redesign

src/main.rs

@@ -3,8 +3,8 @@
 extern crate serde;
 #[macro_use]
 extern crate serde_derive;
-extern crate serde_json;
 extern crate ledb;
+extern crate serde_json;
 #[macro_use]
 extern crate ledb_derive;
 extern crate ledb_types;
@@ -14,15 +14,17 @@ extern crate ledb_types;
 
 //use tera::Context;
 
-#[macro_use] extern crate rocket;
+#[macro_use]
+extern crate rocket;
 extern crate rocket_contrib;
 
-use rocket::{Rocket, State};
 use rocket::response::Redirect;
+use rocket::{Rocket, State};
 use rocket_contrib::serve::StaticFiles;
 use rocket_contrib::templates::Template;
 
-use rand::seq::IteratorRandom;
+use rand::distributions::Uniform;
+use rand::Rng;
 
 use ledb::{Options, Storage};
 
@@ -101,6 +103,21 @@ struct Question {
 
 struct AppState {
     storage: Storage,
+    database_distribution: Uniform<u32>,
+}
+
+fn get_database_distribution(storage: &Storage) -> Uniform<u32> {
+    let collection = storage
+        .collection("questions")
+        .expect("collection \"questions\"");
+    let last_id = collection.last_id().expect("\"questions\" last_id");
+
+    rand::distributions::Uniform::new_inclusive(1u32, last_id)
+}
+
+fn random_question_id(database_distribution: &Uniform<u32>) -> u32 {
+    let mut rng = rand::thread_rng();
+    rng.sample(database_distribution)
 }
 
 fn get_question(storage: &Storage, id: u32) -> Result<Option<Question>, ()> {
@@ -108,7 +125,9 @@ fn get_question(storage: &Storage, id: u32) -> Result<Option<Question>, ()> {
         return Ok(None);
     }
 
-    let collection = storage.collection("questions").expect("collection \"questions\"");
+    let collection = storage
+        .collection("questions")
+        .expect("collection \"questions\"");
     let last_id = collection.last_id().expect("\"questions\" last_id");
 
     if id > last_id {
@@ -123,7 +142,11 @@ fn get_question(storage: &Storage, id: u32) -> Result<Option<Question>, ()> {
     }
 }
 
-fn show_question_details(template_name: &'static str, data: &AppState, id: u32) -> Result<Template, Redirect>  {
+fn show_question_details(
+    template_name: &'static str,
+    data: &AppState,
+    id: u32,
+) -> Result<Template, Redirect> {
     let question = get_question(&data.storage, id);
 
     if question.is_ok() {
@@ -131,7 +154,12 @@ fn show_question_details(template_name: &'static str, data: &AppState, id: u32)
 
         if question.is_some() {
             let question = question.unwrap();
-            Ok(Template::render(template_name, &question))
+            let mut context = serde_json::to_value(question).expect("question serialize");
+            if context.is_object() {
+                let next_id = random_question_id(&data.database_distribution);
+                context["next"] = serde_json::to_value(next_id).expect("question id serialize");
+            }
+            Ok(Template::render(template_name, &context))
         } else {
             Err(Redirect::permanent("/q/"))
         }
@@ -154,11 +182,7 @@ fn show_answer(data: State<AppState>, id: u32) -> Result<Template, Redirect> {
 
 #[get("/")]
 fn index(data: State<AppState>) -> Redirect {
-    let mut rng = rand::thread_rng();
-    let collection = data.storage.collection("questions").expect("collection \"questions\"");
-    let last_id = collection.last_id().expect("\"questions\" last_id");
-    let id = (1..(last_id + 1)).choose(&mut rng).unwrap();
-
+    let id = random_question_id(&data.database_distribution);
     Redirect::temporary(format!("/q/{}", id))
 }
 
@@ -176,12 +200,13 @@ fn rocket() -> Rocket {
     }))
     .unwrap();
 
-    let state = AppState {
-        storage: Storage::new("db", options).expect("open db")
+    let mut state = AppState {
+        storage: Storage::new("db", options).expect("open db"),
+        database_distribution: Uniform::new(1, 3),
     };
+    state.database_distribution = get_database_distribution(&state.storage);
 
-    let collection = state.storage.collection("questions").expect("collection \"questions\"");
-    collection.last_id().expect("\"questions\" last_id");
+    let state = state;
 
     rocket::ignite()
         .manage(state)