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

use std::str::FromStr;

use http::header;
use smallvec::SmallVec;
use unic_langid::LanguageIdentifier;

use crate::{
    error::I18NError,
    i18n::{I18NArgs, I18NBundle, I18NResources},
    FromRequest, Request, RequestBody, Result,
};

type LanguageArray = SmallVec<[LanguageIdentifier; 8]>;

/// An extractor that parses the `Accept-Language` header and negotiates
/// language bundles.
///
/// # Example
///
/// ```
/// use poem::{
///     handler,
///     http::header,
///     i18n::{I18NResources, Locale},
///     test::TestClient,
///     Endpoint, EndpointExt, Request, Route,
/// };
///
/// let resources = I18NResources::builder()
///     .add_ftl("en-US", "hello-world = hello world!")
///     .add_ftl("zh-CN", "hello-world = 你好世界！")
///     .build()
///     .unwrap();
///
/// #[handler]
/// async fn index(locale: Locale) -> String {
///     locale
///         .text("hello-world")
///         .unwrap_or_else(|_| "error".to_string())
/// }
///
/// let app = Route::new().at("/", index).data(resources);
/// let cli = TestClient::new(app);
///
/// # tokio::runtime::Runtime::new().unwrap().block_on(async {
/// let resp = cli
///     .get("/")
///     .header(header::ACCEPT_LANGUAGE, "en-US")
///     .send()
///     .await;
/// resp.assert_status_is_ok();
/// resp.assert_text("hello world!").await;
///
/// let resp = cli
///     .get("/")
///     .header(header::ACCEPT_LANGUAGE, "zh-CN")
///     .send()
///     .await;
/// resp.assert_status_is_ok();
/// resp.assert_text("你好世界！").await;
/// # });
/// ```
pub struct Locale {
    bundle: I18NBundle,
}

impl Locale {
    /// Gets the text with arguments.
    ///
    /// See also: [`I18NBundle::text_with_args`](I18NBundle::text_with_args)
    pub fn text_with_args<'a>(
        &self,
        id: impl AsRef<str>,
        args: impl Into<I18NArgs<'a>>,
    ) -> Result<String, I18NError> {
        self.bundle.text_with_args(id, args)
    }

    /// Gets the text.
    ///
    /// See also: [`I18NBundle::text`](I18NBundle::text)
    pub fn text(&self, id: impl AsRef<str>) -> Result<String, I18NError> {
        self.bundle.text(id)
    }
}

impl<'a> FromRequest<'a> for Locale {
    async fn from_request(req: &'a Request, _body: &mut RequestBody) -> Result<Self> {
        let resources = req
            .extensions()
            .get::<I18NResources>()
            .expect("To use the `Locale` extractor, the `I18NResources` data is required.");

        let accept_languages = req
            .headers()
            .get(header::ACCEPT_LANGUAGE)
            .and_then(|value| value.to_str().ok())
            .map(parse_accept_languages)
            .unwrap_or_default();

        Ok(Self {
            bundle: resources.negotiate_languages(&accept_languages),
        })
    }
}

fn parse_accept_languages(value: &str) -> LanguageArray {
    let mut languages = SmallVec::<[_; 8]>::new();

    for s in value.split(',').map(str::trim) {
        if let Some(res) = parse_language(s) {
            languages.push(res);
        }
    }

    languages.sort_by(|(_, a), (_, b)| b.cmp(a));
    languages
        .into_iter()
        .map(|(language, _)| language)
        .collect()
}

fn parse_language(value: &str) -> Option<(LanguageIdentifier, u16)> {
    let mut parts = value.split(';');
    let name = parts.next()?.trim();
    let quality = match parts.next() {
        Some(quality) => parse_quality(quality).unwrap_or_default(),
        None => 1000,
    };
    let language = LanguageIdentifier::from_str(name).ok()?;
    Some((language, quality))
}

fn parse_quality(value: &str) -> Option<u16> {
    let mut parts = value.split('=');
    let name = parts.next()?.trim();
    if name != "q" {
        return None;
    }
    let q = parts.next()?.trim().parse::<f32>().ok()?;
    Some((q.clamp(0.0, 1.0) * 1000.0) as u16)
}

#[cfg(test)]
mod tests {
    use unic_langid::langids;

    use super::*;

    #[test]
    fn test_parse_accept_languages() {
        assert_eq!(
            parse_accept_languages("zh-CN;q=0.5,en-US;q=0.7,fr;q=0.3").into_vec(),
            langids!("en-US", "zh-CN", "fr")
        );

        assert_eq!(
            parse_accept_languages("zh-CN ; q=0.5,en-US;q = 0.7,   fr;q=0.3").into_vec(),
            langids!("en-US", "zh-CN", "fr")
        );

        assert_eq!(
            parse_accept_languages("en-US;q=0.7,zh-CN,fr;q=0.3").into_vec(),
            langids!("zh-CN", "en-US", "fr")
        );
    }
}