import {
  CacheConfig,
  CacheLevel,
  CacheProvider,
  CacheEntry,
  CacheMetrics,
  CacheStats,
  InvalidationRule,
  CacheStatus,
  ContentType,
  CacheStrategy,
} from "./types";

export interface CacheManagerOptions {
  levels: CacheLevel[];
  defaultTTL: number;
  maxMemoryUsage: number; // MB
  compressionEnabled: boolean;
  metricsEnabled: boolean;
  debugMode: boolean;
}

export class CacheManager {
  private configs: Map<CacheLevel, CacheConfig> = new Map();
  private providers: Map<CacheLevel, CacheProvider> = new Map();
  private metrics: CacheMetrics;
  private invalidationRules: InvalidationRule[] = [];
  private options: CacheManagerOptions;

  constructor(options: CacheManagerOptions) {
    this.options = options;
    this.metrics = this.initializeMetrics();
    this.setupDefaultConfigs();
  }

  /**
   * 캐시 설정 초기화
   */
  private setupDefaultConfigs(): void {
    // 브라우저 캐시 설정
    this.configs.set("browser", {
      level: "browser",
      provider: "browser",
      strategy: "ttl",
      ttl: 3600, // 1시간
      maxSize: 50, // MB
      compression: true,
      encryption: false,
      tags: ["static-assets", "components"],
      headers: {
        "Cache-Control": "public, max-age=3600",
        ETag: "auto-generated",
      },
      invalidationRules: [
        {
          id: "version-change",
          strategy: "version-based",
          trigger: "deployment",
          scope: "global",
          priority: "high",
          conditions: ["version_update"],
        },
      ],
    });

    // CDN 캐시 설정
    this.configs.set("cdn", {
      level: "cdn",
      provider: "cloudflare",
      strategy: "ttl",
      ttl: 86400, // 24시간
      maxSize: 1000, // MB
      compression: true,
      encryption: false,
      tags: ["static-assets", "images", "css", "js"],
      headers: {
        "Cache-Control": "public, max-age=86400",
        Vary: "Accept-Encoding",
      },
      invalidationRules: [
        {
          id: "asset-update",
          strategy: "tag-based",
          trigger: "content_update",
          scope: "tagged",
          priority: "medium",
          conditions: ["asset_change", "content_publish"],
        },
      ],
    });

    // 서버 캐시 설정
    this.configs.set("server", {
      level: "server",
      provider: "redis",
      strategy: "lru",
      ttl: 1800, // 30분
      maxSize: 500, // MB
      compression: true,
      encryption: true,
      tags: ["api-responses", "component-data", "templates"],
      headers: {},
      invalidationRules: [
        {
          id: "content-update",
          strategy: "dependency-based",
          trigger: "data_change",
          scope: "related",
          priority: "high",
          conditions: ["content_edit", "component_update"],
        },
      ],
    });
  }

  /**
   * 메트릭 초기화
   */
  private initializeMetrics(): CacheMetrics {
    return {
      hitRate: 0,
      missRate: 0,
      totalRequests: 0,
      totalHits: 0,
      totalMisses: 0,
      averageResponseTime: 0,
      memoryUsage: 0,
      diskUsage: 0,
      networkTraffic: 0,
      errors: 0,
      evictions: 0,
      compressionRatio: 0,
      lastUpdated: new Date(),
    };
  }

  /**
   * 캐시에서 데이터 조회
   */
  async get<T>(
    key: string,
    contentType: ContentType,
    options?: {
      levels?: CacheLevel[];
      fallback?: () => Promise<T>;
    }
  ): Promise<{ data: T | null; status: CacheStatus; level?: CacheLevel }> {
    const startTime = Date.now();
    const levels = options?.levels || this.options.levels;

    // 캐시 레벨별로 순차 조회
    for (const level of levels) {
      try {
        const config = this.configs.get(level);
        if (!config) continue;

        const entry = await this.getFromLevel<T>(key, level);
        if (entry && this.isValidEntry(entry)) {
          this.updateMetrics("hit", Date.now() - startTime, level);
          return {
            data: entry.data,
            status: "hit",
            level,
          };
        }
      } catch (error) {
        console.error(`캐시 조회 오류 (${level}):`, error);
        this.metrics.errors++;
      }
    }

