Fix flyway baseline setup

wizard-server/src/main/java/org/cobbzilla/wizard/server/listener/FlywayMigrationListener.java

@@ -1,7 +1,9 @@
 package org.cobbzilla.wizard.server.listener;
 
 import lombok.Getter;
+import lombok.NonNull;
 import lombok.extern.slf4j.Slf4j;
+import org.cobbzilla.util.jdbc.ResultSetBean;
 import org.cobbzilla.util.jdbc.UncheckedSqlException;
 import org.cobbzilla.wizard.server.RestServer;
 import org.cobbzilla.wizard.server.RestServerLifecycleListenerBase;
@@ -38,22 +40,17 @@ public class FlywayMigrationListener<C extends RestServerConfiguration> extends
     protected boolean skipDefaultResolvers() { return false; }
     protected MigrationResolver[] getResolvers() { return null; }
 
-    public String getBaselineVersion() { return DATE_FORMAT_YYYYMMDD.print(now())+"99"; }
+    public String getBaselineVersion() { return DATE_FORMAT_YYYYMMDD.print(now()) + "99"; }
 
-    public void migrate(PgRestServerConfiguration configuration) {
+    public void migrate(@NonNull final PgRestServerConfiguration configuration) {
 
         // check to see if flyway tables exist
-        boolean baseline = false;
-        final String flywayTable = getFlywayTableName();
-        try {
-            configuration.execSql("SELECT * from " + flywayTable);
-        } catch (UncheckedSqlException e) {
-            if (e.getSqlException() != null && e.getSqlException() instanceof PSQLException && e.getMessage().contains(" does not exist")) {
-                log.warn(flywayTable + " table does not exist, will baseline DB");
-                baseline = true;
-            } else {
-                throw e;
-            }
+        final var flywayTable = getFlywayTableName();
+        final var baseline = checkIfBaseline(configuration, flywayTable);
+        final var baselineVersion = baseline ? MigrationVersion.fromVersion(getBaselineVersion())
+                                             : MigrationVersion.EMPTY;
+        if (baseline) {
+            log.warn(flywayTable + " table does not exist or is empty, will baseline DB with " + baselineVersion);
         }
 
         final DatabaseConfiguration dbConfig = configuration.getDatabase();
@@ -64,12 +61,11 @@ public class FlywayMigrationListener<C extends RestServerConfiguration> extends
                 .skipDefaultResolvers(skipDefaultResolvers())
                 .resolvers(resolvers != null ? resolvers : new MigrationResolver[0])
                 .baselineOnMigrate(baseline)
-                .baselineVersion(MigrationVersion.fromVersion(getBaselineVersion())));
+                .baselineVersion(baselineVersion));
 
         int applied;
         try {
             applied = flyway.migrate();
-
         } catch (FlywaySqlScriptException e) {
             if (e.getStatement().trim().toLowerCase().startsWith("drop ") && e.getMessage().contains("does not exist")) {
                 log.info("migrate: drop statement ("+e.getStatement()+") failed, ignoring: "+e, e);
@@ -94,4 +90,28 @@ public class FlywayMigrationListener<C extends RestServerConfiguration> extends
         log.info("migrate: successfully applied "+applied+" migrations");
     }
 
+    private boolean checkIfBaseline(@NonNull final PgRestServerConfiguration configuration,
+                                    @NonNull final String flywayTable) {
+        final ResultSetBean rs;
+        try {
+            rs = configuration.execSql("SELECT 1 FROM " + flywayTable + " LIMIT 1");
+        } catch (UncheckedSqlException e) {
+            if (e.getSqlException() == null || !(e.getSqlException() instanceof PSQLException)
+                    || !e.getMessage().contains(" does not exist")) {
+                throw e;
+            }
+            // else, if table is not present, set baseline:
+            return true;
+        }
+
+        // Also, if present flyway migration history table is empty -> set baseline
+        if (rs.rowCount() == 0) {
+            // dropping the existing empty table so flyway inner baseline will work properly
+            configuration.execSql("DROP TABLE " + flywayTable);
+            return true;
+        }
+
+        return false;
+    }
+
 }