treehouse/crates/treehouse/src/vfs/content_version_cache.rs

use std::fmt::{self, Debug};

use dashmap::DashMap;

use super::{Dir, DirEntry, EditPath, ImageSize, VPath, VPathBuf};

pub struct Blake3ContentVersionCache<T> {
    inner: T,
    cache: DashMap<VPathBuf, String>,
}

impl<T> Blake3ContentVersionCache<T> {
    pub fn new(inner: T) -> Self {
        Self {
            inner,
            cache: DashMap::new(),
        }
    }
}

impl<T> Dir for Blake3ContentVersionCache<T>
where
    T: Dir,
{
    fn dir(&self, path: &VPath) -> Vec<DirEntry> {
        self.inner.dir(path)
    }

    fn content(&self, path: &VPath) -> Option<Vec<u8>> {
        self.inner.content(path)
    }

    fn content_version(&self, path: &VPath) -> Option<String> {
        self.cache.get(path).map(|x| x.clone()).or_else(|| {
            let version = self.inner.content(path).map(|content| {
                let hash = blake3::hash(&content).to_hex();
                format!("b3-{}", &hash[0..8])
            });
            if let Some(version) = &version {
                self.cache.insert(path.to_owned(), version.clone());
            }
            version
        })
    }

    fn image_size(&self, path: &VPath) -> Option<ImageSize> {
        self.inner.image_size(path)
    }

    fn anchor(&self, path: &VPath) -> Option<VPathBuf> {
        self.inner.anchor(path)
    }

    fn edit_path(&self, path: &VPath) -> Option<EditPath> {
        self.inner.edit_path(path)
    }
}

impl<T> fmt::Debug for Blake3ContentVersionCache<T>
where
    T: Debug,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "Blake3ContentVersionCache({:?})", self.inner)
    }
}