import { NextResponse } from 'next/server'
import { createClient } from '@supabase/supabase-js'
import { decrypt } from '@/lib/whatsapp/encryption'
import { getMediaUrl, downloadMedia } from '@/lib/whatsapp/meta-api'
import { normalizePhone, phonesMatch } from '@/lib/whatsapp/phone-utils'

// Lazy-initialized to avoid build-time crash when env vars are missing
// eslint-disable-next-line @typescript-eslint/no-explicit-any
let _adminClient: any = null
function supabaseAdmin() {
  if (!_adminClient) {
    _adminClient = createClient(
      process.env.NEXT_PUBLIC_SUPABASE_URL!,
      process.env.SUPABASE_SERVICE_ROLE_KEY!
    )
  }
  return _adminClient
}

interface WhatsAppMessage {
  id: string
  from: string
  timestamp: string
  type: string
  text?: { body: string }
  image?: { id: string; mime_type: string; caption?: string }
  video?: { id: string; mime_type: string; caption?: string }
  document?: { id: string; mime_type: string; filename?: string; caption?: string }
  audio?: { id: string; mime_type: string }
  location?: { latitude: number; longitude: number; name?: string; address?: string }
  reaction?: { message_id: string; emoji: string }
}

interface WhatsAppWebhookEntry {
  id: string
  changes: Array<{
    value: {
      messaging_product: string
      metadata: {
        display_phone_number: string
        phone_number_id: string
      }
      contacts?: Array<{
        profile: { name: string }
        wa_id: string
      }>
      messages?: WhatsAppMessage[]
      statuses?: Array<{
        id: string
        status: string
        timestamp: string
        recipient_id: string
      }>
    }
    field: string
  }>
}

// GET - Webhook verification
export async function GET(request: Request) {
  try {
    const { searchParams } = new URL(request.url)
    const mode = searchParams.get('hub.mode')
    const challenge = searchParams.get('hub.challenge')
    const verifyToken = searchParams.get('hub.verify_token')

    if (mode !== 'subscribe' || !challenge || !verifyToken) {
      return NextResponse.json(
        { error: 'Missing verification parameters' },
        { status: 400 }
      )
    }

    // Fetch all whatsapp configs to check verify tokens
    const { data: configs, error: configError } = await supabaseAdmin()
      .from('whatsapp_config')
      .select('id, verify_token')

    if (configError || !configs) {
      console.error('Error fetching configs for verification:', configError)
      return NextResponse.json(
        { error: 'Verification failed' },
        { status: 403 }
      )
    }

    // Check if any config's verify_token matches
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const matched = configs.some((config: any) => {
      if (!config.verify_token) return false
      try {
        const decrypted = decrypt(config.verify_token)
        return decrypted === verifyToken
      } catch {
        return false
      }
    })

    if (matched) {
      // Return challenge as plain text
      return new Response(challenge, {
        status: 200,
        headers: { 'Content-Type': 'text/plain' },
      })
    }

    return NextResponse.json(
      { error: 'Verification token mismatch' },
      { status: 403 }
    )
  } catch (error) {
    console.error('Error in webhook GET verification:', error)
    return NextResponse.json(
      { error: 'Internal server error' },
      { status: 500 }
    )
  }
}

// POST - Receive messages
export async function POST(request: Request) {
  // Always return 200 immediately to acknowledge receipt
  const body = await request.json()

  // Process asynchronously
  processWebhook(body).catch((error) => {
    console.error('Error processing webhook:', error)
  })

  return NextResponse.json({ status: 'received' }, { status: 200 })
}

async function processWebhook(body: { entry?: WhatsAppWebhookEntry[] }) {
  if (!body.entry) return

  for (const entry of body.entry) {
    for (const change of entry.changes) {
      const value = change.value

      // Handle status updates
      if (value.statuses) {
        for (const status of value.statuses) {
          await handleStatusUpdate(status)
        }
      }

