Compute dashboard stats

Track open rate for new post notifications (user clicked the button in
the link or not). No data about the user is collected during the
process, it only uses an ID inserted by the issue delivery worker.

src/routes/posts.rs

@@ -8,7 +8,7 @@ use anyhow::Context;
 use askama::Template;
 use axum::{
     extract::{Path, Query, State},
-    response::{Html, IntoResponse, Response},
+    response::{Html, IntoResponse, Redirect, Response},
 };
 use sqlx::PgPool;
 use uuid::Uuid;
@@ -62,12 +62,29 @@ async fn get_posts_table_size(connection_pool: &PgPool) -> Result<i64, sqlx::Err
         .map(|r| r.count.unwrap())
 }
 
+#[derive(serde::Deserialize)]
+pub struct PostParams {
+    origin: Option<Uuid>,
+}
+
 pub async fn see_post(
     State(AppState {
         connection_pool, ..
     }): State<AppState>,
     Path(post_id): Path<Uuid>,
+    Query(PostParams { origin }): Query<PostParams>,
 ) -> Result<Response, AppError> {
+    if let Some(origin) = origin {
+        sqlx::query!(
+            "UPDATE notifications_delivered SET opened = TRUE WHERE email_id = $1",
+            origin,
+        )
+        .execute(&connection_pool)
+        .await
+        .context("Failed to mark email as opened.")
+        .map_err(AppError::unexpected_page)?;
+        return Ok(Redirect::to(&format!("/posts/{}", post_id)).into_response());
+    }
     let post = get_post_data(&connection_pool, post_id)
         .await
         .context(format!("Failed to fetch post #{}", post_id))