Improve rss/atom feed subscription (#13)

* feat: does not fetch old items from RSS feeds

* feat: fetch automatically the rss/atom in the page source

* fix: check if the link is a feed or not

* fix: remove `clone`

* feat: handle exception if feed table already exists

* fix: resolve prevented multiple items from being imported

* chore: `cargo fmt`

* fix: remove excessive database access

* fix: modify error if nothing is entered when adding a feed

* chore: execute second `cargo fmt`

* fix: check most recent only when fetch_old_items is false

* fix: use `pub`

* fix: add table column using `add_column_if_not_exists`

* fix: handle errors when generating feeds in `errors.rc`.

* fix: get feed ids for most recent items

* fix: delete unnecessary HTTP request

* chore: check clippy point

src-tauri/Cargo.toml

@@ -26,6 +26,7 @@ reqwest = { version = "0.11", features = ["blocking"] }
 sha1_smol = { version = "1", features = ["std"] }
 thiserror = "1.0"
 regex = "1.9"
+scraper = "0.18.1"
 
 [dev-dependencies]
 pretty_assertions = "1.4"

src-tauri/src/commands/feeds.rs

@@ -2,26 +2,47 @@ use tauri::State;
 
 use crate::models::settings;
 use crate::models::settings::SettingKey;
+use crate::syndication::Feed as _Feed;
 use crate::{
     models::feeds::{self, Feed, FeedToCreate, FeedToUpdate},
     producer::create_new_items,
-    syndication::fetch_feed_title,
+    syndication::{fetch_content, fetch_feed_title, find_feed_link},
     DbState,
 };
 
+use crate::error::Error;
+
 #[tauri::command]
 pub fn create_feed(db_state: State<DbState>, arg: FeedToCreate) -> Result<String, String> {
+    if arg.link.is_empty() {
+        return Err(Error::EmptyString.to_string());
+    }
+
     let db = db_state.db.lock().unwrap();
     let proxy = settings::read(&db, &SettingKey::Proxy)
         .map(|x| x.value)
         .ok();
-    let title = match fetch_feed_title(&arg.link, proxy.as_deref()) {
+
+    let html_content = fetch_content(&arg.link, proxy.as_deref()).unwrap();
+    let is_feed = html_content.parse::<_Feed>().is_ok();
+
+    let link = if is_feed {
+        arg.link.clone()
+    } else if let Some(rss_link) = find_feed_link(&html_content).unwrap() {
+        rss_link
+    } else {
+        return Err(Error::InvalidFeedLink(arg.link).to_string());
+    };
+
+    let title = match fetch_feed_title(&link, proxy.as_deref()) {
         Ok(title) => title,
         Err(err) => return Err(err.to_string()),
     };
+
     let arg = FeedToCreate {
         title,
-        link: arg.link,
+        link,
+        fetch_old_items: arg.fetch_old_items,
     };
 
     match feeds::create(&db, &arg) {

src-tauri/src/error.rs

@@ -8,12 +8,18 @@ pub enum Error {
     #[error("invalid key `{0}` for `{1}`")]
     InvalidEnumKey(String, String),
 
+    #[error("invalid feed link `{0}`")]
+    InvalidFeedLink(String),
+
     #[error("forbidden")]
     Forbidden,
 
     #[error("failed to parse syndication feed")]
     SyndicationParsingFailure,
 
+    #[error("empty string")]
+    EmptyString,
+
     #[error("unknown")]
     Unknown,
 

src-tauri/src/models/database.rs

@@ -16,6 +16,7 @@ pub enum Feeds {
     Link,
     Status,
     CheckedAt,
+    FetchOldItems,
 }
 
 #[derive(Iden)]
@@ -65,6 +66,12 @@ pub fn migrate(db: &Connection) -> Result<()> {
                 .default("subscribed"),
         )
         .col(ColumnDef::new(Feeds::CheckedAt).date_time().not_null())
+        .col(
+            ColumnDef::new(Feeds::FetchOldItems)
+                .boolean()
+                .not_null()
+                .default(true),
+        )
         .index(
             Index::create()
                 .unique()
@@ -147,6 +154,19 @@ pub fn migrate(db: &Connection) -> Result<()> {
     let _ = insert_settings(db, "theme", "system");
     let _ = insert_settings(db, "items_order", "ReceivedDateDesc");
     let _ = insert_settings(db, "proxy", "");
+    let _ = insert_settings(db, "fetch_old_items", "1");
+
+    let add_feeds_columns = Table::alter()
+        .table(Feeds::Table)
+        .add_column_if_not_exists(
+            ColumnDef::new(Feeds::FetchOldItems)
+                .boolean()
+                .not_null()
+                .default(true),
+        )
+        .build(SqliteQueryBuilder);
+
+    db.execute(&add_feeds_columns, [])?;
 
     Ok(())
 }