<script setup lang="ts">
interface ParsedRow {
  Name: string
  Email: string
  Phone: string
  PlusOnes: number
}
interface RowError {
  row: number
  reason: string
}
interface PreviewResponse {
  rows: ParsedRow[]
  errors?: RowError[]
  total_count: number
}
interface ImportResponse {
  added: number
  skipped: number
  skipped_emails?: string[]
  errors?: RowError[]
  total_count: number
}

const props = defineProps<{ eventId: string }>()
const emit = defineEmits<{ (e: 'imported'): void }>()

const config = useRuntimeConfig()
const apiBase = config.public.apiBase as string

type Stage = 'idle' | 'preview' | 'committing' | 'done'
const stage = ref<Stage>('idle')
const fileName = ref('')
const dragging = ref(false)
const error = ref<string | null>(null)
const preview = ref<PreviewResponse | null>(null)
const result = ref<ImportResponse | null>(null)
let pendingFile: File | null = null

function reset() {
  stage.value = 'idle'
  fileName.value = ''
  preview.value = null
  result.value = null
  error.value = null
  pendingFile = null
}

async function onFiles(files: FileList | File[] | null) {
  if (!files || !files.length) return
  const f = files[0]
  if (f.size > 1024 * 1024) {
    error.value = 'File is larger than 1MB.'
    return
  }
  fileName.value = f.name
  error.value = null
  pendingFile = f
  await runPreview()
}

async function runPreview() {
  if (!pendingFile) return
  try {
    const fd = new FormData()
    fd.append('file', pendingFile)
    preview.value = await useApi<PreviewResponse>(
      `/events/${props.eventId}/guests/import/preview`,
      { method: 'POST', body: fd },
    )
    stage.value = 'preview'
  } catch (e: any) {
    error.value = useErrMessage(e, 'Could not parse that CSV')
    stage.value = 'idle'
    pendingFile = null
  }
}

async function commit() {
  if (!pendingFile) return
  stage.value = 'committing'
  error.value = null
  try {
    const fd = new FormData()
    fd.append('file', pendingFile)
    result.value = await useApi<ImportResponse>(
      `/events/${props.eventId}/guests/import`,
      { method: 'POST', body: fd },
    )
    stage.value = 'done'
    emit('imported')
  } catch (e: any) {
    error.value = useErrMessage(e, 'Import failed')
    stage.value = 'preview'
  }
}

function onDrop(e: DragEvent) {
  dragging.value = false
  onFiles(e.dataTransfer?.files ?? null)
}

const templateUrl = computed(() => `${apiBase}/events/${props.eventId}/guests/import/template`)

async function downloadTemplate() {
  // The endpoint requires a Bearer header, which a plain <a download> can't
  // attach — fetch through useApi (which adds auth + handles refresh) then
  // synthesise an anchor click on the resulting blob.
  try {
    const res: any = await useApi(`/events/${props.eventId}/guests/import/template`, {
      method: 'GET',
    })
    // useApi auto-parses JSON; for CSV the response body is plain text.
    const text = typeof res === 'string' ? res : JSON.stringify(res)
    const blob = new Blob([text], { type: 'text/csv;charset=utf-8' })
    const url = URL.createObjectURL(blob)
    const a = document.createElement('a')
    a.href = url
    a.download = 'guestguard-import-template.csv'
    a.click()
    URL.revokeObjectURL(url)
  } catch (e: any) {
    error.value = useErrMessage(e, 'Could not download template')
  }
}
</script>

<template>
  <!-- No outer .card chrome: this component is now embedded inside a
       modal that supplies the surface. -->
  <div>
    <div class="mb-3 flex items-center justify-end">
      <button class="text-xs text-zinc-400 hover:text-zinc-200" @click="downloadTemplate">
        Download template
      </button>
    </div>

