implement Markdown rendering

Cargo.lock

@@ -1,5 +1,11 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+[[package]]
+name = "bitflags"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
+
 [[package]]
 name = "bumpalo"
 version = "3.2.1"
@@ -28,6 +34,12 @@ version = "0.1.29"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1b980f2816d6ee8673b6517b52cb0e808a180efc92e5c19d02cdda79066703ef"
 
+[[package]]
+name = "hex"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "644f9158b2f133fd50f5fb3242878846d9eb792e445c893805ff0e3824006e35"
+
 [[package]]
 name = "itoa"
 version = "0.4.5"
@@ -64,6 +76,12 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "memchr"
+version = "2.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3728d817d99e5ac407411fa471ff9800a778d88a24685968b36824eaf4bee400"
+
 [[package]]
 name = "memory_units"
 version = "0.4.0"
@@ -76,8 +94,10 @@ version = "0.1.0"
 dependencies = [
  "cfg-if",
  "console_error_panic_hook",
+ "hex",
  "js-sys",
  "lazy_static",
+ "pulldown-cmark",
  "serde",
  "serde_json",
  "wasm-bindgen",
@@ -105,6 +125,17 @@ dependencies = [
  "unicode-xid 0.2.0",
 ]
 
+[[package]]
+name = "pulldown-cmark"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2c2d7fd131800e0d63df52aff46201acaab70b431a4a1ec6f0343fe8e64f35a4"
+dependencies = [
+ "bitflags",
+ "memchr",
+ "unicase",
+]
+
 [[package]]
 name = "quote"
 version = "0.6.13"
@@ -177,6 +208,15 @@ dependencies = [
  "unicode-xid 0.2.0",
 ]
 
+[[package]]
+name = "unicase"
+version = "2.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "50f37be617794602aabbeee0be4f259dc1778fabe05e2d67ee8f79326d5cb4f6"
+dependencies = [
+ "version_check",
+]
+
 [[package]]
 name = "unicode-xid"
 version = "0.1.0"
@@ -189,6 +229,12 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "826e7639553986605ec5979c7dd957c7895e93eabed50ab2ffa7f6128a75097c"
 
+[[package]]
+name = "version_check"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "078775d0255232fb988e6fccf26ddc9d1ac274299aaedcedce21c6f72cc533ce"
+
 [[package]]
 name = "wasm-bindgen"
 version = "0.2.60"

Cargo.toml

@@ -13,16 +13,20 @@ default = ["console_error_panic_hook", "wee_alloc"]
 [dependencies]
 cfg-if = "0.1.2"
 lazy_static = "1.4"
+hex = "0.4"
 js-sys = "0.3"
+pulldown-cmark = { version = "0.7", default-features = false }
 serde = { version = "1.0", features = [ "derive" ] }
 serde_json = "1.0"
 wasm-bindgen = "0.2"
 wasm-bindgen-futures = "0.4"
 web-sys = { version = "0.3", features = [
+    "Crypto",
     "Headers",
     "Request",
     "Response",
     "ResponseInit",
+    "SubtleCrypto",
     "Url",
     "UrlSearchParams"
 ] }

src/blog.rs

@@ -6,6 +6,7 @@
 // unnecessary from KV.
 use crate::store;
 use crate::utils::*;
+use pulldown_cmark::*;
 use serde::{Serialize, Deserialize};
 use std::vec::Vec;
 
