package com.xiaopeng.order.utils;

import com.xiaopeng.common.core.utils.StringUtils;

import java.util.Objects;
import java.util.Optional;

public final class RegionCodeFilterUtil {

    private RegionCodeFilterUtil() {
    }

    public enum MatchType {
        EQ,
        LIKE_RIGHT
    }

    public static final class CityCodeFilter {
        private final MatchType matchType;
        private final String value;

        private CityCodeFilter(MatchType matchType, String value) {
            this.matchType = matchType;
            this.value = value;
        }

        public MatchType getMatchType() {
            return matchType;
        }

        public String getValue() {
            return value;
        }
    }

    public static Optional<CityCodeFilter> resolveCityCodeFilter(String cityCode) {
        if (StringUtils.isBlank(cityCode)) {
            return Optional.empty();
        }

        String trimmed = cityCode.trim();
        if (StringUtils.isBlank(trimmed)) {
            return Optional.empty();
        }

        if (trimmed.length() == 6) {
            if (trimmed.endsWith("0000")) {
                return Optional.of(new CityCodeFilter(MatchType.LIKE_RIGHT, safeSubstring(trimmed, 0, 2)));
            }
            if (trimmed.endsWith("00")) {
                return Optional.of(new CityCodeFilter(MatchType.LIKE_RIGHT, safeSubstring(trimmed, 0, 4)));
            }
            return Optional.of(new CityCodeFilter(MatchType.EQ, trimmed));
        }

        if (trimmed.length() == 2 || trimmed.length() == 4) {
            return Optional.of(new CityCodeFilter(MatchType.LIKE_RIGHT, trimmed));
        }

        return Optional.of(new CityCodeFilter(MatchType.EQ, trimmed));
    }

    private static String safeSubstring(String str, int start, int end) {
        if (StringUtils.isBlank(str)) {
            return "";
        }
        int safeStart = Math.max(0, start);
        int safeEnd = Math.min(str.length(), end);
        if (safeStart >= safeEnd) {
            return "";
        }
        return Objects.toString(str.substring(safeStart, safeEnd), "");
    }
}