export type MembershipProductType = "credit_pack" | "trial" | "subscription";

export type MembershipEntitlement = {
  featureKey: string;
  allowanceType: string;
  allowanceCount: number | null;
  resetPeriod: string;
  modelTier: string | null;
  fairUsePolicyId: string | null;
  metadata: unknown;
};

export type MembershipProduct = {
  id: string;
  productId: string;
  code: string;
  version: number;
  name: string;
  description: string;
  productType: MembershipProductType;
  billingPeriod: "none" | "day" | "month" | "year";
  intervalCount: number;
  priceCents: number;
  currency: string;
  credits: number;
  entitlements: MembershipEntitlement[];
};

export type MembershipPlanAlias = "trial" | "monthly" | "yearly";

export function membershipHref(source: string, options: { plan?: MembershipPlanAlias } = {}) {
  const params = new URLSearchParams({ source });
  if (options.plan) params.set("plan", options.plan);
  return `/membership?${params.toString()}`;
}

export function planDisplayLabel(alias: MembershipPlanAlias) {
  const labels: Record<MembershipPlanAlias, string> = {
    trial: "体验",
    monthly: "月卡",
    yearly: "年卡",
  };
  return labels[alias];
}

export function formatPrice(priceCents: number, currency = "CNY") {
  return `${currency === "CNY" ? "¥" : `${currency} `}${(priceCents / 100).toFixed(2)}`;
}

export function formatMembershipDate(value: string | null | undefined) {
  if (!value) return "";
  const date = new Date(value);
  if (Number.isNaN(date.getTime())) return "";
  return date.toLocaleDateString("zh-CN");
}

export function orderStatusLabel(status: string | null | undefined) {
  const labels: Record<string, string> = {
    paid: "已支付",
    pending: "待支付",
    failed: "支付失败",
    closed: "已关闭",
    cancelled: "已取消",
  };
  return (status && labels[status]) || status || "未知";
}

export function membershipSourceNotice(source: string | null | undefined) {
  const notices: Record<string, string> = {
    credits: "来自对话页余额入口",
    "account-menu": "来自账户菜单",
    "insufficient-credits": "余额不足，请先补充点数或开通会员后再发送问题",
    rectification: "生时校正需要点数或会员权益",
  };
  return notices[source ?? ""] ?? "";
}

export const BALANCE_SYNC_KEY = "jyotisha:balance:updated";
export const BALANCE_CHANGED_EVENT = "jyotisha:balance:changed";

export function notifyBalanceChanged(credits: number) {
  try {
    localStorage.setItem(BALANCE_SYNC_KEY, JSON.stringify({ credits, at: Date.now() }));
  } catch {
    // Storage can be unavailable in privacy modes; the window event still fires.
  }
  if (typeof window !== "undefined") {
    window.dispatchEvent(new CustomEvent(BALANCE_CHANGED_EVENT, { detail: { credits } }));
  }
}

export function planAlias(product: Pick<MembershipProduct, "productType" | "billingPeriod">): MembershipPlanAlias | null {
  if (product.productType === "trial") return "trial";
  if (product.productType !== "subscription") return null;
  if (product.billingPeriod === "month") return "monthly";
  if (product.billingPeriod === "year") return "yearly";
  return null;
}

export function selectMembershipPlans(products: readonly MembershipProduct[]) {
  const aliases: MembershipPlanAlias[] = ["trial", "monthly", "yearly"];
  return aliases.flatMap((alias) => {
    const product = products.find((candidate) => planAlias(candidate) === alias);
    return product ? [product] : [];
  });
}

export function formatProductDuration(product: Pick<MembershipProduct, "productType" | "billingPeriod" | "intervalCount">) {
  if (product.productType === "credit_pack") return "购买后立即到账";
  const unit = product.billingPeriod === "day" ? "天" : product.billingPeriod === "month" ? "个月" : "年";
  return `${product.intervalCount} ${unit}`;
}

export function productAudience(product: Pick<MembershipProduct, "productType" | "billingPeriod">) {
  if (product.productType === "trial") return "适合初次体验完整咨询流程";
  if (product.productType === "credit_pack") return "适合按需补充点数、灵活使用";
  if (product.billingPeriod === "year") return "适合长期记录与持续复盘";
  return "适合稳定使用咨询与报告功能";
}

const featureLabels: Record<string, string> = {
  "chat.standard": "标准 AI 咨询",
  "report.full": "完整个人报告",
  rectification: "生时校正",
};

export function entitlementLabel(entitlement: MembershipEntitlement) {
  const feature = featureLabels[entitlement.featureKey] ?? entitlement.featureKey;
  if (entitlement.allowanceType === "unlimited") return `${feature}不限点数（遵循合理使用规则）`;
  if (entitlement.allowanceType === "credits") return `${entitlement.allowanceCount ?? 0} 点咨询点数`;
  if (typeof entitlement.allowanceCount === "number") return `${feature} ${entitlement.allowanceCount} 次`;
  return feature;
}

export function redeemErrorMessage(status: number, payload: unknown) {
  if (status === 429) return "请求过于频繁";
  if (payload && typeof payload === "object" && "code" in payload) {
    const code = String((payload as { code?: unknown }).code ?? "");
    const messages: Record<string, string> = {
      invalid_code: "兑换码不存在",
      expired_code: "兑换码已过期",
      already_redeemed: "兑换码已被使用",
      account_not_eligible: "兑换码不适用于当前账户",
      rate_limited: "请求过于频繁",
    };
    if (messages[code]) return messages[code];
  }
  if (status >= 500) return "系统异常，请稍后重试";
  if (payload && typeof payload === "object" && "error" in payload) {
    const error = (payload as { error?: unknown }).error;
    if (typeof error === "string" && error) return error;
  }
  return "系统异常，请稍后重试";
}