import { useState, useEffect, useCallback, useId, type ReactNode } from 'react'
import { createPortal } from 'react-dom'
import { X, RefreshCw, Calendar, Power } from 'lucide-react'
import { SubscribeLinks } from './SubscribeLinks'
import { useIsPhone } from '../../mobile/useIsPhone'
import { DialogButton, DialogFooter, DialogHeader, DialogShell, DialogTile, FooterSpacer, NEUTRAL_TINT, fs } from '../shared/DialogShell'

interface IcsSubscribeModalProps {
  /** Token endpoint base, e.g. `/api/trips/123/feed` or `/api/feed/user`. */
  endpoint: string
  title: string
  description: string
  onClose: () => void
}

// A server that has no APP_URL configured hands back a host-relative path; the
// webcal:// handoff and Google deep link need an absolute URL, so resolve it
// against the current origin as a fallback.
function absolutize(url: string): string {
  if (!url) return ''
  if (/^https?:\/\//i.test(url)) return url
  if (url.startsWith('/')) return window.location.origin + url
  return url
}

/**
 * Shared subscribe dialog for the per-trip and all-trips ICS feeds. Opening it
 * only *reads* the current token — it never mints one silently. The user
 * explicitly enables the public link, and can rotate or fully turn it off.
 *
 * The phone keeps its own markup; the desktop draws the same steps in the
 * planner's dialog frame, with the link's controls in the bar at the foot.
 */
export function IcsSubscribeModal({ endpoint, title, description, onClose }: IcsSubscribeModalProps) {
  const tokenUrl = `${endpoint}/token`
  const [feedUrl, setFeedUrl] = useState<string | null>(null)
  const [loading, setLoading] = useState(true)
  const [busy, setBusy] = useState(false)
  const isPhone = useIsPhone()
  const titleId = useId()

  const httpsUrl = feedUrl ? absolutize(feedUrl) : ''
  const webcalUrl = httpsUrl ? httpsUrl.replace(/^https?:\/\//, 'webcal://') : ''

  const load = useCallback(async () => {
    setLoading(true)
    try {
      const res = await fetch(tokenUrl, { credentials: 'include' })
      if (res.ok) {
        const data = await res.json() as { feed_url: string | null }
        setFeedUrl(data.feed_url)
      }
    } catch { /* ignore */ }
    setLoading(false)
  }, [tokenUrl])

  useEffect(() => { load() }, [load])

  const mutate = async (method: 'POST' | 'PUT' | 'DELETE') => {
    setBusy(true)
    try {
      const res = await fetch(tokenUrl, { method, credentials: 'include' })
      if (res.ok) {
        const data = await res.json() as { feed_url: string | null }
        setFeedUrl(data.feed_url)
      }
    } catch { /* ignore */ }
    setBusy(false)
  }

  if (!isPhone) {
    return (
      <DesktopSubscribeDialog
        titleId={titleId}
        title={title}
        description={description}
        onClose={onClose}
        loading={loading}
        busy={busy}
        feedUrl={feedUrl}
        httpsUrl={httpsUrl}
        webcalUrl={webcalUrl}
        mutate={mutate}
      />
    )
  }

  return createPortal(
    <div
      role="presentation"
      style={{
        position: 'fixed', inset: 0, zIndex: 9999,
        background: 'rgba(0,0,0,0.5)',
        display: 'flex', alignItems: 'center', justifyContent: 'center',
        padding: '16px',
      }}
      onClick={e => { if (e.target === e.currentTarget) onClose() }}
    >
      <div style={{
        background: 'var(--bg-card, white)',
        borderRadius: 14,
        padding: '22px 24px',
        width: '100%',
        maxWidth: 420,
        boxShadow: '0 16px 48px rgba(0,0,0,0.22)',
        border: '1px solid var(--border-faint)',
        color: 'var(--text-primary)',
        fontFamily: 'inherit',
        position: 'relative',
      }}>
        {/* Header */}
        <div style={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', marginBottom: 14 }}>
          <div style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
            <Calendar size={16} strokeWidth={2} style={{ color: 'var(--accent, #6366f1)' }} />
            <span style={{ fontWeight: 600, fontSize: 14 }}>{title}</span>
          </div>
          <button type="button"
            onClick={onClose}
            style={{
              background: 'none', border: 'none', cursor: 'pointer', padding: 4,
              color: 'var(--text-muted)', borderRadius: 6, display: 'flex',
            }}
          >
            <X size={15} strokeWidth={2} />
          </button>
        </div>

        <p style={{ fontSize: 12, color: 'var(--text-muted)', marginBottom: 16, lineHeight: 1.5 }}>
          {description}
        </p>

