'use client'

import { useCallback, useEffect, useRef, useState } from 'react'
import { motion } from 'motion/react'
import { Inbox, GraduationCap, Bell, Sparkles, Layers, ChevronLeft, ChevronRight } from 'lucide-react'
import { useLanguage } from '@/lib/i18n'
import { cn } from '@/lib/utils'

export interface DashboardActionStripProps {
  inboxCount: number
  dueFlashcards: number
  reminderCount: number
  discoveryCount: number
  themeCount: number
  inboxPulse?: number
  onInbox: () => void
  onReview: () => void
  onReminders: () => void
  onDiscoveries: () => void
  onThemes: () => void
  prefersReducedMotion?: boolean
}

function updateOverflow(el: HTMLDivElement) {
  const max = el.scrollWidth - el.clientWidth
  if (max <= 4) return { canPrev: false, canNext: false }
  const pos = Math.abs(el.scrollLeft)
  return {
    canPrev: pos > 6,
    canNext: pos < max - 6,
  }
}

export function DashboardActionStrip({
  inboxCount,
  dueFlashcards,
  reminderCount,
  discoveryCount,
  themeCount,
  inboxPulse = 0,
  onInbox,
  onReview,
  onReminders,
  onDiscoveries,
  onThemes,
  prefersReducedMotion,
}: DashboardActionStripProps) {
  const { t, language } = useLanguage()
  const scrollerRef = useRef<HTMLDivElement>(null)
  const [canPrev, setCanPrev] = useState(false)
  const [canNext, setCanNext] = useState(false)
  const isRtl = language === 'fa' || language === 'ar'
  const numberLocale = language === 'fa' ? 'fa-IR' : language === 'zh' ? 'zh-CN' : language

  const refreshOverflow = useCallback(() => {
    const el = scrollerRef.current
    if (!el) return
    const next = updateOverflow(el)
    setCanPrev(next.canPrev)
    setCanNext(next.canNext)
  }, [])

  useEffect(() => {
    const el = scrollerRef.current
    if (!el) return
    refreshOverflow()
    const ro = typeof ResizeObserver !== 'undefined' ? new ResizeObserver(refreshOverflow) : null
    ro?.observe(el)
    el.addEventListener('scroll', refreshOverflow, { passive: true })
    window.addEventListener('resize', refreshOverflow)
    return () => {
      ro?.disconnect()
      el.removeEventListener('scroll', refreshOverflow)
      window.removeEventListener('resize', refreshOverflow)
    }
  }, [refreshOverflow, inboxCount, dueFlashcards, reminderCount, discoveryCount, themeCount])

  const scrollByPage = (direction: 1 | -1) => {
    const el = scrollerRef.current
    if (!el) return
    const delta = Math.max(el.clientWidth * 0.7, 140) * direction
    const left = isRtl ? -delta : delta
    el.scrollBy({ left, behavior: prefersReducedMotion ? 'auto' : 'smooth' })
  }

  const items = [
    {
      key: 'inbox',
      icon: Inbox,
      label: t('homeDashboard.inbox'),
      value: inboxCount,
      onClick: onInbox,
      accent: inboxCount > 0,
      pulse: inboxPulse > 0,
    },
    {
      key: 'review',
      icon: GraduationCap,
      label: t('homeDashboard.review'),
      value: dueFlashcards,
      onClick: onReview,
      accent: dueFlashcards > 0,
    },
    {
      key: 'reminders',
      icon: Bell,
      label: t('homeDashboard.reminders'),
      value: reminderCount,
      onClick: onReminders,
      accent: reminderCount > 0,
    },
    {
      key: 'discoveries',
      icon: Sparkles,
      label: t('homeDashboard.aiFound'),
      value: discoveryCount,
      onClick: onDiscoveries,
      accent: discoveryCount > 0,
    },
    {
      key: 'themes',
      icon: Layers,
      label: t('homeDashboard.themes'),
      value: themeCount,
      onClick: onThemes,
      accent: themeCount > 0,
    },
  ]

