import java.sql.*;
import java.util.ArrayList;
import java.util.List;

/**
 * Add lobster_workflow_instance.binding_id on tenant DB(s).
 * Usage:
 *   java -cp ".;mysql-connector-j.jar" ApplyLobsterBindingIdMigration all
 *   java -cp ".;mysql-connector-j.jar" ApplyLobsterBindingIdMigration 33 32
 */
public class ApplyLobsterBindingIdMigration {

    private static final String MASTER_HOST = getenv("DB_HOST", "cq-cdb-8fjmemkb.sql.tencentcdb.com");
    private static final int MASTER_PORT = Integer.parseInt(getenv("DB_PORT", "27220"));
    private static final String MASTER_USER = getenv("DB_USER", "root");
    private static final String MASTER_PASSWORD = getenv("DB_PASSWORD", "Ylrz_1q2w3e4r5t6y");
    private static final String MASTER_DB = getenv("DB_NAME", "ylrz_saas");

    public static void main(String[] args) throws Exception {
        List<Long> tenantIds = resolveTenantIds(args);
        if (tenantIds.isEmpty()) {
            System.err.println("Usage: ApplyLobsterBindingIdMigration all | tenantId ...");
            System.exit(1);
        }

        try (Connection master = open(MASTER_HOST, MASTER_PORT, MASTER_DB, MASTER_USER, MASTER_PASSWORD)) {
            for (Long tenantId : tenantIds) {
                TenantDb tenant = loadTenant(master, tenantId);
                if (tenant == null) {
                    System.err.println("[SKIP] tenant " + tenantId + " not found");
                    continue;
                }
                System.out.println("[RUN] tenant " + tenantId + " -> " + tenant.host + ":" + tenant.port + "/" + tenant.database);
                try (Connection tenantConn = open(tenant.host, tenant.port, tenant.database, tenant.user, tenant.password)) {
                    applyBindingIdColumn(tenantConn);
                }
                System.out.println("[OK] tenant " + tenantId);
            }
        }
    }

    private static List<Long> resolveTenantIds(String[] args) throws SQLException {
        List<Long> ids = new ArrayList<>();
        if (args.length == 0) {
            ids.add(33L);
            return ids;
        }
        if ("all".equalsIgnoreCase(args[0].trim())) {
            try (Connection master = open(MASTER_HOST, MASTER_PORT, MASTER_DB, MASTER_USER, MASTER_PASSWORD);
                 Statement st = master.createStatement();
                 ResultSet rs = st.executeQuery("SELECT id FROM tenant_info WHERE status = 1 ORDER BY id")) {
                while (rs.next()) {
                    ids.add(rs.getLong(1));
                }
            }
            return ids;
        }
        for (String arg : args) {
            ids.add(Long.parseLong(arg.trim()));
        }
        return ids;
    }

    private static void applyBindingIdColumn(Connection conn) throws SQLException {
        if (!tableExists(conn, "lobster_workflow_instance")) {
            System.out.println("  skip: table lobster_workflow_instance not found");
            return;
        }
        addColumnIfMissing(conn, "lobster_workflow_instance", "binding_id",
                "ALTER TABLE lobster_workflow_instance ADD COLUMN binding_id BIGINT NULL "
                        + "COMMENT 'tag binding id' AFTER workflow_id");
        addIndexIfMissing(conn, "lobster_workflow_instance", "idx_lobster_instance_binding",
                "CREATE INDEX idx_lobster_instance_binding "
                        + "ON lobster_workflow_instance (company_id, binding_id, del_flag)");
    }

    private static void addColumnIfMissing(Connection conn, String table, String column, String ddl) throws SQLException {
        if (columnExists(conn, table, column)) {
            System.out.println("  column exists: " + table + "." + column);
            return;
        }
        try (Statement st = conn.createStatement()) {
            st.execute(ddl);
            System.out.println("  added column: " + table + "." + column);
        }
    }