        {loading ? (
          <div style={{ textAlign: 'center', padding: '16px 0', color: 'var(--text-muted)', fontSize: 12 }}>
            Loading…
          </div>
        ) : !feedUrl ? (
          <>
            <button type="button"
              onClick={() => mutate('POST')}
              disabled={busy}
              style={{
                display: 'flex', alignItems: 'center', justifyContent: 'center', gap: 8,
                width: '100%', padding: '9px 14px', borderRadius: 9, border: 'none',
                background: 'var(--accent, #6366f1)', color: 'var(--accent-text, #fff)',
                fontSize: 12, fontWeight: 600, fontFamily: 'inherit',
                cursor: busy ? 'default' : 'pointer', opacity: busy ? 0.6 : 1,
              }}
            >
              <Calendar size={14} strokeWidth={2} />
              Enable calendar subscription
            </button>
            <p style={{ fontSize: 10, color: 'var(--text-muted)', marginTop: 8, lineHeight: 1.4 }}>
              Creates a secret link anyone with it can read without logging in. You can turn it off anytime.
            </p>
          </>
        ) : (
          <>
            <SubscribeLinks httpsUrl={httpsUrl} webcalUrl={webcalUrl} />

            <div style={{ marginTop: 16, paddingTop: 12, borderTop: '1px solid var(--border-faint)', display: 'flex', gap: 8 }}>
              <button type="button"
                onClick={() => mutate('PUT')}
                disabled={busy}
                style={{
                  display: 'flex', alignItems: 'center', gap: 6,
                  background: 'none', border: '1px solid var(--border-primary)',
                  borderRadius: 7, padding: '5px 10px',
                  fontSize: 11, color: 'var(--text-muted)',
                  cursor: busy ? 'default' : 'pointer',
                  fontFamily: 'inherit', opacity: busy ? 0.6 : 1,
                }}
              >
                <RefreshCw size={11} strokeWidth={2} style={{ animation: busy ? 'spin 0.8s linear infinite' : 'none' }} />
                Regenerate
              </button>
              <button type="button"
                onClick={() => mutate('DELETE')}
                disabled={busy}
                style={{
                  display: 'flex', alignItems: 'center', gap: 6,
                  background: 'none', border: '1px solid var(--border-primary)',
                  borderRadius: 7, padding: '5px 10px',
                  fontSize: 11, color: 'var(--danger, #dc2626)',
                  cursor: busy ? 'default' : 'pointer',
                  fontFamily: 'inherit', opacity: busy ? 0.6 : 1,
                }}
              >
                <Power size={11} strokeWidth={2} />
                Turn off
              </button>
            </div>
            <p style={{ fontSize: 10, color: 'var(--text-muted)', marginTop: 6, lineHeight: 1.4 }}>
              Regenerating creates a new link and invalidates the old one. Turning off disables the link entirely.
            </p>
          </>
        )}
      </div>

      <style>{`@keyframes spin { to { transform: rotate(360deg); } }`}</style>
    </div>,
  document.body
  )
}

// A secondary footer button in the danger colour, for the switch that takes the link away.
const TURN_OFF_BTN = 'inline-flex items-center gap-1.5 rounded-[10px] bg-surface-tertiary px-3.5 py-2 font-medium text-danger hover:bg-danger-soft disabled:cursor-default disabled:opacity-50'

function DesktopSubscribeDialog({ titleId, title, description, onClose, loading, busy, feedUrl, httpsUrl, webcalUrl, mutate }: {
  titleId: string
  title: string
  description: string
  onClose: () => void
  loading: boolean
  busy: boolean
  feedUrl: string | null
  httpsUrl: string
  webcalUrl: string
  mutate: (method: 'POST' | 'PUT' | 'DELETE') => Promise<void>
}) {
  const header = (
    <DialogHeader
      tile={<DialogTile><Calendar size={20} strokeWidth={1.9} className="text-content-muted" /></DialogTile>}
      tint={NEUTRAL_TINT}
      labelId={titleId}
      onClose={onClose}
      title={title}
      sub={description}
      subWraps
    />
  )

  const hint = 'm-0 leading-normal text-content-muted'
  let body: ReactNode
  let footer: ReactNode = null
  if (loading) {
    body = <div className="py-4 text-center text-content-muted" style={fs(12.5, 'body')}>Loading…</div>
  } else if (!feedUrl) {
    body = (
      <p className={hint} style={fs(12.5, 'body')}>
        Creates a secret link anyone with it can read without logging in. You can turn it off anytime.
      </p>
    )
    footer = (
      <DialogFooter>
        <FooterSpacer />
        <DialogButton variant="primary" onClick={() => mutate('POST')} disabled={busy} icon={<Calendar size={14} strokeWidth={2} />}>
          Enable calendar subscription
        </DialogButton>
      </DialogFooter>
    )
  } else {
    body = (
      <>
        <SubscribeLinks httpsUrl={httpsUrl} webcalUrl={webcalUrl} />
        <p className={hint} style={fs(11.5)}>
          Regenerating creates a new link and invalidates the old one. Turning off disables the link entirely.
        </p>
      </>
    )
    footer = (
      <DialogFooter>
        <DialogButton onClick={() => mutate('PUT')} disabled={busy} icon={<RefreshCw size={14} strokeWidth={2} className={busy ? 'animate-spin' : ''} />}>
          Regenerate
        </DialogButton>
        <FooterSpacer />
        <button type="button" onClick={() => mutate('DELETE')} disabled={busy} className={TURN_OFF_BTN} style={fs(13, 'body')}>
          <Power size={14} strokeWidth={2} />
          Turn off
        </button>
      </DialogFooter>
    )
  }

  return (
    <DialogShell onClose={onClose} labelledBy={titleId} width="narrow" header={header} footer={footer}>
      {body}
    </DialogShell>
  )
}