/**
 * 生产环境矢量图形渲染管理器
 * 统一管理所有矢量图形的渲染策略和错误处理
 */

import { VECTOR_EXPORT_CONFIG } from '@/config/vectorExportConfig';
import { svg2Base64 } from './svg2Base64';
import { renderElementToBase64, getElementDimensions } from './canvasRenderer';

// 渲染策略枚举
export enum RenderStrategy {
  SVG_SERIALIZATION = 'svg_serialization',
  CANVAS_RENDER = 'canvas_render',
  SIMPLIFIED_SVG = 'simplified_svg',
  PLACEHOLDER = 'placeholder'
}

// 渲染结果接口
export interface RenderResult {
  success: boolean;
  data?: string;
  strategy: RenderStrategy;
  duration: number;
  error?: Error;
  metadata?: {
    width: number;
    height: number;
    format: string;
    size: number;
  };
}

// 性能监控器
class PerformanceMonitor {
  private static instance: PerformanceMonitor;
  private metrics: Map<string, number[]> = new Map();
  
  static getInstance(): PerformanceMonitor {
    if (!this.instance) {
      this.instance = new PerformanceMonitor();
    }
    return this.instance;
  }
  
  recordMetric(operation: string, duration: number): void {
    if (!VECTOR_EXPORT_CONFIG.PERFORMANCE_CONFIG.MONITORING.ENABLED) return;
    
    if (!this.metrics.has(operation)) {
      this.metrics.set(operation, []);
    }
    
    const metrics = this.metrics.get(operation)!;
    metrics.push(duration);
    
    // 保持最近的记录数量
    const maxCount = VECTOR_EXPORT_CONFIG.PERFORMANCE_CONFIG.MONITORING.MAX_METRICS_COUNT;
    if (metrics.length > maxCount) {
      metrics.shift();
    }
  }
  
  getAverageTime(operation: string): number {
    const metrics = this.metrics.get(operation);
    if (!metrics || metrics.length === 0) return 0;
    return metrics.reduce((sum, time) => sum + time, 0) / metrics.length;
  }
  
  getMetrics(): Record<string, { average: number; count: number; latest: number }> {
    const result: Record<string, { average: number; count: number; latest: number }> = {};
    
    for (const [operation, times] of this.metrics.entries()) {
      if (times.length > 0) {
        result[operation] = {
          average: this.getAverageTime(operation),
          count: times.length,
          latest: times[times.length - 1]
        };
      }
    }
    
    return result;
  }
}

// 错误处理器
class ErrorHandler {
  static logError(error: Error, context: string, element?: Element): void {
    const config = VECTOR_EXPORT_CONFIG.ERROR_CONFIG.LOGGING;
    
    if (config.ERROR_ONLY && VECTOR_EXPORT_CONFIG.ENVIRONMENT.isProduction()) {
      console.error(`VectorRenderManager[${context}]: ${error.message}`);
    } else if (config.VERBOSE) {
      console.error(`VectorRenderManager[${context}]:`, {
        error: error.message,
        stack: config.INCLUDE_STACK_TRACE ? error.stack : undefined,
        element: element ? {
          tagName: element.tagName,
          className: element.className,
          id: element.id
        } : undefined
      });
    }
  }
  
  static async retry<T>(
    operation: () => Promise<T>,
    context: string,
    maxAttempts: number = VECTOR_EXPORT_CONFIG.ERROR_CONFIG.RETRY.MAX_ATTEMPTS
  ): Promise<T> {
    let lastError: Error;
    
    for (let attempt = 1; attempt <= maxAttempts; attempt++) {
      try {
        return await operation();
      } catch (error) {
        lastError = error as Error;
        
        if (attempt === maxAttempts) {
          this.logError(lastError, `${context} (final attempt ${attempt}/${maxAttempts})`);
          throw lastError;
        }
        
        const delay = VECTOR_EXPORT_CONFIG.ERROR_CONFIG.RETRY.DELAY_MS * 
                     Math.pow(VECTOR_EXPORT_CONFIG.ERROR_CONFIG.RETRY.BACKOFF_MULTIPLIER, attempt - 1);
        
        this.logError(lastError, `${context} (attempt ${attempt}/${maxAttempts}, retrying in ${delay}ms)`);
        await new Promise(resolve => setTimeout(resolve, delay));
      }
    }
    
    throw lastError!;
  }
}

// 主渲染管理器
export class VectorRenderManager {
  private static instance: VectorRenderManager;
  private monitor: PerformanceMonitor;
  
  private constructor() {
    this.monitor = PerformanceMonitor.getInstance();
  }
  
  static getInstance(): VectorRenderManager {
    if (!this.instance) {
      this.instance = new VectorRenderManager();
    }
    return this.instance;
  }
  
