import { cities, type City } from "@/app/data/cities";

const CITY_SLUG_BY_NAME: Record<string, string> = {
  大理: "dali",
  成都: "chengdu",
  深圳: "shenzhen",
  上海: "shanghai",
  杭州: "hangzhou",
  厦门: "xiamen",
  北京: "beijing",
  广州: "guangzhou",
  重庆: "chongqing",
  昆明: "kunming",
  三亚: "sanya",
  丽江: "lijiang",
  西安: "xian",
  南京: "nanjing",
  长沙: "changsha",
  青岛: "qingdao",
  苏州: "suzhou",
  珠海: "zhuhai",
};

function normalizeSlug(value: string): string {
  return value
    .trim()
    .toLowerCase()
    .replace(/['’]/g, "")
    .replace(/[^a-z0-9]+/g, "-")
    .replace(/^-+|-+$/g, "");
}

export function citySlug(city: Pick<City, "slug" | "name" | "nameEn" | "id">): string {
  if (city.slug) return normalizeSlug(city.slug);
  if (CITY_SLUG_BY_NAME[city.name]) return CITY_SLUG_BY_NAME[city.name];
  if (city.nameEn) return normalizeSlug(city.nameEn);
  return `city-${city.id}`;
}

export function cityVolunteerHref(city: Pick<City, "slug" | "name" | "nameEn" | "id">): string {
  return `/city/${encodeURIComponent(citySlug(city))}/volunteer`;
}

export function findCityBySlug(slug: string): City | undefined {
  const decoded = decodeURIComponent(slug).trim();
  const normalized = normalizeSlug(decoded);
  return cities.find((city) => {
    const candidates = [
      city.slug,
      citySlug(city),
      city.name,
      city.nameEn,
      CITY_SLUG_BY_NAME[city.name],
    ].filter(Boolean);
    return candidates.some((candidate) => {
      const text = String(candidate);
      return text === decoded || normalizeSlug(text) === normalized;
    });
  });
}