1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168

//! Authentication for Google API endpoints
//!
//! Allows users to provide custom authentication implementations to suite their needs.
//!
//! By default, [`GetToken`] is implemented for:
//! - [`Authenticator`] : An authenticator which supports a variety of authentication methods
//! - [`String`] : Plain oauth2 token in String format
//! - [`NoToken`] : No token, used for APIs which do not require a token
//!
//! # Usage
//! [`GetToken`] instances are designed to be used with the Hub constructor provided by the
//! generated APIs.
//!
//! If you intend to use the API libraries on client devices,
//! [`Authenticator`] supports a variety of client-side authentication methods,
//! and should be used to provide authentication.
//!
//! If you intend to use the API libraries server-side, with server-side client authentication,
//! use the [`oauth2`] crate and convert the resulting [`AccessToken`] to [`String`].
//!
//! If you intend to use APIs which do not require authentication, use [`NoToken`].
//!
//! If you have custom authentication requirements, you can implement [`GetToken`] manually.
//!
//! # Example
//! ```rust
//! use core::future::Future;
//! use core::pin::Pin;
//!
//! use google_apis_common::{GetToken, oauth2};
//!
//! use http::Uri;
//! use hyper::client::connect::Connection;
//! use tokio::io::{AsyncRead, AsyncWrite};
//! use tower_service::Service;
//! use oauth2::authenticator::Authenticator;
//!
//! #[derive(Clone)]
//! struct AuthenticatorWithRetry<S> {
//!     auth: Authenticator<S>,
//!     retries: usize,
//! }
//!
//! impl<S> GetToken for AuthenticatorWithRetry<S>
//! where
//!     S: Service<Uri> + Clone + Send + Sync + 'static,
//!     S::Response: Connection + AsyncRead + AsyncWrite + Send + Unpin + 'static,
//!     S::Future: Send + Unpin + 'static,
//!     S::Error: Into<Box<dyn std::error::Error + Send + Sync>>,
//! {
//!     fn get_token<'a>(
//!         &'a self,
//!         scopes: &'a [&str],
//!     ) -> Pin<Box<dyn Future<Output = Result<Option<String>, Box<dyn std::error::Error + Send + Sync>>> + Send + 'a>> {
//!         Box::pin(async move {
//!             let mut auth_token = Ok(None);
//!             for _ in 0..=self.retries {
//!                 match self.auth.token(scopes).await {
//!                     Ok(token) => {
//!                         auth_token = Ok(token.token().map(|t| t.to_owned()));
//!                         break;
//!                     },
//!                     Err(e) => auth_token = Err(e.into()),
//!                 }
//!             }
//!             auth_token
//!         })
//!     }
//! }
//! ```
//! [`oauth2`]: https://docs.rs/oauth2/latest/oauth2/
//! [`AccessToken`]: https://docs.rs/oauth2/latest/oauth2/struct.AccessToken.html
//! [`Authenticator`]: yup_oauth2::authenticator::Authenticator
use std::future::Future;
use std::pin::Pin;

type GetTokenOutput<'a> = Pin<
    Box<
        dyn Future<Output = Result<Option<String>, Box<dyn std::error::Error + Send + Sync>>>
            + Send
            + 'a,
    >,
>;

pub trait GetToken: GetTokenClone + Send + Sync {
    /// Called whenever an API call requires authentication via an oauth2 token.
    /// Returns `Ok(None)` if a token is not necessary - otherwise, returns an error
    /// indicating the reason why a token could not be produced.
    fn get_token<'a>(&'a self, _scopes: &'a [&str]) -> GetTokenOutput<'a>;
}

pub trait GetTokenClone {
    fn clone_box(&self) -> Box<dyn GetToken>;
}

impl<T> GetTokenClone for T
where
    T: 'static + GetToken + Clone,
{
    fn clone_box(&self) -> Box<dyn GetToken> {
        Box::new(self.clone())
    }
}

impl Clone for Box<dyn GetToken> {
    fn clone(&self) -> Box<dyn GetToken> {
        self.clone_box()
    }
}

impl GetToken for String {
    fn get_token<'a>(&'a self, _scopes: &'a [&str]) -> GetTokenOutput<'a> {
        Box::pin(async move { Ok(Some(self.clone())) })
    }
}

/// In the event that the API endpoint does not require an oauth2 token, `NoToken` should be provided to the hub to avoid specifying an
/// authenticator.
#[derive(Default, Clone)]
pub struct NoToken;

impl GetToken for NoToken {
    fn get_token<'a>(&'a self, _scopes: &'a [&str]) -> GetTokenOutput<'a> {
        Box::pin(async move { Ok(None) })
    }
}

#[cfg(feature = "yup-oauth2")]
mod yup_oauth2_impl {
    use super::{GetToken, GetTokenOutput};

    use http::Uri;
    use hyper::client::connect::Connection;
    use tokio::io::{AsyncRead, AsyncWrite};
    use tower_service::Service;
    use yup_oauth2::authenticator::Authenticator;

    impl<S> GetToken for Authenticator<S>
    where
        S: Service<Uri> + Clone + Send + Sync + 'static,
        S::Response: Connection + AsyncRead + AsyncWrite + Send + Unpin + 'static,
        S::Future: Send + Unpin + 'static,
        S::Error: Into<Box<dyn std::error::Error + Send + Sync>>,
    {
        fn get_token<'a>(&'a self, scopes: &'a [&str]) -> GetTokenOutput<'a> {
            Box::pin(async move {
                self.token(scopes)
                    .await
                    .map(|t| t.token().map(|t| t.to_owned()))
                    .map_err(|e| e.into())
            })
        }
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn dyn_get_token_is_send() {
        fn with_send(_x: impl Send) {}

        let mut gt = String::new();
        let dgt: &mut dyn GetToken = &mut gt;
        with_send(dgt);
    }
}