  /**
   * 渲染元素为Base64图像
   */
  async renderElement(element: Element, preferredStrategy?: RenderStrategy): Promise<RenderResult> {
    const startTime = performance.now();
    
    // 验证元素
    const validation = this.validateElement(element);
    if (!validation.valid) {
      return {
        success: false,
        strategy: RenderStrategy.PLACEHOLDER,
        duration: performance.now() - startTime,
        error: new Error(validation.reason || 'Element validation failed')
      };
    }
    
    // 确定渲染策略顺序
    const strategies = this.getStrategies(element, preferredStrategy);
    
    // 尝试每个策略
    for (const strategy of strategies) {
      try {
        const result = await this.executeStrategy(element, strategy);
        
        if (result.success) {
          const duration = performance.now() - startTime;
          this.monitor.recordMetric(`render_success_${strategy}`, duration);
          
          return {
            ...result,
            duration
          };
        }
      } catch (error) {
        ErrorHandler.logError(error as Error, `Strategy ${strategy}`, element);
        continue;
      }
    }
    
    // 所有策略都失败，返回占位符
    const duration = performance.now() - startTime;
    this.monitor.recordMetric('render_fallback_placeholder', duration);
    
    return this.createPlaceholder(element, duration);
  }
  
  /**
   * 验证元素是否可以渲染
   */
  private validateElement(element: Element): { valid: boolean; reason?: string } {
    if (!element) {
      return { valid: false, reason: 'Element is null or undefined' };
    }
    
    // 检查元素尺寸
    const dimensions = getElementDimensions(element as HTMLElement);
    const config = VECTOR_EXPORT_CONFIG.VALIDATION_CONFIG.DIMENSIONS;
    
    if (!dimensions.isValid) {
      return { valid: false, reason: 'Element has invalid dimensions' };
    }
    
    if (dimensions.width < config.MIN_WIDTH || dimensions.height < config.MIN_HEIGHT) {
      return { valid: false, reason: 'Element dimensions too small' };
    }
    
    if (dimensions.width > config.MAX_WIDTH || dimensions.height > config.MAX_HEIGHT) {
      return { valid: false, reason: 'Element dimensions too large' };
    }
    
    return { valid: true };
  }
  
  /**
   * 获取渲染策略顺序
   */
  private getStrategies(element: Element, preferred?: RenderStrategy): RenderStrategy[] {
    const isSVG = element.tagName.toLowerCase() === 'svg';
    const isHuggingface = VECTOR_EXPORT_CONFIG.ENVIRONMENT.isHuggingface();
    const canvasSupported = VECTOR_EXPORT_CONFIG.COMPATIBILITY_CONFIG.FEATURES.CANVAS_SUPPORT();
    
    let strategies: RenderStrategy[] = [];
    
    // 如果指定了首选策略，优先使用
    if (preferred) {
      strategies.push(preferred);
    }
    
    // 根据环境和元素类型确定策略顺序
    if (isSVG) {
      if (!strategies.includes(RenderStrategy.SVG_SERIALIZATION)) {
        strategies.push(RenderStrategy.SVG_SERIALIZATION);
      }
      if (!strategies.includes(RenderStrategy.SIMPLIFIED_SVG)) {
        strategies.push(RenderStrategy.SIMPLIFIED_SVG);
      }
    }
    
    // Canvas渲染（如果支持且不是Huggingface环境）
    if (canvasSupported && !isHuggingface && !strategies.includes(RenderStrategy.CANVAS_RENDER)) {
      strategies.push(RenderStrategy.CANVAS_RENDER);
    }
    
    // 最后的占位符策略
    if (!strategies.includes(RenderStrategy.PLACEHOLDER)) {
      strategies.push(RenderStrategy.PLACEHOLDER);
    }
    
    return strategies;
  }
  
  /**
   * 执行特定的渲染策略
   */
  private async executeStrategy(element: Element, strategy: RenderStrategy): Promise<RenderResult> {
    const startTime = performance.now();
    
    switch (strategy) {
      case RenderStrategy.SVG_SERIALIZATION:
        return this.executeSVGSerialization(element, startTime);
        
      case RenderStrategy.CANVAS_RENDER:
        return this.executeCanvasRender(element, startTime);
        
      case RenderStrategy.SIMPLIFIED_SVG:
        return this.executeSimplifiedSVG(element, startTime);
        
      case RenderStrategy.PLACEHOLDER:
        return this.createPlaceholder(element, performance.now() - startTime);
        
