import type { DB } from './db'
import type { GmailDeps, SendResult } from './gmail'
import { sendReminderEmail } from './gmail'
import { getClient } from './repos-clients'
import { getClientModule } from './repos-modules'
import { getDocument } from './repos-documents'
import { getAmc } from './repos-amc'
import { getReminder, setReminderStatus } from './repos-reminders'
import { reminderEmail, type ReminderContext } from './reminder-templates'
import { documentHtml } from './templates'

/** Turn a queued/failed reminder into an actual email — used by the manual-queue
 *  Send button and by the scheduler's auto path. Reuses gmail.sendReminderEmail. */

export interface SendReminderDeps {
  gmail: GmailDeps
  renderPdf: (html: string) => Promise<Buffer>
  company: () => Record<string, string>
  now?: () => string
}

export async function sendReminder(
  db: DB, deps: SendReminderDeps, reminderId: string, userId: string,
): Promise<SendResult> {
  const reminder = getReminder(db, reminderId)
  if (reminder === null) throw new Error('Reminder not found')
  if (reminder.ruleKind === 'follow_up' || reminder.ruleKind === 'email_bounced') {
    throw new Error(`A ${reminder.ruleKind} reminder is an internal item, not a sendable email`)
  }
  const client = getClient(db, reminder.clientId)
  if (client === null) throw new Error('Client not found')
  const company = deps.company()
  const companyName = company['company.name'] ?? ''

  // Build the per-rule context.
  const ctx: ReminderContext = { clientName: client.name, companyName }
  let attachment: { filename: string; data: Buffer } | undefined
  let documentId: string | undefined
  if (reminder.docId !== null) {
    const doc = getDocument(db, reminder.docId)
    if (doc === null) throw new Error('Reminder document not found')
    documentId = doc.id
    ctx.docNo = doc.docNo ?? undefined
    ctx.amountPaise = doc.payablePaise
    ctx.period = reminder.duePeriod
    const pdf = await deps.renderPdf(documentHtml(doc, client, company))
    attachment = { filename: `${(doc.docNo ?? 'draft').replaceAll('/', '-')}.pdf`, data: pdf }
  } else if (reminder.ruleKind === 'renewal_due') {
    const cm = getClientModule(db, reminder.subjectId)
    if (cm !== null && cm.nextRenewal !== null) ctx.dueDate = cm.nextRenewal
  } else if (reminder.ruleKind === 'amc_expiring') {
    const amc = getAmc(db, reminder.subjectId)
    if (amc !== null) { ctx.coverage = amc.coverage; ctx.dueDate = amc.periodTo }
  }

  const to = client.contacts.find((c) => c.email !== undefined && c.email !== '')?.email
  if (to === undefined) throw new Error('No recipient: add a contact email to the client')

  const mail = reminderEmail(reminder.ruleKind, ctx)
  const out = await sendReminderEmail(db, deps.gmail, {
    to, subject: mail.subject, bodyText: mail.bodyText,
    ...(attachment !== undefined ? { attachment } : {}),
    ...(documentId !== undefined ? { documentId } : {}),
  })
  const now = deps.now?.() ?? new Date().toISOString()
  if (out.ok) setReminderStatus(db, userId, reminderId, 'sent', { sentAt: now, error: null })
  else setReminderStatus(db, userId, reminderId, 'failed', { error: out.error })
  return out
}