#  Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
#  SPDX-License-Identifier: Apache-2.0
from collections.abc import Iterator
from dataclasses import dataclass
from enum import Enum
from typing import Protocol


class FieldPosition(Enum):
    """The type of a field.

    Defines its placement in a request or response.
    """

    HEADER = 0
    """Header field.

    In HTTP this is a header as defined in RFC 9110 Section 6.3. Implementations of
    other protocols may use this FieldPosition for similar types of metadata.
    """

    TRAILER = 1
    """Trailer field.

    In HTTP this is a trailer as defined in RFC 9110 Section 6.5. Implementations of
    other protocols may use this FieldPosition for similar types of metadata.
    """


class Field(Protocol):
    """A name-value pair representing a single field in a request or response.

    The kind will dictate metadata placement within an the message, for example as
    header or trailer field in a HTTP request as defined in RFC 9110 Section 5.

    All field names are case insensitive and case-variance must be treated as
    equivalent. Names may be normalized but should be preserved for accuracy during
    transmission.
    """

    name: str
    values: list[str]
    kind: FieldPosition = FieldPosition.HEADER

    def add(self, value: str) -> None:
        """Append a value to a field."""
        ...

    def set(self, values: list[str]) -> None:
        """Overwrite existing field values."""
        ...

    def remove(self, value: str) -> None:
        """Remove all matching entries from list."""
        ...

    def as_string(self) -> str:
        """Serialize the ``Field``'s values into a single line string."""
        ...

    def as_tuples(self) -> list[tuple[str, str]]:
        """Get list of ``name``, ``value`` tuples where each tuple represents one
        value."""
        ...


class Fields(Protocol):
    """Protocol agnostic mapping of key-value pair request metadata, such as HTTP
    fields."""

    # Entries are keyed off the name of a provided Field
    entries: dict[str, Field]
    encoding: str = "utf-8"

    def set_field(self, field: Field) -> None:
        """Alias for __setitem__ to utilize the field.name for the entry key."""
        ...

    def __setitem__(self, name: str, field: Field) -> None:
        """Set entry for a Field name."""
        ...

    def __getitem__(self, name: str) -> Field:
        """Retrieve Field entry."""
        ...

    def __delitem__(self, name: str) -> None:
        """Delete entry from collection."""
        ...

    def __iter__(self) -> Iterator[Field]:
        """Allow iteration over entries."""
        ...

    def __len__(self) -> int:
        """Get total number of Field entries."""
        ...

    def __contains__(self, key: str) -> bool:
        """Allows in/not in checks on Field entries."""
        ...

    def get_by_type(self, kind: FieldPosition) -> list[Field]:
        """Helper function for retrieving specific types of fields.

        Used to grab all headers or all trailers.
        """
        ...

    def extend(self, other: "Fields") -> None:
        """Merges ``entries`` of ``other`` into the current ``entries``.

        For every `Field` in the ``entries`` of ``other``: If the normalized name
        already exists in the current ``entries``, the values from ``other`` are
        appended. Otherwise, the ``Field`` is added to the list of ``entries``.
        """
        ...


QueryParamsList = list[tuple[str, str]]


@dataclass(kw_only=True)
class HTTPClientConfiguration:
    """Client-level HTTP configuration.

    :param force_http_2: Whether to require HTTP/2.
    """

    force_http_2: bool = False


@dataclass(kw_only=True)
class HTTPRequestConfiguration:
    """Request-level HTTP configuration.

    :param read_timeout: How long, in seconds, the client will attempt to read the first
        byte over an established, open connection before timing out.
    """

    read_timeout: float | None = None