Files
narlblog/backend/src/post/cache.rs
T
2026-05-16 23:52:20 +02:00

114 lines
3.6 KiB
Rust

//! The in-memory posts cache: rebuilt from disk at startup and after every
//! mutation, plus prev/next neighbour lookup over the visible set.
use tokio::fs;
use tracing::warn;
use crate::models::{PostInfo, PostMeta, PostNeighbor};
use crate::post::images::{cover_from, dim_for_url, extract_images};
use crate::post::parse::{excerpt_from, parse_post, reading_time};
use crate::{AppState, CachedPost};
fn build_post_info(slug: &str, meta: &PostMeta, body: &str) -> PostInfo {
let images = extract_images(body);
PostInfo {
slug: slug.to_string(),
date: meta.date,
title: meta.title.clone(),
summary: meta.summary.clone(),
tags: meta.tags.clone(),
draft: meta.draft,
reading_time: reading_time(body),
excerpt: excerpt_from(meta, body),
cover_image: cover_from(&images),
image_count: images.len() as u32,
}
}
/// Scans the posts directory and replaces the in-memory cache.
/// Called at startup and after any mutation (create/rename/delete).
pub(crate) async fn rebuild_posts_cache(state: &AppState) {
let posts_dir = state.data_dir.join("posts");
let mut posts: Vec<CachedPost> = Vec::new();
let mut rd = match fs::read_dir(&posts_dir).await {
Ok(rd) => rd,
Err(_) => {
*state.posts_cache.write().await = posts;
return;
}
};
loop {
match rd.next_entry().await {
Ok(Some(entry)) => {
let path = entry.path();
if path.extension().and_then(|e| e.to_str()) != Some("md") {
continue;
}
let Some(slug) = path.file_stem().and_then(|s| s.to_str()) else {
continue;
};
if slug.starts_with('.') {
continue;
}
let Ok(raw) = fs::read_to_string(&path).await else {
continue;
};
let Ok((meta, body)) = parse_post(&raw) else {
warn!("Skipping post with bad frontmatter: {}", slug);
continue;
};
let mut info = build_post_info(slug, &meta, &body);
if let Some(cover) = info.cover_image.as_mut() {
if let Some(d) = dim_for_url(state, &cover.url).await {
cover.w = Some(d.w);
cover.h = Some(d.h);
}
}
posts.push(CachedPost { info, body });
}
Ok(None) => break,
Err(e) => {
warn!("Error iterating posts dir: {}", e);
break;
}
}
}
posts.sort_by(|a, b| {
b.info
.date
.cmp(&a.info.date)
.then_with(|| a.info.slug.cmp(&b.info.slug))
});
*state.posts_cache.write().await = posts;
}
pub(crate) async fn neighbors_from_cache(
state: &AppState,
slug: &str,
admin: bool,
) -> (Option<PostNeighbor>, Option<PostNeighbor>) {
let cache = state.posts_cache.read().await;
let visible: Vec<&PostInfo> = cache
.iter()
.filter(|p| admin || !p.info.draft)
.map(|p| &p.info)
.collect();
let Some(i) = visible.iter().position(|p| p.slug == slug) else {
return (None, None);
};
let to_neighbor = |p: &PostInfo| PostNeighbor {
slug: p.slug.clone(),
title: p.title.clone(),
};
let prev = if i > 0 {
Some(to_neighbor(visible[i - 1]))
} else {
None
};
let next = visible.get(i + 1).map(|p| to_neighbor(p));
(prev, next)
}