import { TEST_NODES } from '../shared/types'

interface Env {
  GLOBALPING_API: string
}

interface MeasurementResponse {
  id: string
  probesCount: number
}

interface ProbeResult {
  probe: {
    continent: string
    country: string
    city: string
    asn: number
    network: string
  }
  result: {
    status: string
    rawOutput: string
    stats?: {
      min: number
      max: number
      avg: number
      total: number
      loss: number
    }
  }
}

interface MeasurementResult {
  id: string
  type: string
  status: 'in-progress' | 'finished'
  results?: ProbeResult[]
}

interface BatchLatencyResult {
  nodeId: string
  latency: number | null
  success: boolean
}

const corsHeaders = {
  'Access-Control-Allow-Origin': '*',
  'Access-Control-Allow-Methods': 'GET, POST, OPTIONS',
  'Access-Control-Allow-Headers': 'Content-Type',
}

function jsonResponse(data: unknown, status = 200): Response {
  return new Response(JSON.stringify(data), {
    status,
    headers: {
      'Content-Type': 'application/json',
      ...corsHeaders,
    },
  })
}

const IP_REGEX = /^(?:(?:25[0-5]|2[0-4]\d|1\d{2}|[1-9]?\d)\.){3}(?:25[0-5]|2[0-4]\d|1\d{2}|[1-9]?\d)$/
const DOMAIN_REGEX = /^(?!:\/\/)([a-zA-Z0-9-]+\.)+[a-zA-Z]{2,}$/

function isValidTarget(target: string): boolean {
  return IP_REGEX.test(target) || DOMAIN_REGEX.test(target)
}

function extractClientIp(request: Request): string | null {
  const cfConnectingIp = request.headers.get('CF-Connecting-IP')
  if (cfConnectingIp) return cfConnectingIp

  const forwarded = request.headers.get('X-Forwarded-For')
  if (forwarded) return forwarded.split(',')[0].trim()

  return null
}

async function createBatchMeasurement(target: string, env: Env): Promise<string> {
  const locations = TEST_NODES.map(node => ({
    country: node.country,
    city: node.city,
    limit: 1
  }))

  const res = await fetch(`${env.GLOBALPING_API}/measurements`, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'User-Agent': 'LatencyTest/1.0.0'
    },
    body: JSON.stringify({
      type: 'ping',
      target,
      inProgressUpdates: true,
      locations,
      measurementOptions: {
        packets: 3
      }
    })
  })

  if (!res.ok) {
    const error = await res.json().catch(() => ({})) as { error?: { message?: string } }
    throw new Error(error.error?.message || `GlobalPing API error: ${res.status}`)
  }

  const data = await res.json() as MeasurementResponse
  return data.id
}

function normalizeLocationName(value?: string | null): string {
  if (!value) return ''
  return value
    .normalize('NFD')
    .replace(/[\u0300-\u036f]/g, '')
    .replace(/[^a-zA-Z0-9]+/g, ' ')
    .trim()
    .toLowerCase()
}

function matchProbeToNode(probe: ProbeResult['probe']): string | null {
  const candidates = TEST_NODES.filter(node => node.country === probe.country)
  if (candidates.length === 0) return null

  const probeCity = normalizeLocationName(probe.city)
  if (probeCity) {
    for (const node of candidates) {
      const nodeCity = normalizeLocationName(node.city)
      if (nodeCity && (probeCity.includes(nodeCity) || nodeCity.includes(probeCity))) {
        return node.id
      }
    }
  }

  if (candidates.length === 1) {
    return candidates[0].id
  }

  return null
}

async function handleGetIp(request: Request): Promise<Response> {
  const ip = extractClientIp(request)
  if (!ip) {
    return jsonResponse({ error: 'Unable to determine IP' }, 500)
  }
  return jsonResponse({ ip })
}

async function handleCreateMeasurement(request: Request, env: Env): Promise<Response> {
  try {
    const body = await request.json() as { target?: string }
    const { target } = body

    if (!target || typeof target !== 'string') {
      return jsonResponse({ error: 'target is required' }, 400)
    }

    const trimmedTarget = target.trim().toLowerCase()

    if (!isValidTarget(trimmedTarget)) {
      return jsonResponse({ error: 'Invalid target. Please enter a valid IP address or domain name.' }, 400)
    }

    const measurementId = await createBatchMeasurement(trimmedTarget, env)
    return jsonResponse({ measurementId })
  } catch (error) {
    console.error('Batch measurement creation error:', error)
    return jsonResponse({ error: 'Failed to create measurement' }, 500)
  }
}

async function handleGetMeasurement(measurementId: string, env: Env): Promise<Response> {
  try {
    const fetchRes = await fetch(`${env.GLOBALPING_API}/measurements/${measurementId}`, {
      headers: {
        'User-Agent': 'LatencyTest/1.0.0'
      }
    })

    if (!fetchRes.ok) {
      return jsonResponse({ error: 'Failed to get measurement' }, fetchRes.status)
    }

    const data = await fetchRes.json() as MeasurementResult
    const results: BatchLatencyResult[] = []
    const matchedNodes = new Set<string>()

    if (data.results) {
      for (const probeResult of data.results) {
        const result = probeResult.result
        const nodeId = matchProbeToNode(probeResult.probe)

        if (nodeId && !matchedNodes.has(nodeId)) {
          matchedNodes.add(nodeId)
          if (result.status === 'finished') {
            const latency = result.stats?.avg != null ? Math.round(result.stats.avg) : null
            results.push({ nodeId, latency, success: latency !== null })
          } else {
            results.push({ nodeId, latency: null, success: false })
          }
        }
      }
    }

    for (const node of TEST_NODES) {
      if (!matchedNodes.has(node.id)) {
        results.push({ nodeId: node.id, latency: null, success: false })
      }
    }

    return jsonResponse({
      status: data.status,
      results
    })
  } catch (error) {
    console.error('Get measurement error:', error)
    return jsonResponse({ error: 'Failed to get measurement' }, 500)
  }
}

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const url = new URL(request.url)
    const path = url.pathname

    // Handle CORS preflight
    if (request.method === 'OPTIONS') {
      return new Response(null, { headers: corsHeaders })
    }

    // API routes
    if (path === '/api/ip' && request.method === 'GET') {
      return handleGetIp(request)
    }

    if (path === '/api/latency/batch' && request.method === 'POST') {
      return handleCreateMeasurement(request, env)
    }

    const batchMatch = path.match(/^\/api\/latency\/batch\/([a-zA-Z0-9-]+)$/)
    if (batchMatch && request.method === 'GET') {
      return handleGetMeasurement(batchMatch[1], env)
    }

    // Serve static files for other routes (handled by Cloudflare Pages/Workers Sites)
    return new Response('Not Found', { status: 404 })
  }
}