import java.io.FileInputStream;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

public class MigrateRun {
    public static void main(String[] args) throws Exception {
        Properties props = new Properties();
        try (FileInputStream in = new FileInputStream(args[0])) { props.load(in); }
        String script = new String(Files.readAllBytes(Paths.get(args[1])), StandardCharsets.UTF_8);

        // split into per-table blocks by "-- ===== " headers
        String[] blocks = script.split("(?m)^-- ===== ");
        List<String[]> tableBatches = new ArrayList<>();
        List<String> tableNames = new ArrayList<>();
        for (String b : blocks) {
            if (b.isBlank()) continue;
            String[] lines = b.split("\\R", 2);
            String name = lines[0].trim();
            String body = lines.length > 1 ? lines[1] : "";
            // skip comment-only tail
            if (!body.contains("ALTER TABLE") && !body.contains("EXEC sp_rename")) continue;
            // split body by GO lines
            List<String> batches = new ArrayList<>();
            StringBuilder cur = new StringBuilder();
            for (String line : body.split("\\R")) {
                if (line.trim().equalsIgnoreCase("GO")) {
                    if (!cur.toString().isBlank()) batches.add(cur.toString());
                    cur.setLength(0);
                } else {
                    cur.append(line).append("\n");
                }
            }
            if (!cur.toString().isBlank()) batches.add(cur.toString());
            tableBatches.add(batches.toArray(new String[0]));
            tableNames.add(name);
        }

        System.out.println("Tables to migrate: " + tableNames.size());
        Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
        int ok = 0;
        try (Connection conn = DriverManager.getConnection(props.getProperty("url"), props.getProperty("username"), props.getProperty("password"))) {
            for (int t = 0; t < tableNames.size(); t++) {
                String tbl = tableNames.get(t);
                String[] batches = tableBatches.get(t);
                conn.setAutoCommit(false);
                boolean failed = false;
                for (String batch : batches) {
                    try (Statement st = conn.createStatement()) {
                        st.execute(batch);
                    } catch (SQLException e) {
                        System.err.println("FAILED on " + tbl + " batch: " + e.getMessage());
                        System.err.println("  SQL: " + batch.replaceAll("\\s+", " ").trim());
                        failed = true;
                        break;
                    }
                }
                if (failed) {
                    conn.rollback();
                    System.err.println("  -> ROLLED BACK " + tbl);
                } else {
                    conn.commit();
                    System.out.println("OK: " + tbl + " (" + batches.length + " batches)");
                    ok++;
                }
            }
        }
        System.out.println("\nMigrated OK: " + ok + "/" + tableNames.size());
    }
}