import { appendLog, readJsonFile, writeJsonFile } from './storage'

type FlowState = Record<string, { step: string; name?: string }>

function normalizeNumber(number?: string | null) {
  return (number || '').replace(/\D+/g, '')
}

export async function sendTextMessage(to: string, message: string) {
  const apiVersion = process.env.WHATSAPP_API_VERSION || 'v23.0'
  const phoneNumberId = process.env.WHATSAPP_PHONE_NUMBER_ID || ''
  const accessToken = process.env.WHATSAPP_ACCESS_TOKEN || ''
  const url = `https://graph.facebook.com/${apiVersion}/${phoneNumberId}/messages`

  const response = await fetch(url, {
    method: 'POST',
    headers: {
      Authorization: `Bearer ${accessToken}`,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      messaging_product: 'whatsapp',
      to,
      type: 'text',
      text: { preview_url: false, body: message },
    }),
  })

  const payload = await response.json().catch(async () => ({ raw: await response.text() }))

  appendLog({ type: 'outgoing_message', to, message, response: payload, success: response.ok, created_at: new Date().toISOString() })

  if (!response.ok) {
    throw new Error('Gagal kirim pesan ke WhatsApp')
  }

  return payload
}

export async function handleWebhook(payload: any) {
  appendLog({ type: 'webhook_received', payload, created_at: new Date().toISOString() })

  for (const entry of payload.entry || []) {
    for (const change of entry.changes || []) {
      const value = change.value || {}

      for (const message of value.messages || []) {
        await handleIncomingMessage(message)
      }

      for (const status of value.statuses || []) {
        appendLog({ type: 'message_status', status, created_at: new Date().toISOString() })
      }
    }
  }
}

async function handleIncomingMessage(message: any) {
  const from = message.from || ''
  appendLog({ type: 'incoming_message', from, message, created_at: new Date().toISOString() })

  if (normalizeNumber(from) !== normalizeNumber(process.env.WA_TEST_NUMBER)) {
    appendLog({ type: 'ignored_message', reason: 'sender_not_test_number', from, created_at: new Date().toISOString() })
    return
  }

  const body = (message.text?.body || '').trim()
  const state = readJsonFile<FlowState>('flow-state.json', {})
  const step = state[from]?.step || 'idle'

  if (body.toLowerCase() === 'daftar' && step === 'idle') {
    state[from] = { step: 'waiting_name' }
    writeJsonFile('flow-state.json', state)
    await sendTextMessage(from, 'Silakan kirim nama Anda.')
    return
  }

  if (step === 'waiting_name' && body) {
    state[from] = { step: 'completed', name: body }
    writeJsonFile('flow-state.json', state)
    await sendTextMessage(from, `Terima kasih ${body}, data testing diterima.`)
    return
  }

  await sendTextMessage(from, 'Kirim "daftar" untuk mulai flow testing.')
}