INSServer/src/main/java/org/openautonomousconnection/ins/DatabaseINSServer.java

package org.openautonomousconnection.ins;

import dev.unlegitdqrk.unlegitlibrary.file.ConfigurationManager;
import org.openautonomousconnection.ins.utils.TargetName;
import org.openautonomousconnection.protocol.side.ins.ProtocolINSServer;
import org.openautonomousconnection.protocol.versions.v1_0_0.beta.INSRecord;
import org.openautonomousconnection.protocol.versions.v1_0_0.beta.INSRecordType;

import java.io.File;
import java.io.IOException;
import java.security.cert.CertificateException;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public final class DatabaseINSServer extends ProtocolINSServer {

    private final String jdbcUrl;
    private final String jdbcUser;
    private final String jdbcPassword;

    private final ConfigurationManager configurationManager;

    /**
     * Creates a new database-backed INS server.
     *
     * @throws IOException          If the base server initialization fails.
     * @throws CertificateException If required certificate files are missing or invalid.
     */
    public DatabaseINSServer() throws IOException, CertificateException {
        super(new File("config.properties"));

        configurationManager = new ConfigurationManager(new File("config.properties"));
        configurationManager.loadProperties();

        if (!configurationManager.isSet("db.url")) {
            configurationManager.set(
                    "db.url",
                    "jdbc:mysql://localhost:3306/ins?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC"
            );
            configurationManager.saveProperties();
        }

        if (!configurationManager.isSet("db.user")) {
            configurationManager.set("db.user", "username");
            configurationManager.saveProperties();
        }

        if (!configurationManager.isSet("db.password")) {
            configurationManager.set("db.password", "password");
            configurationManager.saveProperties();
        }

        jdbcUrl = configurationManager.getString("db.url");
        jdbcUser = configurationManager.getString("db.user");
        jdbcPassword = configurationManager.getString("db.password");
    }

    private Connection openConnection() throws SQLException {
        return DriverManager.getConnection(jdbcUrl, jdbcUser, jdbcPassword);
    }

    /**
     * Resolves a request for an INS record based on TLN, name, subname and record type.
     * <p>
     * This implementation:
     * <ul>
     *     <li>Locates the corresponding InfoName in the SQL schema</li>
     *     <li>Returns all matching {@link INSRecord} entries</li>
     *     <li>Performs CNAME recursion (with a depth limit) when no direct
     *     records for the requested type exist</li>
     * </ul>
     */
    @Override
    public List<INSRecord> resolve(String tln, String name, String sub, INSRecordType type) {
        try {
            return resolveInternal(tln, name, sub, type, 0);
        } catch (SQLException ex) {
            getProtocolBridge().getLogger().exception("INS resolve failed for " + formatName(tln, name, sub) + " type=" + type, ex);
            return new ArrayList<>();
        }
    }

    /**
     * Resolves the TLN info site,
     * which is used when a client queries {@code info.<tln>} without any sub-name.
     * <p>
     * The value is read from {@code tln.info} and must be of the form
     * {@code "host:port"}.
     */
    @Override
    public String resolveTLNInfoSite(String tln) {
        String sql = "SELECT info FROM tln WHERE name = ?";

        try (Connection conn = openConnection();
             PreparedStatement ps = conn.prepareStatement(sql)) {

            ps.setString(1, tln);

            try (ResultSet rs = ps.executeQuery()) {
                if (rs.next()) return rs.getString("info"); // expected "host:port"
            }
        } catch (SQLException ex) {
            getProtocolBridge().getLogger().exception("Failed to resolve TLN info site for tln=" + tln, ex);
        }

        return null;
    }

    private String formatName(String tln, String name, String sub) {
        if (sub == null || sub.isEmpty()) return name + "." + tln;
        return sub + "." + name + "." + tln;
    }

    /**
     * Recursive resolver with CNAME handling and depth limit.
     */
    private List<INSRecord> resolveInternal(String tln, String name, String sub, INSRecordType requestedType, int depth) throws SQLException {
        final int MAX_CNAME_DEPTH = 8;

        if (depth > MAX_CNAME_DEPTH) {
            getProtocolBridge().getLogger().warn("CNAME recursion limit exceeded for " + formatName(tln, name, sub) + " type=" + requestedType);
            return new ArrayList<>();
        }

        try (Connection conn = openConnection()) {
            // Get IDs
            Integer tlnId = findTLNId(conn, tln);
            if (tlnId == null) return new ArrayList<>();

            Integer infoNameId = findInfoNameId(conn, tlnId, name);
            if (infoNameId == null) return new ArrayList<>();

            Integer subNameId = findSubNameId(conn, infoNameId, sub);

