'use client'

import { useEffect, useRef, useState } from 'react'
import { useBack } from '@/hooks/useBack'
import ResourceViewer from '@/components/ui/ResourceViewer'
import { useVisitor } from '@/context/VisitorContext'
import { t, tPlain } from '@/lib/i18n'
import type { SectionDTO } from '@/lib/api/types'
import AppBar from '@/components/ui/AppBar'
import { trackEvent } from '@/lib/stats'

interface Props {
  section: SectionDTO
  slug: string
  configId: string
  languages: string[]
}

export default function ArticleSection({ section, configId, languages }: Props) {
  const { language, setAvailableLanguages, instanceId } = useVisitor()
  const back = useBack()
  const article = section.article
  const [isPlaying, setIsPlaying] = useState(false)
  const [currentTime, setCurrentTime] = useState(0)
  const [duration, setDuration] = useState(0)
  const audioRef = useRef<HTMLAudioElement>(null)
  const scrollRef = useRef<HTMLElement>(null)
  const articleReadTrackedRef = useRef(false)

  useEffect(() => { setAvailableLanguages([]) }, [languages])

  useEffect(() => {
    const el = scrollRef.current
    if (!el || !instanceId) return
    const onScroll = () => {
      if (articleReadTrackedRef.current) return
      const total = el.scrollHeight - el.clientHeight
      if (total <= 0) return
      const ratio = el.scrollTop / total
      if (ratio >= 0.8) {
        articleReadTrackedRef.current = true
        trackEvent({
          instanceId, configurationId: configId, sectionId: section.id,
          eventType: 'ArticleRead', language,
        })
      }
    }
    el.addEventListener('scroll', onScroll, { passive: true })
    return () => el.removeEventListener('scroll', onScroll)
  }, [instanceId, configId, section.id, language])

  const audioUrl = article?.audioIds?.find((a) => a.language === language)?.value
    ?? article?.audioIds?.[0]?.value

  useEffect(() => {
    if (article?.isReadAudioAuto && audioRef.current) {
      audioRef.current.play().catch(() => {})
      setIsPlaying(true)
    }
  }, [article?.isReadAudioAuto])

  function toggleAudio() {
    if (!audioRef.current) return
    if (isPlaying) { audioRef.current.pause(); setIsPlaying(false) }
    else { audioRef.current.play(); setIsPlaying(true) }
  }

  const contents = [...(article?.contents ?? [])].sort((a, b) => (a.order ?? 0) - (b.order ?? 0))
  const htmlContent = t(article?.content, language)

  return (
    <div className="min-h-screen flex flex-col" style={{ background: 'var(--color-background)' }}>
      <AppBar title={tPlain(section.title, language)} onBack={back} />

      <main ref={scrollRef} className="flex-1 overflow-y-auto pb-28">
        {/* Carousel images */}
        {contents.length > 0 && (
          <ImageCarousel contents={contents} language={language} />
        )}

        {/* HTML content */}
        {htmlContent && (
          <div
            className="px-4 py-5 prose prose-sm max-w-none"
            style={{ color: 'var(--color-text)' }}
            dangerouslySetInnerHTML={{ __html: htmlContent }}
          />
        )}
      </main>

