export interface RecipientConfig {
  qq: string;
  anonQq: string;
}

export type DeliveryTargetStatus = "reachable" | "not_added" | "unreachable" | "unknown";

export interface DeliveryTargetHealth {
  platform?: string;
  selfId?: string;
  channelId?: string;
  channelType?: string;
  recipientId?: string;
  status: DeliveryTargetStatus;
  source?: string;
  detail?: string;
}

export type RecipientReadinessCode =
  | "ready"
  | "missing_target"
  | "invalid_target"
  | "target_mismatch"
  | "target_not_added"
  | "target_unreachable"
  | "health_unavailable";

export interface RecipientReadiness {
  ok: boolean;
  code: RecipientReadinessCode;
  healthStatus: DeliveryTargetStatus;
  message: string;
}

const QQ_ID_PATTERN = /^\d{5,12}$/;

function isObject(value: unknown): value is Record<string, unknown> {
  return Boolean(value) && typeof value === "object" && !Array.isArray(value);
}

function configuredQq(value: unknown, path: string, fallback: string): string {
  if (value === undefined) return fallback;
  if (typeof value !== "string") {
    throw new Error(`配置项 ${path} 必须是 QQ 号字符串`);
  }
  // A fresh public installation has no personal target. It can load normally,
  // but evaluateRecipient() refuses activation until both QQ ids are valid.
  return value.trim();
}

export function normalizeRecipientConfig(value: unknown, defaults: RecipientConfig): RecipientConfig {
  if (value === undefined) return { ...defaults };
  if (!isObject(value)) throw new Error("配置项 recipient 必须是 JSON 对象");
  const unknown = Object.keys(value).filter((key) => !["qq", "anonQq"].includes(key));
  if (unknown.length) throw new Error(`配置项 recipient 包含未知字段：${unknown.join(", ")}`);
  return {
    qq: configuredQq(value.qq, "recipient.qq", defaults.qq),
    anonQq: configuredQq(value.anonQq, "recipient.anonQq", defaults.anonQq),
  };
}

export function isValidQq(value: string): boolean {
  return QQ_ID_PATTERN.test(value);
}

export function deliveryTargetStatus(value: unknown): DeliveryTargetStatus {
  return value === "reachable" || value === "not_added" || value === "unreachable" || value === "unknown"
    ? value
    : "unknown";
}

export function formatTargetStatus(status: DeliveryTargetStatus): string {
  switch (status) {
    case "reachable": return "reachable";
    case "not_added": return "not_added (目标可能尚未添加 Anon)";
    case "unreachable": return "unreachable (服务端报告目标不可达)";
    case "unknown": return "unknown (服务端未提供好友状态检查)";
  }
}

export function recipientConfigSummary(config: RecipientConfig): string {
  const qq = config.qq || "missing";
  const anonQq = config.anonQq || "missing";
  return `Anon QQ=${anonQq}, target QQ=${qq}`;
}

export function evaluateRecipient(
  config: RecipientConfig,
  health?: DeliveryTargetHealth,
  healthError?: string,
): RecipientReadiness {
  const healthStatus = health?.status ?? "unknown";
  if (!config.qq || !config.anonQq) {
    return {
      ok: false,
      code: "missing_target",
      healthStatus,
      message: `Anon 通知尚未启用：目标 QQ 配置不完整（${recipientConfigSummary(config)}）。请先配置目标 QQ 和 Anon QQ，再重试裸命令 /anon-notify。`,
    };
  }
  if (!isValidQq(config.qq) || !isValidQq(config.anonQq)) {
    return {
      ok: false,
      code: "invalid_target",
      healthStatus,
      message: `Anon 通知尚未启用：QQ 配置无效（${recipientConfigSummary(config)}）。QQ 号应为 5 到 12 位数字，请修正配置后重试。`,
    };
  }
  if (health?.recipientId && health.recipientId !== config.qq) {
    return {
      ok: false,
      code: "target_mismatch",
      healthStatus,
      message: `Anon 通知尚未启用：本地目标 QQ ${config.qq} 与服务端配置的目标 QQ ${health.recipientId} 不一致。请先统一配置后重试。${health.detail ? ` 服务端信息：${health.detail}` : ""}`,
    };
  }
  if (healthStatus === "not_added") {
    return {
      ok: false,
      code: "target_not_added",
      healthStatus,
      message: `Anon 通知尚未启用：服务端报告目标 QQ ${config.qq} 可能还没有添加 Anon（Anon QQ：${config.anonQq}）。请先在 QQ 中添加 Anon，或先向 Anon 发起一次私聊，然后重新执行裸命令 /anon-notify。${health?.detail ? ` 服务端信息：${health.detail}` : ""}`,
    };
  }
  if (healthStatus === "unreachable") {
    return {
      ok: false,
      code: "target_unreachable",
      healthStatus,
      message: `Anon 通知尚未启用：服务端报告目标 QQ ${config.qq} 当前不可达（Anon QQ：${config.anonQq}）。请先确认目标已添加 Anon 并可以接收私聊，之后重新执行裸命令 /anon-notify。${health?.detail ? ` 服务端信息：${health.detail}` : ""}`,
    };
  }
  if (healthError) {
    return {
      ok: true,
      code: "health_unavailable",
      healthStatus: "unknown",
      message: `目标 QQ 配置有效（${recipientConfigSummary(config)}），但暂时无法核验服务端状态：${healthError}。这不表示目标未添加 Anon；如发送失败，请先确认目标 QQ 已添加 Anon 后再重试。`,
    };
  }
  return {
    ok: true,
    code: "ready",
    healthStatus,
    message: healthStatus === "unknown"
      ? `目标 QQ 配置有效（${recipientConfigSummary(config)}），服务端未提供可靠的好友状态检查；不会据此判断目标是否已添加 Anon。`
      : `目标 QQ 配置和服务端状态可用（${recipientConfigSummary(config)}，status=${formatTargetStatus(healthStatus)}）。`,
  };
}