            // Get records
            List<INSRecord> direct = loadRecords(conn, infoNameId, subNameId, requestedType);

            // No more recursion when CNAME received
            if (requestedType == INSRecordType.CNAME) return direct;

            if (!direct.isEmpty()) return direct;

            // CNAME lookup
            List<INSRecord> cnames = loadRecords(conn, infoNameId, subNameId, INSRecordType.CNAME);
            if (cnames.isEmpty()) return direct; // empty

            List<INSRecord> aggregated = new ArrayList<>();
            for (INSRecord cname : cnames) {
                TargetName target = parseCnameTarget(cname.value);

                if (target == null) {
                    getProtocolBridge().getLogger().warn("Invalid CNAME target '" + cname.value + "' on " + formatName(tln, name, sub));
                    continue;
                }

                // Rekursiv den Zielnamen auflösen
                aggregated.addAll(resolveInternal(target.tln, target.name, target.sub, requestedType, depth + 1));
            }

            return aggregated;
        }
    }

    /**
     * Loads all records of a given type for (infoname_id, subname_id).
     *
     * @param type May be {@code null} to load all types.
     */
    private List<INSRecord> loadRecords(Connection conn, int infonameId, Integer subnameId, INSRecordType type) throws SQLException {

        StringBuilder sql = new StringBuilder("SELECT type, value, ttl, priority, port, weight FROM records WHERE infoname_id = ? ");

        if (subnameId == null) sql.append("AND subname_id IS NULL ");
        else sql.append("AND subname_id = ? ");

        if (type != null) sql.append("AND type = ? ");

        try (PreparedStatement ps = conn.prepareStatement(sql.toString())) {
            int idx = 1;
            ps.setInt(idx++, infonameId);

            if (subnameId != null) ps.setInt(idx++, subnameId);

            if (type != null) ps.setString(idx, type.name());

            List<INSRecord> result = new ArrayList<>();

            try (ResultSet rs = ps.executeQuery()) {
                while (rs.next()) {
                    INSRecordType rType = INSRecordType.valueOf(rs.getString("type"));
                    String value = rs.getString("value");
                    int ttl = rs.getInt("ttl");
                    int priority = rs.getInt("priority");
                    int port = rs.getInt("port");
                    int weight = rs.getInt("weight");

                    result.add(new INSRecord(rType, value, priority, weight, port, ttl));
                }
            }

            return result;
        }
    }

    private Integer findTLNId(Connection conn, String tln) throws SQLException {
        String sql = "SELECT id FROM tln WHERE name = ?";

        try (PreparedStatement ps = conn.prepareStatement(sql)) {
            ps.setString(1, tln);

            try (ResultSet rs = ps.executeQuery()) {
                if (rs.next()) return rs.getInt("id");
            }
        }
        return null;
    }

    private Integer findInfoNameId(Connection conn, int tlnId, String infoName) throws SQLException {
        String sql = "SELECT id FROM infonames WHERE tln_id = ? AND info = ?";

        try (PreparedStatement ps = conn.prepareStatement(sql)) {
            ps.setInt(1, tlnId);
            ps.setString(2, infoName);

            try (ResultSet rs = ps.executeQuery()) {
                if (rs.next()) return rs.getInt("id");
            }
        }

        return null;
    }

    private Integer findSubNameId(Connection conn, int infoNameId, String sub) throws SQLException {
        if (sub == null || sub.isEmpty()) return null;

        String sql = "SELECT id FROM subnames WHERE infoname_id = ? AND name = ?";

        try (PreparedStatement ps = conn.prepareStatement(sql)) {
            ps.setInt(1, infoNameId);
            ps.setString(2, sub);
            try (ResultSet rs = ps.executeQuery()) {
                if (rs.next()) return rs.getInt("id");
            }
        }

        return null;
    }

    /**
     * Parses a CNAME target string into TLN, InfoName and optional subname.
     * <p>
     *
     * @param value Raw CNAME value from the {@code records} table.
     * @return Parsed {@link TargetName} or {@code null} if the value is invalid.
     */
    private TargetName parseCnameTarget(String value) {
        if (value == null) return null;
        String trimmed = value.trim();
        if (trimmed.isEmpty()) return null;

        String[] parts = trimmed.split("\\.");
        if (parts.length < 2) return null; // at least "<name>.<tln>"

        String tln = parts[parts.length - 1];
        String name = parts[parts.length - 2];
        String sub = null;

        if (parts.length > 2) {
            StringBuilder sb = new StringBuilder();

            for (int i = 0; i < parts.length - 2; i++) {
                if (i > 0) sb.append('.');
                sb.append(parts[i]);
            }

            sub = sb.toString();
        }

        return new TargetName(tln, name, sub);
    }
}