/**
 * Push Notifications Extension
 *
 * Converts system events into instant push notifications.
 * Also provides cron-based scheduling for time-dependent checks
 * (tax deadlines, invoice due/overdue).
 *
 * Event handlers follow the gate pattern:
 *   check extension setting -> build payload -> send via unified pipeline
 */

import type { Extension, ExtensionContext } from '@/lib/extensions/types'
import type { EventPayload } from '@/lib/events/types'
import { pushNotificationsApiRoutes } from './api-routes'
import { sendNotificationToUser } from './notification-sender'
import {
  createPeriodLockedPayload,
  createYearClosedPayload,
  createInvoiceSentPayload,
  createReceiptExtractedPayload,
  createReceiptMatchedPayload,
} from './payload-builders'
import { invoiceNumberDisplay } from '@/lib/invoices/display'

// ============================================================
// Settings
// ============================================================

export interface PushNotificationSettings {
  periodLockedEnabled: boolean
  periodYearClosedEnabled: boolean
  invoiceSentEnabled: boolean
  receiptExtractedEnabled: boolean
  receiptMatchedEnabled: boolean
  missingUnderlagEnabled: boolean
}

const DEFAULT_SETTINGS: PushNotificationSettings = {
  periodLockedEnabled: true,
  periodYearClosedEnabled: true,
  invoiceSentEnabled: false,
  receiptExtractedEnabled: true,
  receiptMatchedEnabled: true,
  missingUnderlagEnabled: true,
}

/** Get settings via ExtensionContext (preferred in event handlers) */
async function getSettingsViaCtx(ctx: ExtensionContext): Promise<PushNotificationSettings> {
  const stored = await ctx.settings.get<Partial<PushNotificationSettings>>()
  return { ...DEFAULT_SETTINGS, ...(stored || {}) }
}

/**
 * Get settings for external callers (settings routes, event handlers).
 *
 * Returns null when the settings row exists but CANNOT BE READ: consent
 * polarity requires every caller to treat that as "do not notify" (and the
 * settings routes to surface an error) instead of falling back to the
 * defaults, which are mostly enabled. A genuinely absent row (maybeSingle
 * with no error) means the user never touched the toggles: defaults apply.
 */
export async function getSettings(userId: string): Promise<PushNotificationSettings | null> {
  const { createClient } = await import('@/lib/supabase/server')
  const supabase = await createClient()

  const { data, error } = await supabase
    .from('notification_settings')
    .select(
      'period_locked_enabled, period_year_closed_enabled, invoice_sent_enabled, receipt_extracted_enabled, receipt_matched_enabled, missing_underlag_enabled'
    )
    .eq('user_id', userId)
    .maybeSingle()

  if (error) return null
  if (!data) return { ...DEFAULT_SETTINGS }
  return {
    periodLockedEnabled: data.period_locked_enabled ?? DEFAULT_SETTINGS.periodLockedEnabled,
    periodYearClosedEnabled: data.period_year_closed_enabled ?? DEFAULT_SETTINGS.periodYearClosedEnabled,
    invoiceSentEnabled: data.invoice_sent_enabled ?? DEFAULT_SETTINGS.invoiceSentEnabled,
    receiptExtractedEnabled: data.receipt_extracted_enabled ?? DEFAULT_SETTINGS.receiptExtractedEnabled,
    receiptMatchedEnabled: data.receipt_matched_enabled ?? DEFAULT_SETTINGS.receiptMatchedEnabled,
    missingUnderlagEnabled: data.missing_underlag_enabled ?? DEFAULT_SETTINGS.missingUnderlagEnabled,
  }
}

export async function saveSettings(
  userId: string,
  partial: Partial<PushNotificationSettings>
): Promise<PushNotificationSettings | null> {
  const current = await getSettings(userId)
  // Unreadable current settings: merging the partial into defaults would
  // silently overwrite the user's stored opt-outs. Refuse the save.
  if (!current) return null
  const merged = { ...current, ...partial }

  const { createClient } = await import('@/lib/supabase/server')
  const supabase = await createClient()

  await supabase
    .from('notification_settings')
    .upsert(
      {
        user_id: userId,
        period_locked_enabled: merged.periodLockedEnabled,
        period_year_closed_enabled: merged.periodYearClosedEnabled,
        invoice_sent_enabled: merged.invoiceSentEnabled,
        receipt_extracted_enabled: merged.receiptExtractedEnabled,
        receipt_matched_enabled: merged.receiptMatchedEnabled,
        missing_underlag_enabled: merged.missingUnderlagEnabled,
      },
      { onConflict: 'user_id' }
    )

  return merged
}

// ============================================================
// Event Handlers
// ============================================================

async function handlePeriodLocked(
  payload: EventPayload<'period.locked'>,
  ctx?: ExtensionContext
): Promise<void> {
  const { period, userId } = payload

