/**
 * Risk Check API Endpoint
 * 
 * Called by n8n workflow before executing trade
 * POST /api/trading/check-risk
 */

import { NextRequest, NextResponse } from 'next/server'
import { getMergedConfig } from '@/config/trading'
import { getInitializedPositionManager } from '@/lib/trading/position-manager'
import { getLastTradeTime, getTradesInLastHour, getTodayPnL } from '@/lib/database/trades'

export interface RiskCheckRequest {
  symbol: string
  direction: 'long' | 'short'
}

export interface RiskCheckResponse {
  allowed: boolean
  reason?: string
  details?: string
}

export async function POST(request: NextRequest): Promise<NextResponse<RiskCheckResponse>> {
  try {
    // Verify authorization
    const authHeader = request.headers.get('authorization')
    const expectedAuth = `Bearer ${process.env.API_SECRET_KEY}`
    
    if (!authHeader || authHeader !== expectedAuth) {
      return NextResponse.json(
        {
          allowed: false,
          reason: 'Unauthorized',
        },
        { status: 401 }
      )
    }

    const body: RiskCheckRequest = await request.json()
    
    console.log('🔍 Risk check for:', body)
    
    const config = getMergedConfig()
    
    // Check for existing positions on the same symbol
    const positionManager = await getInitializedPositionManager()
    const existingTrades = Array.from(positionManager.getActiveTrades().values())
    const existingPosition = existingTrades.find(trade => trade.symbol === body.symbol)
    
    if (existingPosition) {
      // Check if it's the SAME direction (duplicate - block it)
      if (existingPosition.direction === body.direction) {
        console.log('🚫 Risk check BLOCKED: Duplicate position (same direction)', {
          symbol: body.symbol,
          existingDirection: existingPosition.direction,
          requestedDirection: body.direction,
          existingEntry: existingPosition.entryPrice,
        })
        
        return NextResponse.json({
          allowed: false,
          reason: 'Duplicate position',
          details: `Already have ${existingPosition.direction} position on ${body.symbol} (entry: $${existingPosition.entryPrice})`,
        })
      }
      
      // OPPOSITE direction - this is a signal flip/reversal (ALLOW IT)
      console.log('🔄 Risk check: Signal flip detected', {
        symbol: body.symbol,
        existingDirection: existingPosition.direction,
        newDirection: body.direction,
        note: 'Will close existing and open opposite',
      })
      
      return NextResponse.json({
        allowed: true,
        reason: 'Signal flip',
        details: `Signal reversed from ${existingPosition.direction} to ${body.direction} - will flip position`,
      })
    }
    
    // 1. Check daily drawdown limit
    const todayPnL = await getTodayPnL()
    if (todayPnL < config.maxDailyDrawdown) {
      console.log('🚫 Risk check BLOCKED: Daily drawdown limit reached', {
        todayPnL: todayPnL.toFixed(2),
        maxDrawdown: config.maxDailyDrawdown,
      })
      
      return NextResponse.json({
        allowed: false,
        reason: 'Daily drawdown limit',
        details: `Today's P&L ($${todayPnL.toFixed(2)}) has reached max drawdown limit ($${config.maxDailyDrawdown})`,
      })
    }
    
    // 2. Check trades per hour limit
    const tradesInLastHour = await getTradesInLastHour()
    if (tradesInLastHour >= config.maxTradesPerHour) {
      console.log('🚫 Risk check BLOCKED: Hourly trade limit reached', {
        tradesInLastHour,
        maxTradesPerHour: config.maxTradesPerHour,
      })
      
      return NextResponse.json({
        allowed: false,
        reason: 'Hourly trade limit',
        details: `Already placed ${tradesInLastHour} trades in the last hour (max: ${config.maxTradesPerHour})`,
      })
    }
    
    // 3. Check cooldown period
    const lastTradeTime = await getLastTradeTime()
    if (lastTradeTime && config.minTimeBetweenTrades > 0) {
      const timeSinceLastTrade = Date.now() - lastTradeTime.getTime()
      const cooldownMs = config.minTimeBetweenTrades * 60 * 1000 // Convert minutes to milliseconds
      
      if (timeSinceLastTrade < cooldownMs) {
        const remainingMs = cooldownMs - timeSinceLastTrade
        const remainingMinutes = Math.ceil(remainingMs / 60000)
        
        console.log('🚫 Risk check BLOCKED: Cooldown period active', {
          lastTradeTime: lastTradeTime.toISOString(),
          timeSinceLastTradeMs: timeSinceLastTrade,
          cooldownMs,
          remainingMinutes,
        })
        
        return NextResponse.json({
          allowed: false,
          reason: 'Cooldown period',
          details: `Must wait ${remainingMinutes} more minute(s) before next trade (cooldown: ${config.minTimeBetweenTrades} min)`,
        })
      }
    }
    
    console.log(`✅ Risk check PASSED: All checks passed`, {
      todayPnL: todayPnL.toFixed(2),
      tradesLastHour: tradesInLastHour,
      cooldownPassed: lastTradeTime ? 'yes' : 'no previous trades',
    })
    
    return NextResponse.json({
      allowed: true,
      details: 'All risk checks passed',
    })

  } catch (error) {
    console.error('❌ Risk check error:', error)
    
    return NextResponse.json(
      {
        allowed: false,
        reason: 'Risk check failed',
        details: error instanceof Error ? error.message : 'Unknown error',
      },
      { status: 500 }
    )
  }
}