package ins.frontend.utils;

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

/**
 * Registrar DAO for schema:
 * <ul>
 *   <li>tln(id, name, info, owner_id, is_public, allow_subdomains)</li>
 *   <li>infonames(id, info, tln_id, uid)</li>
 *   <li>subnames(id, name, infoname_id)</li>
 *   <li>records(id, infoname_id, subname_id, type, value, ttl, priority, port, weight)</li>
 * </ul>
 *
 * <p>Rules:</p>
 * <ul>
 *   <li>Create InfoName under TLN allowed if TLN is public OR owned by user.</li>
 *   <li>Subnames allowed for non-owner only if allow_subdomains=1. Owner always allowed.</li>
 *   <li>TLN name is not editable; only info/is_public/allow_subdomains are editable (owner-only).</li>
 * </ul>
 */
public final class RegistrarDao {

    private final UserDao.DataSourceProvider dataSource;

    /**
     * Creates the DAO.
     *
     * @param dataSource JDBC connection provider
     */
    public RegistrarDao(UserDao.DataSourceProvider dataSource) {
        this.dataSource = Objects.requireNonNull(dataSource, "dataSource");
    }

    // ---------- TLN ----------

    /**
     * TLN usable for creating InfoNames if public OR owned.
     *
     * @param tln    TLN row
     * @param userId current user id
     * @return allowed
     */
    public static boolean canUseTln(TlnRow tln, int userId) {
        if (tln == null || userId <= 0) return false;
        if (tln.isPublic) return true;
        return tln.ownerId != null && tln.ownerId == userId;
    }

    /**
     * Subdomain/subname allowed if:
     * <ul>
     *   <li>no sub requested (root) OR</li>
     *   <li>TLN allows subdomains OR</li>
     *   <li>user is TLN owner</li>
     * </ul>
     *
     * @param tln    TLN row
     * @param userId current user id
     * @param sub    sub label (nullable)
     * @return allowed
     */
    public static boolean canUseSubname(TlnRow tln, int userId, String sub) {
        if (tln == null || userId <= 0) return false;
        boolean wantsSub = sub != null && !sub.isBlank();
        if (!wantsSub) return true;
        if (tln.allowSubdomains) return true;
        return tln.ownerId != null && tln.ownerId == userId;
    }

    private static TlnRow mapTln(ResultSet rs) throws SQLException {
        return new TlnRow(
                rs.getInt("id"),
                rs.getString("name"),
                rs.getString("info"),
                (Integer) rs.getObject("owner_id"),
                rs.getInt("is_public") == 1,
                rs.getInt("allow_subdomains") == 1
        );
    }

    /**
     * Creates a TLN.
     *
     * @param name            tln.name (unique)
     * @param info            tln.info (editable, can be null/blank)
     * @param ownerId         owner user id (nullable in DB, pass null to create unowned TLN)
     * @param isPublic        tln.is_public
     * @param allowSubdomains tln.allow_subdomains
     * @return new tln.id
     * @throws SQLException on SQL errors
     */
    public int createTln(String name, String info, Integer ownerId, boolean isPublic, boolean allowSubdomains) throws SQLException {
        if (name == null || name.isBlank()) throw new IllegalArgumentException("name must not be blank");

        String sql = "INSERT INTO tln (name, info, owner_id, is_public, allow_subdomains) VALUES (?, ?, ?, ?, ?)";

        try (Connection c = dataSource.getConnection();
             PreparedStatement ps = c.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)) {

            ps.setString(1, name.trim());
            ps.setString(2, info);
            if (ownerId == null) ps.setNull(3, Types.INTEGER);
            else ps.setInt(3, ownerId);
            ps.setInt(4, isPublic ? 1 : 0);
            ps.setInt(5, allowSubdomains ? 1 : 0);

            ps.executeUpdate();

            try (ResultSet rs = ps.getGeneratedKeys()) {
                if (rs.next()) return rs.getInt(1);
            }
        }

        throw new SQLException("No generated key returned for tln.id");
    }

    /**
     * Finds TLN by name.
     *
     * @param name tln.name
     * @return optional row
     * @throws SQLException on SQL errors
     */
    public Optional<TlnRow> findTlnByName(String name) throws SQLException {
        if (name == null || name.isBlank()) return Optional.empty();