  // getSettings() returns null when the row is unreadable: do not notify.
  const settings = ctx ? await getSettingsViaCtx(ctx) : await getSettings(userId)
  if (!settings?.periodLockedEnabled) return

  const supabase = ctx?.supabase ?? await (await import('@/lib/supabase/server')).createClient()
  const notificationPayload = createPeriodLockedPayload(period.name, period.id)

  const result = await sendNotificationToUser(
    supabase,
    userId,
    notificationPayload,
    'period_locked',
    period.id
  )

  if (result.sent) {
    (ctx?.log ?? console).info(`Period locked notification sent for ${period.name}`)
  }
}

async function handleYearClosed(
  payload: EventPayload<'period.year_closed'>,
  ctx?: ExtensionContext
): Promise<void> {
  const { period, userId } = payload

  const settings = ctx ? await getSettingsViaCtx(ctx) : await getSettings(userId)
  if (!settings?.periodYearClosedEnabled) return

  const supabase = ctx?.supabase ?? await (await import('@/lib/supabase/server')).createClient()
  const notificationPayload = createYearClosedPayload(period.name, period.id)

  const result = await sendNotificationToUser(
    supabase,
    userId,
    notificationPayload,
    'period_year_closed',
    period.id
  )

  if (result.sent) {
    (ctx?.log ?? console).info(`Year closed notification sent for ${period.name}`)
  }
}

async function handleInvoiceSent(
  payload: EventPayload<'invoice.sent'>,
  ctx?: ExtensionContext
): Promise<void> {
  const { invoice, userId } = payload

  const settings = ctx ? await getSettingsViaCtx(ctx) : await getSettings(userId)
  if (!settings?.invoiceSentEnabled) return

  const supabase = ctx?.supabase ?? await (await import('@/lib/supabase/server')).createClient()
  const notificationPayload = createInvoiceSentPayload(
    invoiceNumberDisplay(invoice.invoice_number),
    invoice.id
  )

  const result = await sendNotificationToUser(
    supabase,
    userId,
    notificationPayload,
    'invoice_sent',
    invoice.id
  )

  if (result.sent) {
    (ctx?.log ?? console).info(`Invoice sent notification for #${invoice.invoice_number}`)
  }
}

async function handleReceiptExtracted(
  payload: EventPayload<'receipt.extracted'>,
  ctx?: ExtensionContext
): Promise<void> {
  const { receipt, userId } = payload

  const settings = ctx ? await getSettingsViaCtx(ctx) : await getSettings(userId)
  if (!settings?.receiptExtractedEnabled) return

  const supabase = ctx?.supabase ?? await (await import('@/lib/supabase/server')).createClient()
  const notificationPayload = createReceiptExtractedPayload(
    receipt.merchant_name,
    receipt.id
  )

  const result = await sendNotificationToUser(
    supabase,
    userId,
    notificationPayload,
    'receipt_extracted',
    receipt.id
  )

  if (result.sent) {
    (ctx?.log ?? console).info(`Receipt extracted notification for ${receipt.id}`)
  }
}

async function handleReceiptMatched(
  payload: EventPayload<'receipt.matched'>,
  ctx?: ExtensionContext
): Promise<void> {
  const { receipt, transaction, userId } = payload

  const settings = ctx ? await getSettingsViaCtx(ctx) : await getSettings(userId)
  if (!settings?.receiptMatchedEnabled) return

  const supabase = ctx?.supabase ?? await (await import('@/lib/supabase/server')).createClient()
  const notificationPayload = createReceiptMatchedPayload(receipt.id, transaction.id)

  const result = await sendNotificationToUser(
    supabase,
    userId,
    notificationPayload,
    'receipt_matched',
    receipt.id
  )

  if (result.sent) {
    (ctx?.log ?? console).info(`Receipt matched notification for ${receipt.id}`)
  }
}

// ============================================================
// Extension Object
// ============================================================

export const pushNotificationsExtension: Extension = {
  id: 'push-notifications',
  name: 'Push-notiser',
  version: '1.0.0',
  sector: 'general',
  apiRoutes: pushNotificationsApiRoutes,
  eventHandlers: [
    { eventType: 'period.locked', handler: handlePeriodLocked },
    { eventType: 'period.year_closed', handler: handleYearClosed },
    { eventType: 'invoice.sent', handler: handleInvoiceSent },
    { eventType: 'receipt.extracted', handler: handleReceiptExtracted },
    { eventType: 'receipt.matched', handler: handleReceiptMatched },
  ],
  settingsPanel: {
    label: 'Push-notiser',
    path: '/settings/extensions/push-notifications',
  },
  async onInstall(ctx) {
    await ctx.settings.set('settings', DEFAULT_SETTINGS)
  },
}