feat(editor): improve qualified table completion

apps/desktop/src/lib/sql/sqlCompletionLookupTarget.ts

@@ -0,0 +1,42 @@
+import type { SqlCompletionContext } from "@/lib/sql/sqlCompletion";
+
+export interface SqlCompletionTableLookupTarget {
+  database: string;
+  schema?: string;
+  filter: string;
+  qualifierDatabase?: string;
+}
+
+function findExactName(names: readonly string[] | undefined, value: string): string | undefined {
+  return names?.find((name) => name.toLowerCase() === value.toLowerCase());
+}
+
+export function resolveSqlCompletionTableLookupTarget(options: {
+  currentDatabase: string;
+  currentSchema?: string;
+  supportsDatabaseQualifier: boolean;
+  completionContext: Pick<SqlCompletionContext, "qualifier" | "prefix" | "suggestTables" | "insertTable">;
+  knownDatabases?: readonly string[];
+}): SqlCompletionTableLookupTarget {
+  const { completionContext } = options;
+  const qualifier = completionContext.qualifier?.trim();
+  const qualifierIsDatabase = options.supportsDatabaseQualifier && !!qualifier && completionContext.suggestTables && !completionContext.insertTable;
+
+  if (qualifierIsDatabase) {
+    // MySQL-compatible engines, including OceanBase MySQL mode, use
+    // database.table. Do not block table completion on a separate database-list
+    // request when the user already typed the database qualifier.
+    const database = findExactName(options.knownDatabases, qualifier) ?? qualifier;
+    return {
+      database,
+      filter: completionContext.prefix,
+      qualifierDatabase: database,
+    };
+  }
+
+  return {
+    database: options.currentDatabase,
+    schema: qualifier && completionContext.suggestTables ? qualifier : options.currentSchema,
+    filter: qualifier && completionContext.suggestTables ? completionContext.prefix : qualifier || completionContext.prefix,
+  };
+}