oops: added the actual file

src/imageprovider.rs

@@ -0,0 +1,86 @@
+// provides NASA image of the day.
+//
+
+use std::io::Cursor;
+
+use anyhow::{Context, Result};
+use bytes::Buf;
+use image::{
+    imageops::{crop_imm, resize, FilterType},
+    ImageReader, RgbImage,
+};
+use std::time::Duration;
+use tokio::time::sleep;
+
+use rss::Channel;
+use tracing::{info, instrument};
+
+use crate::{app::AppState, dither::DitherMethod, dither::DitheredImage, eink::Palette};
+
+const NASA_IOTD_RSS_FEED: &str = "https://www.nasa.gov/rss/dyn/lg_image_of_the_day.rss";
+
+const TARGET_ASPECT: f32 = 800.0 / 480.0;
+
+async fn get_latest_image() -> Result<Box<RgbImage>> {
+    let content = reqwest::get(NASA_IOTD_RSS_FEED).await?.bytes().await?;
+    let channel = Channel::read_from(content.reader())?;
+
+    let latest_item = &channel.items()[0];
+    let image_enc = latest_item
+        .enclosure()
+        .context("no enclosure in first item")?;
+
+    // now we have an image url
+    info!(
+        "found image with type {}, size {}",
+        image_enc.mime_type(),
+        image_enc.length()
+    );
+
+    let image_request = reqwest::get(image_enc.url()).await?;
+    let reader =
+        ImageReader::new(Cursor::new(image_request.bytes().await?)).with_guessed_format()?;
+
+    let image = reader.decode()?;
+    Ok(Box::new(image.into()))
+}
+
+async fn get_nasa() -> Result<RgbImage> {
+    let img = get_latest_image().await?;
+    let (width, height) = img.dimensions();
+
+    #[allow(clippy::cast_precision_loss)]
+    let input_aspect = width as f32 / height as f32;
+    let resize = if input_aspect > TARGET_ASPECT {
+        let new_width = (height as f32 * TARGET_ASPECT) as u32;
+        let offset = (width - new_width) / 2;
+        (offset, 0, new_width, height)
+    } else {
+        let new_height = (width as f32 / TARGET_ASPECT) as u32;
+        let offset = (height - new_height) / 2;
+        (0, offset, width, new_height)
+    };
+
+    let cropped = crop_imm(&*img, resize.0, resize.1, resize.2, resize.3).to_image();
+
+    Ok(cropped)
+}
+
+#[instrument(skip(ctx))]
+pub async fn nasa_task(ctx: AppState) {
+    info!("Starting NASA IOTD task");
+    loop {
+        if let Ok(img) = get_nasa().await {
+            let mut buf = DitheredImage::new(800, 480, Palette::Default.value().to_vec());
+            let resized = resize(&img, 800, 480, FilterType::Lanczos3);
+            {
+                let mut dither = DitherMethod::Atkinson.get_ditherer();
+                dither.dither(&resized, &mut buf);
+            }
+            ctx.display_channel.send(Box::new(buf));
+            info!("Nasa image updated");
+        }
+
+        sleep(Duration::from_secs(60 * 60 * 24)).await;
+    }
+}