1use std::sync::Arc;
 2
 3use crate::ImageData;
 4use collections::HashMap;
 5use futures::{
 6    future::{BoxFuture, Shared},
 7    AsyncReadExt, FutureExt,
 8};
 9use image::ImageError;
10use parking_lot::Mutex;
11use thiserror::Error;
12use util::{
13    arc_cow::ArcCow,
14    http::{self, HttpClient},
15};
16
17#[derive(Debug, Error, Clone)]
18pub enum Error {
19    #[error("http error: {0}")]
20    Client(#[from] http::Error),
21    #[error("IO error: {0}")]
22    Io(Arc<std::io::Error>),
23    #[error("unexpected http status: {status}, body: {body}")]
24    BadStatus {
25        status: http::StatusCode,
26        body: String,
27    },
28    #[error("image error: {0}")]
29    Image(Arc<ImageError>),
30}
31
32impl From<std::io::Error> for Error {
33    fn from(error: std::io::Error) -> Self {
34        Error::Io(Arc::new(error))
35    }
36}
37
38impl From<ImageError> for Error {
39    fn from(error: ImageError) -> Self {
40        Error::Image(Arc::new(error))
41    }
42}
43
44pub struct ImageCache {
45    client: Arc<dyn HttpClient>,
46    images: Arc<Mutex<HashMap<ArcCow<'static, str>, FetchImageFuture>>>,
47}
48
49type FetchImageFuture = Shared<BoxFuture<'static, Result<Arc<ImageData>, Error>>>;
50
51impl ImageCache {
52    pub fn new(client: Arc<dyn HttpClient>) -> Self {
53        ImageCache {
54            client,
55            images: Default::default(),
56        }
57    }
58
59    pub fn get(
60        &self,
61        uri: impl Into<ArcCow<'static, str>>,
62    ) -> Shared<BoxFuture<'static, Result<Arc<ImageData>, Error>>> {
63        let uri = uri.into();
64        let mut images = self.images.lock();
65
66        match images.get(uri.as_ref()) {
67            Some(future) => future.clone(),
68            None => {
69                let client = self.client.clone();
70                let future = {
71                    let uri = uri.clone();
72                    async move {
73                        let mut response = client.get(uri.as_ref(), ().into(), true).await?;
74                        let mut body = Vec::new();
75                        response.body_mut().read_to_end(&mut body).await?;
76
77                        if !response.status().is_success() {
78                            return Err(Error::BadStatus {
79                                status: response.status(),
80                                body: String::from_utf8_lossy(&body).into_owned(),
81                            });
82                        }
83
84                        let format = image::guess_format(&body)?;
85                        let image =
86                            image::load_from_memory_with_format(&body, format)?.into_bgra8();
87
88                        Ok(ImageData::new(image))
89                    }
90                }
91                .boxed()
92                .shared();
93
94                images.insert(uri, future.clone());
95                future
96            }
97        }
98    }
99}