  const chevronBtn =
    'absolute top-1/2 z-10 flex h-11 w-11 -translate-y-1/2 items-center justify-center rounded-full border border-border/40 bg-[#F9F8F6]/95 dark:bg-[#0D0D0D]/95 text-foreground shadow-sm hover:bg-brand-accent/10 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-brand-accent'

  return (
    <div className="relative">
      {canPrev && (
        <button
          type="button"
          className={cn(chevronBtn, 'start-0')}
          aria-label={t('homeDashboard.actionStripPrev')}
          onClick={() => scrollByPage(-1)}
        >
          <ChevronLeft size={18} className="rtl:rotate-180" />
        </button>
      )}
      {canNext && (
        <button
          type="button"
          className={cn(chevronBtn, 'end-0')}
          aria-label={t('homeDashboard.actionStripNext')}
          onClick={() => scrollByPage(1)}
        >
          <ChevronRight size={18} className="rtl:rotate-180" />
        </button>
      )}

      <div
        aria-hidden={!canPrev}
        className={cn(
          'pointer-events-none absolute inset-y-0 start-0 z-[1] w-8 bg-gradient-to-r from-[#F9F8F6] to-transparent dark:from-[#0D0D0D] transition-opacity',
          canPrev ? 'opacity-100' : 'opacity-0',
        )}
      />
      <div
        aria-hidden={!canNext}
        className={cn(
          'pointer-events-none absolute inset-y-0 end-0 z-[1] w-8 bg-gradient-to-l from-[#F9F8F6] to-transparent dark:from-[#0D0D0D] transition-opacity',
          canNext ? 'opacity-100' : 'opacity-0',
        )}
      />

      <div
        ref={scrollerRef}
        role="navigation"
        aria-label={t('homeDashboard.actionStripLabel')}
        className={cn(
          'dashboard-action-strip flex gap-2 overflow-x-auto overscroll-x-contain pb-2 -mx-0.5 px-0.5 snap-x snap-mandatory',
          canPrev && 'ps-8',
          canNext && 'pe-8',
        )}
      >
        {items.map(item => {
          const Icon = item.icon
          const Wrapper = item.pulse && !prefersReducedMotion ? motion.button : 'button'
          const motionProps = item.pulse && !prefersReducedMotion
            ? {
                animate: { scale: [1, 1.03, 1] },
                transition: { duration: 0.45 },
              }
            : {}
          return (
            <Wrapper
              key={item.pulse && !prefersReducedMotion ? `inbox-pulse-${inboxPulse}` : item.key}
              type="button"
              onClick={item.onClick}
              onFocus={(e: { currentTarget: HTMLElement }) => {
                e.currentTarget.scrollIntoView({
                  inline: 'nearest',
                  block: 'nearest',
                  behavior: prefersReducedMotion ? 'auto' : 'smooth',
                })
              }}
              {...motionProps}
              className={`snap-start shrink-0 flex min-h-11 min-w-[128px] items-center gap-2.5 px-3.5 py-2.5 rounded-xl border transition-colors text-start ${
                item.accent
                  ? 'border-brand-accent/30 bg-brand-accent/[0.06] hover:border-brand-accent/50 hover:bg-brand-accent/10 shadow-sm'
                  : 'border-border/25 bg-white/60 dark:bg-zinc-900/40 hover:border-border/50'
              }`}
            >
              <div className={`w-7 h-7 rounded-lg flex items-center justify-center shrink-0 ${
                item.accent ? 'bg-brand-accent/15 text-brand-accent' : 'bg-stone-100 dark:bg-zinc-800 text-concrete'
              }`}>
                <Icon size={13} strokeWidth={2} />
              </div>
              <div className="min-w-0">
                <p className={`text-lg font-serif font-bold leading-none tabular-nums ${
                  item.accent ? 'text-ink dark:text-dark-ink' : 'text-concrete/80'
                }`}>
                  {item.value.toLocaleString(numberLocale)}
                </p>
                <p className="text-[13px] font-medium text-concrete truncate mt-0.5">
                  {item.label}
                </p>
              </div>
            </Wrapper>
          )
        })}
      </div>
    </div>
  )
}