import { useQuery } from '@tanstack/react-query'
import { useEffect, useRef, useState } from 'react'
import { listDirectories } from '../api/client'
import { useFocusTrap } from '../lib/useFocusTrap'

interface DirectoryPickerDialogProps {
  open: boolean
  initialPath: string
  onSelect: (path: string) => void
  onClose: () => void
}

/**
 * 页面内的目录浏览器：从盘符开始逐级进入文件夹，最终把绝对路径回填到表单。
 * 浏览器拿不到系统文件对话框的真实路径，因此目录浏览由后端提供列表接口。
 */
export function DirectoryPickerDialog({
  open,
  initialPath,
  onSelect,
  onClose,
}: DirectoryPickerDialogProps) {
  const [currentPath, setCurrentPath] = useState<string | null>(null)
  const [draftPath, setDraftPath] = useState('')
  const dialogRef = useRef<HTMLElement>(null)
  useFocusTrap(open, dialogRef, '[data-picker-path]')

  useEffect(() => {
    if (!open) {
      return
    }
    const start = initialPath.trim()
    setCurrentPath(start || null)
    setDraftPath(start)
  }, [initialPath, open])

  const listing = useQuery({
    queryKey: ['directories', currentPath],
    queryFn: ({ signal }) => listDirectories(currentPath ?? undefined, signal),
    enabled: open,
    retry: false,
  })

  useEffect(() => {
    if (listing.data?.path) {
      setDraftPath(listing.data.path)
    }
  }, [listing.data?.path])

  useEffect(() => {
    if (!open) {
      return
    }
    const onKeyDown = (event: KeyboardEvent) => {
      if (event.key === 'Escape') {
        onClose()
      }
    }
    window.addEventListener('keydown', onKeyDown)
    return () => window.removeEventListener('keydown', onKeyDown)
  }, [onClose, open])

  if (!open) {
    return null
  }

  const entries = listing.data?.entries ?? []
  const currentDirectory = listing.data?.path ?? null
  const parent = listing.data?.parent ?? null

  const navigate = (path: string | null) => {
    setCurrentPath(path)
    setDraftPath(path ?? '')
  }

  return (
    <div
      className="modal-overlay"
      onMouseDown={(event) => {
        if (event.currentTarget === event.target) {
          onClose()
        }
      }}
    >
      <section
        ref={dialogRef}
        className="modal-card directory-picker"
        role="dialog"
        aria-modal="true"
        aria-labelledby="directory-picker-title"
        tabIndex={-1}
      >
        <header className="modal-header">
          <div>
            <p className="eyebrow">WORKING DIRECTORY</p>
            <h2 id="directory-picker-title">选择项目工作目录</h2>
          </div>
          <button
            type="button"
            className="icon-button"
            onClick={onClose}
            aria-label="关闭目录选择"
          >
            ×
          </button>
        </header>

        <div className="directory-picker-toolbar">
          <button
            type="button"
            className="button button-secondary button-small"
            onClick={() => navigate(parent)}
            disabled={!parent}
          >
            上一级
          </button>
          <button
            type="button"
            className="button button-secondary button-small"
            onClick={() => navigate(null)}
          >
            盘符
          </button>
          <form
            className="directory-path-form"
            onSubmit={(event) => {
              event.preventDefault()
              navigate(draftPath.trim() || null)
            }}
          >
            <input
              className="field-input mono"
              value={draftPath}
              onChange={(event) => setDraftPath(event.target.value)}
              placeholder="输入或粘贴绝对路径，例如 D:\Projects\sync"
              aria-label="目录路径"
              data-picker-path
              spellCheck={false}
            />
          </form>
        </div>

        <div className="directory-picker-body">
          {listing.isPending ? (
            <p className="muted-copy">正在读取目录…</p>
          ) : null}
          {listing.isError ? (
            <div className="inline-alert inline-alert-error" role="alert">
              {listing.error.message}
            </div>
          ) : null}
          {!listing.isPending && !listing.isError && entries.length === 0 ? (
            <p className="empty-inline">
              {currentDirectory ? '该目录下没有子文件夹' : '没有可用的盘符'}
            </p>
          ) : null}
          {entries.length > 0 ? (
            <ul className="directory-list">
              {entries.map((entry) => (
                <li key={entry.path}>
                  <button
                    type="button"
                    className="directory-row"
                    onClick={() => navigate(entry.path)}
                    title={entry.path}
                  >
                    <span className="directory-icon" aria-hidden="true">
                      📁
                    </span>
                    <span className="directory-name">{entry.name}</span>
                  </button>
                </li>
              ))}
            </ul>
          ) : null}
          {listing.data?.truncated ? (
            <p className="field-hint">文件夹过多，仅列出前 500 个。</p>
          ) : null}
        </div>

        <footer className="directory-picker-footer">
          <div className="directory-picker-summary">
            <span className="section-label">将使用</span>
            <code>{currentDirectory ?? '尚未选择目录'}</code>
          </div>
          <div className="modal-actions directory-picker-actions">
            <button type="button" className="button button-secondary" onClick={onClose}>
              取消
            </button>
            <button
              type="button"
              className="button button-primary"
              disabled={!currentDirectory}
              onClick={() => {
                if (currentDirectory) {
                  onSelect(currentDirectory)
                  onClose()
                }
              }}
            >
              使用此目录
            </button>
          </div>
        </footer>
      </section>
    </div>
  )
}