        String sql = "SELECT id, name, info, owner_id, is_public, allow_subdomains FROM tln WHERE name = ? LIMIT 1";

        try (Connection c = dataSource.getConnection();
             PreparedStatement ps = c.prepareStatement(sql)) {

            ps.setString(1, name.trim());

            try (ResultSet rs = ps.executeQuery()) {
                if (!rs.next()) return Optional.empty();
                return Optional.of(mapTln(rs));
            }
        }
    }

    // ---------- Permissions ----------

    /**
     * Lists TLNs visible to a user: owned OR public OR unowned+public.
     *
     * @param userId current user id
     * @return rows
     * @throws SQLException on SQL errors
     */
    public TlnRow[] listVisibleTlns(int userId) throws SQLException {
        String sql = """
                SELECT id, name, info, owner_id, is_public, allow_subdomains
                FROM tln
                WHERE is_public = 1 OR owner_id = ?
                ORDER BY name ASC
                """;

        List<TlnRow> out = new ArrayList<>();

        try (Connection c = dataSource.getConnection();
             PreparedStatement ps = c.prepareStatement(sql)) {

            ps.setInt(1, userId);

            try (ResultSet rs = ps.executeQuery()) {
                while (rs.next()) out.add(mapTln(rs));
            }
        }

        return out.toArray(new TlnRow[0]);
    }

    /**
     * Updates TLN fields except name (owner-only).
     *
     * @param tlnId           tln.id
     * @param ownerUserId     users.id (must match tln.owner_id)
     * @param newInfo         new info text (nullable)
     * @param isPublic        is_public
     * @param allowSubdomains allow_subdomains
     * @return true if updated, false if not owned/not found
     * @throws SQLException on SQL errors
     */
    public boolean updateTlnOwned(int tlnId, int ownerUserId, String newInfo, boolean isPublic, boolean allowSubdomains) throws SQLException {
        if (tlnId <= 0) throw new IllegalArgumentException("tlnId must be > 0");
        if (ownerUserId <= 0) throw new IllegalArgumentException("ownerUserId must be > 0");

        String sql = "UPDATE tln SET info = ?, is_public = ?, allow_subdomains = ? WHERE id = ? AND owner_id = ?";

        try (Connection c = dataSource.getConnection();
             PreparedStatement ps = c.prepareStatement(sql)) {

            ps.setString(1, newInfo);
            ps.setInt(2, isPublic ? 1 : 0);
            ps.setInt(3, allowSubdomains ? 1 : 0);
            ps.setInt(4, tlnId);
            ps.setInt(5, ownerUserId);

            return ps.executeUpdate() > 0;
        }
    }

    // ---------- InfoNames ----------

    /**
     * Deletes TLN (owner-only).
     *
     * @param tlnId       tln.id
     * @param ownerUserId users.id
     * @return true if deleted
     * @throws SQLException on SQL errors
     */
    public boolean deleteTlnOwned(int tlnId, int ownerUserId) throws SQLException {
        if (tlnId <= 0) throw new IllegalArgumentException("tlnId must be > 0");
        if (ownerUserId <= 0) throw new IllegalArgumentException("ownerUserId must be > 0");

        String sql = "DELETE FROM tln WHERE id = ? AND owner_id = ?";

        try (Connection c = dataSource.getConnection();
             PreparedStatement ps = c.prepareStatement(sql)) {

            ps.setInt(1, tlnId);
            ps.setInt(2, ownerUserId);

            return ps.executeUpdate() > 0;
        }
    }

    /**
     * Creates an InfoName under the given TLN.
     *
     * @param tln    TLN row
     * @param info   infonames.info
     * @param userId infonames.uid (users.id)
     * @return new infonames.id
     * @throws SQLException on SQL errors
     */
    public int createInfoName(TlnRow tln, String info, int userId) throws SQLException {
        if (tln == null) throw new IllegalArgumentException("tln must not be null");
        if (userId <= 0) throw new IllegalArgumentException("userId must be > 0");
        if (!canUseTln(tln, userId)) throw new SQLException("TLN not public and not owned by user.");
        if (info == null || info.isBlank()) throw new IllegalArgumentException("info must not be blank");

