import { useState, useEffect } from "react";
import { Plus, Trash2, ChevronLeft, ChevronRight } from "lucide-react";

/**
 * ChatSidebar Component
 * 
 * Features:
 * - Display chat history from local storage
 * - Create new chat
 * - Delete chat history
 * - Switch between chats
 * - Collapsible sidebar
 * - Glassmorphism UI matching theme
 */

export interface ChatSession {
  id: string;
  title: string;
  timestamp: number;
  mode: "ask" | "imagine";
  messageCount: number;
}

interface ChatSidebarProps {
  currentChatId: string | null;
  onNewChat: () => void;
  onSelectChat: (chatId: string) => void;
  onDeleteChat: (chatId: string) => void;
  isOpen: boolean;
  onToggle: () => void;
}

export default function ChatSidebar({
  currentChatId,
  onNewChat,
  onSelectChat,
  onDeleteChat,
  isOpen,
  onToggle,
}: ChatSidebarProps) {
  const [chats, setChats] = useState<ChatSession[]>([]);

  // Load chats from local storage
  useEffect(() => {
    const savedChats = localStorage.getItem("domify_chats");
    if (savedChats) {
      try {
        const parsed = JSON.parse(savedChats);
        setChats(parsed.sort((a: ChatSession, b: ChatSession) => b.timestamp - a.timestamp));
      } catch (error) {
        console.error("Error loading chats:", error);
      }
    }
  }, []);

  // Handle delete chat
  const handleDelete = (chatId: string, e: React.MouseEvent) => {
    e.stopPropagation();
    
    // Remove from local storage
    const savedChats = localStorage.getItem("domify_chats");
    if (savedChats) {
      const parsed = JSON.parse(savedChats);
      const filtered = parsed.filter((c: ChatSession) => c.id !== chatId);
      localStorage.setItem("domify_chats", JSON.stringify(filtered));
      setChats(filtered);
    }

    // Also remove the chat messages
    localStorage.removeItem(`domify_chat_${chatId}`);
    
    onDeleteChat(chatId);
  };

  // Format date
  const formatDate = (timestamp: number) => {
    const date = new Date(timestamp);
    const today = new Date();
    const yesterday = new Date(today);
    yesterday.setDate(yesterday.getDate() - 1);

    if (date.toDateString() === today.toDateString()) {
      return date.toLocaleTimeString("en-US", { hour: "2-digit", minute: "2-digit" });
    } else if (date.toDateString() === yesterday.toDateString()) {
      return "Yesterday";
    } else {
      return date.toLocaleDateString("en-US", { month: "short", day: "numeric" });
    }
  };

  return (
    <>
      {/* Sidebar */}
      <div
        className={`fixed left-0 top-0 h-screen glass-panel-lg rounded-none border-r border-white/10 transition-all duration-300 z-40 flex flex-col ${
          isOpen ? "w-64" : "w-0"
        } overflow-hidden`}
      >
        {/* Header */}
        <div className="p-4 border-b border-white/10 flex items-center justify-between">
          <h2 className="text-lg font-semibold gradient-text">Chats</h2>
          <button
            onClick={onToggle}
            className="p-2 hover:bg-white/5 rounded-lg transition-smooth"
            title="Close sidebar"
          >
            <ChevronLeft size={20} />
          </button>
        </div>

        {/* New Chat Button */}
        <div className="p-4 border-b border-white/10">
          <button
            onClick={onNewChat}
            className="w-full flex items-center justify-center gap-2 px-4 py-2 rounded-lg bg-primary/20 text-primary border border-primary/30 hover:bg-primary/30 transition-smooth"
          >
            <Plus size={18} />
            <span>New Chat</span>
          </button>
        </div>

        {/* Chat List */}
        <div className="flex-1 overflow-y-auto scrollbar-thin p-2 space-y-2">
          {chats.length === 0 ? (
            <div className="text-center py-8 text-muted-foreground text-sm">
              <p>No chats yet</p>
              <p className="text-xs mt-2">Start a new conversation</p>
            </div>
          ) : (
            chats.map((chat) => (
              <button
                key={chat.id}
                onClick={() => onSelectChat(chat.id)}
                className={`w-full text-left p-3 rounded-lg transition-smooth group ${
                  currentChatId === chat.id
                    ? "bg-primary/20 border border-primary/30"
                    : "hover:bg-white/5 border border-transparent"
                }`}
              >
                <div className="flex items-start justify-between gap-2">
                  <div className="flex-1 min-w-0">
                    <p className="text-sm font-medium truncate text-foreground">
                      {chat.title}
                    </p>
                    <div className="flex items-center gap-2 mt-1">
                      <span className="text-xs text-muted-foreground">
                        {formatDate(chat.timestamp)}
                      </span>
                      <span className="text-xs px-2 py-0.5 rounded bg-white/5 text-muted-foreground">
                        {chat.mode === "ask" ? "💬" : "🎨"} {chat.messageCount}
                      </span>
                    </div>
                  </div>

                  {/* Delete Button */}
                  <button
                    onClick={(e) => handleDelete(chat.id, e)}
                    className="p-1.5 hover:bg-destructive/20 rounded transition-smooth opacity-0 group-hover:opacity-100"
                    title="Delete chat"
                  >
                    <Trash2 size={16} className="text-destructive" />
                  </button>
                </div>
              </button>
            ))
          )}
        </div>

        {/* Footer */}
        <div className="p-4 border-t border-white/10 text-xs text-muted-foreground text-center">
          <p>Chats stored locally</p>
        </div>
      </div>

      {/* Toggle Button (when sidebar is closed) */}
      {!isOpen && (
        <button
          onClick={onToggle}
          className="fixed left-4 top-4 z-40 p-2 glass-panel hover:bg-white/10 transition-smooth"
          title="Open sidebar"
        >
          <ChevronRight size={20} />
        </button>
      )}

      {/* Overlay (when sidebar is open on mobile) */}
      {isOpen && (
        <div
          className="fixed inset-0 bg-black/20 backdrop-blur-sm z-30 md:hidden"
          onClick={onToggle}
        />
      )}
    </>
  );
}