    // 캐시 미스 처리
    this.updateMetrics("miss", Date.now() - startTime);

    if (options?.fallback) {
      try {
        const data = await options.fallback();
        // 폴백 데이터를 캐시에 저장
        await this.set(key, data, contentType);
        return { data, status: "miss" };
      } catch (error) {
        console.error("폴백 함수 실행 오류:", error);
        return { data: null, status: "error" };
      }
    }

    return { data: null, status: "miss" };
  }

  /**
   * 캐시에 데이터 저장
   */
  async set<T>(
    key: string,
    data: T,
    contentType: ContentType,
    options?: {
      ttl?: number;
      levels?: CacheLevel[];
      tags?: string[];
    }
  ): Promise<boolean> {
    const levels = options?.levels || this.options.levels;
    let success = true;

    for (const level of levels) {
      try {
        const config = this.configs.get(level);
        if (!config) continue;

        const entry: CacheEntry<T> = {
          key,
          data,
          contentType,
          level,
          ttl: options?.ttl || config.ttl,
          tags: options?.tags || config.tags,
          createdAt: new Date(),
          expiresAt: new Date(Date.now() + (options?.ttl || config.ttl) * 1000),
          hits: 0,
          lastAccessed: new Date(),
          size: this.calculateSize(data),
          compressed: config.compression,
          metadata: {
            version: "1.0",
            checksum: this.calculateChecksum(data),
          },
        };

        await this.setToLevel(entry, level);
      } catch (error) {
        console.error(`캐시 저장 오류 (${level}):`, error);
        success = false;
        this.metrics.errors++;
      }
    }

    return success;
  }

  /**
   * 캐시 무효화
   */
  async invalidate(
    pattern: string | string[],
    options?: {
      levels?: CacheLevel[];
      strategy?: "key" | "tag" | "pattern";
    }
  ): Promise<number> {
    const levels = options?.levels || this.options.levels;
    const strategy = options?.strategy || "key";
    let invalidatedCount = 0;

    for (const level of levels) {
      try {
        const count = await this.invalidateFromLevel(pattern, level, strategy);
        invalidatedCount += count;
      } catch (error) {
        console.error(`캐시 무효화 오류 (${level}):`, error);
        this.metrics.errors++;
      }
    }

    return invalidatedCount;
  }

  /**
   * 캐시 통계 조회
   */
  getStats(): CacheStats {
    const levelStats = new Map<CacheLevel, any>();

    for (const level of this.options.levels) {
      levelStats.set(level, {
        hitRate: this.calculateHitRate(level),
        memoryUsage: this.getMemoryUsage(level),
        entryCount: this.getEntryCount(level),
        averageSize: this.getAverageSize(level),
      });
    }

    return {
      overall: this.metrics,
      byLevel: levelStats,
      topKeys: this.getTopKeys(),
      recentActivity: this.getRecentActivity(),
      errors: this.getRecentErrors(),
    };
  }

  /**
   * 캐시 워밍 (사전 로딩)
   */
  async warmUp(
    keys: Array<{
      key: string;
      contentType: ContentType;
      loader: () => Promise<any>;
    }>
  ): Promise<number> {
    let warmedCount = 0;

    await Promise.allSettled(
      keys.map(async ({ key, contentType, loader }) => {
        try {
          const data = await loader();
          await this.set(key, data, contentType);
          warmedCount++;
        } catch (error) {
          console.error(`캐시 워밍 오류 (${key}):`, error);
        }
      })
    );

    return warmedCount;
  }

  /**
   * 캐시 클리어
   */
  async clear(levels?: CacheLevel[]): Promise<boolean> {
    const targetLevels = levels || this.options.levels;
    let success = true;

    for (const level of targetLevels) {
      try {
        await this.clearLevel(level);
      } catch (error) {
        console.error(`캐시 클리어 오류 (${level}):`, error);
        success = false;
      }
    }

