/**
 * Token管理服务
 * 负责处理OAuth访问令牌的刷新和管理
 * 如果需要添加新的Token相关功能：
 * 1. 优先考虑在 `TokenManager` 中添加
 * 2. 如果需要新的网络请求，在 `OAuthClient` 中添加
 */
import { OAuthClient } from "./oauth-client";
import { OAUTH_CONFIG } from "~/config/api-config";

interface TokenInfo {
  accessToken: string;
  refreshToken: string;
  tokenIssuedAt: number;
  tokenExpiresIn: number;
}

interface RefreshResult {
  success: boolean;
  newTokenInfo?: TokenInfo;
  error?: string;
}

/**
 * Token管理服务
 * 负责处理OAuth访问令牌的刷新和管理
 */
export class TokenManager {
  private oauthClient: OAuthClient;

  constructor() {
    this.oauthClient = new OAuthClient(OAUTH_CONFIG);
  }

  /**
   * 检查token是否过期
   */
  isTokenExpired(tokenInfo: TokenInfo): boolean {
    const now = Date.now();
    const expiresAt = tokenInfo.tokenIssuedAt + (tokenInfo.tokenExpiresIn * 1000);
    return now >= expiresAt;
  }

  /**
   * 检查token是否需要刷新（提前5分钟）
   */
  shouldRefreshToken(tokenInfo: TokenInfo, refreshThresholdMinutes: number = 5): boolean {
    const now = Date.now();
    const expiresAt = tokenInfo.tokenIssuedAt + (tokenInfo.tokenExpiresIn * 1000);
    const refreshThreshold = refreshThresholdMinutes * 60 * 1000;
    return now >= (expiresAt - refreshThreshold);
  }

  /**
   * 获取token剩余有效时间（秒）
   */
  getTokenRemainingTime(tokenInfo: TokenInfo): number {
    const now = Date.now();
    const expiresAt = tokenInfo.tokenIssuedAt + (tokenInfo.tokenExpiresIn * 1000);
    return Math.floor((expiresAt - now) / 1000);
  }

  /**
   * 刷新访问令牌
   */
  async refreshToken(refreshToken: string): Promise<RefreshResult> {
    try {
      console.log("开始刷新访问令牌...");
      
      const newTokenResponse = await this.oauthClient.refreshAccessToken(refreshToken);
      
      if (!newTokenResponse) {
        console.error("刷新令牌失败：服务器返回空响应");
        return {
          success: false,
          error: "服务器返回空响应"
        };
      }

      const newTokenInfo: TokenInfo = {
        accessToken: newTokenResponse.access_token,
        refreshToken: newTokenResponse.refresh_token,
        tokenIssuedAt: Date.now(),
        tokenExpiresIn: newTokenResponse.expires_in
      };

      console.log(`令牌刷新成功，新令牌有效期: ${newTokenResponse.expires_in}秒`);

      return {
        success: true,
        newTokenInfo
      };

    } catch (error) {
      console.error("刷新令牌时发生错误:", error);
      return {
        success: false,
        error: error instanceof Error ? error.message : "未知错误"
      };
    }
  }

  /**
   * 检查并自动刷新token（如果需要）
   */
  async checkAndRefreshToken(tokenInfo: TokenInfo): Promise<RefreshResult> {
    // 如果token已过期，必须刷新
    if (this.isTokenExpired(tokenInfo)) {
      console.log("Token已过期，尝试刷新...");
      return this.refreshToken(tokenInfo.refreshToken);
    }

    // 如果token即将过期，主动刷新
    if (this.shouldRefreshToken(tokenInfo)) {
      const remainingTime = this.getTokenRemainingTime(tokenInfo);
      console.log(`Token将在${remainingTime}秒后过期，主动刷新...`);
      return this.refreshToken(tokenInfo.refreshToken);
    }

    // Token仍然有效，无需刷新
    return {
      success: true,
      newTokenInfo: tokenInfo
    };
  }

  /**
   * 格式化token到期时间
   */
  formatTokenExpiry(tokenInfo: TokenInfo): string {
    const expiresAt = new Date(tokenInfo.tokenIssuedAt + (tokenInfo.tokenExpiresIn * 1000));
    return expiresAt.toLocaleString('zh-CN');
  }

  /**
   * 获取token状态信息（用于调试）
   */
  getTokenStatus(tokenInfo: TokenInfo): {
    isExpired: boolean;
    shouldRefresh: boolean;
    remainingTime: number;
    expiryTime: string;
  } {
    return {
      isExpired: this.isTokenExpired(tokenInfo),
      shouldRefresh: this.shouldRefreshToken(tokenInfo),
      remainingTime: this.getTokenRemainingTime(tokenInfo),
      expiryTime: this.formatTokenExpiry(tokenInfo)
    };
  }
}

// 导出单例实例
export const tokenManager = new TokenManager();