'use client';

import React from 'react';
import { Plus, MessageSquare } from 'lucide-react';
import { cn } from '@/lib/utils';
import { ScrollArea } from '@/components/ui/scroll-area';
import type { ControlCenterConversation } from '@/types/control-center';

interface ConversationSidebarProps {
  /** List of conversations to display */
  conversations: ControlCenterConversation[];
  /** ID of the currently selected conversation */
  currentId?: string;
  /** Callback when a conversation is selected */
  onSelect: (id: string) => void;
  /** Callback when the user wants to start a new conversation */
  onNew: () => void;
}

/**
 * Format a date string to relative time (e.g., "2 hours ago", "Yesterday")
 */
function formatRelativeTime(dateString: string): string {
  const date = new Date(dateString);
  const now = new Date();
  const diffInSeconds = Math.floor((now.getTime() - date.getTime()) / 1000);

  if (diffInSeconds < 60) {
    return 'Just now';
  }

  const diffInMinutes = Math.floor(diffInSeconds / 60);
  if (diffInMinutes < 60) {
    return `${diffInMinutes} minute${diffInMinutes !== 1 ? 's' : ''} ago`;
  }

  const diffInHours = Math.floor(diffInMinutes / 60);
  if (diffInHours < 24) {
    return `${diffInHours} hour${diffInHours !== 1 ? 's' : ''} ago`;
  }

  const diffInDays = Math.floor(diffInHours / 24);
  if (diffInDays === 1) {
    return 'Yesterday';
  }
  if (diffInDays < 7) {
    return `${diffInDays} days ago`;
  }

  const diffInWeeks = Math.floor(diffInDays / 7);
  if (diffInWeeks < 4) {
    return `${diffInWeeks} week${diffInWeeks !== 1 ? 's' : ''} ago`;
  }

  const diffInMonths = Math.floor(diffInDays / 30);
  if (diffInMonths < 12) {
    return `${diffInMonths} month${diffInMonths !== 1 ? 's' : ''} ago`;
  }

  const diffInYears = Math.floor(diffInDays / 365);
  return `${diffInYears} year${diffInYears !== 1 ? 's' : ''} ago`;
}

/**
 * ConversationSidebar - Displays conversation history for the Control Center
 *
 * Shows a scrollable list of past conversations with relative timestamps,
 * plus a button to start new conversations.
 */
export const ConversationSidebar: React.FC<ConversationSidebarProps> = ({
  conversations,
  currentId,
  onSelect,
  onNew,
}) => {
  return (
    <div
      className={cn(
        'flex flex-col',
        'h-full',
        'bg-[#F0F4F8]',
        'rounded-2xl',
        'shadow-[6px_6px_12px_#bfc3cc,-6px_-6px_12px_#ffffff]',
        'overflow-hidden'
      )}
    >
      {/* Header with New Chat button */}
      <div className="p-4 border-b border-gray-200/50">
        <button
          onClick={onNew}
          className={cn(
            'w-full',
            'flex items-center justify-center gap-2',
            'px-4 py-3',
            'bg-indigo-500',
            'text-white',
            'rounded-xl',
            'font-medium',
            'shadow-[4px_4px_8px_#bfc3cc,-4px_-4px_8px_#ffffff]',
            'hover:bg-indigo-600',
            'hover:shadow-[2px_2px_4px_#bfc3cc,-2px_-2px_4px_#ffffff]',
            'active:shadow-[inset_2px_2px_4px_rgba(0,0,0,0.1)]',
            'transition-all duration-200'
          )}
        >
          <Plus className="w-5 h-5" />
          <span>New Chat</span>
        </button>
      </div>

      {/* Conversation list */}
      <ScrollArea className="flex-1">
        <div className="p-3">
          {conversations.length === 0 ? (
            // Empty state
            <div className="flex flex-col items-center justify-center py-12 px-4">
              <div
                className={cn(
                  'w-16 h-16',
                  'flex items-center justify-center',
                  'rounded-2xl',
                  'bg-[#F0F4F8]',
                  'shadow-[inset_3px_3px_6px_rgba(0,0,0,0.06),inset_-3px_-3px_6px_rgba(255,255,255,0.9)]',
                  'mb-4'
                )}
              >
                <MessageSquare className="w-8 h-8 text-gray-400" />
              </div>
              <h3 className="text-sm font-medium text-gray-600 mb-1">
                No conversations yet
              </h3>
              <p className="text-xs text-gray-400 text-center">
                Start a new chat to begin exploring your GHL account
              </p>
            </div>
          ) : (
            // Conversation items
            <div className="flex flex-col gap-2">
              {conversations.map((conversation) => {
                const isSelected = conversation.id === currentId;
                const displayTitle = conversation.title || 'New conversation';

                return (
                  <button
                    key={conversation.id}
                    onClick={() => onSelect(conversation.id)}
                    className={cn(
                      'w-full',
                      'text-left',
                      'px-4 py-3',
                      'rounded-xl',
                      'transition-all duration-200',
                      isSelected
                        ? [
                            'bg-[#F0F4F8]',
                            'shadow-[inset_4px_4px_8px_rgba(0,0,0,0.05),inset_-4px_-4px_8px_rgba(255,255,255,0.8)]',
                            'border-2 border-indigo-500',
                          ]
                        : [
                            'bg-[#F0F4F8]',
                            'shadow-[3px_3px_6px_#c5c9d1,-3px_-3px_6px_#ffffff]',
                            'border-2 border-transparent',
                            'hover:shadow-[2px_2px_4px_#c5c9d1,-2px_-2px_4px_#ffffff]',
                            'hover:border-gray-300',
                          ]
                    )}
                  >
                    <div className="flex flex-col gap-1">
                      <span
                        className={cn(
                          'text-sm font-medium truncate',
                          isSelected ? 'text-indigo-700' : 'text-gray-700'
                        )}
                      >
                        {displayTitle}
                      </span>
                      <span className="text-xs text-gray-400">
                        {formatRelativeTime(conversation.createdAt)}
                      </span>
                    </div>
                  </button>
                );
              })}
            </div>
          )}
        </div>
      </ScrollArea>
    </div>
  );
};

export default ConversationSidebar;