"""This module implements the auth layer."""

# Third-party imports
from requests import auth

# Local imports
from uplink import utils
from uplink.compat import abc

__all__ = [
    "ApiTokenHeader",
    "ApiTokenParam",
    "BasicAuth",
    "BearerToken",
    "MultiAuth",
    "ProxyAuth",
]


def get_auth(auth_object=None):
    if auth_object is None:
        return utils.no_op
    if isinstance(auth_object, abc.Iterable):
        return BasicAuth(*auth_object)
    if callable(auth_object):
        return auth_object
    raise ValueError(f"Invalid authentication strategy: {auth_object}")


class ApiTokenParam:
    """
    Authorizes requests using a token or key in a query parameter.

    Users may use this directly, or API library authors may subclass this
    to predefine the query parameter name to use. If supplying query parameter
    name on a subclass, define the `_param` property or attribute and
    override `__init__()` without using `super()`.

    Examples:
        Direct use:
            ```python
            token_param = ApiTokenParam(QUERY_PARAM_NAME, TOKEN)
            api_consumer = SomeApiConsumerClass(BASE_URL, auth=token_param)
            ```

        Subclass in API library:
            ```python
            class ExampleApiTokenParam(ApiTokenParam):
                _param = "api-token"
                def __init__(self, token):
                    self._param_value = token

            # using the subclass
            token_param = ExampleApiTokenParam(TOKEN)
            api_consumer = SomeApiConsumerClass(BASE_URL, auth=token_param)
            ```
    """

    def __init__(self, param, token):
        self._param = param
        self._param_value = token

    def __call__(self, request_builder):
        request_builder.info["params"][self._param] = self._param_value


class ApiTokenHeader:
    """
    Authorizes requests using a token or key in a header.
    Users should subclass this class to define which header is the token header.
    The subclass may also, optionally, define a token prefix (such as in BearerToken)

    Users may use this directly, or API library authors may subclass this
    to predefine the header name or a prefix to use. If supplying header name or prefix
    in a subclass, define the `_header` and/or `_prefix` properties or attributes
    and override `__init__()` without using `super()`.

    Examples:
        Direct use:
            ```python
            token_header = ApiTokenHeader(HEADER_NAME, TOKEN)
            api_consumer = SomeApiConsumerClass(BASE_URL, auth=token_header)
            ```

        Subclass in API library with a prefix:
            ```python
            class ExampleApiTokenHeader(ApiTokenHeader):
                _header = "X-Api-Token"
                def __init__(self, token):
                    self._token = token

            # using the subclass
            token_header = ExampleApiTokenHeader(TOKEN)
            api_consumer = SomeApiConsumerClass(BASE_URL, auth=token_header)
            ```

        Subclass in API library with a prefix:
            ```python
            class ExampleApiTokenHeader(ApiTokenHeader):
                _header = "X-App-Id"
                _prefix = "APP"
                def __init__(self, token):
                    self._token = token

            # using the subclass
            token_header = ExampleApiTokenHeader(TOKEN)
            api_consumer = SomeApiConsumerClass(BASE_URL, auth=token_header)
            ```
    """

    _header = None
    _prefix = None

    def __init__(self, header, token, prefix=None):
        self._header = header
        self._prefix = prefix
        self._token = token

    @property
    def _header_value(self):
        if self._prefix:
            return f"{self._prefix} {self._token}"
        return self._token

    def __call__(self, request_builder):
        request_builder.info["headers"][self._header] = self._header_value


class BasicAuth(ApiTokenHeader):
    """
    Authorizes requests using HTTP Basic Authentication.

    There are two ways to use BasicAuth with a Consumer:

    ```python
    # implicit BasicAuth
    github = Github(BASE_URL, auth=(USER, PASS))

    # explicit BasicAuth
    github = GitHub(BASE_URL, auth=BasicAuth(USER, PASS))
    ```
    """

    _header = "Authorization"

    def __init__(self, username, password):
        self._username = username
        self._password = password

    @property
    def _header_value(self):
        return auth._basic_auth_str(self._username, self._password)


class ProxyAuth(BasicAuth):
    """
    Authorizes requests with an intermediate HTTP proxy.

    If both API auth and intermediate Proxy auth are required,
    wrap ProxyAuth in MultiAuth:

    ```python
    # only ProxyAuth
    github = Github(BASE_URL, auth=ProxyAuth(PROXYUSER, PROXYPASS))

    # both BasicAuth and ProxyAuth
    auth_methods = MultiAuth(
        BasicAuth(USER, PASS),
        ProxyAuth(PROXYUSER, PROXYPASS)
    )
    github = GitHub(BASE_URL, auth=auth_methods)
    ```
    """

    _header = "Proxy-Authorization"


class BearerToken(ApiTokenHeader):
    """
    Authorizes requests using a Bearer Token.

    ```python
    token = something_like_oauth_that_returns_a_token()
    bearer = BearerToken(token)
    api_consumer = SomeApiConsumerClass(BASE_URL, auth=bearer)
    ```
    """

    _header = "Authorization"
    _prefix = "Bearer"

    def __init__(self, token):
        self._token = token


class MultiAuth:
    """
    Authorizes requests using multiple auth methods at the same time.

    This is useful for API users to supply both API credentials and
    intermediary credentials (such as for a proxy).

    ```python
    auth_methods = MultiAuth(
        BasicAuth(USER, PASS),
        ProxyAuth(PROXY_USER, PROXY_PASS)
    )
    api_consumer = SomeApiConsumerClass(BASE_URL, auth=auth_methods)
    ```

    This may also be used if an API requires multiple Auth Tokens.

    ```python
    auth_methods = MultiAuth(
        BearerToken(API_TOKEN),
        ApiTokenParam(QUERY_PARAMETER_NAME, QUERY_PARAMETER_VALUE),
        ApiTokenHeader(API_HEADER_NAME, API_TOKEN_2)
    )
    api_consumer = SomeApiConsumerClass(BASE_URL, auth=auth_methods)
    ```

    API library authors may find it more helpful to treat MultiAuth as
    a list using `append` or `extend` to add aditional auth methods.

    ```python
    auth_methods = MultiAuth()

    auth_methods.append(BearerToken(API_TOKEN))
    auth_methods.extend([
        ApiTokenParam(QUERY_PARAMETER_NAME, QUERY_PARAMETER_VALUE),
        ApiTokenHeader(API_HEADER_NAME, API_TOKEN_2)
    ])
    api_consumer = SomeApiConsumerClass(BASE_URL, auth=auth_methods)

    # looping over contained auth methods is also supported
    for method in auth_methods:
        print(method.__class__.__name__)
    ```
    """

    def __init__(self, *auth_methods):
        self._auth_methods = [get_auth(auth_method) for auth_method in auth_methods]

    def __call__(self, request_builder):
        for auth_method in self._auth_methods:
            auth_method(request_builder)

    def __getitem__(self, index):
        return self._auth_methods[index]

    def __len__(self):
        return len(self._auth_methods)

    def append(self, auth_method):
        self._auth_methods.append(get_auth(auth_method))

    def extend(self, auth_methods):
        self._auth_methods.extend(
            [get_auth(auth_method) for auth_method in auth_methods]
        )