import { Link, useLocation } from 'react-router-dom'
import type { LucideIcon } from 'lucide-react'
import { cn } from '@/lib/utils'
import { prefetchForRoute } from '@/lib/routePrefetch'

interface NavSubItem {
  href: string
  label: string
  count?: number
  isActive?: boolean
}

interface NavItemProps {
  href: string
  icon: LucideIcon
  label: string
  badge?: number | 'dot'
  iconColor?: string
  matchPaths?: string[]
  collapsed?: boolean
  children?: NavSubItem[]
}

export function NavItem({ href, icon: Icon, label, badge, iconColor, matchPaths, collapsed, children }: NavItemProps) {
  const location = useLocation()
  const fullPath = location.pathname + location.search
  const isActive = matchPaths
    ? matchPaths.some(p => location.pathname.startsWith(p))
    : href === '/'
      ? location.pathname === '/'
      : location.pathname.startsWith(href)

  // Check if any child is specifically active
  const activeChild = children?.find(c => fullPath === c.href || fullPath.startsWith(c.href + '&'))
  const isParentDimmed = !!activeChild && isActive

  if (collapsed) {
    return (
      <Link
        to={href}
        onMouseEnter={() => prefetchForRoute(href)}
        className={cn(
          'group relative flex items-center justify-center rounded-lg p-2 transition-all duration-120',
          isActive
            ? 'bg-[var(--sidebar-active)] text-foreground'
            : 'text-muted-foreground hover:bg-[var(--sidebar-hover)] hover:text-foreground'
        )}
        title={label}
      >
        {isActive && (
          <div className="absolute left-0 top-1/2 h-6 w-[3px] -translate-y-1/2 rounded-r-full bg-primary" />
        )}
        <Icon size={18} className={cn('shrink-0', isActive ? 'opacity-100' : 'opacity-70')} style={iconColor ? { color: iconColor } : undefined} />
        {badge !== undefined && badge !== 0 && badge !== 'dot' && (
          <span className="absolute -right-0.5 -top-0.5 flex h-4 w-4 items-center justify-center rounded-full bg-primary text-[0.5rem] font-bold text-primary-foreground">
            {badge}
          </span>
        )}
      </Link>
    )
  }

  return (
    <div className="group/nav">
      <Link
        to={href}
        onMouseEnter={() => prefetchForRoute(href)}
        className={cn(
          'group relative flex items-center gap-3 rounded-lg px-3 py-2 text-[0.8125rem] font-medium transition-all duration-120',
          isActive
            ? isParentDimmed
              ? 'bg-[var(--sidebar-active)]/50 text-foreground/70'
              : 'bg-[var(--sidebar-active)] text-foreground'
            : 'text-muted-foreground hover:bg-[var(--sidebar-hover)] hover:text-foreground'
        )}
      >
        {/* Active indicator bar */}
        {isActive && !isParentDimmed && (
          <div className="absolute left-0 top-1/2 h-6 w-[3px] -translate-y-1/2 rounded-r-full bg-primary" />
        )}

        <Icon size={18} className={cn('shrink-0', isActive ? 'opacity-100' : 'opacity-70')} style={iconColor ? { color: iconColor } : undefined} />
        <span className="truncate">{label}</span>

        {/* Badge */}
        {badge !== undefined && badge !== 0 && (
          badge === 'dot' ? (
            <span className="ml-auto h-1.5 w-1.5 shrink-0 rounded-full bg-brand-gradient-from" />
          ) : (
            <span className="ml-auto shrink-0 rounded-full bg-card border border-border px-2 text-[0.6875rem] font-mono text-muted-foreground">
              {badge}
            </span>
          )
        )}
      </Link>

      {/* Sub-items — visible on hover or when a child is active */}
      {children && children.length > 0 && (
        <div className={cn(
          'mt-0.5 space-y-0.5 overflow-hidden transition-all duration-200',
          isActive || activeChild
            ? 'max-h-40 opacity-100'
            : 'max-h-0 opacity-0 group-hover/nav:max-h-40 group-hover/nav:opacity-100'
        )}>
          {children.map(child => {
            const childActive = fullPath === child.href || fullPath.startsWith(child.href + '&')
            return (
              <Link
                key={child.href}
                to={child.href}
                className={cn(
                  'flex items-center gap-2 rounded-lg pl-9 pr-3 py-1.5 text-[0.8125rem] font-medium transition-colors',
                  childActive
                    ? 'bg-[var(--sidebar-active)] text-foreground'
                    : 'text-muted-foreground hover:bg-[var(--sidebar-hover)] hover:text-foreground'
                )}
              >
                <span className="truncate">{child.label}</span>
                {child.count !== undefined && (
                  <span className="ml-auto shrink-0 rounded-full bg-card border border-border px-2 text-[0.6875rem] font-mono text-muted-foreground">
                    {child.count}
                  </span>
                )}
              </Link>
            )
          })}
        </div>
      )}
    </div>
  )
}