import { useState, useRef, useEffect } from 'react';
import { History, Trash2, Check, X, RefreshCw, Loader2 } from 'lucide-react';

import { Button } from '@/components/ui/button';
import { cn } from '@/lib/utils';
import type { AIWritingSessionSummary } from '../../api/ai-writing-sessions';

export const STATUS_LABELS: Record<string, { label: string; color: string }> = {
  in_progress: { label: '进行中', color: 'text-blue-500' },
  // 后台挂起中：后端正自动驱动到定稿（离页/刷新/切号不打断）。
  background:   { label: '挂起中', color: 'text-sky-500' },
  draft_ready:  { label: '草稿', color: 'text-amber-500' },
  review_ready: { label: '审核', color: 'text-purple-500' },
  done:         { label: '完成', color: 'text-green-500' },
  error:        { label: '错误', color: 'text-destructive' },
};

export function formatRelative(isoStr: string): string {
  const ms = Date.now() - new Date(isoStr).getTime();
  const mins = Math.floor(ms / 60000);
  if (mins < 1)  return '刚刚';
  if (mins < 60) return `${mins} 分钟前`;
  const hrs = Math.floor(mins / 60);
  if (hrs  < 24) return `${hrs} 小时前`;
  const days = Math.floor(hrs / 24);
  if (days < 7)  return `${days} 天前`;
  return new Date(isoStr).toLocaleDateString('zh-CN', { month: 'short', day: 'numeric' });
}

export interface SessionItemProps {
  session: AIWritingSessionSummary;
  isSelected: boolean;
  onSelect: () => void;
  /** 「挂起中」记录点击时改为查看进度（流程图弹窗），不直接打开会话。 */
  onShowProgress?: () => void;
  onDelete: () => void;
  onRename: (title: string) => void;
}

export function SessionItem({ session, isSelected, onSelect, onShowProgress, onDelete, onRename }: SessionItemProps) {
  const isBackground = session.status === 'background';
  const handleRowClick = isBackground && onShowProgress ? onShowProgress : onSelect;
  const [editing, setEditing] = useState(false);
  const [editValue, setEditValue] = useState(session.title);
  const inputRef = useRef<HTMLInputElement>(null);
  const { label, color } = STATUS_LABELS[session.status] ?? { label: session.status, color: 'text-muted-foreground' };

  useEffect(() => {
    if (editing) inputRef.current?.focus();
  }, [editing]);

  function commitRename() {
    const trimmed = editValue.trim();
    if (trimmed && trimmed !== session.title) onRename(trimmed);
    setEditing(false);
  }

  function handleKeyDown(e: React.KeyboardEvent) {
    if (e.key === 'Enter') commitRename();
    else if (e.key === 'Escape') { setEditValue(session.title); setEditing(false); }
  }

  return (
    <div
      className={cn(
        'group relative flex items-start gap-2 px-3 py-2.5 cursor-pointer transition-colors',
        isSelected ? 'bg-accent' : 'hover:bg-accent/60',
      )}
      onClick={!editing ? handleRowClick : undefined}
    >
      <div className="flex-1 min-w-0">
        {editing ? (
          <div className="flex items-center gap-1" onClick={(e) => e.stopPropagation()}>
            <input
              ref={inputRef}
              className="flex-1 text-xs bg-background border rounded px-1.5 py-0.5 outline-none focus:ring-1 focus:ring-ring"
              value={editValue}
              onChange={(e) => setEditValue(e.target.value)}
              onKeyDown={handleKeyDown}
            />
            <button className="shrink-0 text-green-500 hover:text-green-600" onClick={commitRename}>
              <Check className="w-3 h-3" />
            </button>
            <button className="shrink-0 text-muted-foreground hover:text-foreground" onClick={() => { setEditValue(session.title); setEditing(false); }}>
              <X className="w-3 h-3" />
            </button>
          </div>
        ) : (
          <p
            className="text-xs font-medium truncate leading-snug"
            onDoubleClick={(e) => { e.stopPropagation(); setEditing(true); }}
            title="双击重命名"
          >
            {session.title}
          </p>
        )}
        <div className="flex items-center gap-1.5 mt-0.5">
          <span className={cn('flex items-center gap-0.5 text-[10px] font-medium', color)}>
            {session.status === 'background' && <Loader2 className="w-2.5 h-2.5 animate-spin" />}
            {label}
          </span>
          <span className="text-[10px] text-muted-foreground">·</span>
          <span className="text-[10px] text-muted-foreground">{formatRelative(session.updated_at)}</span>
        </div>
      </div>

