/**
 * Reduce Position API Endpoint
 * 
 * Partially closes a position and recalculates TP/SL orders
 * POST /api/trading/reduce-position
 */

import { NextRequest, NextResponse } from 'next/server'
import { getMergedConfig } from '@/config/trading'
import { getInitializedPositionManager } from '@/lib/trading/position-manager'
import { initializeDriftService } from '@/lib/drift/client'
import { closePosition, placeExitOrders, cancelAllOrders } from '@/lib/drift/orders'

interface ReducePositionRequest {
  tradeId: string
  reducePercent?: number // 25 = close 25%, 50 = close 50%
}

interface ReducePositionResponse {
  success: boolean
  message: string
  closedSize?: number
  remainingSize?: number
  closePrice?: number
  realizedPnL?: number
  newTP1?: number
  newTP2?: number
  newSL?: number
}

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

    const body: ReducePositionRequest = await request.json()
    
    console.log('📉 Reducing position:', body)
    
    if (!body.tradeId) {
      return NextResponse.json(
        {
          success: false,
          message: 'tradeId is required',
        },
        { status: 400 }
      )
    }

    const reducePercent = body.reducePercent || 50 // Default: close 50%
    
    if (reducePercent < 10 || reducePercent > 90) {
      return NextResponse.json(
        {
          success: false,
          message: 'Reduce percent must be between 10 and 90',
        },
        { status: 400 }
      )
    }

    // Get current configuration
    const config = getMergedConfig()
    
    // Get Position Manager
    const positionManager = await getInitializedPositionManager()
    const activeTrades = positionManager.getActiveTrades()
    const trade = activeTrades.find(t => t.id === body.tradeId)
    
    if (!trade) {
      return NextResponse.json(
        {
          success: false,
          message: `Position ${body.tradeId} not found`,
        },
        { status: 404 }
      )
    }

    console.log(`📊 Current position: ${trade.symbol} ${trade.direction}`)
    console.log(`   Entry: $${trade.entryPrice}`)
    console.log(`   Size: ${trade.currentSize} (${trade.positionSize} USD)`)
    console.log(`   Reducing by: ${reducePercent}%`)

    // Initialize Drift service
    const driftService = await initializeDriftService()

    // Close portion of position at market
    console.log(`💰 Closing ${reducePercent}% of position...`)

    const closeResult = await closePosition({
      symbol: trade.symbol,
      percentToClose: reducePercent,
      slippageTolerance: config.slippageTolerance,
    })

    if (!closeResult.success || !closeResult.closePrice) {
      throw new Error(`Failed to close position: ${closeResult.error}`)
    }

    console.log(`✅ Closed at $${closeResult.closePrice}`)
    console.log(`💵 Realized P&L: $${closeResult.realizedPnL || 0}`)

    // Calculate remaining position size
    const remainingPercent = 100 - reducePercent
    const remainingSizeUSD = (trade.positionSize * remainingPercent) / 100

    console.log(`📊 Remaining position: $${remainingSizeUSD} (${remainingPercent}%)`)

    // Cancel all existing exit orders
    console.log('🗑️ Cancelling old TP/SL orders...')
    try {
      await cancelAllOrders(trade.symbol)
      console.log('✅ Old orders cancelled')
    } catch (cancelError) {
      console.error('⚠️ Failed to cancel orders:', cancelError)
      // Continue anyway
    }

    // Calculate TP/SL prices (entry price stays the same)
    const calculatePrice = (entry: number, percent: number, direction: 'long' | 'short') => {
      if (direction === 'long') {
        return entry * (1 + percent / 100)
      } else {
        return entry * (1 - percent / 100)
      }
    }

    const newTP1 = calculatePrice(trade.entryPrice, config.takeProfit1Percent, trade.direction)
    const newTP2 = calculatePrice(trade.entryPrice, config.takeProfit2Percent, trade.direction)
    const newSL = calculatePrice(trade.entryPrice, config.stopLossPercent, trade.direction)

    console.log(`🎯 New targets (same entry, reduced size):`)
    console.log(`   TP1: $${newTP1} (${config.takeProfit1Percent}%)`)
    console.log(`   TP2: $${newTP2} (${config.takeProfit2Percent}%)`)
    console.log(`   SL: $${newSL} (${config.stopLossPercent}%)`)

    // Place new exit orders with reduced size
    console.log('📝 Placing new TP/SL orders...')
    const exitOrders = await placeExitOrders({
      symbol: trade.symbol,
      direction: trade.direction,
      positionSizeUSD: remainingSizeUSD,
      tp1Price: newTP1,
      tp2Price: newTP2,
      stopLossPrice: newSL,
      tp1SizePercent: config.takeProfit1SizePercent,
      tp2SizePercent: config.takeProfit2SizePercent,
      useDualStops: config.useDualStops,
      softStopPrice: config.useDualStops ? calculatePrice(trade.entryPrice, config.softStopPercent, trade.direction) : undefined,
      softStopBuffer: config.useDualStops ? config.softStopBuffer : undefined,
      hardStopPrice: config.useDualStops ? calculatePrice(trade.entryPrice, config.hardStopPercent, trade.direction) : undefined,
    })

    console.log(`✅ New exit orders placed`)

    // Update Position Manager with new values
    trade.positionSize = remainingSizeUSD
    trade.currentSize = remainingSizeUSD
    trade.realizedPnL += closeResult.realizedPnL || 0
    
    // Update prices (stay the same but refresh)
    trade.tp1Price = newTP1
    trade.tp2Price = newTP2
    trade.stopLossPrice = newSL

    console.log(`💾 Updated Position Manager`)

    return NextResponse.json({
      success: true,
      message: `Reduced position by ${reducePercent}% - Remaining: $${remainingSizeUSD.toFixed(0)}`,
      closedSize: (trade.positionSize * reducePercent) / 100,
      remainingSize: remainingSizeUSD,
      closePrice: closeResult.closePrice,
      realizedPnL: closeResult.realizedPnL,
      newTP1: newTP1,
      newTP2: newTP2,
      newSL: newSL,
    })

  } catch (error) {
    console.error('❌ Reduce position error:', error)
    
    return NextResponse.json(
      {
        success: false,
        message: error instanceof Error ? error.message : 'Unknown error',
      },
      { status: 500 }
    )
  }
}