import { forwardRef, useState, useEffect, useRef, useCallback, useImperativeHandle } from 'react'
import { filesystemApi } from '../../api/filesystem'
import { useTranslation } from '../../i18n'

type DirEntry = {
  name: string
  path: string
  isDirectory: boolean
}

export type FileSearchMenuHandle = {
  handleKeyDown: (e: KeyboardEvent) => void
}

type Props = {
  cwd: string
  filter?: string
  onSelect: (path: string, relativePath: string) => void
}

export const FileSearchMenu = forwardRef<FileSearchMenuHandle, Props>(({ cwd, filter = '', onSelect }, ref) => {
  const t = useTranslation()
  const [entries, setEntries] = useState<DirEntry[]>([])
  const [currentPath, setCurrentPath] = useState(cwd)
  const [loading, setLoading] = useState(false)
  const [selectedIndex, setSelectedIndex] = useState(0)
  const listRef = useRef<HTMLDivElement>(null)
  const currentPathRef = useRef(cwd)

  // Parse filter: if it contains '/', navigate to that subdir and search the rest
  // Uses currentPathRef as base so nested paths navigate from current depth
  const parseFilter = (rawFilter: string): { navigateTo: string; searchQuery: string } => {
    const base = currentPathRef.current
    if (!rawFilter || !rawFilter.includes('/')) {
      return { navigateTo: base, searchQuery: rawFilter }
    }
    const lastSlash = rawFilter.lastIndexOf('/')
    const dirPart = rawFilter.slice(0, lastSlash + 1)
    const searchPart = rawFilter.slice(lastSlash + 1)
    const navigateTo = dirPart === '' ? base : `${base}/${dirPart}`
    return { navigateTo, searchQuery: searchPart }
  }

  // Load directory entries
  const loadDir = useCallback(async (dirPath: string, searchQuery: string) => {
    setLoading(true)
    // Only update currentPath if actually navigating to a different directory
    if (dirPath !== currentPathRef.current) {
      setCurrentPath(dirPath)
      currentPathRef.current = dirPath
    }
    try {
      if (searchQuery) {
        const result = await filesystemApi.search(searchQuery, dirPath)
        setEntries(result.entries)
      } else {
        const result = await filesystemApi.browse(dirPath, { includeFiles: true })
        setEntries(result.entries)
      }
      setSelectedIndex(0)
    } catch {
      setEntries([])
    }
    setLoading(false)
  }, [])

  // Initial load: parse filter path and navigate accordingly
  useEffect(() => {
    currentPathRef.current = cwd
    const { navigateTo, searchQuery } = parseFilter(filter)
    void loadDir(navigateTo, searchQuery)
  }, [cwd, filter, loadDir])

  // Keyboard navigation handler exposed via ref
  const handleKeyDown = useCallback((e: KeyboardEvent) => {
    if (e.key === 'ArrowDown') {
      e.preventDefault()
      setSelectedIndex((prev) => Math.min(prev + 1, entries.length - 1))
      return
    }
    if (e.key === 'ArrowUp') {
      e.preventDefault()
      setSelectedIndex((prev) => Math.max(prev - 1, 0))
      return
    }
    if (e.key === 'Enter' || e.key === 'Tab') {
      e.preventDefault()
      if (entries[selectedIndex]) {
        onSelect(entries[selectedIndex]!.path, entries[selectedIndex]!.name)
      }
      return
    }
  // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [entries, selectedIndex])

  useImperativeHandle(ref, () => ({ handleKeyDown }), [handleKeyDown])

  // Scroll selected into view
  useEffect(() => {
    const el = listRef.current?.querySelector(`[data-index="${selectedIndex}"]`) as HTMLButtonElement | null
    el?.scrollIntoView({ block: 'nearest' })
  }, [selectedIndex])

