import { useEffect, useState } from 'react'
import { Modal } from './Modal'
import { DnsProviderSwitch } from './DnsProviderSwitch'
import { ApiError } from '../lib/api'
import { applyMailDns } from '../services/domainService'
import type { DomainListItem, ParkedDnsProvider } from '../types/domain'
import { useToast } from '../context/ToastContext'
import tableStyles from '../pages/BusinessesPage.module.css'
import parkedStyles from './ParkedDomainsModal.module.css'
import styles from './EmailDnsModal.module.css'

interface EmailDnsModalProps {
  domain: DomainListItem | null
  onClose: () => void
}

const DEFAULT_ED25519_SELECTOR = 'v1-ed25519-20260901'
const DEFAULT_RSA_SELECTOR = 'v1-rsa-20260901'

function pasteIncludesDomainkey(paste: string) {
  return /[a-z0-9][a-z0-9-]*\._domainkey/i.test(paste)
}

/** Prefer typed selector; otherwise default when the paste has no …._domainkey. */
function resolveSelector(paste: string, selector: string, fallback: string) {
  const typed = selector.trim()
  if (typed) return typed
  if (pasteIncludesDomainkey(paste)) return ''
  return fallback
}

export function EmailDnsModal({ domain, onClose }: EmailDnsModalProps) {
  const { showToast } = useToast()
  const [dnsProvider, setDnsProvider] = useState<ParkedDnsProvider>('arvan')
  const [ed25519Selector, setEd25519Selector] = useState(DEFAULT_ED25519_SELECTOR)
  const [ed25519Key, setEd25519Key] = useState('')
  const [rsaSelector, setRsaSelector] = useState(DEFAULT_RSA_SELECTOR)
  const [rsaKey, setRsaKey] = useState('')
  const [submitting, setSubmitting] = useState(false)
  const [error, setError] = useState('')

  useEffect(() => {
    if (!domain) return
    setDnsProvider('arvan')
    setEd25519Selector(DEFAULT_ED25519_SELECTOR)
    setEd25519Key('')
    setRsaSelector(DEFAULT_RSA_SELECTOR)
    setRsaKey('')
    setError('')
    setSubmitting(false)
  }, [domain])

  if (!domain) return null
  const target = domain
  const canSubmit = Boolean(rsaKey.trim())

  async function submit() {
    if (!rsaKey.trim()) {
      const message = 'Paste the RSA DKIM TXT value from Stalwart.'
      setError(message)
      showToast(message, 'error')
      return
    }

    const ed25519Paste = ed25519Key.trim()
    const rsaPaste = rsaKey.trim()
    const resolvedRsaSelector = resolveSelector(
      rsaPaste,
      rsaSelector,
      DEFAULT_RSA_SELECTOR,
    )
    const resolvedEd25519Selector = ed25519Paste
      ? resolveSelector(
          ed25519Paste,
          ed25519Selector,
          DEFAULT_ED25519_SELECTOR,
        )
      : ''

    // Show resolved defaults in the fields if they were cleared.
    if (!rsaSelector.trim() && resolvedRsaSelector) {
      setRsaSelector(resolvedRsaSelector)
    }
    if (ed25519Paste && !ed25519Selector.trim() && resolvedEd25519Selector) {
      setEd25519Selector(resolvedEd25519Selector)
    }

    setSubmitting(true)
    setError('')
    try {
      const result = await applyMailDns(target.id, {
        dnsProvider,
        rsaKey: rsaPaste,
        ...(resolvedRsaSelector ? { rsaSelector: resolvedRsaSelector } : {}),
        ...(ed25519Paste ? { ed25519Key: ed25519Paste } : {}),
        ...(ed25519Paste && resolvedEd25519Selector
          ? { ed25519Selector: resolvedEd25519Selector }
          : {}),
      })
      showToast(result.message, 'success')
      onClose()
    } catch (err) {
      const message =
        err instanceof ApiError ? err.message : 'Unable to update mail DNS.'
      setError(message)
      showToast(message, 'error')
    } finally {
      setSubmitting(false)
    }
  }