@@ -112,4 +113,89 @@ impl Post {
         Self::create_url_mapping(&self.url, &self.uuid).await?;
         store::put_obj(&Self::uuid_to_post_key(&self.uuid), self).await
     }
+}
+
+const CACHE_VERSION: &'static str = "0001";
+
+// Cached version of rendered blog content HTMLs
+// compiled from Markdown
+#[derive(Serialize, Deserialize)]
+pub struct PostContentCache {
+    // UUID of the original post
+    uuid: String,
+    // If version != CACHE_VERSION, the cache is invalidated
+    version: String,
+    // Digest of the original content
+    orig_digest: String,
+    // Compiled content in HTML
+    pub content: String
+}
+
+impl PostContentCache {
+    fn uuid_to_cache_key(uuid: &str) -> String {
+        format!("content_cache_{}", uuid)
+    }
+
+    async fn find_by_uuid(uuid: &str) -> MyResult<PostContentCache> {
+        store::get_obj(&Self::uuid_to_cache_key(uuid)).await
+    }
+
+    pub async fn find_by_post(post: &Post) -> Option<PostContentCache> {
+        let cache = match Self::find_by_uuid(&post.uuid).await {
+            Ok(cache) => cache,
+            Err(_) => return None
+        };
+
+        if cache.version != CACHE_VERSION {
+            return None;
+        }
+
+        if cache.orig_digest != crate::utils::sha1(&post.content).await {
+            return None;
+        }
+
+        Some(cache)
+    }
+
+    // Only renders the content and spits out a cache object
+    // can be used to display the page or to write to cache
+    // Despite the signature, this function BLOCKS
+    // async only comes from digesting via SubtleCrypto
+    pub async fn render(post: &Post) -> PostContentCache {
+        // TODO: enable some options; pre-process posts to enable
+        //       inline image caching; also generate a summary (?)
+        //       from first few paragraphs
+        let parser = Parser::new(&post.content);
+        let mut html_output = String::new();
+        html::push_html(&mut html_output, parser);
+        PostContentCache {
+            uuid: post.uuid.clone(),
+            version: CACHE_VERSION.to_owned(),
+            orig_digest: crate::utils::sha1(&post.content).await,
+            content: html_output
+        }
+    }
+
+    // Tries to find the rendered content cache of post
+    // if a valid cache cannot be found, this method
+    // will render the content, write that into cache
+    // and return this newly-rendered one
+    // This will block if it tries to render; if that's a
+    // concern, use find_by_post
+    pub async fn find_or_render(post: &Post) -> PostContentCache {
+        match Self::find_by_post(post).await {
+            Some(cache) => cache,
+            None => {
+                let ret = Self::render(post).await;
+                // Ignore save error since if save failed, it can be regenerated anyway
+                let _ = ret.save().await;
+                ret
+            }
+        }
+    }
+
+    // Save the current cache object to KV
+    pub async fn save(&self) -> MyResult<()> {
+        store::put_obj(&Self::uuid_to_cache_key(&self.uuid), self).await
+    }
 }

src/lib.rs

@@ -77,7 +77,7 @@ async fn default_route(_req: Request, url: Url) -> MyResult<Response> {
             } else {
                 // TODO: Actually render the page...
                 return Response::new_with_opt_str_and_init(
-                    Some(&post.content),
+                    Some(&blog::PostContentCache::find_or_render(&post).await.content),
                     ResponseInit::new()
                         .status(200)
                         .headers(headers!{

src/sn.rs

@@ -225,6 +225,9 @@ async fn create_or_update_post(req: Request, url: Url) -> MyResult<Response> {
     } else {
         list.remove_post(&post.uuid).await?;
     }
+    // Also pre-render the post
+    blog::PostContentCache::find_or_render(&post).await;
+    // Finally, save the post
     post.write_to_kv().await?;
 
     Response::new_with_opt_str_and_init(

src/utils.rs

@@ -1,6 +1,9 @@
 use cfg_if::cfg_if;
 use serde::Deserialize;
-use web_sys::Headers;
+use js_sys::*;
+use wasm_bindgen::prelude::*;
+use wasm_bindgen_futures::*;
+use web_sys::*;
 
 cfg_if! {
     // When the `console_error_panic_hook` feature is enabled, we can call the
@@ -61,6 +64,20 @@ pub fn title_to_url(uuid: &str, title: &str) -> String {
     format!("{}/{}", &uuid[0..4], title_part)
 }
 
+#[wasm_bindgen]
+extern "C" {
+    static crypto: Crypto;
+}
+
+// SHA-1 digest (hexed) via SubtleCrypto
+pub async fn sha1(s: &str) -> String {
+    let mut bytes: Vec<u8> = s.bytes().collect();
+    let promise = crypto.subtle().digest_with_str_and_u8_array("SHA-1", &mut bytes).unwrap();
+    let buffer: ArrayBuffer = JsFuture::from(promise).await.unwrap().into();
+    let digest_arr = Uint8Array::new(&buffer).to_vec();
+    hex::encode(digest_arr)
+}
+
 pub trait HeadersExt {
     fn add_cors(self) -> Self;
 }