      // Handle incoming messages
      if (!value.messages || !value.contacts) continue

      const phoneNumberId = value.metadata.phone_number_id

      // Find user's config by phone_number_id
      const { data: config, error: configError } = await supabaseAdmin()
        .from('whatsapp_config')
        .select('*')
        .eq('phone_number_id', phoneNumberId)
        .single()

      if (configError || !config) {
        console.error('No config found for phone_number_id:', phoneNumberId)
        continue
      }

      const decryptedAccessToken = decrypt(config.access_token)

      for (let i = 0; i < value.messages.length; i++) {
        const message = value.messages[i]
        const contact = value.contacts[i] || value.contacts[0]

        await processMessage(
          message,
          contact,
          config.user_id,
          decryptedAccessToken
        )
      }
    }
  }
}

async function handleStatusUpdate(status: {
  id: string
  status: string
  timestamp: string
  recipient_id: string
}) {
  // The messages table schema uses `message_id` (not whatsapp_message_id)
  // and has no `updated_at` column. Meta's status values (sent/delivered/
  // read/failed) already match our CHECK constraint.
  const { error } = await supabaseAdmin()
    .from('messages')
    .update({ status: status.status })
    .eq('message_id', status.id)

  if (error) {
    console.error('Error updating message status:', error)
  }
}

async function processMessage(
  message: WhatsAppMessage,
  contact: { profile: { name: string }; wa_id: string },
  userId: string,
  accessToken: string
) {
  const senderPhone = normalizePhone(message.from)
  const contactName = contact.profile.name

  // Parse message content based on type
  const { contentText, mediaUrl, mediaType } = await parseMessageContent(
    message,
    accessToken
  )

  // Find or create contact
  const contactRecord = await findOrCreateContact(
    userId,
    senderPhone,
    contactName
  )
  if (!contactRecord) return

  // Find or create conversation
  const conversation = await findOrCreateConversation(
    userId,
    contactRecord.id
  )
  if (!conversation) return

  // Insert message — field names MUST match the messages table schema
  // (see supabase/migrations/001_initial_schema.sql):
  //   conversation_id, sender_type, content_type, content_text,
  //   media_url, template_name, message_id, status, created_at
  // `mediaType` is intentionally unused — the schema has no media_type
  // column; the MIME type is only used to construct the proxy URL during
  // parseMessageContent. Silence the unused-var warning:
  void mediaType
  const { error: msgError } = await supabaseAdmin().from('messages').insert({
    conversation_id: conversation.id,
    sender_type: 'customer',
    content_type: message.type,
    content_text: contentText,
    media_url: mediaUrl,
    message_id: message.id,
    status: 'delivered',
    created_at: new Date(parseInt(message.timestamp) * 1000).toISOString(),
  })

  if (msgError) {
    console.error('Error inserting message:', msgError)
    return
  }

  // Update conversation
  const { error: convError } = await supabaseAdmin()
    .from('conversations')
    .update({
      last_message_text: contentText || `[${message.type}]`,
      last_message_at: new Date().toISOString(),
      unread_count: (conversation.unread_count || 0) + 1,
      updated_at: new Date().toISOString(),
    })
    .eq('id', conversation.id)

  if (convError) {
    console.error('Error updating conversation:', convError)
  }
}

async function parseMessageContent(
  message: WhatsAppMessage,
  accessToken: string
): Promise<{
  contentText: string | null
  mediaUrl: string | null
  mediaType: string | null
}> {
  switch (message.type) {
    case 'text':
      return {
        contentText: message.text?.body || null,
        mediaUrl: null,
        mediaType: null,
      }

    case 'image':
      if (message.image) {
        try {
          await getMediaUrl(accessToken, message.image.id)
          return {
            contentText: message.image.caption || null,
            mediaUrl: `/api/whatsapp/media/${message.image.id}`,
            mediaType: message.image.mime_type,
          }
        } catch (error) {
          console.error('Error verifying image media:', error)
        }
      }
      return { contentText: message.image?.caption || null, mediaUrl: null, mediaType: null }

