import { NextRequest, NextResponse } from 'next/server'

/**
 * eBay API Proxy Route
 * Proxies requests to eBay Finding API to avoid CORS issues
 */

interface eBaySearchParams {
  keywords: string
  categoryId?: string
  sortOrder?: string
  maxResults?: number
}

interface eBaySearchResult {
  itemId: string
  title: string
  price: string
  currency: string
  imageUrl?: string
  viewItemUrl: string
  condition?: string
  shippingCost?: string
  affiliateLink: string
}

type MaybeArray<T> = T | T[]

// Affiliate campaign ID for generating links
const AFFILIATE_CAMPAIGN_ID = process.env.EBAY_AFFILIATE_CAMPAIGN_ID?.trim() || ''

// Generate eBay affiliate link
function generateAffiliateLink(viewItemUrl: string): string {
  if (!AFFILIATE_CAMPAIGN_ID) {
    return viewItemUrl
  }
  
  try {
    const url = new URL(viewItemUrl)
    url.searchParams.set('mkcid', '1')
    url.searchParams.set('mkrid', '711-53200-19255-0')
    url.searchParams.set('siteid', '0')
    url.searchParams.set('campid', AFFILIATE_CAMPAIGN_ID)
    url.searchParams.set('toolid', '10001')
    url.searchParams.set('mkevt', '1')
    return url.toString()
  } catch {
    return viewItemUrl
  }
}

function first<T>(value: MaybeArray<T> | undefined): T | undefined {
  if (!value) {
    return undefined
  }

  return Array.isArray(value) ? value[0] : value
}

function normalizeItem(item: any): eBaySearchResult {
  const currentPrice = first(item.sellingStatus?.currentPrice)
  const shippingCost = first(item.shippingInfo?.shippingServiceCost)
  const condition = first(item.condition)
  const viewItemUrl = item.viewItemURL || item.viewItemUrl || ''

  return {
    itemId: item.itemId || '',
    title: item.title || 'Unknown Item',
    price: `${currentPrice?.value || '0'} ${currentPrice?.currencyId || 'USD'}`,
    currency: currentPrice?.currencyId || 'USD',
    imageUrl: first(item.galleryURL) || undefined,
    viewItemUrl,
    condition: condition?.conditionDisplayName || undefined,
    shippingCost: shippingCost?.value
      ? `${shippingCost.value} ${shippingCost.currencyId || currentPrice?.currencyId || 'USD'}`
      : undefined,
    affiliateLink: generateAffiliateLink(viewItemUrl),
  }
}

export async function GET(request: NextRequest) {
  const { searchParams } = new URL(request.url)
  
  const keywords = searchParams.get('keywords')
  const categoryId = searchParams.get('categoryId') || undefined
  const sortOrder = searchParams.get('sortOrder') || 'BestMatch'
  const maxResults = parseInt(searchParams.get('maxResults') || '6', 10)
  
  if (!keywords) {
    return NextResponse.json({ error: 'Keywords parameter is required' }, { status: 400 })
  }
  
  const appId = process.env.EBAY_APP_ID?.trim()
  
  if (!appId) {
    console.error('EBAY_APP_ID not configured')
    return NextResponse.json(
      { error: 'eBay API not configured. Please set EBAY_APP_ID environment variable.' },
      { status: 503 }
    )
  }
  
  // Build eBay Finding API URL
  const baseUrl = 'https://svcs.ebay.com/services/search/FindingService/v1'
  const url = new URL(baseUrl)
  
  url.searchParams.set('OPERATION-NAME', 'findItemsAdvanced')
  url.searchParams.set('SERVICE-VERSION', '1.0.0')
  url.searchParams.set('SECURITY-APPNAME', appId)
  url.searchParams.set('RESPONSE-DATA-FORMAT', 'JSON')
  url.searchParams.set('REST-PAYLOAD', 'true')
  url.searchParams.set('keywords', keywords)
  url.searchParams.set('sortOrder', sortOrder)
  url.searchParams.set('paginationInput.entriesPerPage', maxResults.toString())
  
  if (categoryId) {
    url.searchParams.set('categoryId', categoryId)
  }
  
  try {
    const response = await fetch(url.toString(), {
      method: 'GET',
      headers: {
        'Accept': 'application/json',
      },
    })
    
    if (!response.ok) {
      const errorText = await response.text()
      console.error('eBay API error:', response.status, errorText)
      return NextResponse.json(
        { error: `eBay API error: ${response.status}` },
        { status: response.status }
      )
    }
    
    const data = await response.json()
    
    // Parse eBay API response
    const findItemsAdvancedResponse = data.findItemsAdvancedResponse?.[0]
    if (!findItemsAdvancedResponse) {
      return NextResponse.json([])
    }
    
    const searchResult = findItemsAdvancedResponse.searchResult?.[0]
    if (!searchResult || !searchResult.item || searchResult.item.length === 0) {
      return NextResponse.json([])
    }
    
    const items = Array.isArray(searchResult.item) ? searchResult.item : [searchResult.item]

    const results: eBaySearchResult[] = items.map((item: any) => normalizeItem(item))
    
    return NextResponse.json(results)
    
  } catch (error) {
    console.error('Error fetching from eBay API:', error)
    return NextResponse.json(
      { error: 'Failed to fetch products from eBay' },
      { status: 500 }
    )
  }
}