Technology implementation

* A stored procedure which implements technologies has been added. It
will mark a pending technology as implemented and remove the
corresponding quantity of money from the empire, then add any newly
available research items to the empire's research.

legacyworlds-server-data/db-structure/parts/040-functions/040-empire.sql

@@ -68,6 +68,92 @@ REVOKE EXECUTE
 	FROM PUBLIC;
 
 
+/*
+ * Implements a technology
+ * ------------------------
+ * 
+ * This stored procedure is called when an empire attempts to implement a
+ * technology. It will check the empire's resources and the technology itself,
+ * then mark it as implemented if necessary. It will also add new research
+ * entries if necessary.
+ * 
+ * Parameters:
+ *		_empire			The empire's identifier
+ *		_technology		The string identifier for the technology to implement
+ */
+DROP FUNCTION emp.technology_implement( INT , TEXT );
+CREATE FUNCTION emp.technology_implement( _empire INT , _technology TEXT )
+		RETURNS BOOLEAN
+		LANGUAGE PLPGSQL
+		STRICT VOLATILE
+		SECURITY DEFINER
+	AS $technology_implement$
+
+DECLARE
+	_impl_data	RECORD;
+
+BEGIN
+
+	-- Access and lock the records
+	SELECT INTO _impl_data
+			technology_name_id , technology_price
+		FROM emp.empires _emp
+			INNER JOIN emp.technologies_v2 _tech
+				ON _tech.empire_id = _emp.name_id
+			INNER JOIN defs.technologies _def
+				USING ( technology_name_id )
+			INNER JOIN defs.strings _name
+				ON _def.technology_name_id = _name.id
+		WHERE _emp.name_id = _empire
+			AND _name.name = _technology
+			AND _tech.emptech_state = 'PENDING'
+			AND _emp.cash >= _def.technology_price
+		FOR UPDATE OF _emp , _tech
+		FOR SHARE OF _def;
+	IF NOT FOUND THEN
+		RETURN FALSE;
+	END IF;
+
+	-- Implement the technology
+	UPDATE emp.empires
+		SET cash = cash - _impl_data.technology_price
+		WHERE name_id = _empire;
+	UPDATE emp.technologies_v2
+		SET emptech_state = 'KNOWN'
+		WHERE empire_id = _empire
+			AND technology_name_id = _impl_data.technology_name_id;
+
+	-- Insert new research
+	INSERT INTO emp.technologies_v2 ( empire_id , technology_name_id )
+		SELECT _empire , _valid.technology_name_id
+			FROM  ( SELECT _tech.technology_name_id ,
+							( COUNT(*) = COUNT(_emptech.emptech_state) ) AS emptech_has_dependencies
+						FROM defs.technologies _tech
+							INNER JOIN defs.technology_dependencies _deps
+									USING ( technology_name_id )
+							LEFT OUTER JOIN emp.technologies_v2 _emptech
+									ON _emptech.technology_name_id = _deps.technology_name_id_depends
+										AND _emptech.emptech_state = 'KNOWN'
+										AND _emptech.empire_id = _empire
+						GROUP BY _tech.technology_name_id ) _valid
+				LEFT OUTER JOIN emp.technologies_v2 _emptech
+					ON _emptech.empire_id = _empire
+						AND _emptech.technology_name_id = _valid.technology_name_id
+			WHERE _emptech.empire_id IS NULL AND _valid.emptech_has_dependencies;
+
+	RETURN TRUE;
+END;
+$technology_implement$;
+
+REVOKE EXECUTE
+	ON FUNCTION emp.technology_implement( INT , TEXT )
+	FROM PUBLIC;
+
+GRANT EXECUTE
+	ON FUNCTION emp.technology_implement( INT , TEXT )
+	TO :dbuser;
+
+
 
 --
 -- Returns a planet owner's empire size
@@ -107,7 +193,7 @@ GRANT EXECUTE ON FUNCTION emp.get_current( INT ) TO :dbuser;
 
 
 --
--- Implements a technology
+-- Implements a technology (OLD VERSION)
 --
 
 CREATE OR REPLACE FUNCTION emp.implement_tech( e_id INT , l_id INT )