import { useEffect, useState } from 'react'
import { useTranslation } from 'react-i18next'
import { MdOutlineWbSunny, MdOutlineNightlightRound } from 'react-icons/md'
import { FaRegSnowflake } from 'react-icons/fa'
import { api, endpoints } from '../api'
// classColors lives under 06_annotations until F3 moves it to its own home.
// Importing through the 06_annotations barrel would create a cycle
// (DetectionClasses -> 06_annotations barrel -> AnnotationsPage -> DetectionClasses).
// STC-ARCH-01 exempts this single path as an F3-pending edge.
import { getClassColor, FALLBACK_CLASS_NAMES } from '../class-colors'
import type { DetectionClass } from '../types'

interface Props {
  selectedClassNum: number
  onSelect: (classNum: number) => void
  photoMode: number
  onPhotoModeChange: (mode: number) => void
}

const FALLBACK_CLASSES: DetectionClass[] = [0, 20, 40].flatMap(modeOffset =>
  FALLBACK_CLASS_NAMES.map((name, i) => ({
    id: i + modeOffset,
    name,
    shortName: name.slice(0, 3),
    color: getClassColor(i),
    maxSizeM: 10,
    photoMode: modeOffset,
  })),
)

export default function DetectionClasses({ selectedClassNum, onSelect, photoMode, onPhotoModeChange }: Props) {
  const { t } = useTranslation()
  const [classes, setClasses] = useState<DetectionClass[]>([])

  useEffect(() => {
    api.get<DetectionClass[]>(endpoints.annotations.classes())
      .then(list => setClasses(list?.length ? list : FALLBACK_CLASSES))
      .catch(() => setClasses(FALLBACK_CLASSES))
  }, [])

  useEffect(() => {
    const handler = (e: KeyboardEvent) => {
      const num = parseInt(e.key)
      if (num >= 1 && num <= 9) {
        const idx = num - 1
        const cls = classes[idx + photoMode]
        if (cls) onSelect(cls.id)
      }
    }
    window.addEventListener('keydown', handler)
    return () => window.removeEventListener('keydown', handler)
  }, [classes, photoMode, onSelect])

  // Auto-select first class of current photoMode when mode changes or classes load
  useEffect(() => {
    const modeClasses = classes.filter(c => c.photoMode === photoMode)
    const currentIsInMode = modeClasses.some(c => c.id === selectedClassNum)
    if (!currentIsInMode && modeClasses.length > 0) {
      onSelect(modeClasses[0].id)
    }
  }, [classes, photoMode, selectedClassNum, onSelect])

  const modes = [
    { value: 0, label: t('annotations.regular'), icon: <MdOutlineWbSunny />, activeClass: 'bg-az-orange text-white', iconColor: 'text-az-orange' },
    { value: 20, label: t('annotations.winter'), icon: <FaRegSnowflake />, activeClass: 'bg-az-blue text-white', iconColor: 'text-az-blue' },
    { value: 40, label: t('annotations.night'), icon: <MdOutlineNightlightRound />, activeClass: 'bg-purple-600 text-white', iconColor: 'text-purple-400' },
  ]

  return (
    <div className="border-t border-az-border p-2">
      <div className="text-xs text-az-muted mb-1 font-semibold">{t('annotations.classes')}</div>
      <div className="space-y-0.5 max-h-48 overflow-y-auto mb-2">
        {classes.filter(c => c.photoMode === photoMode).map((c, i) => (
          <button
            key={c.id}
            onClick={() => onSelect(c.id)}
            className={`w-full flex items-center gap-1.5 px-1.5 py-0.5 rounded text-xs text-left ${
              selectedClassNum === c.id ? 'bg-az-border text-white' : 'text-az-text hover:bg-az-bg'
            }`}
          >
            <span className="w-2.5 h-2.5 rounded-full shrink-0" style={{ backgroundColor: getClassColor(c.id) }} />
            <span className="text-az-muted">{i + 1}.</span>
            <span className="truncate">{c.name}</span>
            <span className="text-az-muted ml-auto">{c.shortName}</span>
          </button>
        ))}
      </div>
      <div className="text-xs text-az-muted mb-1 font-semibold">{t('annotations.photoMode')}</div>
      <div className="flex gap-1">
        {modes.map(m => (
          <button
            key={m.value}
            onClick={() => onPhotoModeChange(m.value)}
            title={m.label}
            className={`flex-1 flex items-center justify-center px-2 py-1 rounded text-base ${photoMode === m.value ? m.activeClass : `bg-az-bg ${m.iconColor} hover:brightness-125`}`}
          >
            {m.icon}
          </button>
        ))}
      </div>
    </div>
  )
}