package org.openautonomousconnection.ins;

import dev.unlegitdqrk.unlegitlibrary.file.ConfigurationManager;
import org.openautonomousconnection.protocol.ProtocolBridge;
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;

/**
 * Concrete INS server implementation backed by a SQL database.
 * <p>
 * This implementation expects a table schema similar to:
 * <pre>
 * CREATE TABLE ins_records (
 *   id        BIGINT PRIMARY KEY AUTO_INCREMENT,
 *   tln       VARCHAR(64)  NOT NULL,
 *   name      VARCHAR(255) NOT NULL,
 *   sub       VARCHAR(255) NULL,
 *   type      VARCHAR(16)  NOT NULL, -- matches {@link INSRecordType#name()}
 *   value     VARCHAR(1024) NOT NULL,
 *   priority  INT NOT NULL,
 *   weight    INT NOT NULL,
 *   port      INT NOT NULL,
 *   ttl       INT NOT NULL
 * );
 *
 * CREATE TABLE ins_tln_info (
 *   tln       VARCHAR(64) PRIMARY KEY,
 *   host      VARCHAR(255) NOT NULL,
 *   port      INT NOT NULL
 * );
 * </pre>
 */
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/DB_NAME?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC\n");
            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 records for the given INS name from the database.
     * <p>
     * This method does a single lookup and returns exactly the records that
     * match the given query (no CNAME recursion here – that is handled on a
     * higher level, e.g. via {@code INSRecordTools.resolveWithCNAME(...)}).
     *
     * @param tln  Top-level-name.
     * @param name InfoName.
     * @param sub  Optional sub-name. May be {@code null}.
     * @param type Desired record type.
     *
     * @return List of matching {@link INSRecord}s, or an empty list if none exist.
     */
    @Override
    public List<INSRecord> resolve(String tln, String name, String sub, INSRecordType type) {
        List<INSRecord> result = new ArrayList<>();

        String sql =
                "SELECT type, value, priority, weight, port, ttl " +
                        "FROM ins_records " +
                        "WHERE tln = ? AND name = ? AND type = ? " +
                        "AND ( (sub IS NULL AND ? IS NULL) OR sub = ? )";

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

            ps.setString(1, tln);
            ps.setString(2, name);
            ps.setString(3, type.name());
            ps.setString(4, sub);
            ps.setString(5, sub);

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

                    result.add(new INSRecord(dbType, value, priority, weight, port, ttl));
                }
            }
        } catch (SQLException ex) {
            getProtocolBridge().getLogger().exception("Failed to resolve INS record from database", ex);
        }

        return result;
    }

    /**
     * Resolves the TLN info site,
     * which is used when a client queries {@code info.<tln>} without any sub-name.
     * <p>
     * The result must be returned as {@code "host:port"}.
     *
     * @param tln The TLN the client is asking about.
     *
     * @return A {@code "host:port"} string or {@code null} if no TLN info site is configured.
     */
    @Override
    public String resolveTLNInfoSite(String tln) {
        String sql = "SELECT host, port FROM ins_tln_info WHERE tln = ?";

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

            ps.setString(1, tln);

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

        return null;
    }
}