        String sql = "INSERT INTO infonames (info, tln_id, uid) VALUES (?, ?, ?)";

        try (Connection c = dataSource.getConnection();
             PreparedStatement ps = c.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)) {

            ps.setString(1, info.trim());
            ps.setInt(2, tln.id);
            ps.setInt(3, userId);

            ps.executeUpdate();

            try (ResultSet rs = ps.getGeneratedKeys()) {
                if (rs.next()) return rs.getInt(1);
            }
        }

        throw new SQLException("No generated key returned for infonames.id");
    }

    /**
     * Checks whether a user owns the infoname.
     *
     * @param infonameId infonames.id
     * @param userId     users.id
     * @return true if owned
     * @throws SQLException on SQL errors
     */
    public boolean isOwnerOfInfoName(int infonameId, int userId) throws SQLException {
        if (infonameId <= 0 || userId <= 0) return false;

        String sql = "SELECT 1 FROM infonames WHERE id = ? AND uid = ? LIMIT 1";

        try (Connection c = dataSource.getConnection();
             PreparedStatement ps = c.prepareStatement(sql)) {

            ps.setInt(1, infonameId);
            ps.setInt(2, userId);

            try (ResultSet rs = ps.executeQuery()) {
                return rs.next();
            }
        }
    }

    /**
     * Deletes an InfoName (owner-only).
     *
     * @param infonameId  infonames.id
     * @param ownerUserId users.id
     * @return true if deleted
     * @throws SQLException on SQL errors
     */
    public boolean deleteInfoNameOwned(int infonameId, int ownerUserId) throws SQLException {
        if (infonameId <= 0) throw new IllegalArgumentException("infonameId must be > 0");
        if (ownerUserId <= 0) throw new IllegalArgumentException("ownerUserId must be > 0");

        String sql = "DELETE FROM infonames WHERE id = ? AND uid = ?";

        try (Connection c = dataSource.getConnection();
             PreparedStatement ps = c.prepareStatement(sql)) {

            ps.setInt(1, infonameId);
            ps.setInt(2, ownerUserId);

            return ps.executeUpdate() > 0;
        }
    }

    // ---------- Subnames + Records ----------

    /**
     * Lists InfoNames owned by user (joined with TLN data).
     *
     * @param userId users.id
     * @return rows
     * @throws SQLException on SQL errors
     */
    public InfoNameRow[] listOwnedInfoNames(int userId) throws SQLException {
        if (userId <= 0) return new InfoNameRow[0];

        String sql = """
                SELECT i.id AS iid, i.info AS info, i.tln_id AS tln_id,
                       t.name AS tln_name, t.info AS tln_info, t.owner_id AS owner_id,
                       t.is_public AS is_public, t.allow_subdomains AS allow_subdomains
                FROM infonames i
                INNER JOIN tln t ON t.id = i.tln_id
                WHERE i.uid = ?
                ORDER BY t.name ASC, i.info ASC
                """;

        List<InfoNameRow> out = new ArrayList<>();

        try (Connection c = dataSource.getConnection();
             PreparedStatement ps = c.prepareStatement(sql)) {

            ps.setInt(1, userId);

            try (ResultSet rs = ps.executeQuery()) {
                while (rs.next()) {
                    TlnRow tln = new TlnRow(
                            rs.getInt("tln_id"),
                            rs.getString("tln_name"),
                            rs.getString("tln_info"),
                            (Integer) rs.getObject("owner_id"),
                            rs.getInt("is_public") == 1,
                            rs.getInt("allow_subdomains") == 1
                    );
                    out.add(new InfoNameRow(
                            rs.getInt("iid"),
                            rs.getString("info"),
                            tln
                    ));
                }
            }
        }

