig] = None
    ) -> Tuple[Runnable[Input, Output], RunnableConfig]:
        config = ensure_config(config)
        which = config.get("configurable", {}).get(self.which.id, self.default_key)
        # remap configurable keys for the chosen alternative
        if self.prefix_keys:
            config = cast(
                RunnableConfig,
                {
                    **config,
                    "configurable": {
                        _strremoveprefix(k, f"{self.which.id}=={which}/"): v
                        for k, v in config.get("configurable", {}).items()
                    },
                },
            )
        # return the chosen alternative
        if which == self.default_key:
            return (self.default, config)
        elif which in self.alternatives:
            alt = self.alternatives[which]
            if isinstance(alt, Runnable):
                return (alt, config)
            else:
                return (alt(), config)
        else:
            raise ValueError(f"Unknown alternative: {which}")


def _strremoveprefix(s: str, prefix: str) -> str:
    """str.removeprefix() is only available in Python 3.9+."""
    return s.replace(prefix, "", 1) if s.startswith(prefix) else s


def prefix_config_spec(
    spec: ConfigurableFieldSpec, prefix: str
) -> ConfigurableFieldSpec:
    """Prefix the id of a ConfigurableFieldSpec.

    This is useful when a RunnableConfigurableAlternatives is used as a
    ConfigurableField of another RunnableConfigurableAlternatives.

    Args:
        spec: The ConfigurableFieldSpec to prefix.
        prefix: The prefix to add.

    Returns:

    """
    return (
        ConfigurableFieldSpec(
            id=f"{prefix}/{spec.id}",
            name=spec.name,
            description=spec.description,
            annotation=spec.annotation,
            default=spec.default,
            is_shared=spec.is_shared,
        )
        if not spec.is_shared
        else spec
    )


def make_options_spec(
    spec: Union[ConfigurableFieldSingleOption, ConfigurableFieldMultiOption],
    description: Optional[str],
) -> ConfigurableFieldSpec:
    """Make a ConfigurableFieldSpec for a ConfigurableFieldSingleOption or
    ConfigurableFieldMultiOption."""
    with _enums_for_spec_lock:
        if enum := _enums_for_spec.get(spec):
            pass
        else:
            enum = StrEnum(  # type: ignore[call-overload]
                spec.name or spec.id,
                ((v, v) for v in list(spec.options.keys())),
            )
            _enums_for_spec[spec] = cast(Type[StrEnum], enum)
    if isinstance(spec, ConfigurableFieldSingleOption):
        return ConfigurableFieldSpec(
            id=spec.id,
            name=spec.name,
            description=spec.description or description,
            annotation=enum,
            default=spec.default,
            is_shared=spec.is_shared,
        )
    else:
        return ConfigurableFieldSpec(
            id=spec.id,
            name=spec.name,
            description=spec.description or description,
            annotation=Sequence[enum],  # type: ignore[valid-type]
            default=spec.default,
            is_shared=spec.is_shared,
        )