  return (
    <Modal
      open
      wide
      title={`Email DNS · ${domain.host}`}
      onClose={() => {
        if (!submitting) onClose()
      }}
    >
      <p className={parkedStyles.hint}>
        Paste the RSA DKIM <strong>TXT value</strong> (<code>v=DKIM1; …</code>) from
        Stalwart, or the full zone line. Ed25519 is optional — leave it empty to
        skip. Selectors default to <code>{DEFAULT_RSA_SELECTOR}</code> /{' '}
        <code>{DEFAULT_ED25519_SELECTOR}</code> when empty. We upsert common mail
        records on {dnsProvider === 'cloudflare' ? 'Cloudflare' : 'Arvan'}{' '}
        (DNS-only / not proxied): <strong>mail</strong> A → 185.214.101.41, MX →
        mail.meshkee.com (priority 10), SPF <code>v=spf1 mx -all</code>, DKIM
        (RSA required, Ed25519 if provided), autoconfig / autodiscover →
        mail.meshkee.com. Extra MX, <strong>dkim._domainkey</strong>, and{' '}
        <strong>_dmarc</strong> are removed.
      </p>
      {error ? (
        <p className={tableStyles.alertError} role="alert">
          {error}
        </p>
      ) : null}
      {submitting ? (
        <p className={tableStyles.helperText} role="status">
          Updating {dnsProvider === 'cloudflare' ? 'Cloudflare' : 'Arvan'} mail DNS…
        </p>
      ) : null}

      <div className={styles.providerRow}>
        <span className={styles.providerLabel}>DNS host</span>
        <DnsProviderSwitch
          value={dnsProvider}
          onChange={setDnsProvider}
          disabled={submitting}
        />
      </div>

      <div className={tableStyles.field}>
        <label htmlFor="mail-dkim-ed25519-selector">
          Ed25519 selector <span className={tableStyles.helperText}>(optional)</span>
        </label>
        <input
          id="mail-dkim-ed25519-selector"
          className={styles.selectorInput}
          type="text"
          value={ed25519Selector}
          onChange={(e) => setEd25519Selector(e.target.value)}
          placeholder={DEFAULT_ED25519_SELECTOR}
          disabled={submitting}
          spellCheck={false}
          dir="ltr"
          autoComplete="off"
        />
        <p className={tableStyles.helperText}>
          Auto-filled when empty. Change it if Stalwart uses a different selector.
        </p>
      </div>
      <div className={tableStyles.field}>
        <label htmlFor="mail-dkim-ed25519">
          Ed25519 domain key{' '}
          <span className={tableStyles.helperText}>(optional)</span>
        </label>
        <textarea
          id="mail-dkim-ed25519"
          className={styles.textarea}
          value={ed25519Key}
          onChange={(e) => setEd25519Key(e.target.value)}
          placeholder="Leave empty to skip — or paste v=DKIM1; k=ed25519; …"
          disabled={submitting}
          spellCheck={false}
          dir="ltr"
          rows={4}
        />
      </div>
      <div style={{ height: 12 }} />
      <div className={tableStyles.field}>
        <label htmlFor="mail-dkim-rsa-selector">RSA selector</label>
        <input
          id="mail-dkim-rsa-selector"
          className={styles.selectorInput}
          type="text"
          value={rsaSelector}
          onChange={(e) => setRsaSelector(e.target.value)}
          placeholder={DEFAULT_RSA_SELECTOR}
          disabled={submitting}
          spellCheck={false}
          dir="ltr"
          autoComplete="off"
        />
        <p className={tableStyles.helperText}>
          Auto-filled when empty. Change it if Stalwart uses a different selector.
        </p>
      </div>
      <div className={tableStyles.field}>
        <label htmlFor="mail-dkim-rsa">RSA domain key</label>
        <textarea
          id="mail-dkim-rsa"
          className={styles.textarea}
          value={rsaKey}
          onChange={(e) => setRsaKey(e.target.value)}
          placeholder='v=DKIM1; k=rsa; h=sha256; p=…'
          disabled={submitting}
          spellCheck={false}
          dir="ltr"
          rows={6}
        />
      </div>

      <div style={{ height: 12 }} />
      <div className={tableStyles.actionsRow}>
        <button
          type="button"
          className={`${tableStyles.btn} ${tableStyles.btnGhost}`}
          onClick={onClose}
          disabled={submitting}
        >
          Cancel
        </button>
        <button
          type="button"
          className={`${tableStyles.btn} ${tableStyles.btnPrimary}`}
          onClick={() => void submit()}
          disabled={submitting || !canSubmit}
        >
          Update DNS
        </button>
      </div>
    </Modal>
  )
}