Replace priority field with dependsOn dependency resolver for Providers

- Removed the `priority` method from `Provider` interface and its implementations.
- Introduced a `dependsOn` method for defining dependencies between Providers.
- Implemented a topological sorting mechanism in `ProviderManager` to handle Provider initialization order based on dependencies.
- Included validation for self-dependencies and unknown dependencies.

src/main/java/dev/coph/flightscore/backend/competition/CompetitionProvider.java

@@ -6,11 +6,6 @@ import dev.coph.simplesql.query.Query;
 public class CompetitionProvider implements Provider {
 
 
-    @Override
-    public int priority() {
-        return 0;
-    }
-
     @Override
     public String key() {
         return "";

src/main/java/dev/coph/flightscore/backend/provider/Provider.java

@@ -2,8 +2,12 @@ package dev.coph.flightscore.backend.provider;
 
 import dev.coph.simplesql.query.Query;
 
+import java.util.Set;
+
 public interface Provider {
-    int priority();
+    default Set<String> dependsOn() {
+        return Set.of();
+    }
 
     String key();
 

src/main/java/dev/coph/flightscore/backend/provider/ProviderManager.java

@@ -3,7 +3,13 @@ package dev.coph.flightscore.backend.provider;
 import dev.coph.flightscore.backend.Backend;
 import dev.coph.simplesql.query.Query;
 
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Deque;
 import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
 
 public class ProviderManager {
     private final Backend backend;
@@ -15,13 +21,13 @@ public class ProviderManager {
 
     public void createAllDatabaseTables() {
         Query query = new Query(backend.databaseAdapter());
-        providers.values().stream().sorted((a, b) -> Integer.compare(b.priority(), a.priority())).forEach(provider -> provider.createDatabaseTables(query));
+        resolveOrder().forEach(provider -> provider.createDatabaseTables(query));
         query.execute();
     }
 
     public void enableAllProviders() {
         Query query = new Query(backend.databaseAdapter());
-        providers.values().stream().sorted((a, b) -> Integer.compare(b.priority(), a.priority())).forEach(provider -> provider.onEnable(query));
+        resolveOrder().forEach(provider -> provider.onEnable(query));
         query.execute();
     }
 
@@ -33,4 +39,49 @@ public class ProviderManager {
         return (T) providers.get(key);
     }
 
+    private List<Provider> resolveOrder() {
+        HashMap<String, Integer> inDegree = new HashMap<>();
+        HashMap<String, Set<String>> dependents = new HashMap<>();
+        for (Provider provider : providers.values()) {
+            inDegree.putIfAbsent(provider.key(), 0);
+            dependents.putIfAbsent(provider.key(), new HashSet<>());
+        }
+        for (Provider provider : providers.values()) {
+            for (String dependency : provider.dependsOn()) {
+                if (dependency.equals(provider.key())) {
+                    throw new IllegalStateException("Provider '" + provider.key() + "' depends on itself.");
+                }
+                if (!providers.containsKey(dependency)) {
+                    throw new IllegalStateException("Provider '" + provider.key() + "' depends on unknown provider '" + dependency + "'.");
+                }
+                if (dependents.get(dependency).add(provider.key())) {
+                    inDegree.merge(provider.key(), 1, Integer::sum);
+                }
+            }
+        }
+
+        Deque<String> ready = new ArrayDeque<>();
+        inDegree.forEach((key, degree) -> {
+            if (degree == 0) ready.add(key);
+        });
+
+        List<Provider> ordered = new ArrayList<>(providers.size());
+        while (!ready.isEmpty()) {
+            String key = ready.poll();
+            ordered.add(providers.get(key));
+            for (String dependent : dependents.get(key)) {
+                if (inDegree.merge(dependent, -1, Integer::sum) == 0) {
+                    ready.add(dependent);
+                }
+            }
+        }
+
+        if (ordered.size() != providers.size()) {
+            Set<String> remaining = new HashSet<>(providers.keySet());
+            ordered.forEach(provider -> remaining.remove(provider.key()));
+            throw new IllegalStateException("Circular dependency detected among providers: " + remaining);
+        }
+        return ordered;
+    }
+
 }

src/main/java/dev/coph/flightscore/backend/user/UserProvider.java

@@ -29,6 +29,7 @@ import java.time.Duration;
 import java.time.Instant;
 import java.util.List;
 import java.util.Locale;
+import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 
@@ -45,8 +46,8 @@ public class UserProvider implements Provider {
     }
 
     @Override
-    public int priority() {
-        return 50;
+    public Set<String> dependsOn() {
+        return Set.of("role-provider");
     }
 
     @Override

src/main/java/dev/coph/flightscore/backend/user/permission/PermissionProvider.java

@@ -20,11 +20,6 @@ public class PermissionProvider implements Provider {
         this.backend = backend;
     }
 
-    @Override
-    public int priority() {
-        return 150;
-    }
-
     @Override
     public String key() {
         return "permission-provider";

src/main/java/dev/coph/flightscore/backend/user/role/RoleProvider.java

@@ -14,6 +14,7 @@ import lombok.experimental.Accessors;
 
 import java.util.HashMap;
 import java.util.List;
+import java.util.Set;
 
 @Accessors(fluent = true)
 public class RoleProvider implements Provider {
@@ -29,8 +30,8 @@ public class RoleProvider implements Provider {
 
 
     @Override
-    public int priority() {
-        return 100;
+    public Set<String> dependsOn() {
+        return Set.of("permission-provider");
     }
 
     @Override