import { useEffect, useState } from 'react'
import { useTranslation } from 'react-i18next'
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 modeClasses = classes.filter(c => c.photoMode === photoMode)

  const modes = [
    { value: 0,  label: t('annotations.regular') },
    { value: 20, label: t('annotations.winter') },
    { value: 40, label: t('annotations.night') },
  ]

  return (
    <div className="border-t border-border-hair">
      {/* Section header */}
      <div className="flex items-center justify-between px-3 h-9 border-b border-border-hair">
        <div className="flex items-center gap-2">
          <span className="sect-head">{t('annotations.classes')}</span>
          <span className="mono text-[10px] text-text-muted">{modeClasses.length.toString().padStart(2, '0')}</span>
        </div>
      </div>

      {/* Column headers */}
      <div className="grid grid-cols-[28px_1fr_auto] px-3 h-6 items-center border-b border-border-hair gap-2">
        <span className="micro">{t('annotations.colNum')}</span>
        <span className="micro">{t('annotations.colName')}</span>
        <span className="micro">{t('annotations.colKey')}</span>
      </div>

      {/* Class rows */}
      <div>
        {modeClasses.map((c, i) => {
          const isActive = selectedClassNum === c.id
          return (
            <div
              key={c.id}
              role="button"
              tabIndex={0}
              onClick={() => onSelect(c.id)}
              onKeyDown={e => { if (e.key === 'Enter' || e.key === ' ') onSelect(c.id) }}
              className={`class-row${isActive ? ' active' : ''}`}
            >
              <span className="swatch" style={{ background: getClassColor(c.id) }} />
              <span className={`truncate${isActive ? ' text-text-primary font-medium' : ' text-text-primary'}`}>
                {c.name}
              </span>
              <span className="kbd">{i + 1}</span>
            </div>
          )
        })}
      </div>

      {/* PhotoMode segmented control */}
      <div className="p-3 border-t border-border-hair">
        <div className="flex items-center justify-between mb-2">
          <span className="micro">{t('annotations.photoMode')}</span>
        </div>
        <div className="seg" style={{ display: 'grid', gridTemplateColumns: 'repeat(3, 1fr)', width: '100%' }}>
          {modes.map(m => (
            <button
              key={m.value}
              type="button"
              className={`seg-btn${photoMode === m.value ? ' active' : ''}`}
              onClick={() => onPhotoModeChange(m.value)}
            >
              {m.label}
            </button>
          ))}
        </div>
      </div>
    </div>
  )
}