  // Build breadcrumb segments from current path relative to cwd
  const breadcrumbs: string[] = []
  if (currentPath !== cwd && currentPath.startsWith(cwd)) {
    const rel = currentPath.slice(cwd.length).replace(/^\//, '')
    if (rel) breadcrumbs.push(...rel.split('/'))
  }

  const dirs = entries.filter((e) => e.isDirectory)
  const files = entries.filter((e) => !e.isDirectory)

  return (
    <div
      id="file-search-menu"
      className="absolute left-0 bottom-full mb-2 z-50 w-full min-w-[480px] overflow-hidden rounded-xl border border-[var(--color-border)] bg-[var(--color-surface-container-lowest)] shadow-[var(--shadow-dropdown)]"
      onMouseDown={(e) => e.stopPropagation()}
    >
      {/* Header with path */}
      <div className="flex items-center gap-1.5 border-b border-[var(--color-border)] px-3 py-2 text-[11px]">
        <span className="material-symbols-outlined text-[14px] text-[var(--color-text-tertiary)]">folder_open</span>
        <span className="text-[var(--color-text-tertiary)] font-mono">{cwd.split('/').pop() || cwd}</span>
        {breadcrumbs.map((seg, i) => (
          <span key={i} className="flex items-center gap-1">
            <span className="text-[var(--color-text-tertiary)]">/</span>
            <span className="text-[var(--color-text-primary)] font-mono">{seg}</span>
          </span>
        ))}
        {loading && (
          <span className="material-symbols-outlined text-[12px] text-[var(--color-text-tertiary)] animate-spin ml-1">progress_activity</span>
        )}
      </div>

      {/* File list */}
      <div ref={listRef} className="max-h-[300px] overflow-y-auto py-1">
        {loading && entries.length === 0 ? (
          <div className="px-4 py-6 text-center text-xs text-[var(--color-text-tertiary)]">{t('fileSearch.searching')}</div>
        ) : entries.length === 0 ? (
          <div className="px-4 py-6 text-center text-xs text-[var(--color-text-tertiary)]">
            {filter ? t('fileSearch.noMatch') : t('fileSearch.noFiles')}
          </div>
        ) : (
          <>
            {/* Directories */}
            {dirs.map((entry, i) => (
              <button
                key={entry.path}
                data-index={i}
                onClick={() => {
                  void loadDir(entry.path, filter)
                }}
                onMouseEnter={() => setSelectedIndex(i)}
                className={`w-full flex items-center gap-3 px-3 py-2 text-left transition-colors ${
                  selectedIndex === i ? 'bg-[var(--color-surface-hover)]' : 'hover:bg-[var(--color-surface-hover)]'
                }`}
              >
                <span className="material-symbols-outlined text-[16px] text-[var(--color-brand)]">folder</span>
                <span className="text-sm text-[var(--color-text-primary)] truncate">{entry.name}</span>
              </button>
            ))}

            {/* Files */}
            {files.map((entry, i) => {
              const idx = dirs.length + i
              return (
                <button
                  key={entry.path}
                  data-index={idx}
                  onClick={() => onSelect(entry.path, entry.name)}
                  onMouseEnter={() => setSelectedIndex(idx)}
                  className={`w-full flex items-center gap-3 px-3 py-2 text-left transition-colors ${
                    selectedIndex === idx ? 'bg-[var(--color-surface-hover)]' : 'hover:bg-[var(--color-surface-hover)]'
                  }`}
                >
                  <span className="material-symbols-outlined text-[16px] text-[var(--color-text-secondary)]">description</span>
                  <span className="text-sm text-[var(--color-text-primary)] truncate">{entry.name}</span>
                </button>
              )
            })}
          </>
        )}
      </div>

      {/* Footer hint */}
      <div className="flex items-center gap-1.5 border-t border-[var(--color-border)] px-3 py-1.5 text-[10px] text-[var(--color-text-tertiary)]">
        <kbd className="rounded border border-[var(--color-border)] bg-[var(--color-surface-container-low)] px-1 py-0.5 font-mono">↑↓</kbd>
        <span>{t('fileSearch.navigate')}</span>
        <kbd className="ml-2 rounded border border-[var(--color-border)] bg-[var(--color-surface-container-low)] px-1 py-0.5 font-mono">Enter</kbd>
        <span>{t('fileSearch.attach')}</span>
        <kbd className="ml-2 rounded border border-[var(--color-border)] bg-[var(--color-surface-container-low)] px-1 py-0.5 font-mono">Esc</kbd>
        <span>{t('fileSearch.close')}</span>
      </div>
    </div>
  )
})

FileSearchMenu.displayName = 'FileSearchMenu'