206 lines
7.3 KiB
Rust
206 lines
7.3 KiB
Rust
// Utility functions and structs for the blogging system
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// Due to limitations of the Cloudflare Workers KV, we do not
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// store the entire state in one record; instead, different
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// parts are stroed in different records. This also increases
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// efficiency, since the program won't need to load anything
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// unnecessary from KV.
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use crate::store;
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use crate::utils::*;
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use pulldown_cmark::*;
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use serde::{Serialize, Deserialize};
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use std::vec::Vec;
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// A list of the UUIDs of all published blog posts
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// This should be SORTED with the newest posts at lower indices (closer to 0)
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// The user may edit this via KV UI to change ordering and such
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// by default new posts are always added to the top
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#[derive(Serialize, Deserialize)]
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pub struct PostsList(pub Vec<String>);
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impl PostsList {
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pub async fn load() -> PostsList {
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match store::get_obj("posts_list").await {
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Ok(v) => PostsList(v),
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// Don't panic on empty
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// TODO: What if the user messed up when editing?
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// That would cause a decode failure and all data will be gone
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// if a new post is added or updated (overwriting the KV value)
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// under this logic
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// (if no new post is added then nothing bad would happen;
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// the user would probably notice when trying to visit the blog home page)
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Err(_) => PostsList(vec![])
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}
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}
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pub fn has_post(&self, uuid: &str) -> bool {
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self.0.contains(&uuid.into())
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}
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// Add a post to the list and then update the record in KV
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// Also consumes self, as this should normally be the last action
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// in an API call
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pub async fn add_post(mut self, uuid: &str) -> MyResult<()> {
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if self.has_post(uuid) {
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return Ok(());
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}
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self.0.insert(0, uuid.into());
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store::put_obj_pretty("posts_list", self.0).await
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}
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// Remove a post from published list
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// may be used when deleting / unpublishing a post
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// Does nothing if uuid not found in list
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pub async fn remove_post(mut self, uuid: &str) -> MyResult<()> {
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self.0.remove_item(&uuid);
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store::put_obj_pretty("posts_list", self.0).await
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}
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}
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#[derive(Serialize, Deserialize)]
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pub struct Post {
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// The UUID of the post (a Standard Notes UUID)
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pub uuid: String,
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// The UNIX timestamp (in seconds) for the post
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pub timestamp: u64,
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// URL of the post (relative to the root of the site)
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pub url: String,
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// Title of the post
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pub title: String,
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// The Markdown content of the post
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// We keep the original content here
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// so that we could make changes to the Markdown parser
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// in the future; we won't be stuck with a parsed version
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pub content: String
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}
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impl Post {
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fn uuid_to_post_key(uuid: &str) -> String {
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format!("post_by_uuid_{}", uuid)
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}
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fn url_to_mapping_key(url: &str) -> String {
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format!("url_mapping_{}", url)
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}
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async fn create_url_mapping(url: &str, uuid: &str) -> MyResult<()> {
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store::put_str(&Self::url_to_mapping_key(url), uuid).await
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}
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// Returns Err(InternalError) if the post is not found
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// Note that the existence status of a post here must
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// be synchronized with the PostsList; that is, if a
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// post is not found in PostsList, it must not be found
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// here either; if a post is found in PostsList, then
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// this method should not return any error.
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// (except for hidden posts, in which case they won't be
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// present in PostsList)
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pub async fn find_by_uuid(uuid: &str) -> MyResult<Post> {
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store::get_obj(&Self::uuid_to_post_key(uuid)).await
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}
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pub async fn find_by_url(url: &str) -> MyResult<Post> {
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let uuid = store::get_str(&Self::url_to_mapping_key(url)).await?;
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Self::find_by_uuid(&uuid).await
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}
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// Write the Post to KV storage; this can be a new post or
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// update to an existing post; either way, the CALLER is
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// responsible for making sure PostsList is updated with the
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// latest set of posts sorted in order.
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// This function will also create a mapping from URL to UUID in the KV
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pub async fn write_to_kv(self) -> MyResult<()> {
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Self::create_url_mapping(&self.url, &self.uuid).await?;
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store::put_obj(&Self::uuid_to_post_key(&self.uuid), self).await
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}
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}
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// This should be bumped each time the parsing / compiling
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// logic of Markdown changes, and each time the Markdown
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// library updates. Updaing this value invalidates all
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// existing cache and they will be recompiled when someone
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// visits.
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const CACHE_VERSION: &'static str = "0001";
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// Cached version of rendered blog content HTMLs
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// compiled from Markdown
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#[derive(Serialize, Deserialize)]
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pub struct PostContentCache {
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// UUID of the original post
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uuid: String,
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// If version != CACHE_VERSION, the cache is invalidated
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version: String,
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// Digest of the original content
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orig_digest: String,
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// Compiled content in HTML
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pub content: String
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}
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impl PostContentCache {
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fn uuid_to_cache_key(uuid: &str) -> String {
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format!("content_cache_{}", uuid)
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}
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async fn find_by_uuid(uuid: &str) -> MyResult<PostContentCache> {
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store::get_obj(&Self::uuid_to_cache_key(uuid)).await
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}
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pub async fn find_by_post(post: &Post) -> Option<PostContentCache> {
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let cache = match Self::find_by_uuid(&post.uuid).await {
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Ok(cache) => cache,
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Err(_) => return None
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};
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if cache.version != CACHE_VERSION {
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return None;
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}
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if cache.orig_digest != crate::utils::sha1(&post.content).await {
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return None;
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}
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Some(cache)
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}
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// Only renders the content and spits out a cache object
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// can be used to display the page or to write to cache
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// Despite the signature, this function BLOCKS
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// async only comes from digesting via SubtleCrypto
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pub async fn render(post: &Post) -> PostContentCache {
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// TODO: enable some options; pre-process posts to enable
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// inline image caching; also generate a summary (?)
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// from first few paragraphs
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let parser = Parser::new(&post.content);
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let mut html_output = String::new();
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html::push_html(&mut html_output, parser);
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PostContentCache {
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uuid: post.uuid.clone(),
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version: CACHE_VERSION.to_owned(),
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orig_digest: crate::utils::sha1(&post.content).await,
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content: html_output
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}
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}
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// Tries to find the rendered content cache of post
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// if a valid cache cannot be found, this method
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// will render the content, write that into cache
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// and return this newly-rendered one
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// This will block if it tries to render; if that's a
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// concern, use find_by_post
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pub async fn find_or_render(post: &Post) -> PostContentCache {
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match Self::find_by_post(post).await {
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Some(cache) => cache,
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None => {
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let ret = Self::render(post).await;
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// Ignore save error since if save failed, it can be regenerated anyway
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let _ = ret.save().await;
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ret
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}
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}
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}
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// Save the current cache object to KV
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pub async fn save(&self) -> MyResult<()> {
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store::put_obj(&Self::uuid_to_cache_key(&self.uuid), self).await
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}
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} |