import { useState, useEffect, useCallback, useMemo } from 'react'
import {
  ClipboardList,
  FileText,
  Pill,
  AlertTriangle,
  FlaskConical,
  FolderOpen,
  Send,
  Search,
  X,
} from 'lucide-react'
import type { ViewId } from '../types/pmr'

interface NavItem {
  id: ViewId
  label: string
  icon: React.ReactNode
}

interface ClinicalSidebarProps {
  activeView: ViewId
  onViewChange: (view: ViewId) => void
}

const navItems: NavItem[] = [
  { id: 'summary', label: 'Summary', icon: <ClipboardList size={18} /> },
  { id: 'consultations', label: 'Consultations', icon: <FileText size={18} /> },
  { id: 'medications', label: 'Medications', icon: <Pill size={18} /> },
  { id: 'problems', label: 'Problems', icon: <AlertTriangle size={18} /> },
  { id: 'investigations', label: 'Investigations', icon: <FlaskConical size={18} /> },
  { id: 'documents', label: 'Documents', icon: <FolderOpen size={18} /> },
  { id: 'referrals', label: 'Referrals', icon: <Send size={18} /> },
]

function getCurrentTime(): string {
  const now = new Date()
  return now.toLocaleTimeString('en-GB', {
    hour: '2-digit',
    minute: '2-digit',
  })
}

export function ClinicalSidebar({ activeView, onViewChange }: ClinicalSidebarProps) {
  const [currentTime, setCurrentTime] = useState(getCurrentTime)
  const [searchQuery, setSearchQuery] = useState('')
  const [isSearchFocused, setIsSearchFocused] = useState(false)

  useEffect(() => {
    const interval = setInterval(() => {
      setCurrentTime(getCurrentTime())
    }, 60000)
    return () => clearInterval(interval)
  }, [])

  useEffect(() => {
    const handleHashChange = () => {
      const hash = window.location.hash.slice(1) as ViewId
      if (navItems.some(item => item.id === hash)) {
        onViewChange(hash)
      }
    }

    handleHashChange()
    window.addEventListener('hashchange', handleHashChange)
    return () => window.removeEventListener('hashchange', handleHashChange)
  }, [onViewChange])

  useEffect(() => {
    const handleKeyDown = (e: KeyboardEvent) => {
      if (e.altKey && e.key >= '1' && e.key <= '7') {
        e.preventDefault()
        const index = parseInt(e.key) - 1
        if (navItems[index]) {
          const view = navItems[index].id
          onViewChange(view)
          window.location.hash = view
        }
      }
      if (e.key === '/' && !isSearchFocused && document.activeElement?.tagName !== 'INPUT') {
        e.preventDefault()
        const searchInput = document.getElementById('sidebar-search')
        searchInput?.focus()
      }
    }

    window.addEventListener('keydown', handleKeyDown)
    return () => window.removeEventListener('keydown', handleKeyDown)
  }, [onViewChange, isSearchFocused])

  const handleNavClick = useCallback(
    (view: ViewId) => {
      onViewChange(view)
      window.location.hash = view
    },
    [onViewChange]
  )

  const handleSearchKeyDown = (e: React.KeyboardEvent<HTMLInputElement>) => {
    if (e.key === 'Escape') {
      setSearchQuery('')
      ;(e.target as HTMLInputElement).blur()
    }
  }

  const clearSearch = () => {
    setSearchQuery('')
    const searchInput = document.getElementById('sidebar-search')
    searchInput?.focus()
  }

  const filteredItems = useMemo(() => {
    if (!searchQuery.trim()) return []
    const query = searchQuery.toLowerCase()
    return navItems.filter(item =>
      item.label.toLowerCase().includes(query)
    )
  }, [searchQuery])

  return (
    <aside
      role="navigation"
      aria-label="Clinical record navigation"
      className="hidden lg:flex flex-col w-[220px] h-screen sticky top-0 bg-pmr-sidebar text-white"
    >
      <div className="p-4 border-b border-white/10">
        <div className="font-inter font-medium text-[13px] text-white/50 leading-tight">
          CareerRecord PMR
        </div>
        <div className="font-inter text-[11px] text-white/40 mt-0.5">v1.0.0</div>
      </div>

      <div className="p-3 border-b border-white/10">
        <div className="relative">
          <Search
            size={14}
            className="absolute left-2.5 top-1/2 -translate-y-1/2 text-white/40 pointer-events-none"
          />
          <input
            id="sidebar-search"
            type="text"
            placeholder="Search record..."
            value={searchQuery}
            onChange={e => setSearchQuery(e.target.value)}
            onFocus={() => setIsSearchFocused(true)}
            onBlur={() => setIsSearchFocused(false)}
            onKeyDown={handleSearchKeyDown}
            className="w-full h-9 pl-8 pr-7 bg-white/5 border border-white/10 rounded text-sm font-inter text-white placeholder-white/40 focus:outline-none focus:border-pmr-nhsblue focus:bg-white/10 transition-colors"
          />
          {searchQuery && (
            <button
              type="button"
              onClick={clearSearch}
              className="absolute right-2 top-1/2 -translate-y-1/2 text-white/40 hover:text-white/70 transition-colors"
              aria-label="Clear search"
            >
              <X size={14} />
            </button>
          )}
          {searchQuery && filteredItems.length > 0 && (
            <div className="absolute top-full left-0 right-0 mt-1 bg-pmr-sidebar border border-white/10 rounded overflow-hidden z-50">
              {filteredItems.map(item => (
                <button
                  key={item.id}
                  type="button"
                  onClick={() => {
                    handleNavClick(item.id)
                    setSearchQuery('')
                  }}
                  className="w-full flex items-center gap-3 px-3 py-2.5 text-left hover:bg-white/10 transition-colors"
                >
                  <span className="text-white/60">{item.icon}</span>
                  <span className="font-inter text-sm">{item.label}</span>
                </button>
              ))}
            </div>
          )}
        </div>
      </div>

      <nav className="flex-1 py-2 overflow-y-auto">
        <ul role="list">
          {navItems.map((item, index) => (
            <li key={item.id}>
              {index === 1 && (
                <div className="mx-3 my-1 border-t border-white/10" role="separator" />
              )}
              <button
                type="button"
                role="menuitem"
                aria-current={activeView === item.id ? 'page' : undefined}
                onClick={() => handleNavClick(item.id)}
                className={`w-full flex items-center gap-3 h-11 px-4 text-left transition-colors ${
                  activeView === item.id
                    ? 'text-white bg-white/12 border-l-[3px] border-pmr-nhsblue font-semibold'
                    : 'text-white/70 hover:text-white hover:bg-white/8'
                }`}
              >
                <span className={activeView === item.id ? 'text-white' : 'text-white/60'}>
                  {item.icon}
                </span>
                <span className="font-inter text-sm">{item.label}</span>
              </button>
            </li>
          ))}
        </ul>
      </nav>

      <div className="p-4 border-t border-white/10">
        <div className="font-inter text-[11px] text-slate-400 leading-relaxed">
          <div>Session: A.CHARLWOOD</div>
          <div>Logged in: {currentTime}</div>
        </div>
      </div>
    </aside>
  )
}