db, add item and functions to get items

Creates item. It's pretty barebowns until I implement fetching.

I also added get functions for feed and channel to get items with.

koucha/src/db/feed.rs

@@ -5,8 +5,10 @@ use crate::{
     Channel,
     ChannelKey,
     FeedKey,
+    Item,
     UserKey,
     channel::UnparsedChannel,
+    item::UnparsedItem,
   },
 };
 
@@ -77,6 +79,22 @@ impl Feed {
     Ok(())
   }
 
+  pub async fn get_items(
+    &self, pool: &AdapterPool, limit: u8, offset: u32
+  ) -> Result<Vec<Item>> {
+    sqlx::query_as!(
+      UnparsedItem,
+      "SELECT i.id as `id!`, i.channel_id, i.fetched_at, i.title, i.description,
+         i.content
+       FROM items i
+       JOIN feed_items fi on i.id = fi.item_id
+       WHERE feed_id = ? AND archived = FALSE
+       ORDER BY score DESC
+       LIMIT ? OFFSET ?",
+      self.key.0, limit, offset
+    ).fetch_all(&pool.0).await?.into_iter().map(UnparsedItem::parse).collect()
+  }
+
   pub async fn get_channels(
     &self, pool: &AdapterPool
   ) -> Result<Vec<Channel>> {