/**
 * パフォーマンス最適化ユーティリティ
 * HuggingFace Spaces制限に対応したメモリ管理とガベージコレクション
 */

// メモリ使用量の監視と報告
export function getMemoryUsage(): {
  used: number;
  total: number;
  percentage: number;
} {
  if (typeof process !== 'undefined' && process.memoryUsage) {
    const usage = process.memoryUsage();
    const total = usage.heapTotal;
    const used = usage.heapUsed;
    return {
      used,
      total,
      percentage: (used / total) * 100,
    };
  }
  return { used: 0, total: 0, percentage: 0 };
}

// メモリ閾値のチェック（デフォルト: 80%）
export function isMemoryThresholdExceeded(threshold = 0.8): boolean {
  const { percentage } = getMemoryUsage();
  return percentage > threshold * 100;
}

// 強制的なガベージコレクション（Node.js環境でのみ動作）
export function forceGarbageCollection(): void {
  if (typeof global !== 'undefined' && global.gc) {
    console.log('Forcing garbage collection...');
    global.gc();
  }
}

// 大きな画像データのクリーンアップ
export function cleanupImageData(imageData: unknown): void {
  if (imageData && typeof imageData === 'object') {
    // ImageDataやBufferの参照を解放
    Object.keys(imageData).forEach((key) => {
      delete (imageData as Record<string, unknown>)[key];
    });
  }
}

// Base64画像のサイズ最適化
export function optimizeBase64Image(
  base64: string,
  maxSizeKB: number = 1024,
): string {
  // Base64のサイズを推定（約1.37倍のオーバーヘッド）
  const estimatedSizeKB = (base64.length * 0.75) / 1024;

  if (estimatedSizeKB > maxSizeKB) {
    console.warn(
      `Image size (${estimatedSizeKB.toFixed(2)}KB) exceeds limit (${maxSizeKB}KB)`,
    );
    // TODO: 実際の画像圧縮処理を実装
  }

  return base64;
}

// 処理の分割実行（大きなタスクを小さなチャンクに分割）
export async function processInChunks<T, R>(
  items: T[],
  processor: (item: T) => Promise<R>,
  chunkSize: number = 10,
  delayMs: number = 100,
): Promise<R[]> {
  const results: R[] = [];

  for (let i = 0; i < items.length; i += chunkSize) {
    const chunk = items.slice(i, i + chunkSize);
    const chunkResults = await Promise.all(chunk.map(processor));
    results.push(...chunkResults);

    // メモリチェックとガベージコレクション
    if (isMemoryThresholdExceeded(0.7)) {
      forceGarbageCollection();
      await new Promise((resolve) => setTimeout(resolve, delayMs * 2));
    } else if (i + chunkSize < items.length) {
      // 次のチャンクの前に短い遅延
      await new Promise((resolve) => setTimeout(resolve, delayMs));
    }
  }

  return results;
}

// デバウンス処理（連続した呼び出しを制限）
export function debounce<T extends (...args: unknown[]) => unknown>(
  func: T,
  wait: number,
): (...args: Parameters<T>) => void {
  let timeout: NodeJS.Timeout | null = null;

  return function (...args: Parameters<T>) {
    if (timeout) clearTimeout(timeout);
    timeout = setTimeout(() => {
      func(...args);
    }, wait);
  };
}

// スロットリング（一定時間内の呼び出し回数を制限）
export function throttle<T extends (...args: unknown[]) => unknown>(
  func: T,
  limit: number,
): (...args: Parameters<T>) => void {
  let inThrottle = false;

  return function (...args: Parameters<T>) {
    if (!inThrottle) {
      func(...args);
      inThrottle = true;
      setTimeout(() => {
        inThrottle = false;
      }, limit);
    }
  };
}

// メモリ効率的な画像処理のためのキャッシュ管理
class ImageCache {
  private cache: Map<string, { data: string; timestamp: number }> = new Map();
  private maxSize: number;
  private ttl: number;

  constructor(maxSize: number = 10, ttlMinutes: number = 5) {
    this.maxSize = maxSize;
    this.ttl = ttlMinutes * 60 * 1000;
  }

  set(key: string, data: string): void {
    // 古いエントリの削除
    this.cleanup();

    // キャッシュサイズ制限
    if (this.cache.size >= this.maxSize) {
      const oldestKey = Array.from(this.cache.entries()).sort(
        (a, b) => a[1].timestamp - b[1].timestamp,
      )[0][0];
      this.cache.delete(oldestKey);
    }

    this.cache.set(key, { data, timestamp: Date.now() });
  }

  get(key: string): string | null {
    const entry = this.cache.get(key);
    if (!entry) return null;

    // TTLチェック
    if (Date.now() - entry.timestamp > this.ttl) {
      this.cache.delete(key);
      return null;
    }

    return entry.data;
  }

  cleanup(): void {
    const now = Date.now();
    for (const [key, entry] of this.cache.entries()) {
      if (now - entry.timestamp > this.ttl) {
        this.cache.delete(key);
      }
    }
  }

  clear(): void {
    this.cache.clear();
  }
}

export const imageCache = new ImageCache();

// 同時処理数の制限
export class ConcurrencyLimiter {
  private running: number = 0;
  private queue: Array<() => void> = [];
  private maxConcurrent: number;

  constructor(maxConcurrent: number = 3) {
    this.maxConcurrent = maxConcurrent;
  }

  async execute<T>(task: () => Promise<T>): Promise<T> {
    while (this.running >= this.maxConcurrent) {
      await new Promise<void>((resolve) => {
        this.queue.push(resolve);
      });
    }

    this.running++;

    try {
      return await task();
    } finally {
      this.running--;
      const next = this.queue.shift();
      if (next) next();
    }
  }
}

// パフォーマンス監視
export class PerformanceMonitor {
  private timings: Map<string, number> = new Map();

  start(label: string): void {
    this.timings.set(label, performance.now());
  }

  end(label: string): number {
    const start = this.timings.get(label);
    if (!start) {
      console.warn(`No start time found for label: ${label}`);
      return 0;
    }

    const duration = performance.now() - start;
    this.timings.delete(label);
    console.log(`[Performance] ${label}: ${duration.toFixed(2)}ms`);

    return duration;
  }

  measure<T>(label: string, fn: () => T): T {
    this.start(label);
    try {
      return fn();
    } finally {
      this.end(label);
    }
  }

  async measureAsync<T>(label: string, fn: () => Promise<T>): Promise<T> {
    this.start(label);
    try {
      return await fn();
    } finally {
      this.end(label);
    }
  }
}

export const performanceMonitor = new PerformanceMonitor();