import { useState, useEffect, useMemo } from 'react'
import { useAuthStore } from '../../store/authStore'
import { useTranslation } from '../../i18n'
import { MessageCircle, StickyNote, Link2, BarChart3, Sparkles } from 'lucide-react'
import CollabChat from './CollabChat'
import CollabNotes from './CollabNotes'
import CollabPolls from './CollabPolls'
import WhatsNextWidget from './WhatsNextWidget'
import CollabLinks from './CollabLinks'
import CollabPanelHead from './CollabPanelHead'

function useIsDesktop(breakpoint = 1024) {
  const [isDesktop, setIsDesktop] = useState(window.innerWidth >= breakpoint)
  useEffect(() => {
    const check = () => setIsDesktop(window.innerWidth >= breakpoint)
    window.addEventListener('resize', check)
    return () => window.removeEventListener('resize', check)
  }, [breakpoint])
  return isDesktop
}

const cardClass = 'flex flex-col bg-surface-secondary rounded-2xl border border-edge-faint overflow-hidden min-h-0'

interface TripMember {
  id: number
  username: string
  avatar_url?: string | null
}

interface CollabFeatures {
  chat: boolean
  notes: boolean
  links?: boolean
  polls: boolean
  whatsnext: boolean
}

interface CollabPanelProps {
  tripId: number
  tripMembers?: TripMember[]
  collabFeatures?: CollabFeatures
}

const ALL_TABS = [
  { id: 'chat', featureKey: 'chat' as const, labelKey: 'collab.tabs.chat', fallback: 'Chat', icon: MessageCircle },
  { id: 'notes', featureKey: 'notes' as const, labelKey: 'collab.tabs.notes', fallback: 'Notes', icon: StickyNote },
  { id: 'links', featureKey: 'links' as const, labelKey: 'collab.tabs.links', fallback: 'Links', icon: Link2 },
  { id: 'polls', featureKey: 'polls' as const, labelKey: 'collab.tabs.polls', fallback: 'Polls', icon: BarChart3 },
  { id: 'next', featureKey: 'whatsnext' as const, labelKey: 'collab.whatsNext.title', fallback: "What's Next", icon: Sparkles },
]

export default function CollabPanel({ tripId, tripMembers = [], collabFeatures }: CollabPanelProps) {
  const { user } = useAuthStore()
  const { t } = useTranslation()
  const isDesktop = useIsDesktop()

  // Older server/admin configs predate the Links feature; merge defaults so a
  // missing `links` key does not silently hide the new panel.
  const features = { chat: true, notes: true, links: true, polls: true, whatsnext: true, ...(collabFeatures || {}) }

  const tabs = useMemo(() =>
    ALL_TABS.filter(tab => features[tab.featureKey]).map(tab => ({
      ...tab,
      label: t(tab.labelKey) || tab.fallback,
    })),
  [features, t])

  const [mobileTab, setMobileTab] = useState(() => tabs[0]?.id || 'chat')

  // If active tab gets disabled, switch to first available
  useEffect(() => {
    if (tabs.length > 0 && !tabs.some(t => t.id === mobileTab)) {
      setMobileTab(tabs[0].id)
    }
  }, [tabs, mobileTab])

  const chatOn = features.chat
  const rightPanels = [
    features.notes && 'notes', features.links && 'links',
    features.polls && 'polls',
    features.whatsnext && 'whatsnext',
  ].filter(Boolean) as string[]

  // One place decides what a panel id renders. It was spelled out at five call
  // sites, and the layout branch below dropped a panel precisely because one of
  // those copies did not list it.
  const renderPanel = (p: string) => (
    <>
      {p === 'notes' && <CollabNotes tripId={tripId} currentUser={user} />}
      {p === 'links' && <CollabLinks tripId={tripId} />}
      {p === 'polls' && <CollabPolls tripId={tripId} currentUser={user} />}
      {p === 'whatsnext' && <WhatsNextWidget tripMembers={tripMembers} />}
    </>
  )
  // The chat carries the same head band as the panels beside it.
  const chatPanel = (
    <>
      <CollabPanelHead icon={MessageCircle} title={t('collab.tabs.chat') || 'Chat'} />
      <div className="flex min-h-0 flex-1 flex-col">
        <CollabChat tripId={tripId} currentUser={user} />
      </div>
    </>
  )
  const panelRow = (ids: string[]) => (
    <div style={{ flex: 1, display: 'flex', gap: 16, minHeight: 0 }}>
      {ids.map(p => <div key={p} className={cardClass} style={{ flex: 1, minWidth: 0 }}>{renderPanel(p)}</div>)}
    </div>
  )