      {/* Floating audio player */}
      {audioUrl && (
        <>
          <audio
            ref={audioRef}
            src={audioUrl}
            onTimeUpdate={() => setCurrentTime(audioRef.current?.currentTime ?? 0)}
            onLoadedMetadata={() => setDuration(audioRef.current?.duration ?? 0)}
            onEnded={() => setIsPlaying(false)}
          />
          <div
            className="fixed bottom-0 left-0 right-0"
            style={{
              padding: 'max(14px, env(safe-area-inset-bottom)) 16px 16px',
              background: 'linear-gradient(to top, #F6F3EE 78%, transparent)',
              zIndex: 30,
            }}
          >
            <div
              style={{
                borderRadius: 16,
                overflow: 'hidden',
                background: '#fff',
                border: '1px solid #E8E3DA',
                boxShadow: '0 6px 16px -12px rgba(0,0,0,0.3)',
              }}
            >
              <div style={{ display: 'flex', alignItems: 'center', gap: 12, padding: '12px 14px' }}>
                <button
                  onClick={toggleAudio}
                  style={{
                    width: 44, height: 44, borderRadius: '50%', border: 'none', cursor: 'pointer', flexShrink: 0,
                    background: '#1E2A33',
                    display: 'flex', alignItems: 'center', justifyContent: 'center',
                  }}
                >
                  {isPlaying ? (
                    <svg width="18" height="18" viewBox="0 0 24 24" fill="#fff">
                      <path d="M6 19h4V5H6v14zm8-14v14h4V5h-4z" />
                    </svg>
                  ) : (
                    <svg width="18" height="18" viewBox="0 0 24 24" fill="#fff">
                      <path d="M8 5v14l11-7z" />
                    </svg>
                  )}
                </button>
                <div style={{ flex: 1, minWidth: 0 }}>
                  <span style={{ color: '#6B7B86', fontSize: 11, fontWeight: 700, letterSpacing: '0.5px' }}>
                    GUIDE AUDIO
                  </span>
                  <div style={{ marginTop: 5 }}>
                    <ArticleWaveform currentTime={currentTime} duration={duration} />
                  </div>
                </div>
                <span style={{ color: '#6B7B86', fontSize: 12.5, fontWeight: 600, flexShrink: 0 }}>
                  {duration > 0 ? formatTime(duration) : '--:--'}
                </span>
              </div>
              {duration > 0 && (
                <div style={{ height: 3, background: '#F0EBE3' }}>
                  <div
                    style={{
                      height: '100%',
                      width: `${(currentTime / duration) * 100}%`,
                      background: 'var(--color-primary)',
                      transition: 'width 0.3s linear',
                    }}
                  />
                </div>
              )}
            </div>
          </div>
        </>
      )}
    </div>
  )
}

function ImageCarousel({ contents, language }: { contents: NonNullable<SectionDTO['article']>['contents'] & object; language: string }) {
  const [index, setIndex] = useState(0)
  if (!contents || contents.length === 0) return null

  return (
    <div className="relative w-full" style={{ height: 240 }}>
      {contents[index]?.resource && (
        <ResourceViewer
          resource={contents[index].resource!}
          alt={tPlain(contents[index].title, language)}
          objectFit="cover"
        />
      )}
      {contents.length > 1 && (
        <>
          <button
            onClick={() => setIndex((i) => Math.max(0, i - 1))}
            disabled={index === 0}
            className="absolute left-2 top-1/2 -translate-y-1/2 bg-black/40 text-white rounded-full p-1 disabled:opacity-20"
          >
            <svg width="20" height="20" viewBox="0 0 24 24" fill="currentColor"><path d="M15.41 7.41L14 6l-6 6 6 6 1.41-1.41L10.83 12z"/></svg>
          </button>
          <button
            onClick={() => setIndex((i) => Math.min(contents.length - 1, i + 1))}
            disabled={index === contents.length - 1}
            className="absolute right-2 top-1/2 -translate-y-1/2 bg-black/40 text-white rounded-full p-1 disabled:opacity-20"
          >
            <svg width="20" height="20" viewBox="0 0 24 24" fill="currentColor"><path d="M10 6L8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg>
          </button>
          <div className="absolute bottom-2 left-0 right-0 flex justify-center gap-1">
            {contents.map((_, i) => (
              <div key={i} className="w-1.5 h-1.5 rounded-full" style={{ background: i === index ? 'white' : 'rgba(255,255,255,0.4)' }} />
            ))}
          </div>
        </>
      )}
    </div>
  )
}

function ArticleWaveform({ currentTime, duration }: { currentTime: number; duration: number }) {
  const bars = [4, 8, 13, 10, 16, 11, 7, 14, 9, 5, 12, 8, 10, 15, 7, 11, 13, 6, 14, 9, 5, 12, 10, 7, 13]
  const progress = duration > 0 ? currentTime / duration : 0
  const total = bars.length * 5
  return (
    <svg width={total} height={18} viewBox={`0 0 ${total} 18`}>
      {bars.map((h, i) => (
        <rect
          key={i}
          x={i * 5}
          y={(18 - h) / 2}
          width={3}
          height={h}
          rx={1.5}
          style={{ fill: i / bars.length <= progress ? 'var(--color-primary)' : 'rgba(100,110,120,0.2)' }}
        />
      ))}
    </svg>
  )
}

function formatTime(s: number): string {
  if (!s || isNaN(s)) return '0:00'
  const m = Math.floor(s / 60)
  const sec = Math.floor(s % 60)
  return `${m}:${sec.toString().padStart(2, '0')}`
}