/**
 * 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, getLastTradeTimeForSymbol, getTradesInLastHour, getTodayPnL } from '@/lib/database/trades'

export interface RiskCheckRequest {
  symbol: string
  direction: 'long' | 'short'
  // Optional context metrics from TradingView
  atr?: number
  adx?: number
  rsi?: number
  volumeRatio?: number
  pricePosition?: number
}

export interface RiskCheckResponse {
  allowed: boolean
  reason?: string
  details?: string
  qualityScore?: number
  qualityReasons?: 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 PER SYMBOL (not global)
    const lastTradeTimeForSymbol = await getLastTradeTimeForSymbol(body.symbol)
    if (lastTradeTimeForSymbol && config.minTimeBetweenTrades > 0) {
      const timeSinceLastTrade = Date.now() - lastTradeTimeForSymbol.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 for', body.symbol, {
          lastTradeTime: lastTradeTimeForSymbol.toISOString(),
          timeSinceLastTradeMs: timeSinceLastTrade,
          cooldownMs,
          remainingMinutes,
        })
        
        return NextResponse.json({
          allowed: false,
          reason: 'Cooldown period',
          details: `Must wait ${remainingMinutes} more minute(s) before next ${body.symbol} trade (cooldown: ${config.minTimeBetweenTrades} min)`,
        })
      }
    }
    
    // 4. Check signal quality (if context metrics provided)
    const hasContextMetrics = body.atr !== undefined && body.atr > 0
    
    if (hasContextMetrics) {
      const qualityScore = scoreSignalQuality({
        atr: body.atr || 0,
        adx: body.adx || 0,
        rsi: body.rsi || 0,
        volumeRatio: body.volumeRatio || 0,
        pricePosition: body.pricePosition || 0,
        direction: body.direction,
        minScore: 60 // Default minimum quality score threshold
      })
      
      if (!qualityScore.passed) {
        console.log('🚫 Risk check BLOCKED: Signal quality too low', {
          score: qualityScore.score,
          reasons: qualityScore.reasons
        })
        
        return NextResponse.json({
          allowed: false,
          reason: 'Signal quality too low',
          details: `Score: ${qualityScore.score}/100 - ${qualityScore.reasons.join(', ')}`,
          qualityScore: qualityScore.score,
          qualityReasons: qualityScore.reasons
        })
      }
      
      console.log(`✅ Risk check PASSED: All checks passed`, {
        todayPnL: todayPnL.toFixed(2),
        tradesLastHour: tradesInLastHour,
        cooldownPassed: lastTradeTimeForSymbol ? 'yes' : `no previous ${body.symbol} trades`,
        qualityScore: qualityScore.score,
        qualityReasons: qualityScore.reasons
      })
      
      return NextResponse.json({
        allowed: true,
        details: 'All risk checks passed',
        qualityScore: qualityScore.score,
        qualityReasons: qualityScore.reasons
      })
    }
    
    console.log(`✅ Risk check PASSED: All checks passed`, {
      todayPnL: todayPnL.toFixed(2),
      tradesLastHour: tradesInLastHour,
      cooldownPassed: lastTradeTimeForSymbol ? 'yes' : `no previous ${body.symbol} 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 }
    )
  }
}

interface SignalQualityResult {
  passed: boolean
  score: number
  reasons: string[]
}

/**
 * Score signal quality based on context metrics from TradingView
 * Returns score 0-100 and array of reasons
 */
function scoreSignalQuality(params: {
  atr: number
  adx: number
  rsi: number
  volumeRatio: number
  pricePosition: number
  direction: 'long' | 'short'
  minScore?: number // Configurable minimum score threshold
}): SignalQualityResult {
  let score = 50 // Base score
  const reasons: string[] = []

