import type { DnsReport, Category, Summary } from '~/types/dns'

interface StreamEvent {
  domain: string
  category: Category
  done?: boolean
}

export function useDnsCheck() {
  const config = useRuntimeConfig()
  const report = ref<DnsReport | null>(null)
  const loading = ref(false)
  const error = ref<string | null>(null)
  const progress = ref(0)
  const totalCategories = 8

  async function checkDomain(domain: string) {
    loading.value = true
    error.value = null
    report.value = null
    progress.value = 0

    // Initialize empty report
    const startTime = Date.now()
    const partialReport: DnsReport = {
      domain,
      timestamp: new Date().toISOString(),
      duration_ms: 0,
      summary: { pass: 0, warn: 0, fail: 0, info: 0 },
      categories: [],
    }

    try {
      const url = `${config.public.apiBase}/check/stream?domain=${encodeURIComponent(domain)}`
      const eventSource = new EventSource(url)

      await new Promise<void>((resolve, reject) => {
        const timeout = setTimeout(() => {
          eventSource.close()
          reject(new Error('Request timed out after 30 seconds'))
        }, 30000)

        eventSource.onmessage = (event) => {
          try {
            const data = JSON.parse(event.data) as StreamEvent & { done?: boolean }

            if (data.done) {
              clearTimeout(timeout)
              eventSource.close()
              partialReport.duration_ms = Date.now() - startTime
              resolve()
              return
            }

            if (data.category) {
              partialReport.categories.push(data.category)
              progress.value = partialReport.categories.length

              // Recalculate summary
              const summary: Summary = { pass: 0, warn: 0, fail: 0, info: 0 }
              for (const cat of partialReport.categories) {
                for (const check of cat.checks) {
                  summary[check.status]++
                }
              }
              partialReport.summary = summary
              partialReport.duration_ms = Date.now() - startTime

              // Update reactively
              report.value = { ...partialReport, categories: [...partialReport.categories] }
            }
          } catch {
            // ignore parse errors
          }
        }

        eventSource.onerror = () => {
          clearTimeout(timeout)
          eventSource.close()
          if (partialReport.categories.length > 0) {
            // Got some results, show them
            partialReport.duration_ms = Date.now() - startTime
            report.value = { ...partialReport }
            resolve()
          } else {
            reject(new Error('Connection to DNS check server failed'))
          }
        }
      })
    } catch (e: any) {
      // Fallback to non-streaming API
      try {
        const data = await $fetch<DnsReport>(`${config.public.apiBase}/check?domain=${encodeURIComponent(domain)}`)
        report.value = data
        progress.value = totalCategories
      } catch (e2: any) {
        error.value = e2.data?.error || e2.message || e.message || 'Failed to check domain'
      }
    } finally {
      loading.value = false
      progress.value = totalCategories
    }
  }

  return { report, loading, error, progress, totalCategories, checkDomain }
}