"""
左侧栏组件
包含用户登录和历史对话列表
"""

import streamlit as st
from datetime import datetime

# 使用绝对导入
from frontend.state import AppState
from frontend.api_client import api_client
from frontend.config import config


def render_sidebar():
    """渲染左侧栏"""
    _render_user_section()
    st.divider()
    _render_history_section()


def _render_user_section():
    """渲染用户登录区域"""
    st.header("👤 用户")
    
    if not AppState.is_logged_in():
        _render_login_form()
    else:
        _render_user_info()


def _render_login_form():
    """渲染登录表单"""
    username = st.text_input(
        "输入用户名（可选）",
        key="login_input",
        placeholder="留空使用默认用户",
        help="未登录将使用 default_user，可能导致对话污染"
    )
    
    if st.button("✅ 进入", type="primary", use_container_width=True):
        AppState.login(username)
        _refresh_threads()
        st.rerun()
    
    st.info("💡 建议登录以隔离对话历史")


def _render_user_info():
    """渲染用户信息"""
    st.success(f"✅ 当前用户: `{AppState.get_user_id()}`")
    
    if st.button("🔄 切换用户", use_container_width=True):
        AppState.logout()
        st.rerun()


def _render_history_section():
    """渲染历史对话列表"""
    st.header("📚 对话历史")
    
    # 操作按钮
    _render_history_actions()
    
    st.divider()
    
    # 历史列表
    _render_thread_list()


def _render_history_actions():
    """渲染历史操作按钮"""
    if st.button("🔄 刷新列表", use_container_width=True):
        _refresh_threads()
    
    if st.button("➕ 新对话", type="primary", use_container_width=True):
        AppState.start_new_thread()
        st.rerun()


def _render_thread_list():
    """渲染线程列表"""
    threads = AppState.get_threads()
    
    if not threads:
        st.info("暂无对话历史")
        return
    
    for thread in threads:
        _render_thread_item(thread)


def _render_thread_item(thread: dict):
    """
    渲染单个线程项
    
    Args:
        thread: 线程信息字典
    """
    thread_id = thread["thread_id"]
    summary = thread.get("summary", "空对话")
    message_count = thread.get("message_count", 0)
    last_updated = thread.get("last_updated", "")
    
    # 格式化时间
    time_str = _format_time(last_updated)
    
    # 判断是否为当前线程
    is_current = thread_id == AppState.get_current_thread_id()
    button_type = "primary" if is_current else "secondary"
    
    # 截断摘要
    summary_display = summary[:config.summary_max_length]
    if len(summary) > config.summary_max_length:
        summary_display += "..."
    
    # 渲染按钮
    if st.button(
        f"💬 {summary_display}\n\n🕐 {time_str} | {message_count}条",
        key=f"thread_{thread_id}",
        use_container_width=True,
        type=button_type
    ):
        _load_thread(thread_id)


def _format_time(time_str: str) -> str:
    """
    格式化时间字符串
    
    Args:
        time_str: ISO 格式时间字符串
        
    Returns:
        格式化后的时间字符串
    """
    if not time_str:
        return "未知"
    
    try:
        dt = datetime.fromisoformat(time_str.replace("Z", "+00:00"))
        return dt.strftime("%m-%d %H:%M")
    except Exception:
        return time_str[:10]


def _refresh_threads():
    """刷新历史线程列表"""
    threads = api_client.get_user_threads(AppState.get_user_id())
    AppState.set_threads(threads)


def _load_thread(thread_id: str):
    """
    加载指定线程的消息历史
    
    Args:
        thread_id: 线程 ID
    """
    messages = api_client.get_thread_messages(thread_id, AppState.get_user_id())
    
    if messages:
        AppState.set_current_thread_id(thread_id)
        AppState.clear_messages()
        for msg in messages:
            AppState.add_message(msg["role"], msg["content"])
        st.rerun()
    else:
        st.error("加载对话失败")