from __future__ import annotations as _annotations

import inspect
import warnings
from pathlib import Path
from typing import Annotated, Any, Literal

from pydantic import Field, model_validator
from pydantic.fields import FieldInfo
from pydantic_settings import (
    BaseSettings,
    EnvSettingsSource,
    PydanticBaseSettingsSource,
    SettingsConfigDict,
)
from typing_extensions import Self

LOG_LEVEL = Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"]

DuplicateBehavior = Literal["warn", "error", "replace", "ignore"]


class ExtendedEnvSettingsSource(EnvSettingsSource):
    """
    A special EnvSettingsSource that allows for multiple env var prefixes to be used.

    Raises a deprecation warning if the old `FASTMCP_SERVER_` prefix is used.
    """

    def get_field_value(
        self, field: FieldInfo, field_name: str
    ) -> tuple[Any, str, bool]:
        if prefixes := self.config.get("env_prefixes"):
            for prefix in prefixes:
                self.env_prefix = prefix
                env_val, field_key, value_is_complex = super().get_field_value(
                    field, field_name
                )
                if env_val is not None:
                    if prefix == "FASTMCP_SERVER_":
                        # Deprecated in 2.8.0
                        warnings.warn(
                            "Using `FASTMCP_SERVER_` environment variables is deprecated. Use `FASTMCP_` instead.",
                            DeprecationWarning,
                            stacklevel=2,
                        )
                    return env_val, field_key, value_is_complex

        return super().get_field_value(field, field_name)


class ExtendedSettingsConfigDict(SettingsConfigDict, total=False):
    env_prefixes: list[str] | None


class Settings(BaseSettings):
    """FastMCP settings."""

    model_config = ExtendedSettingsConfigDict(
        env_prefixes=["FASTMCP_", "FASTMCP_SERVER_"],
        env_file=".env",
        extra="ignore",
        env_nested_delimiter="__",
        nested_model_default_partial_update=True,
    )

    @classmethod
    def settings_customise_sources(
        cls,
        settings_cls: type[BaseSettings],
        init_settings: PydanticBaseSettingsSource,
        env_settings: PydanticBaseSettingsSource,
        dotenv_settings: PydanticBaseSettingsSource,
        file_secret_settings: PydanticBaseSettingsSource,
    ) -> tuple[PydanticBaseSettingsSource, ...]:
        # can remove this classmethod after deprecated FASTMCP_SERVER_ prefix is
        # removed
        return (
            init_settings,
            ExtendedEnvSettingsSource(settings_cls),
            dotenv_settings,
            file_secret_settings,
        )

    @property
    def settings(self) -> Self:
        """
        This property is for backwards compatibility with FastMCP < 2.8.0,
        which accessed fastmcp.settings.settings
        """
        # Deprecated in 2.8.0
        warnings.warn(
            "Using fastmcp.settings.settings is deprecated. Use fastmcp.settings instead.",
            DeprecationWarning,
            stacklevel=2,
        )
        return self

    home: Path = Path.home() / ".fastmcp"

    test_mode: bool = False
    log_level: LOG_LEVEL = "INFO"
    enable_rich_tracebacks: Annotated[
        bool,
        Field(
            description=inspect.cleandoc(
                """
                If True, will use rich tracebacks for logging.
                """
            )
        ),
    ] = True

    client_raise_first_exceptiongroup_error: Annotated[
        bool,
        Field(
            default=True,
            description=inspect.cleandoc(
                """
                Many MCP components operate in anyio taskgroups, and raise
                ExceptionGroups instead of exceptions. If this setting is True, FastMCP Clients
                will `raise` the first error in any ExceptionGroup instead of raising
                the ExceptionGroup as a whole. This is useful for debugging, but may
                mask other errors.
                """
            ),
        ),
    ] = True

    resource_prefix_format: Annotated[
        Literal["protocol", "path"],
        Field(
            default="path",
            description=inspect.cleandoc(
                """
                When perfixing a resource URI, either use path formatting (resource://prefix/path)
                or protocol formatting (prefix+resource://path). Protocol formatting was the default in FastMCP < 2.4;
                path formatting is current default.
                """
            ),
        ),
    ] = "path"

    tool_attempt_parse_json_args: Annotated[
        bool,
        Field(
            default=False,
            description=inspect.cleandoc(
                """
                Note: this enables a legacy behavior. If True, will attempt to parse
                stringified JSON lists and objects strings in tool arguments before
                passing them to the tool. This is an old behavior that can create
                unexpected type coercion issues, but may be helpful for less powerful
                LLMs that stringify JSON instead of passing actual lists and objects.
                Defaults to False.
                """
            ),
        ),
    ] = False

    client_init_timeout: Annotated[
        float | None,
        Field(
            description="The timeout for the client's initialization handshake, in seconds. Set to None or 0 to disable.",
        ),
    ] = None

    @model_validator(mode="after")
    def setup_logging(self) -> Self:
        """Finalize the settings."""
        from fastmcp.utilities.logging import configure_logging

        configure_logging(
            self.log_level, enable_rich_tracebacks=self.enable_rich_tracebacks
        )

        return self

    # HTTP settings
    host: str = "127.0.0.1"
    port: int = 8000
    sse_path: str = "/sse"
    message_path: str = "/messages/"
    streamable_http_path: str = "/mcp"
    debug: bool = False

    # error handling
    mask_error_details: Annotated[
        bool,
        Field(
            default=False,
            description=inspect.cleandoc(
                """
                If True, error details from user-supplied functions (tool, resource, prompt)
                will be masked before being sent to clients. Only error messages from explicitly
                raised ToolError, ResourceError, or PromptError will be included in responses.
                If False (default), all error details will be included in responses, but prefixed
                with appropriate context.
                """
            ),
        ),
    ] = False

    server_dependencies: Annotated[
        list[str],
        Field(
            default_factory=list,
            description="List of dependencies to install in the server environment",
        ),
    ] = []

    # StreamableHTTP settings
    json_response: bool = False
    stateless_http: bool = (
        False  # If True, uses true stateless mode (new transport per request)
    )

    # Auth settings
    default_auth_provider: Annotated[
        Literal["bearer_env"] | None,
        Field(
            description=inspect.cleandoc(
                """
                Configure the authentication provider. This setting is intended only to
                be used for remote confirugation of providers that fully support
                environment variable configuration.

                If None, no automatic configuration will take place.

                This setting is *always* overriden by any auth provider passed to the
                FastMCP constructor.
                """
            ),
        ),
    ] = None

    include_tags: Annotated[
        set[str] | None,
        Field(
            default=None,
            description=inspect.cleandoc(
                """
                If provided, only components that match these tags will be
                exposed to clients. A component is considered to match if ANY of
                its tags match ANY of the tags in the set.
                """
            ),
        ),
    ] = None
    exclude_tags: Annotated[
        set[str] | None,
        Field(
            default=None,
            description=inspect.cleandoc(
                """
                If provided, components that match these tags will be excluded
                from the server. A component is considered to match if ANY of
                its tags match ANY of the tags in the set.
                """
            ),
        ),
    ] = None


settings = Settings()