    case 'video':
      if (message.video) {
        try {
          await getMediaUrl(accessToken, message.video.id)
          return {
            contentText: message.video.caption || null,
            mediaUrl: `/api/whatsapp/media/${message.video.id}`,
            mediaType: message.video.mime_type,
          }
        } catch (error) {
          console.error('Error verifying video media:', error)
        }
      }
      return { contentText: message.video?.caption || null, mediaUrl: null, mediaType: null }

    case 'document':
      if (message.document) {
        try {
          await getMediaUrl(accessToken, message.document.id)
          return {
            contentText: message.document.caption || message.document.filename || null,
            mediaUrl: `/api/whatsapp/media/${message.document.id}`,
            mediaType: message.document.mime_type,
          }
        } catch (error) {
          console.error('Error verifying document media:', error)
        }
      }
      return { contentText: message.document?.filename || null, mediaUrl: null, mediaType: null }

    case 'audio':
      if (message.audio) {
        try {
          await getMediaUrl(accessToken, message.audio.id)
          return {
            contentText: null,
            mediaUrl: `/api/whatsapp/media/${message.audio.id}`,
            mediaType: message.audio.mime_type,
          }
        } catch (error) {
          console.error('Error verifying audio media:', error)
        }
      }
      return { contentText: null, mediaUrl: null, mediaType: null }

    case 'location':
      if (message.location) {
        const loc = message.location
        const locationText = [loc.name, loc.address, `${loc.latitude},${loc.longitude}`]
          .filter(Boolean)
          .join(' - ')
        return {
          contentText: locationText,
          mediaUrl: null,
          mediaType: null,
        }
      }
      return { contentText: null, mediaUrl: null, mediaType: null }

    case 'reaction':
      return {
        contentText: message.reaction?.emoji || null,
        mediaUrl: null,
        mediaType: null,
      }

    default:
      return {
        contentText: `[Unsupported message type: ${message.type}]`,
        mediaUrl: null,
        mediaType: null,
      }
  }
}

async function findOrCreateContact(
  userId: string,
  phone: string,
  name: string
) {
  // Look up existing contacts for this user
  const { data: contacts, error: contactsError } = await supabaseAdmin()
    .from('contacts')
    .select('*')
    .eq('user_id', userId)

  if (contactsError) {
    console.error('Error fetching contacts:', contactsError)
    return null
  }

  // Use phonesMatch for flexible matching
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  const existingContact = contacts?.find((c: any) => phonesMatch(c.phone, phone))

  if (existingContact) {
    // Update name if it changed
    if (name && name !== existingContact.name) {
      await supabaseAdmin()
        .from('contacts')
        .update({ name, updated_at: new Date().toISOString() })
        .eq('id', existingContact.id)
    }
    return existingContact
  }

  // Create new contact
  const { data: newContact, error: createError } = await supabaseAdmin()
    .from('contacts')
    .insert({
      user_id: userId,
      phone,
      name: name || phone,
    })
    .select()
    .single()

  if (createError) {
    console.error('Error creating contact:', createError)
    return null
  }

  return newContact
}

async function findOrCreateConversation(userId: string, contactId: string) {
  // Look for existing conversation
  const { data: existing, error: findError } = await supabaseAdmin()
    .from('conversations')
    .select('*')
    .eq('user_id', userId)
    .eq('contact_id', contactId)
    .single()

  if (!findError && existing) {
    return existing
  }

  // Create new conversation
  const { data: newConv, error: createError } = await supabaseAdmin()
    .from('conversations')
    .insert({
      user_id: userId,
      contact_id: contactId,
    })
    .select()
    .single()

  if (createError) {
    console.error('Error creating conversation:', createError)
    return null
  }

  return newConv
}