import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;

/**
 * 只读探针：只打印某张表有差异的行——仅左库有 / 仅右库有 / 同主键但内容不同（两侧并列）。
 *
 * <p>用法：java DiffRows &lt;左url&gt; &lt;右url&gt; &lt;表名&gt; &lt;展示列,展示列...&gt;
 */
public class DiffRows {

    public static void main(String[] args) throws Exception {
        String table = args[2];
        String[] columns = args[3].split(",");
        try (Connection left = DriverManager.getConnection(args[0], "root", "123456");
             Connection right = DriverManager.getConnection(args[1], "root", "123456")) {
            Map<String, String> leftRows = rows(left, table, columns);
            Map<String, String> rightRows = rows(right, table, columns);
            System.out.println("== " + table + "：仅左库（本机 dev）有 ==");
            for (Map.Entry<String, String> entry : leftRows.entrySet()) {
                if (!rightRows.containsKey(entry.getKey())) System.out.println("  " + entry.getValue());
            }
            System.out.println("== " + table + "：仅右库（服务器）有 ==");
            for (Map.Entry<String, String> entry : rightRows.entrySet()) {
                if (!leftRows.containsKey(entry.getKey())) System.out.println("  " + entry.getValue());
            }
            System.out.println("== " + table + "：同主键内容不同 ==");
            for (Map.Entry<String, String> entry : leftRows.entrySet()) {
                String other = rightRows.get(entry.getKey());
                if (other == null || other.equals(entry.getValue())) continue;
                System.out.println("  左 " + entry.getValue());
                System.out.println("  右 " + other);
                System.out.println();
            }
        }
    }

    private static Map<String, String> rows(Connection connection, String table, String[] columns) throws Exception {
        Map<String, String> lines = new TreeMap<>();
        String selection = String.join(", ", java.util.Arrays.stream(columns).map(c -> "`" + c + "`").toList());
        try (PreparedStatement statement = connection.prepareStatement(
                "select id, " + selection + " from `" + table + "`");
             ResultSet result = statement.executeQuery()) {
            while (result.next()) {
                StringBuilder line = new StringBuilder("#" + result.getObject(1));
                for (int index = 0; index < columns.length; index++) {
                    Object value = result.getObject(index + 2);
                    String text = value == null ? "NULL" : String.valueOf(value);
                    if (text.length() > 70) text = text.substring(0, 70) + "…";
                    line.append(" | ").append(columns[index]).append('=').append(text);
                }
                lines.put(String.valueOf(result.getObject(1)), line.toString());
            }
        }
        return new LinkedHashMap<>(lines);
    }
}