Issue #5: Vorschlag für den Aufbau des Projekts

* Maven-Projekt direkt im Hauptverzeichnis
* Anpassung der Maven-POM-Datei - nicht benötigte Abhängigkeiten entfernt
* Gitignore-Datei angelegt

src/main/java/ATCCodes/services/OnkostarAgentCodeService.java

@@ -0,0 +1,54 @@
+package ATCCodes.services;
+
+import ATCCodes.AgentCode;
+import ATCCodes.UnregisteredCode;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.stereotype.Service;
+
+import javax.sql.DataSource;
+import java.util.List;
+
+/**
+ * Implementation of {@link AgentCodeService} that uses database to query for unregistered agents
+ *
+ * @author Paul-Christian Volkmer
+ * @since 0.1.0
+ */
+@Service
+public class OnkostarAgentCodeService implements AgentCodeService {
+
+    private final JdbcTemplate jdbcTemplate;
+
+    public OnkostarAgentCodeService(final DataSource dataSource) {
+        this.jdbcTemplate = new JdbcTemplate(dataSource);
+    }
+
+    /**
+     * Queries source for agents code starting with or name containing query string.
+     * If size is zero, all available results will be returned.
+     *
+     * @param query The query string
+     * @param size  Maximal amount of responses
+     * @return A list with agent codes
+     */
+    @Override
+    public List<AgentCode> findAgentCodes(final String query, final int size) {
+        var sql = "SELECT code, shortdesc\n" +
+                "    FROM property_catalogue\n" +
+                "    JOIN property_catalogue_version ON (property_catalogue_version.datacatalog_id = property_catalogue.id)\n" +
+                "    JOIN property_catalogue_version_entry p ON (p.property_version_id = property_catalogue_version.id)\n" +
+                "    WHERE name = 'OS.Substanzen'\n" +
+                "    AND (LOWER(code) LIKE ? OR LOWER(shortdesc) LIKE ? OR LOWER(synonyms) LIKE ?)";
+
+        if (size > 0) {
+            sql = sql + " LIMIT " + size;
+        }
+
+        return jdbcTemplate.query(
+                sql,
+                new Object[]{query + "%", "%" + query + "%", "%" + query + "%"},
+                (resultSet, i) ->
+                        new UnregisteredCode(resultSet.getString("code"), resultSet.getString("shortdesc"))
+        );
+    }
+}