Refactor building upgrade requirements procedure (#9)

Refactor building requirements procedure to include target level validation and upgrade prerequisites

procedures/get/building.sql

@@ -18,19 +18,41 @@ BEGIN
     WHERE building_id = p_building_id;
 END //
 
-CREATE OR REPLACE PROCEDURE get_building_prerequisites(IN p_building_id INT)
+CREATE OR REPLACE PROCEDURE get_building_upgrade_requirements(
+    IN p_building_id INT,
+    IN target_level INT
+)
 BEGIN
-    SELECT prerequisite_id
-    FROM building_prerequisite
-    WHERE building_id = p_building_id;
-END //
+    -- Check if the building level is valid
+    DECLARE max_building_level INT;
 
--- This procedure is used to get the requirements for a building
-CREATE OR REPLACE PROCEDURE get_building_requirements(IN p_building_id INT)
-BEGIN
-    SELECT required_wood, required_stone, required_silver, required_population
-    FROM building_requirement
+    SELECT max_level INTO max_building_level
+    FROM building
     WHERE building_id = p_building_id;
+
+    IF target_level > max_building_level THEN
+        SIGNAL SQLSTATE '45000'
+        SET MESSAGE_TEXT = 'Target level exceeds maximum building level.';
+    END IF;
+
+    -- Fetch required resources
+    SELECT
+        br.required_wood,
+        br.required_stone,
+        br.required_silver,
+        br.required_population
+    FROM building_requirement br
+    WHERE br.building_id = p_building_id AND br.building_level = target_level;
+
+    -- Fetch prerequisite buildings
+    SELECT
+        bp.prerequisite_building_id,
+        b.building_name AS prerequisite_building_name,
+        bp.building_level AS required_level
+    FROM building_prerequisite bp
+    JOIN building b ON bp.prerequisite_building_id = b.building_id
+    WHERE bp.building_id = p_building_id AND bp.building_level = target_level;
+
 END //
 
 DELIMITER ;