fix(athena): accept a query that ends in a semicolon

Athena runs a statement with or without its closing semicolon, but the query
engine wraps it in COPY (...) TO ..., where the semicolon is a syntax error, so
SELECT * FROM orders; always failed. Trailing semicolons are now dropped before
the statement is handed to the engine.

src/main/java/io/github/hectorvent/floci/services/athena/AthenaService.java

@@ -59,6 +59,7 @@ public class AthenaService {
     public static final String DEFAULT_CATALOG = "AwsDataCatalog";
     private static final String DEFAULT_OUTPUT_BUCKET = "floci-athena-results";
     private static final String DEFAULT_WORKGROUP = "primary";
+    private static final Pattern TRAILING_SEMICOLONS = Pattern.compile("[\\s;]+$");
     private static final String DEFAULT_ENGINE_VERSION = "Athena engine version 3";
     private static final long MIN_BYTES_SCANNED_CUTOFF_PER_QUERY = 10_000_000L;
     private static final String WORKGROUP_RESOURCE = "workgroup/";
@@ -191,7 +192,7 @@ public class AthenaService {
             if (outputLocation != null) {
                 ensureOutputBucket(outputLocation);
             }
-            duckClient.execute(query, setupDdl, outputLocation);
+            duckClient.execute(withoutTrailingSemicolons(query), setupDdl, outputLocation);
             return null;
         }).onSuccess(v -> {
             markSucceeded(id, execution);
@@ -555,6 +556,15 @@ public class AthenaService {
         return properties;
     }
 
+    /**
+     * Athena accepts one statement with or without a closing semicolon. The engine wraps the
+     * statement in {@code COPY (...) TO ...}, where a semicolon is a syntax error, so it is
+     * dropped before the query is handed over.
+     */
+    static String withoutTrailingSemicolons(String query) {
+        return query == null ? null : TRAILING_SEMICOLONS.matcher(query).replaceFirst("");
+    }
+
     private static boolean producesResultRows(String query) {
         return RESULT_STATEMENT_PATTERN.matcher(statementText(query)).find();
     }

src/test/java/io/github/hectorvent/floci/services/athena/AthenaTrailingSemicolonTest.java

@@ -0,0 +1,15 @@
+package io.github.hectorvent.floci.services.athena;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class AthenaTrailingSemicolonTest {
+
+    @Test
+    void dropsTheClosingSemicolonsAthenaAccepts() {
+        assertEquals("SELECT * FROM orders LIMIT 10", AthenaService.withoutTrailingSemicolons("SELECT * FROM orders LIMIT 10;"));
+        assertEquals("SELECT 1", AthenaService.withoutTrailingSemicolons("SELECT 1 ; ;\n"));
+        assertEquals("SELECT ';' AS s", AthenaService.withoutTrailingSemicolons("SELECT ';' AS s"));
+    }
+}