  if (tabs.length === 0) return null

  if (isDesktop) {
    // Chat always 380px fixed when on. Right panels share remaining space.
    // If chat off, all panels share full width equally.
    if (chatOn && rightPanels.length === 0) {
      // Only chat
      return (
        <div className="flex h-full min-h-0 gap-4 overflow-hidden px-7 py-6">
          <div className={cardClass} style={{ flex: 1 }}>
            {chatPanel}
          </div>
        </div>
      )
    }

    if (chatOn) {
      // Chat left (380px) + right panels
      return (
        <div className="flex h-full min-h-0 gap-4 overflow-hidden px-7 py-6">
          <div className={cardClass} style={{ flex: '0 0 380px' }}>
            {chatPanel}
          </div>
          <div style={{ flex: 1, display: 'flex', flexDirection: 'column', gap: 16, overflow: 'hidden', minHeight: 0 }}>
            {rightPanels.length <= 2 && panelRow(rightPanels)}
            {rightPanels.length >= 3 && (() => {
              // Two rows, split by kind rather than by a pair being present:
              // the old condition needed notes AND links together, so turning
              // the new Links feature off dropped Notes out of the layout
              // entirely. Each row renders only when it has something in it.
              const written = rightPanels.filter(p => p === 'notes' || p === 'links')
              const rest = rightPanels.filter(p => p !== 'notes' && p !== 'links')
              return <>
                {written.length > 0 && panelRow(written)}
                {rest.length > 0 && panelRow(rest)}
              </>
            })()}
          </div>
        </div>
      )
    }

    // Chat off — remaining panels share full width
    const panels = rightPanels
    return (
      <div className="flex h-full min-h-0 gap-4 overflow-hidden px-7 py-6">
        {panels.map(p => (
          <div key={p} className={cardClass} style={{ flex: 1 }}>{renderPanel(p)}</div>
        ))}
      </div>
    )
  }

  // Mobile: tab bar + single panel (only enabled tabs)
  return (
    <div style={{ height: '100%', display: 'flex', flexDirection: 'column', overflow: 'hidden', position: 'absolute', inset: 0 }}>
      <div style={{
        display: 'flex', gap: 2, padding: '8px 12px', borderBottom: '1px solid var(--border-faint)',
        background: 'var(--bg-card)', flexShrink: 0,
      }}>
        {tabs.map(tab => {
          const active = mobileTab === tab.id
          return (
            <button key={tab.id} onClick={() => setMobileTab(tab.id)} style={{
              flex: 1, display: 'flex', alignItems: 'center', justifyContent: 'center', gap: 6,
              padding: '8px 0', borderRadius: 10, border: 'none', cursor: 'pointer',
              background: active ? 'var(--accent)' : 'transparent',
              color: active ? 'var(--accent-text)' : 'var(--text-muted)',
              fontSize: 'calc(11px * var(--fs-scale-caption, 1))', fontWeight: 600, fontFamily: 'inherit',
              transition: 'all 0.15s',
            }}>
              {tab.label}
            </button>
          )
        })}
      </div>

      <div style={{ flex: 1, overflow: 'hidden', minHeight: 0 }}>
        {mobileTab === 'chat' && features.chat && <CollabChat tripId={tripId} currentUser={user} />}
        {mobileTab === 'notes' && features.notes && <CollabNotes tripId={tripId} currentUser={user} />}
        {mobileTab === 'links' && features.links && <CollabLinks tripId={tripId} />}
        {mobileTab === 'polls' && features.polls && <CollabPolls tripId={tripId} currentUser={user} />}
        {mobileTab === 'next' && features.whatsnext && <WhatsNextWidget tripMembers={tripMembers} />}
      </div>
    </div>
  )
}