import java.sql.Connection;
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import java.sql.DriverManager;
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import java.sql.ResultSet;
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import java.sql.SQLException;
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import java.sql.Statement;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* Drops every table and view of one database so Flyway can rebuild the schema from the migrations.
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*
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* <p>Run through {@code scripts/reset-test-db.ps1}; this program exists because the checkout has no
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* MySQL client and no Docker, while the JDBC driver is already required by the application.
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*/
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public final class ResetTestDatabase {
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public static void main(String[] args) throws Exception {
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if (args.length < 3) {
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System.err.println("usage: ResetTestDatabase <jdbcUrl> <user> <password>");
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System.exit(2);
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}
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String url = args[0];
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String user = args[1];
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String password = args[2];
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String database = databaseName(url);
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if (database.isEmpty()) {
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System.err.println("The JDBC URL must name the database to reset: " + url);
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System.exit(2);
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}
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try (Connection connection = DriverManager.getConnection(url, user, password)) {
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List<String> views = objects(connection, database, "VIEW");
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List<String> tables = objects(connection, database, "BASE TABLE");
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dropAll(connection, views, tables);
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System.out.println("reset " + database + ": dropped " + views.size() + " views and " + tables.size() + " tables");
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if (!tables.isEmpty()) {
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System.out.println(" dropped: " + summary(tables));
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}
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System.out.println("The next test run recreates the schema from db/migration.");
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return;
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} catch (SQLException exception) {
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if (!unknownDatabase(exception)) throw exception;
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}
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try (Connection connection = DriverManager.getConnection(serverUrl(url), user, password);
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Statement statement = connection.createStatement()) {
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statement.executeUpdate("create database if not exists `" + database + "` default charset utf8mb4");
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}
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System.out.println("created empty database " + database + " (it did not exist yet)");
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}
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private static List<String> objects(Connection connection, String database, String type) throws SQLException {
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List<String> names = new ArrayList<>();
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try (var statement = connection.prepareStatement("""
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select table_name from information_schema.tables
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where table_schema = ? and table_type = ?
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order by table_name
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""")) {
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statement.setString(1, database);
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statement.setString(2, type);
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try (ResultSet result = statement.executeQuery()) {
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while (result.next()) names.add(result.getString(1));
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}
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}
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return names;
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}
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private static void dropAll(Connection connection, List<String> views, List<String> tables) throws SQLException {
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try (Statement statement = connection.createStatement()) {
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statement.execute("set foreign_key_checks = 0");
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try {
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for (String view : views) statement.executeUpdate("drop view if exists `" + view + "`");
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for (String table : tables) statement.executeUpdate("drop table if exists `" + table + "`");
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} finally {
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statement.execute("set foreign_key_checks = 1");
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}
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}
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}
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/** The database name of a JDBC URL such as jdbc:mysql://host:port/db?params. */
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static String databaseName(String url) {
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int pathStart = pathStart(url);
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if (pathStart < 0) return "";
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String tail = url.substring(pathStart + 1);
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int query = tail.indexOf('?');
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return (query < 0 ? tail : tail.substring(0, query)).trim();
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}
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/** The same URL without its database, used to create a database that does not exist yet. */
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static String serverUrl(String url) {
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int pathStart = pathStart(url);
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if (pathStart < 0) return url;
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int query = url.indexOf('?', pathStart);
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return url.substring(0, pathStart + 1) + (query < 0 ? "" : url.substring(query));
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}
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/**
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* Index of the slash that separates the host from the database path. Splitting on the last slash
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* would break on URLs that carry a path-like parameter, for example serverTimezone=Asia/Shanghai.
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*/
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private static int pathStart(String url) {
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int schemeEnd = url.indexOf("//");
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return schemeEnd < 0 ? -1 : url.indexOf('/', schemeEnd + 2);
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}
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private static boolean unknownDatabase(SQLException exception) {
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for (SQLException current = exception; current != null; current = current.getNextException()) {
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if (current.getErrorCode() == 1049) return true;
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String message = current.getMessage();
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if (message != null && message.toLowerCase().contains("unknown database")) return true;
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}
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return false;
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}
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private static String summary(List<String> names) {
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if (names.size() <= 12) return String.join(", ", names);
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return String.join(", ", names.subList(0, 12)) + ", ... (" + (names.size() - 12) + " more)";
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}
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}
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