Check if user is qualified before allowing to start contest

src/core.rs

@@ -286,6 +286,18 @@ pub struct ContestStartConstraints {
     pub grade_matching: bool,
 }
 
+fn check_contest_qualification<T: MedalConnection>(conn: &T, session: &SessionUser, contest: &Contest) -> Option<bool> {
+    let required_contests = contest.requires_contest.as_ref()?.split(",");
+
+    for req_contest in required_contests {
+        if conn.has_participation_by_contest_file(session.id, &contest.location, req_contest) {
+            return Some(true);
+        }
+    }
+
+    Some(false)
+}
+
 fn check_contest_constraints(session: &SessionUser, contest: &Contest) -> ContestStartConstraints {
     let now = time::get_time();
     let student_grade = session.grade % 100 - if session.grade / 100 == 1 { 1 } else { 0 };
@@ -305,7 +317,8 @@ fn check_contest_constraints(session: &SessionUser, contest: &Contest) -> Contes
                               contest_running,
                               grade_too_low,
                               grade_too_high,
-                              grade_matching }
+                              grade_matching,
+                            }
 }
 
 pub fn show_contest<T: MedalConnection>(conn: &T, contest_id: i32, session_token: &str,
@@ -333,11 +346,13 @@ pub fn show_contest<T: MedalConnection>(conn: &T, contest_id: i32, session_token
     fill_oauth_data(login_info, &mut data);
 
     let constraints = check_contest_constraints(&session, &contest);
+    let is_qualified = check_contest_qualification(conn, &session, &contest).unwrap_or(true);
 
-    let can_start = session.is_logged_in() && constraints.contest_running && constraints.grade_matching;
+    let can_start = session.is_logged_in() && constraints.contest_running && constraints.grade_matching && is_qualified;
     let has_duration = contest.duration > 0;
 
     data.insert("constraints".to_string(), to_json(&constraints));
+    data.insert("is_qualified".to_string(), to_json(&is_qualified));
     data.insert("has_duration".to_string(), to_json(&has_duration));
     data.insert("can_start".to_string(), to_json(&can_start));
 
@@ -516,6 +531,12 @@ pub fn start_contest<T: MedalConnection>(conn: &T, contest_id: i32, session_toke
         return Err(MedalError::AccessDenied);
     }
 
+    let is_qualified = check_contest_qualification(conn, &session, &contest);
+
+    if is_qualified == Some(false) {
+        return Err(MedalError::AccessDenied);
+    }
+
     // Start contest
     match conn.new_participation(&session_token, contest_id) {
         Ok(_) => Ok(()),

src/db_conn.base.rs

@@ -1203,6 +1203,16 @@ impl MedalConnection for Connection {
             .unwrap()
     }
 
+    fn has_participation_by_contest_file(&self, session_id: i32, location: &str, filename: &str) -> bool {
+        let query = "SELECT participation.contest
+                     FROM participation
+                     JOIN contest ON participation.contest = contest.id
+                     WHERE participation.session = $1
+                     AND contest.location = $2
+                     AND contest.filename = $3";
+        self.exists(query, &[&session_id, &location, &filename])
+    }
+
     fn new_participation(&self, session: &str, contest_id: i32) -> Result<Participation, ()> {
         let query = "SELECT session, start_date
                      FROM participation

src/db_conn.rs

@@ -123,6 +123,8 @@ pub trait MedalConnection {
     /// Returns an `Vec` that contains pairs of all participations with their associated contests.
     fn get_all_participations_complete(&self, session_id: i32) -> Vec<(Participation, Contest)>;
 
+    fn has_participation_by_contest_file(&self, session_id: i32, location: &str, filename: &str) -> bool;
+
     /// Start a new participation of the session identified by the session token `session` for the contest with the
     /// contest id `contest_id`. It checks whether the session is allowed to start the participation.
     ///

src/db_conn_postgres.rs

@@ -1322,6 +1322,16 @@ impl MedalConnection for Connection {
             .unwrap()
     }
 
+    fn has_participation_by_contest_file(&self, session_id: i32, location: &str, filename: &str) -> bool {
+        let query = "SELECT participation.contest
+                     FROM participation
+                     JOIN contest ON participation.contest = contest.id
+                     WHERE participation.session = $1
+                     AND contest.location = $2
+                     AND contest.filename = $3";
+        self.exists(query, &[&session_id, &location, &filename])
+    }
+
     fn new_participation(&self, session: &str, contest_id: i32) -> Result<Participation, ()> {
         let query = "SELECT session, start_date
                      FROM participation

src/db_conn_sqlite_new.rs

@@ -1322,6 +1322,16 @@ impl MedalConnection for Connection {
             .unwrap()
     }
 
+    fn has_participation_by_contest_file(&self, session_id: i32, location: &str, filename: &str) -> bool {
+        let query = "SELECT participation.contest
+                     FROM participation
+                     JOIN contest ON participation.contest = contest.id
+                     WHERE participation.session = ?1
+                     AND contest.location = ?2
+                     AND contest.filename = ?3";
+        self.exists(query, &[&session_id, &location, &filename])
+    }
+
     fn new_participation(&self, session: &str, contest_id: i32) -> Result<Participation, ()> {
         let query = "SELECT session, start_date
                      FROM participation

templates/jwinf/contest.hbs

@@ -134,11 +134,16 @@
                 {{/if}}
               {{else}}
                 {{#if logged_in}}
-                  {{#if constraints.grade_too_low}}
-                    <p>Deine angegebene Jahrgangsstufe entspricht nicht den für diesen Wettbewerb vorgesehenen Altersgruppen.</p>
-                  {{/if}}
-                  {{#if constraints.grade_too_high}}
-                    <p>Deine angegebene Jahrgangsstufe entspricht nicht den für diesen Wettbewerb vorgesehenen Altersgruppen.</p>
+                  {{#if is_qualified}}
+                    {{#if constraints.grade_too_low}}
+                      <p>Deine angegebene Jahrgangsstufe entspricht nicht den für diesen Wettbewerb vorgesehenen Altersgruppen.</p>
+                    {{/if}}
+                    {{#if constraints.grade_too_high}}
+                      <p>Deine angegebene Jahrgangsstufe entspricht nicht den für diesen Wettbewerb vorgesehenen Altersgruppen.</p>
+                    {{/if}}
+                  {{else}}
+                    <p>Du bist für diesen Wettbewerb nicht qualifiziert.</p>
+                    <p>Du hast nicht an der vorhergehenden Wettbewerbsrunde teilgenommen, die Voraussetzung für diesen Wettbewerb ist oder nicht die vorhergehenden Aufgaben bearbeitet, die Voraussetzung für diese Aufgaben sind.</p>
                   {{/if}}
                 {{else}}
                   <p>Möglicherweise musst du dich zunächst <a href="/login">einloggen</a>.</p>