/**
 * NextcloudFolderPicker — modal that lets the user navigate their
 * Nextcloud `files/` tree and register a subfolder as a SourceRoot in
 * mule-image. Lazy-loads each level via GET /nextcloud/browse?path=...,
 * so opening the picker doesn't slurp the whole tree.
 *
 * Path scoping is enforced server-side; we still avoid showing a `..`
 * affordance above the user's root so the UI never surfaces the idea
 * that there's something to escape to.
 */
import { useCallback, useEffect, useState } from 'react'
import { ChevronRight, Folder, FolderOpen, Loader2, X } from 'lucide-react'

import { nextcloud, type NextcloudBrowseEntry } from '../../services/api'
import { toast } from '../ToastContainer'

interface Props {
  open: boolean
  onClose: () => void
  onCreated: () => void  // called after a successful POST so the parent refetches
}

export function NextcloudFolderPicker({ open, onClose, onCreated }: Props) {
  const [path, setPath] = useState('')
  const [entries, setEntries] = useState<NextcloudBrowseEntry[]>([])
  const [parentRel, setParentRel] = useState<string | null>(null)
  const [ncUser, setNcUser] = useState('')
  const [loading, setLoading] = useState(false)
  const [error, setError] = useState<string | null>(null)
  const [submitting, setSubmitting] = useState(false)
  const [name, setName] = useState('')

  const loadPath = useCallback(async (target: string) => {
    setLoading(true)
    setError(null)
    try {
      const r = await nextcloud.browse(target)
      setEntries(r.entries)
      setParentRel(r.parent_rel)
      setNcUser(r.nc_username)
      setPath(r.rel_path)
      // Default the SourceRoot name from the leaf folder name.
      const leaf = r.rel_path.split('/').filter(Boolean).slice(-1)[0]
      if (leaf) setName(leaf)
      else setName(`${r.nc_username} library`)
    } catch (e) {
      const message = e instanceof Error ? e.message : String(e)
      setError(message)
    } finally {
      setLoading(false)
    }
  }, [])

  useEffect(() => {
    if (open) {
      void loadPath('')
    }
  }, [open, loadPath])

  const submit = useCallback(async () => {
    if (!path) {
      toast.error('Pick a subfolder first — the root is too broad.')
      return
    }
    if (!name.trim()) {
      toast.error('Library name is required')
      return
    }
    setSubmitting(true)
    try {
      await nextcloud.createSourceRoot(name.trim(), path)
      toast.success(`Added "${name.trim()}" to your libraries`)
      onCreated()
      onClose()
    } catch (e) {
      const message = e instanceof Error ? e.message : String(e)
      toast.error(`Could not add library: ${message}`)
    } finally {
      setSubmitting(false)
    }
  }, [path, name, onCreated, onClose])

  if (!open) return null

  // Breadcrumb segments for the current path. "/" rendered as the user's
  // root → click jumps back to that level.
  const segments = path ? path.split('/').filter(Boolean) : []

  return (
    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50">
      <div className="flex h-[36rem] w-[40rem] flex-col rounded-lg border border-border bg-surface shadow-xl">
        <div className="flex items-center justify-between border-b border-border px-4 py-2">
          <div className="flex items-center gap-2 text-sm font-medium">
            <FolderOpen className="h-4 w-4" />
            Add library from Nextcloud
          </div>
          <button
            onClick={onClose}
            className="rounded p-1 text-text-muted hover:bg-surface-2"
            aria-label="Close"
          >
            <X className="h-4 w-4" />
          </button>
        </div>

        {/* Breadcrumb */}
        <div className="flex items-center gap-1 border-b border-border bg-surface-2 px-4 py-2 text-xs text-text-muted">
          <button
            onClick={() => loadPath('')}
            className="font-mono text-text hover:underline"
            disabled={loading}
          >
            {ncUser || 'home'}
          </button>
          {segments.map((seg, i) => {
            const target = segments.slice(0, i + 1).join('/')
            return (
              <span key={target} className="flex items-center gap-1">
                <ChevronRight className="h-3 w-3" />
                <button
                  onClick={() => loadPath(target)}
                  className="font-mono text-text hover:underline"
                  disabled={loading}
                >
                  {seg}
                </button>
              </span>
            )
          })}
        </div>

        {/* List */}
        <div className="flex-1 overflow-y-auto px-2 py-2">
          {loading && (
            <div className="flex h-full items-center justify-center text-xs text-text-muted">
              <Loader2 className="mr-2 h-4 w-4 animate-spin" />
              Loading…
            </div>
          )}
          {error && !loading && (
            <div className="rounded border border-red-500/40 bg-red-500/10 p-3 text-xs text-red-300">
              {error}
            </div>
          )}
          {!loading && !error && entries.length === 0 && (
            <div className="px-3 py-6 text-center text-xs text-text-muted">
              No subfolders here. Use Nextcloud to create a folder, then come
              back to register it.
            </div>
          )}
          {!loading && !error && entries.length > 0 && (
            <ul className="space-y-0.5">
              {/* "Up one level" — only shown when not already at root */}
              {parentRel !== null && (
                <li>
                  <button
                    onClick={() => loadPath(parentRel)}
                    className="flex w-full items-center gap-2 rounded px-2 py-1 text-left text-sm hover:bg-surface-2"
                  >
                    <ChevronRight className="h-4 w-4 rotate-180 text-text-muted" />
                    <span className="text-text-muted">..</span>
                  </button>
                </li>
              )}
              {entries.map((e) => (
                <li key={e.path}>
                  <button
                    onClick={() => loadPath(e.path)}
                    disabled={!e.has_children && false}
                    className="flex w-full items-center gap-2 rounded px-2 py-1 text-left text-sm hover:bg-surface-2"
                  >
                    <Folder className="h-4 w-4 text-primary/70" />
                    <span className="truncate">{e.name}</span>
                    {e.has_children && (
                      <ChevronRight className="ml-auto h-3 w-3 text-text-muted" />
                    )}
                  </button>
                </li>
              ))}
            </ul>
          )}
        </div>

        {/* Footer */}
        <div className="border-t border-border bg-surface-2 px-4 py-3">
          <div className="mb-2 text-[11px] uppercase tracking-wide text-text-muted">
            Selected
          </div>
          <div className="mb-2 truncate font-mono text-xs" title={path || '(root)'}>
            {path ? `${ncUser}/files/${path}` : '(pick a subfolder)'}
          </div>
          <div className="flex items-center gap-2">
            <input
              type="text"
              value={name}
              onChange={(e) => setName(e.target.value)}
              placeholder="Library name"
              className="flex-1 rounded border border-border bg-surface px-2 py-1 text-sm"
            />
            <button
              onClick={() => void submit()}
              disabled={!path || !name.trim() || submitting}
              className="rounded bg-primary px-3 py-1 text-sm font-medium text-primary-foreground hover:bg-primary/90 disabled:opacity-50"
            >
              {submitting ? 'Adding…' : 'Add this folder'}
            </button>
          </div>
        </div>
      </div>
    </div>
  )
}