        return out.toArray(new InfoNameRow[0]);
    }

    /**
     * Ensures a subname exists for an infoname; returns subnames.id.
     *
     * <p>If sub is null/blank, returns null (root).</p>
     *
     * @param infonameId infonames.id
     * @param sub        sub label (nullable)
     * @return subnames.id or null for root
     * @throws SQLException on SQL errors
     */
    public Integer ensureSubname(int infonameId, String sub) throws SQLException {
        if (sub == null || sub.isBlank()) return null;
        if (infonameId <= 0) throw new IllegalArgumentException("infonameId must be > 0");

        String name = sub.trim();

        // 1) find
        String find = "SELECT id FROM subnames WHERE infoname_id = ? AND name = ? LIMIT 1";
        try (Connection c = dataSource.getConnection();
             PreparedStatement ps = c.prepareStatement(find)) {

            ps.setInt(1, infonameId);
            ps.setString(2, name);

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

        // 2) insert
        String ins = "INSERT INTO subnames (name, infoname_id) VALUES (?, ?)";
        try (Connection c = dataSource.getConnection();
             PreparedStatement ps = c.prepareStatement(ins, Statement.RETURN_GENERATED_KEYS)) {

            ps.setString(1, name);
            ps.setInt(2, infonameId);
            ps.executeUpdate();

            try (ResultSet rs = ps.getGeneratedKeys()) {
                if (rs.next()) return rs.getInt(1);
            }
        }

        throw new SQLException("No generated key returned for subnames.id");
    }

    /**
     * Adds a DNS-like record.
     *
     * @param infonameId infonames.id
     * @param subnameId  subnames.id or null for root
     * @param type       enum type (A/AAAA/TXT/CNAME/MX/SRV/NS)
     * @param value      record value
     * @param ttl        ttl (default 3600)
     * @param priority   priority (MX/SRV)
     * @param port       port (SRV)
     * @param weight     weight (SRV)
     * @return new records.id
     * @throws SQLException on SQL errors
     */
    public int addRecord(int infonameId,
                         Integer subnameId,
                         String type,
                         String value,
                         int ttl,
                         Integer priority,
                         Integer port,
                         Integer weight) throws SQLException {

        if (infonameId <= 0) throw new IllegalArgumentException("infonameId must be > 0");
        if (type == null || type.isBlank()) throw new IllegalArgumentException("type must not be blank");
        if (value == null || value.isBlank()) throw new IllegalArgumentException("value must not be blank");
        if (ttl <= 0) ttl = 3600;

        String t = type.trim().toUpperCase();

        String sql = """
                INSERT INTO records (infoname_id, subname_id, type, value, ttl, priority, port, weight)
                VALUES (?, ?, ?, ?, ?, ?, ?, ?)
                """;

        try (Connection c = dataSource.getConnection();
             PreparedStatement ps = c.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)) {

            ps.setInt(1, infonameId);

            if (subnameId == null) ps.setNull(2, Types.INTEGER);
            else ps.setInt(2, subnameId);

            ps.setString(3, t);
            ps.setString(4, value.trim());
            ps.setInt(5, ttl);

            if (priority == null) ps.setNull(6, Types.INTEGER);
            else ps.setInt(6, priority);

            if (port == null) ps.setNull(7, Types.INTEGER);
            else ps.setInt(7, port);

            if (weight == null) ps.setNull(8, Types.INTEGER);
            else ps.setInt(8, weight);

            ps.executeUpdate();

            try (ResultSet rs = ps.getGeneratedKeys()) {
                if (rs.next()) return rs.getInt(1);
            }
        }

        throw new SQLException("No generated key returned for records.id");
    }

    /**
     * TLN row.
     */
    public record TlnRow(int id, String name, String info, Integer ownerId, boolean isPublic, boolean allowSubdomains) {
    }

    /**
     * InfoName row (includes TLN).
     */
    public record InfoNameRow(int id, String info, TlnRow tln) {
    }
}