    private static void addIndexIfMissing(Connection conn, String table, String indexName, String ddl) throws SQLException {
        if (indexExists(conn, table, indexName)) {
            System.out.println("  index exists: " + table + "." + indexName);
            return;
        }
        try (Statement st = conn.createStatement()) {
            st.execute(ddl);
            System.out.println("  added index: " + table + "." + indexName);
        }
    }

    private static boolean tableExists(Connection conn, String table) throws SQLException {
        String sql = "SELECT COUNT(*) FROM information_schema.TABLES "
                + "WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = ?";
        try (PreparedStatement ps = conn.prepareStatement(sql)) {
            ps.setString(1, table);
            try (ResultSet rs = ps.executeQuery()) {
                return rs.next() && rs.getInt(1) > 0;
            }
        }
    }

    private static boolean columnExists(Connection conn, String table, String column) throws SQLException {
        String sql = "SELECT COUNT(*) FROM information_schema.COLUMNS "
                + "WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = ? AND COLUMN_NAME = ?";
        try (PreparedStatement ps = conn.prepareStatement(sql)) {
            ps.setString(1, table);
            ps.setString(2, column);
            try (ResultSet rs = ps.executeQuery()) {
                return rs.next() && rs.getInt(1) > 0;
            }
        }
    }

    private static boolean indexExists(Connection conn, String table, String indexName) throws SQLException {
        String sql = "SELECT COUNT(*) FROM information_schema.STATISTICS "
                + "WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = ? AND INDEX_NAME = ?";
        try (PreparedStatement ps = conn.prepareStatement(sql)) {
            ps.setString(1, table);
            ps.setString(2, indexName);
            try (ResultSet rs = ps.executeQuery()) {
                return rs.next() && rs.getInt(1) > 0;
            }
        }
    }

    private static TenantDb loadTenant(Connection master, long tenantId) throws SQLException {
        String sql = "SELECT db_url, db_account, db_pwd FROM tenant_info WHERE id = ? AND status = 1 LIMIT 1";
        try (PreparedStatement ps = master.prepareStatement(sql)) {
            ps.setLong(1, tenantId);
            try (ResultSet rs = ps.executeQuery()) {
                if (!rs.next()) {
                    return null;
                }
                return parseJdbcUrl(rs.getString("db_url"), rs.getString("db_account"), rs.getString("db_pwd"));
            }
        }
    }

    private static TenantDb parseJdbcUrl(String jdbcUrl, String user, String password) {
        if (jdbcUrl == null || !jdbcUrl.startsWith("jdbc:mysql://")) {
            throw new IllegalArgumentException("Unsupported db_url: " + jdbcUrl);
        }
        String body = jdbcUrl.substring("jdbc:mysql://".length());
        int slash = body.indexOf('/');
        if (slash < 0) {
            throw new IllegalArgumentException("Invalid db_url: " + jdbcUrl);
        }
        String hostPort = body.substring(0, slash);
        String rest = body.substring(slash + 1);
        int q = rest.indexOf('?');
        String database = q >= 0 ? rest.substring(0, q) : rest;
        String host;
        int port;
        int colon = hostPort.indexOf(':');
        if (colon >= 0) {
            host = hostPort.substring(0, colon);
            port = Integer.parseInt(hostPort.substring(colon + 1));
        } else {
            host = hostPort;
            port = 3306;
        }
        TenantDb t = new TenantDb();
        t.host = host;
        t.port = port;
        t.database = database;
        t.user = user != null ? user : MASTER_USER;
        t.password = password != null ? password : MASTER_PASSWORD;
        return t;
    }

    private static Connection open(String host, int port, String database, String user, String password)
            throws SQLException {
        String url = "jdbc:mysql://" + host + ":" + port + "/" + database
                + "?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT%2B8&allowMultiQueries=true";
        return DriverManager.getConnection(url, user, password);
    }

    private static String getenv(String key, String defaultValue) {
        String v = System.getenv(key);
        return v != null && !v.isEmpty() ? v : defaultValue;
    }

    private static final class TenantDb {
        String host;
        int port;
        String database;
        String user;
        String password;
    }
}