add experimental support for temporary links

src/db.rs

@@ -1,3 +1,5 @@
+use std::time::{Duration, SystemTime};
+
 use rocket::futures::lock::Mutex;
 use tokio_postgres::{Client, Error, Statement};
 
@@ -5,7 +7,9 @@ use crate::GlobalState;
 
 pub const STATEMENT_GET_LINK: usize = 0;
 pub const STATEMENT_ADD_LINK: usize = 1;
-pub const N_STATEMENTS: usize = 2;
+pub const STATEMENT_ADD_TEMP_LINK: usize = 2;
+pub const STATEMENT_DELETE_EXPIRED: usize = 3;
+pub const N_STATEMENTS: usize = 4;
 
 pub async fn get_link(state: &Mutex<GlobalState>, link: &str) -> Result<Option<String>, Error> {
     let lock = state.lock().await;
@@ -18,13 +22,28 @@ pub async fn add_link(state: &Mutex<GlobalState>, link: &str, url: &str) -> Resu
     Ok(())
 }
 
+pub async fn add_temporary_link(state: &Mutex<GlobalState>, link: &str, url: &str, ttl: u64) -> Result<(), Error> {
+    let time = SystemTime::now() + Duration::from_secs(ttl);
+    let lock = state.lock().await;
+    lock.db_client.execute(&lock.statements[STATEMENT_ADD_TEMP_LINK], &[&link, &url, &time]).await?;
+    Ok(())
+}
+
+pub async fn delete_expired_links(state: &Mutex<GlobalState>) -> Result<(), Error> {
+    let lock = state.lock().await;
+    lock.db_client.execute(&lock.statements[STATEMENT_DELETE_EXPIRED], &[]).await?;
+    Ok(())
+}
+
 pub async fn prepare_statements(db: &Client) -> Result<[Statement; N_STATEMENTS], Error> {
     Ok([db.prepare("SELECT url FROM links WHERE id = $1").await?,
         db.prepare("INSERT INTO links (id, url) VALUES ($1, $2)").await?,
+        db.prepare("INSERT INTO links (id, url, valid_until) VALUES ($1, $2, $3)").await?,
+        db.prepare("DELETE FROM links WHERE valid_until < NOW()").await?
     ])
 }
 
 pub async fn prepare_tables(db: &Client) -> Result<(), Error> {
-    db.execute("CREATE TABLE IF NOT EXISTS links (id TEXT PRIMARY KEY, url TEXT NOT NULL)", &[]).await?;
+    db.execute("CREATE TABLE IF NOT EXISTS links (id TEXT PRIMARY KEY, url TEXT NOT NULL, valid_until TIMESTAMP NOT NULL)", &[]).await?;
     Ok(())
 }