  // ATR check (volatility gate: 0.15% - 2.5%)
  if (params.atr > 0) {
    if (params.atr < 0.15) {
      score -= 15
      reasons.push(`ATR too low (${params.atr.toFixed(2)}% - dead market)`)
    } else if (params.atr > 2.5) {
      score -= 20
      reasons.push(`ATR too high (${params.atr.toFixed(2)}% - too volatile)`)
    } else if (params.atr >= 0.15 && params.atr < 0.4) {
      score += 5
      reasons.push(`ATR moderate (${params.atr.toFixed(2)}%)`)
    } else {
      score += 10
      reasons.push(`ATR healthy (${params.atr.toFixed(2)}%)`)
    }
  }

  // ADX check (trend strength: want >18)
  if (params.adx > 0) {
    if (params.adx > 25) {
      score += 15
      reasons.push(`Strong trend (ADX ${params.adx.toFixed(1)})`)
    } else if (params.adx < 18) {
      score -= 15
      reasons.push(`Weak trend (ADX ${params.adx.toFixed(1)})`)
    } else {
      score += 5
      reasons.push(`Moderate trend (ADX ${params.adx.toFixed(1)})`)
    }
  }

  // RSI check (momentum confirmation)
  if (params.rsi > 0) {
    if (params.direction === 'long') {
      if (params.rsi > 50 && params.rsi < 70) {
        score += 10
        reasons.push(`RSI supports long (${params.rsi.toFixed(1)})`)
      } else if (params.rsi > 70) {
        score -= 10
        reasons.push(`RSI overbought (${params.rsi.toFixed(1)})`)
      }
    } else { // short
      if (params.rsi < 50 && params.rsi > 30) {
        score += 10
        reasons.push(`RSI supports short (${params.rsi.toFixed(1)})`)
      } else if (params.rsi < 30) {
        score -= 10
        reasons.push(`RSI oversold (${params.rsi.toFixed(1)})`)
      }
    }
  }

  // Volume check (want > 1.0 = above average)
  if (params.volumeRatio > 0) {
    if (params.volumeRatio > 1.5) {
      score += 15
      reasons.push(`Very strong volume (${params.volumeRatio.toFixed(2)}x avg)`)
    } else if (params.volumeRatio > 1.2) {
      score += 10
      reasons.push(`Strong volume (${params.volumeRatio.toFixed(2)}x avg)`)
    } else if (params.volumeRatio < 0.8) {
      score -= 10
      reasons.push(`Weak volume (${params.volumeRatio.toFixed(2)}x avg)`)
    }
  }

  // Price position check (avoid chasing vs breakout detection)
  if (params.pricePosition > 0) {
    if (params.direction === 'long' && params.pricePosition > 95) {
      // High volume breakout at range top can be good
      if (params.volumeRatio > 1.4) {
        score += 5
        reasons.push(`Volume breakout at range top (${params.pricePosition.toFixed(0)}%, vol ${params.volumeRatio.toFixed(2)}x)`)
      } else {
        score -= 15
        reasons.push(`Price near top of range (${params.pricePosition.toFixed(0)}%) - risky long`)
      }
    } else if (params.direction === 'short' && params.pricePosition < 5) {
      // High volume breakdown at range bottom can be good
      if (params.volumeRatio > 1.4) {
        score += 5
        reasons.push(`Volume breakdown at range bottom (${params.pricePosition.toFixed(0)}%, vol ${params.volumeRatio.toFixed(2)}x)`)
      } else {
        score -= 15
        reasons.push(`Price near bottom of range (${params.pricePosition.toFixed(0)}%) - risky short`)
      }
    } else {
      score += 5
      reasons.push(`Price position OK (${params.pricePosition.toFixed(0)}%)`)
    }
  }

  // Volume breakout bonus (high volume can override other weaknesses)
  if (params.volumeRatio > 1.8 && params.atr < 0.6) {
    score += 10
    reasons.push(`Volume breakout compensates for low ATR`)
  }

  const minScore = params.minScore ?? 60 // Use config value or default to 60
  return {
    passed: score >= minScore,
    score,
    reasons
  }
}