// ============================================================
// SessionSidebar — 会话历史侧边栏
// 职责：展示会话列表、新建/切换/删除/重命名会话
// ============================================================

import { useState } from "react";
import { useI18n } from "../../lib/i18n";
import type { SessionSummary } from "../../types";

interface SessionSidebarProps {
  sessions: SessionSummary[];
  activeSessionId: string | null;
  collapsed: boolean;
  onToggleCollapse: () => void;
  onNewSession: () => void;
  onSelectSession: (id: string) => void;
  onDeleteSession: (id: string) => void;
  onRenameSession: (id: string, title: string) => void;
}

/** 格式化相对时间 */
function formatRelativeTime(ts: number): string {
  const now = Date.now();
  const diff = now - ts;
  const min = 60 * 1000;
  const hour = 60 * min;
  const day = 24 * hour;

  if (diff < min) return "刚刚";
  if (diff < hour) return `${Math.floor(diff / min)}分钟前`;
  if (diff < day) return `${Math.floor(diff / hour)}小时前`;
  if (diff < 2 * day) return "昨天";
  if (diff < 7 * day) return `${Math.floor(diff / day)}天前`;
  const d = new Date(ts);
  return `${d.getMonth() + 1}/${d.getDate()}`;
}

export function SessionSidebar({
  sessions,
  activeSessionId,
  collapsed,
  onToggleCollapse,
  onNewSession,
  onSelectSession,
  onDeleteSession,
  onRenameSession,
}: SessionSidebarProps) {
  const { t } = useI18n();
  const [editingId, setEditingId] = useState<string | null>(null);
  const [editTitle, setEditTitle] = useState("");

  const handleStartRename = (id: string, currentTitle: string) => {
    setEditingId(id);
    setEditTitle(currentTitle);
  };

  const handleConfirmRename = () => {
    if (editingId && editTitle.trim()) {
      onRenameSession(editingId, editTitle.trim());
    }
    setEditingId(null);
    setEditTitle("");
  };

  const handleCancelRename = () => {
    setEditingId(null);
    setEditTitle("");
  };

  if (collapsed) {
    return (
      <div className="sidebar sidebar--collapsed">
        <button className="sidebar__toggle" onClick={onToggleCollapse} title={t("sidebar.expand")}>
          ☰
        </button>
        <button className="sidebar__new-btn" onClick={onNewSession} title={t("sidebar.new")}>
          ✚
        </button>
      </div>
    );
  }

  return (
    <div className="sidebar">
      <div className="sidebar__header">
        <button className="sidebar__new-btn sidebar__new-btn--full" onClick={onNewSession}>
          ✚ {t("sidebar.new")}
        </button>
        <button className="sidebar__toggle" onClick={onToggleCollapse} title={t("sidebar.collapse")}>
          ◀
        </button>
      </div>

      <div className="sidebar__list">
        {sessions.length === 0 ? (
          <div className="sidebar__empty">{t("sidebar.empty")}</div>
        ) : (
          sessions.map((session) => (
            <div
              key={session.id}
              className={`sidebar__item ${session.id === activeSessionId ? "sidebar__item--active" : ""}`}
              onClick={() => onSelectSession(session.id)}
            >
              {editingId === session.id ? (
                <div className="sidebar__edit" onClick={(e) => e.stopPropagation()}>
                  <input
                    className="sidebar__edit-input"
                    value={editTitle}
                    onChange={(e) => setEditTitle(e.target.value)}
                    onKeyDown={(e) => {
                      if (e.key === "Enter") handleConfirmRename();
                      if (e.key === "Escape") handleCancelRename();
                    }}
                    autoFocus
                  />
                  <button className="sidebar__edit-btn" onClick={handleConfirmRename}>✓</button>
                  <button className="sidebar__edit-btn" onClick={handleCancelRename}>✕</button>
                </div>
              ) : (
                <>
                  <div className="sidebar__item-content">
                    <div className="sidebar__item-title">{session.title}</div>
                    <div className="sidebar__item-meta">
                      {session.messageCount > 0 && (
                        <span>{session.messageCount}{t("sidebar.messages")}</span>
                      )}
                      <span>{formatRelativeTime(session.lastActiveAt)}</span>
                    </div>
                  </div>
                  <div className="sidebar__item-actions">
                    <button
                      className="sidebar__action-btn"
                      onClick={(e) => {
                        e.stopPropagation();
                        handleStartRename(session.id, session.title);
                      }}
                      title={t("sidebar.rename")}
                    >
                      ✏
                    </button>
                    <button
                      className="sidebar__action-btn sidebar__action-btn--danger"
                      onClick={(e) => {
                        e.stopPropagation();
                        onDeleteSession(session.id);
                      }}
                      title={t("sidebar.delete")}
                    >
                      🗑
                    </button>
                  </div>
                </>
              )}
            </div>
          ))
        )}
      </div>
    </div>
  );
}