import { EventEmitter } from 'eventemitter3';
import { createLogger, Logger } from '@stock-bot/logger';
import { EventBus } from '@stock-bot/event-bus';
import { DataFrame } from '@stock-bot/data-frame';

// Core types
export interface MarketData {
  symbol: string;
  timestamp: number;
  open: number;
  high: number;
  low: number;
  close: number;
  volume: number;
  [key: string]: any;
}

export interface TradingSignal {
  type: 'BUY' | 'SELL' | 'HOLD';
  symbol: string;
  timestamp: number;
  price: number;
  quantity: number;
  confidence: number;
  reason: string;
  metadata?: Record<string, any>;
}

export interface StrategyContext {
  symbol: string;
  timeframe: string;
  data: DataFrame;
  indicators: Record<string, any>;
  position?: Position;
  portfolio: PortfolioSummary;
  timestamp: number;
}

export interface Position {
  symbol: string;
  quantity: number;
  averagePrice: number;
  currentPrice: number;
  unrealizedPnL: number;
  side: 'LONG' | 'SHORT';
}

export interface PortfolioSummary {
  totalValue: number;
  cash: number;
  positions: Position[];
  totalPnL: number;
  dayPnL: number;
}

export interface StrategyConfig {
  id: string;
  name: string;
  description?: string;
  symbols: string[];
  timeframes: string[];
  parameters: Record<string, any>;
  riskLimits: RiskLimits;
  enabled: boolean;
}

export interface RiskLimits {
  maxPositionSize: number;
  maxDailyLoss: number;
  maxDrawdown: number;
  stopLoss?: number;
  takeProfit?: number;
}

// Abstract base strategy class
export abstract class BaseStrategy extends EventEmitter {
  protected logger;
  protected eventBus: EventBus;
  protected config: StrategyConfig;
  protected isActive: boolean = false;

  constructor(config: StrategyConfig, eventBus: EventBus) {
    super();
    this.config = config;
    this.eventBus = eventBus;
    this.logger = createLogger(`strategy:${config.id}`);
  }

  // Abstract methods that must be implemented by concrete strategies
  abstract initialize(): Promise<void>;
  abstract onMarketData(context: StrategyContext): Promise<TradingSignal[]>;
  abstract onSignal(signal: TradingSignal): Promise<void>;
  abstract cleanup(): Promise<void>;

  // Optional lifecycle methods
  onStart?(): Promise<void>;
  onStop?(): Promise<void>;
  onError?(error: Error): Promise<void>;

  // Control methods
  async start(): Promise<void> {
    if (this.isActive) {
      this.logger.warn('Strategy already active');
      return;
    }

    try {
      await this.initialize();
      
      if (this.onStart) {
        await this.onStart();
      }

      this.isActive = true;
      this.logger.info('Strategy started', { strategyId: this.config.id });
      this.emit('started');
    } catch (error) {
      this.logger.error('Failed to start strategy', { error, strategyId: this.config.id });
      throw error;
    }
  }

  async stop(): Promise<void> {
    if (!this.isActive) {
      this.logger.warn('Strategy not active');
      return;
    }

    try {
      if (this.onStop) {
        await this.onStop();
      }

      await this.cleanup();
      this.isActive = false;
      this.logger.info('Strategy stopped', { strategyId: this.config.id });
      this.emit('stopped');
    } catch (error) {
      this.logger.error('Failed to stop strategy', { error, strategyId: this.config.id });
      throw error;
    }
  }

  // Utility methods
  protected async emitSignal(signal: TradingSignal): Promise<void> {
    await this.eventBus.publish(this.config.id, signal);
    this.emit('signal', signal);
    this.logger.info('Signal generated', { 
      signal: signal.type, 
      symbol: signal.symbol, 
      confidence: signal.confidence 
    });
  }

  protected checkRiskLimits(signal: TradingSignal, context: StrategyContext): boolean {
    const limits = this.config.riskLimits;
    
    // Check position size limit
    if (signal.quantity > limits.maxPositionSize) {
      this.logger.warn('Signal exceeds max position size', { 
        requested: signal.quantity, 
        limit: limits.maxPositionSize 
      });
      return false;
    }