    <!-- Stage 1: drag-drop zone -->
    <div v-if="stage === 'idle'">
      <label
        class="flex cursor-pointer flex-col items-center justify-center rounded-lg border-2 border-dashed bg-zinc-900/50 p-6 text-center transition"
        :class="dragging ? 'border-brand-500 bg-brand-500/5' : 'border-zinc-700 hover:border-zinc-600'"
        @dragover.prevent="dragging = true"
        @dragleave.prevent="dragging = false"
        @drop.prevent="onDrop"
      >
        <span class="mb-1 text-sm text-zinc-200">Drop a CSV here or click to choose</span>
        <span class="text-xs text-zinc-500">Up to 5,000 rows · 1MB max</span>
        <input type="file" accept=".csv,text/csv" class="hidden" @change="onFiles(($event.target as HTMLInputElement).files)" />
      </label>
      <p class="mt-2 text-xs text-zinc-500">
        Required column: <code>name</code>. Optional: <code>email</code>, <code>phone</code>, <code>plus_ones</code>.
      </p>
      <p v-if="error" class="mt-3 text-sm text-red-400">{{ error }}</p>
    </div>

    <!-- Stage 2: preview -->
    <div v-else-if="stage === 'preview' && preview">
      <p class="mb-2 text-sm">
        <span class="text-zinc-200">{{ fileName }}</span>
        <span class="text-zinc-500"> — {{ preview.rows.length }} valid row{{ preview.rows.length === 1 ? '' : 's' }}, {{ preview.errors?.length || 0 }} error{{ preview.errors?.length === 1 ? '' : 's' }}.</span>
      </p>

      <div v-if="preview.errors && preview.errors.length" class="mb-3 max-h-32 overflow-auto rounded border border-amber-900/40 bg-amber-950/20 p-2 text-xs text-amber-200">
        <p class="mb-1 font-medium">Rows with problems (these will be skipped):</p>
        <ul class="space-y-0.5">
          <li v-for="(err, i) in preview.errors" :key="i">
            row {{ err.row }} — {{ err.reason }}
          </li>
        </ul>
      </div>

      <div v-if="preview.rows.length" class="mb-3 max-h-64 overflow-auto rounded border border-zinc-800">
        <table class="w-full text-xs">
          <thead class="bg-zinc-900 text-zinc-400">
            <tr>
              <th class="px-2 py-1.5 text-left">Name</th>
              <th class="px-2 py-1.5 text-left">Email</th>
              <th class="px-2 py-1.5 text-left">Phone</th>
              <th class="px-2 py-1.5 text-right">+1s</th>
            </tr>
          </thead>
          <tbody class="divide-y divide-zinc-800">
            <tr v-for="(r, i) in preview.rows.slice(0, 100)" :key="i" class="text-zinc-200">
              <td class="px-2 py-1">{{ r.Name }}</td>
              <td class="px-2 py-1 text-zinc-400">{{ r.Email || '—' }}</td>
              <td class="px-2 py-1 text-zinc-400">{{ r.Phone || '—' }}</td>
              <td class="px-2 py-1 text-right tabular-nums">{{ r.PlusOnes }}</td>
            </tr>
          </tbody>
        </table>
        <p v-if="preview.rows.length > 100" class="px-2 py-1 text-xs text-zinc-500">
          + {{ preview.rows.length - 100 }} more not shown.
        </p>
      </div>

      <div class="flex items-center gap-2">
        <button class="btn-primary" :disabled="!preview.rows.length || stage === 'committing'" @click="commit">
          Looks good — import {{ preview.rows.length }} guest{{ preview.rows.length === 1 ? '' : 's' }}
        </button>
        <button class="btn-ghost" @click="reset">Cancel</button>
      </div>
      <p v-if="error" class="mt-3 text-sm text-red-400">{{ error }}</p>
    </div>

    <!-- Stage 3: committing -->
    <div v-else-if="stage === 'committing'" class="text-sm text-zinc-400">Importing…</div>

    <!-- Stage 4: done -->
    <div v-else-if="stage === 'done' && result" class="text-sm">
      <p class="mb-1 font-medium text-brand-300">Imported {{ result.added }} guest{{ result.added === 1 ? '' : 's' }}.</p>
      <p v-if="result.skipped" class="text-zinc-400">Skipped {{ result.skipped }} duplicate{{ result.skipped === 1 ? '' : 's' }} (already on this event).</p>
      <p v-if="result.errors?.length" class="text-zinc-400">{{ result.errors.length }} row{{ result.errors.length === 1 ? '' : 's' }} had errors and were not imported.</p>
      <button class="btn-ghost mt-3" @click="reset">Import another file</button>
    </div>
  </div>
</template>