    // 메트릭 리셋
    if (!levels || levels.length === this.options.levels.length) {
      this.metrics = this.initializeMetrics();
    }

    return success;
  }

  /**
   * 헬스 체크
   */
  async healthCheck(): Promise<{
    healthy: boolean;
    levels: Map<CacheLevel, boolean>;
    issues: string[];
  }> {
    const levelHealth = new Map<CacheLevel, boolean>();
    const issues: string[] = [];
    let overallHealthy = true;

    for (const level of this.options.levels) {
      try {
        const isHealthy = await this.checkLevelHealth(level);
        levelHealth.set(level, isHealthy);

        if (!isHealthy) {
          overallHealthy = false;
          issues.push(`${level} 캐시 레벨에 문제가 있습니다`);
        }
      } catch (error) {
        levelHealth.set(level, false);
        overallHealthy = false;
        issues.push(`${level} 헬스 체크 실패: ${error}`);
      }
    }

    // 메모리 사용량 체크
    if (this.metrics.memoryUsage > this.options.maxMemoryUsage * 0.9) {
      overallHealthy = false;
      issues.push("메모리 사용량이 임계값에 근접했습니다");
    }

    // 에러율 체크
    const errorRate =
      this.metrics.errors / Math.max(this.metrics.totalRequests, 1);
    if (errorRate > 0.05) {
      // 5% 이상
      overallHealthy = false;
      issues.push("에러율이 높습니다");
    }

    return {
      healthy: overallHealthy,
      levels: levelHealth,
      issues,
    };
  }

  // Private helper methods
  private async getFromLevel<T>(
    key: string,
    level: CacheLevel
  ): Promise<CacheEntry<T> | null> {
    // 실제 구현은 provider별로 다름
    return null;
  }

  private async setToLevel<T>(
    entry: CacheEntry<T>,
    level: CacheLevel
  ): Promise<void> {
    // 실제 구현은 provider별로 다름
  }

  private async invalidateFromLevel(
    pattern: string | string[],
    level: CacheLevel,
    strategy: string
  ): Promise<number> {
    // 실제 구현은 provider별로 다름
    return 0;
  }

  private async clearLevel(level: CacheLevel): Promise<void> {
    // 실제 구현은 provider별로 다름
  }

  private async checkLevelHealth(level: CacheLevel): Promise<boolean> {
    // 실제 구현은 provider별로 다름
    return true;
  }

  private isValidEntry<T>(entry: CacheEntry<T>): boolean {
    return entry.expiresAt > new Date();
  }

  private updateMetrics(
    type: "hit" | "miss",
    responseTime: number,
    level?: CacheLevel
  ): void {
    this.metrics.totalRequests++;

    if (type === "hit") {
      this.metrics.totalHits++;
    } else {
      this.metrics.totalMisses++;
    }

    this.metrics.hitRate = this.metrics.totalHits / this.metrics.totalRequests;
    this.metrics.missRate =
      this.metrics.totalMisses / this.metrics.totalRequests;
    this.metrics.averageResponseTime =
      (this.metrics.averageResponseTime + responseTime) / 2;
    this.metrics.lastUpdated = new Date();
  }

  private calculateSize(data: any): number {
    return JSON.stringify(data).length;
  }

  private calculateChecksum(data: any): string {
    // 간단한 체크섬 계산
    const str = JSON.stringify(data);
    let hash = 0;
    for (let i = 0; i < str.length; i++) {
      const char = str.charCodeAt(i);
      hash = (hash << 5) - hash + char;
      hash = hash & hash; // 32bit 정수로 변환
    }
    return hash.toString(16);
  }

  private calculateHitRate(level: CacheLevel): number {
    // 레벨별 히트율 계산
    return 0;
  }

  private getMemoryUsage(level: CacheLevel): number {
    // 레벨별 메모리 사용량
    return 0;
  }

  private getEntryCount(level: CacheLevel): number {
    // 레벨별 엔트리 수
    return 0;
  }

  private getAverageSize(level: CacheLevel): number {
    // 레벨별 평균 크기
    return 0;
  }

  private getTopKeys(): Array<{ key: string; hits: number }> {
    // 인기 키 목록
    return [];
  }

  private getRecentActivity(): Array<{
    timestamp: Date;
    action: string;
    key: string;
  }> {
    // 최근 활동 로그
    return [];
  }

  private getRecentErrors(): Array<{
    timestamp: Date;
    error: string;
    level: CacheLevel;
  }> {
    // 최근 에러 로그
    return [];
  }
}

export default CacheManager;