    // Check daily loss limit
    if (context.portfolio.dayPnL <= -limits.maxDailyLoss) {
      this.logger.warn('Daily loss limit reached', { 
        dayPnL: context.portfolio.dayPnL, 
        limit: -limits.maxDailyLoss 
      });
      return false;
    }

    return true;
  }

  // Getters
  get id(): string {
    return this.config.id;
  }

  get name(): string {
    return this.config.name;
  }

  get active(): boolean {
    return this.isActive;
  }

  get configuration(): StrategyConfig {
    return { ...this.config };
  }
}

// Strategy execution engine
export class StrategyEngine extends EventEmitter {
  private strategies: Map<string, BaseStrategy> = new Map();
  private logger;
  private eventBus: EventBus;
  private isRunning: boolean = false;

  constructor(eventBus: EventBus) {
    super();
    this.eventBus = eventBus;
    this.logger = createLogger('strategy-engine');
  }

  async initialize(): Promise<void> {
    // Subscribe to market data events
    await this.eventBus.subscribe('market.data', this.handleMarketData.bind(this));
    await this.eventBus.subscribe('order.update', this.handleOrderUpdate.bind(this));
    await this.eventBus.subscribe('portfolio.update', this.handlePortfolioUpdate.bind(this));
    
    this.logger.info('Strategy engine initialized');
  }

  async registerStrategy(strategy: BaseStrategy): Promise<void> {
    if (this.strategies.has(strategy.id)) {
      throw new Error(`Strategy ${strategy.id} already registered`);
    }

    this.strategies.set(strategy.id, strategy);
    
    // Forward strategy events
    strategy.on('signal', (signal) => this.emit('signal', signal));
    strategy.on('error', (error) => this.emit('error', error));
    
    this.logger.info('Strategy registered', { strategyId: strategy.id });
  }

  async unregisterStrategy(strategyId: string): Promise<void> {
    const strategy = this.strategies.get(strategyId);
    if (!strategy) {
      throw new Error(`Strategy ${strategyId} not found`);
    }

    if (strategy.active) {
      await strategy.stop();
    }

    strategy.removeAllListeners();
    this.strategies.delete(strategyId);
    
    this.logger.info('Strategy unregistered', { strategyId });
  }

  async startStrategy(strategyId: string): Promise<void> {
    const strategy = this.strategies.get(strategyId);
    if (!strategy) {
      throw new Error(`Strategy ${strategyId} not found`);
    }

    await strategy.start();
  }

  async stopStrategy(strategyId: string): Promise<void> {
    const strategy = this.strategies.get(strategyId);
    if (!strategy) {
      throw new Error(`Strategy ${strategyId} not found`);
    }

    await strategy.stop();
  }

  async startAll(): Promise<void> {
    if (this.isRunning) {
      this.logger.warn('Engine already running');
      return;
    }

    const startPromises = Array.from(this.strategies.values())
      .filter(strategy => strategy.configuration.enabled)
      .map(strategy => strategy.start());

    await Promise.all(startPromises);
    this.isRunning = true;
    this.logger.info('All strategies started');
    this.emit('started');
  }

  async stopAll(): Promise<void> {
    if (!this.isRunning) {
      this.logger.warn('Engine not running');
      return;
    }

    const stopPromises = Array.from(this.strategies.values())
      .filter(strategy => strategy.active)
      .map(strategy => strategy.stop());

    await Promise.all(stopPromises);
    this.isRunning = false;
    this.logger.info('All strategies stopped');
    this.emit('stopped');
  }

  private async handleMarketData(message: any): Promise<void> {
    const { symbol, ...data } = message.data;
    
    // Find strategies that trade this symbol
    const relevantStrategies = Array.from(this.strategies.values())
      .filter(strategy => 
        strategy.active && 
        strategy.configuration.symbols.includes(symbol)
      );

    for (const strategy of relevantStrategies) {
      try {
        // Create context for this strategy
        const context: StrategyContext = {
          symbol,
          timeframe: '1m', // TODO: Get from strategy config
          data: new DataFrame([data]), // TODO: Use historical data
          indicators: {},
          portfolio: {
            totalValue: 100000, // TODO: Get real portfolio data
            cash: 50000,
            positions: [],
            totalPnL: 0,
            dayPnL: 0
          },
          timestamp: data.timestamp
        };

        const signals = await strategy.onMarketData(context);
        
        for (const signal of signals) {
          await strategy.onSignal(signal);
        }
      } catch (error) {
        this.logger.error('Error processing market data for strategy', {
          error,
          strategyId: strategy.id,
          symbol
        });
      }
    }
  }

  private async handleOrderUpdate(message: any): Promise<void> {
    // Handle order updates - notify relevant strategies
    this.logger.debug('Order update received', { data: message.data });
  }

  private async handlePortfolioUpdate(message: any): Promise<void> {
    // Handle portfolio updates - notify relevant strategies
    this.logger.debug('Portfolio update received', { data: message.data });
  }

  getStrategy(strategyId: string): BaseStrategy | undefined {
    return this.strategies.get(strategyId);
  }

  getStrategies(): BaseStrategy[] {
    return Array.from(this.strategies.values());
  }

  getActiveStrategies(): BaseStrategy[] {
    return this.getStrategies().filter(strategy => strategy.active);
  }

  async shutdown(): Promise<void> {
    await this.stopAll();
    this.strategies.clear();
    this.removeAllListeners();
    this.logger.info('Strategy engine shutdown');
  }
}