      default:
        throw new Error(`Unknown strategy: ${strategy}`);
    }
  }
  
  /**
   * SVG序列化策略
   */
  private async executeSVGSerialization(element: Element, startTime: number): Promise<RenderResult> {
    try {
      const base64 = svg2Base64(element);
      const duration = performance.now() - startTime;
      
      return {
        success: true,
        data: base64,
        strategy: RenderStrategy.SVG_SERIALIZATION,
        duration,
        metadata: {
          width: element.getBoundingClientRect().width,
          height: element.getBoundingClientRect().height,
          format: 'svg',
          size: base64.length
        }
      };
    } catch (error) {
      return {
        success: false,
        strategy: RenderStrategy.SVG_SERIALIZATION,
        duration: performance.now() - startTime,
        error: error as Error
      };
    }
  }
  
  /**
   * Canvas渲染策略
   */
  private async executeCanvasRender(element: Element, startTime: number): Promise<RenderResult> {
    try {
      const base64 = await renderElementToBase64(element as HTMLElement, {
        scale: VECTOR_EXPORT_CONFIG.PERFORMANCE_CONFIG.CANVAS.DEFAULT_SCALE,
        backgroundColor: VECTOR_EXPORT_CONFIG.PERFORMANCE_CONFIG.CANVAS.BACKGROUND_COLOR,
        timeout: VECTOR_EXPORT_CONFIG.PERFORMANCE_CONFIG.RENDER_TIMEOUT
      });
      
      const duration = performance.now() - startTime;
      
      return {
        success: true,
        data: base64,
        strategy: RenderStrategy.CANVAS_RENDER,
        duration,
        metadata: {
          width: element.getBoundingClientRect().width,
          height: element.getBoundingClientRect().height,
          format: 'png',
          size: base64.length
        }
      };
    } catch (error) {
      return {
        success: false,
        strategy: RenderStrategy.CANVAS_RENDER,
        duration: performance.now() - startTime,
        error: error as Error
      };
    }
  }
  
  /**
   * 简化SVG策略
   */
  private async executeSimplifiedSVG(element: Element, startTime: number): Promise<RenderResult> {
    try {
      const rect = element.getBoundingClientRect();
      const width = rect.width || 100;
      const height = rect.height || 100;
      
      // 创建简化的SVG
      const simplifiedSvg = `<svg xmlns="http://www.w3.org/2000/svg" width="${width}" height="${height}" viewBox="0 0 ${width} ${height}">
        <rect width="100%" height="100%" fill="#f0f0f0" stroke="#ccc" stroke-width="1"/>
        <text x="50%" y="50%" text-anchor="middle" dy="0.3em" font-size="14" fill="#666">SVG</text>
      </svg>`;
      
      const base64 = `data:image/svg+xml;base64,${btoa(simplifiedSvg)}`;
      const duration = performance.now() - startTime;
      
      return {
        success: true,
        data: base64,
        strategy: RenderStrategy.SIMPLIFIED_SVG,
        duration,
        metadata: {
          width,
          height,
          format: 'svg',
          size: base64.length
        }
      };
    } catch (error) {
      return {
        success: false,
        strategy: RenderStrategy.SIMPLIFIED_SVG,
        duration: performance.now() - startTime,
        error: error as Error
      };
    }
  }
  
  /**
   * 创建占位符
   */
  private createPlaceholder(element: Element, duration: number): RenderResult {
    const rect = element.getBoundingClientRect();
    const width = rect.width || 100;
    const height = rect.height || 100;
    const config = VECTOR_EXPORT_CONFIG.ERROR_CONFIG.FALLBACK;
    
    const placeholderSvg = `<svg xmlns="http://www.w3.org/2000/svg" width="${width}" height="${height}" viewBox="0 0 ${width} ${height}">
      <rect width="100%" height="100%" fill="${config.PLACEHOLDER_COLOR}" stroke="#ddd" stroke-width="1"/>
      <text x="50%" y="50%" text-anchor="middle" dy="0.3em" font-size="12" fill="#999">${config.PLACEHOLDER_TEXT}</text>
    </svg>`;
    
    const base64 = `data:image/svg+xml;base64,${btoa(placeholderSvg)}`;
    
    return {
      success: true,
      data: base64,
      strategy: RenderStrategy.PLACEHOLDER,
      duration,
      metadata: {
        width,
        height,
        format: 'svg',
        size: base64.length
      }
    };
  }
  
  /**
   * 获取性能指标
   */
  getPerformanceMetrics(): Record<string, { average: number; count: number; latest: number }> {
    return this.monitor.getMetrics();
  }
}

// 导出单例实例
export const vectorRenderManager = VectorRenderManager.getInstance();
export default vectorRenderManager;