      {/* 删除按钮，hover 时显示 */}
      {!editing && (
        <button
          className="opacity-0 group-hover:opacity-100 shrink-0 p-0.5 text-muted-foreground hover:text-destructive transition-opacity"
          onClick={(e) => { e.stopPropagation(); onDelete(); }}
          title="删除"
        >
          <Trash2 className="w-3 h-3" />
        </button>
      )}
    </div>
  );
}

interface AIWritingHistoryDropdownProps {
  sessions: AIWritingSessionSummary[];
  selectedId: string | null;
  loading: boolean;
  onSelect: (session: AIWritingSessionSummary) => void;
  /** 点击「挂起中」记录时查看进度（流程图弹窗），不直接打开会话。 */
  onShowProgress?: (session: AIWritingSessionSummary) => void;
  onDelete: (id: string) => void;
  onRename: (id: string, title: string) => void;
  onRefresh: () => void;
}

export function AIWritingHistoryDropdown({
  sessions,
  selectedId,
  loading,
  onSelect,
  onShowProgress,
  onDelete,
  onRename,
  onRefresh,
}: AIWritingHistoryDropdownProps) {
  const [open, setOpen] = useState(false);
  const containerRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    if (!open) return;
    function handleClickOutside(e: MouseEvent) {
      if (containerRef.current && !containerRef.current.contains(e.target as Node)) {
        setOpen(false);
      }
    }
    document.addEventListener('mousedown', handleClickOutside);
    return () => document.removeEventListener('mousedown', handleClickOutside);
  }, [open]);

  function handleOpen() {
    setOpen((v) => {
      if (!v) onRefresh();
      return !v;
    });
  }

  return (
    <div ref={containerRef} className="relative">
      <Button
        variant="ghost"
        size="sm"
        className="h-7 px-2 text-xs gap-1"
        onClick={handleOpen}
        title="查看历史记录"
      >
        <History className="size-3" />
        历史
      </Button>

      {open && (
        <div className="absolute right-0 top-full mt-1 z-50 w-64 rounded-lg border bg-popover shadow-lg overflow-hidden">
          {/* 头部 */}
          <div className="flex items-center justify-between px-3 py-2 border-b">
            <span className="text-xs font-semibold">写作历史</span>
            <button
              className={cn('text-muted-foreground hover:text-foreground transition-transform', loading && 'animate-spin')}
              onClick={onRefresh}
              title="刷新"
            >
              <RefreshCw className="w-3 h-3" />
            </button>
          </div>

          {/* 列表 */}
          <div className="max-h-72 overflow-y-auto">
            {sessions.length === 0 ? (
              <div className="text-center py-6 text-xs text-muted-foreground">
                {loading ? '加载中…' : '暂无历史记录'}
              </div>
            ) : (
              sessions.map((s) => (
                <SessionItem
                  key={s.id}
                  session={s}
                  isSelected={s.id === selectedId}
                  onSelect={() => { onSelect(s); setOpen(false); }}
                  onShowProgress={onShowProgress ? () => { onShowProgress(s); setOpen(false); } : undefined}
                  onDelete={() => onDelete(s.id)}
                  onRename={(title) => onRename(s.id, title)}
                />
              ))
            )}
          </div>
        </div>
      )}
    </div>
  );
}