import React, { useState, useRef, useEffect, useCallback } from 'react'
import { Search, TrendingUp, Loader2, LogOut, Star, BarChart2, User, X, Gem, ScanLine, Droplets } from 'lucide-react'
import { searchStocks, SearchResult } from '../api/stockApi'

export type Market = 'tw' | 'us' | 'fund'

const MARKET_TABS: { key: Market; label: string; flag: string }[] = [
  { key: 'tw',   label: '台股', flag: '🇹🇼' },
  { key: 'us',   label: '美股', flag: '🇺🇸' },
  { key: 'fund', label: '基金', flag: '📊' },
]

const MARKET_PLACEHOLDER: Record<Market, string> = {
  tw:   '台股代號 (e.g. 7856)',
  us:   '美股代號 (e.g. AAPL)',
  fund: '基金代號 (e.g. PIM91)',
}

interface HeaderProps {
  input: string
  setInput: (val: string) => void
  months: number
  setMonths: (val: number) => void
  loading: boolean
  onSubmit: (e: React.FormEvent) => void
  onLogout: () => void
  currentUser: string
  userPhotoURL?: string
  view: 'main' | 'favorites' | 'metals' | 'oil' | 'recommend'
  onViewChange: (v: 'main' | 'favorites' | 'metals' | 'oil' | 'recommend') => void
  favoritesCount: number
  market: Market
  onMarketChange: (m: Market) => void
  onSelect: (stockNo: string) => void
}

export const Header: React.FC<HeaderProps> = ({
  input, setInput,
  months, setMonths,
  loading,
  onSubmit,
  onLogout,
  currentUser,
  userPhotoURL,
  view, onViewChange,
  favoritesCount,
  market, onMarketChange,
  onSelect,
}) => {
  const [suggestions, setSuggestions] = useState<SearchResult[]>([])
  const [showDrop, setShowDrop] = useState(false)
  const [searching, setSearching] = useState(false)
  const debounceRef = useRef<ReturnType<typeof setTimeout> | null>(null)
  const wrapperRef = useRef<HTMLDivElement>(null)

  // Close dropdown when clicking outside
  useEffect(() => {
    const handler = (e: MouseEvent) => {
      if (wrapperRef.current && !wrapperRef.current.contains(e.target as Node)) {
        setShowDrop(false)
      }
    }
    document.addEventListener('mousedown', handler)
    return () => document.removeEventListener('mousedown', handler)
  }, [])

  const fetchSuggestions = useCallback(async (q: string, mkt: Market) => {
    if (!q.trim()) { setSuggestions([]); setShowDrop(false); return }
    // For TW: need at least 1 char; for US/fund: 1 char
    if (q.length < 1) return
    setSearching(true)
    try {
      const results = await searchStocks(q, mkt)
      setSuggestions(results)
      setShowDrop(results.length > 0)
    } catch {
      setSuggestions([])
      setShowDrop(false)
    } finally {
      setSearching(false)
    }
  }, [])

  const handleInputChange = (val: string) => {
    setInput(val)
    if (debounceRef.current) clearTimeout(debounceRef.current)
    debounceRef.current = setTimeout(() => fetchSuggestions(val, market), 350)
  }

  const handleSelect = (stockNo: string) => {
    setInput(stockNo)
    setSuggestions([])
    setShowDrop(false)
    onSelect(stockNo)
  }

  const handleMarketChange = (m: Market) => {
    onMarketChange(m)
    setSuggestions([])
    setShowDrop(false)
    setInput('')
  }

  const handleFormSubmit = (e: React.FormEvent) => {
    setShowDrop(false)
    onSubmit(e)
  }

  const exchangeColor: Record<string, string> = {
    TWSE: 'text-blue-400', TPEX: 'text-purple-400',
    基金: 'text-yellow-400', MoneyDJ: 'text-yellow-400',
    NYSE: 'text-green-400', NASDAQ: 'text-green-400',
  }

  return (
    <header className="bg-slate-900 border-b border-slate-800 sticky top-0 z-20">
      <div className="max-w-7xl mx-auto px-4 py-3 flex flex-col sm:flex-row items-start sm:items-center gap-3">

        {/* Brand */}
        <div className="flex items-center gap-2 mr-2 flex-shrink-0">
          <TrendingUp className="text-blue-400" size={22} />
          <h1 className="text-lg font-bold tracking-tight text-white whitespace-nowrap hidden sm:block">ML 股票預測</h1>
        </div>

        {/* View nav (分析 / 最愛) */}
        <nav className="flex items-center gap-1 flex-shrink-0">
          <button
            onClick={() => onViewChange('main')}
            className={`flex items-center gap-1.5 px-3 py-1.5 rounded-lg text-sm font-medium transition-colors ${
              view === 'main' ? 'bg-blue-600/20 text-blue-400' : 'text-slate-400 hover:text-white hover:bg-slate-800'
            }`}
          >
            <BarChart2 size={14} /> 分析
          </button>
          <button
            onClick={() => onViewChange('favorites')}
            className={`flex items-center gap-1.5 px-3 py-1.5 rounded-lg text-sm font-medium transition-colors ${
              view === 'favorites' ? 'bg-yellow-500/20 text-yellow-400' : 'text-slate-400 hover:text-white hover:bg-slate-800'
            }`}
          >
            <Star size={14} fill={view === 'favorites' ? 'currentColor' : 'none'} />
            最愛
            {favoritesCount > 0 && (
              <span className="bg-yellow-500 text-black text-[10px] font-bold rounded-full w-4 h-4 flex items-center justify-center leading-none">
                {favoritesCount > 9 ? '9+' : favoritesCount}
              </span>
            )}
          </button>
          <button
            onClick={() => onViewChange('metals')}
            className={`flex items-center gap-1.5 px-3 py-1.5 rounded-lg text-sm font-medium transition-colors ${
              view === 'metals' ? 'bg-yellow-500/20 text-yellow-400' : 'text-slate-400 hover:text-white hover:bg-slate-800'
            }`}
          >
            <Gem size={14} />
            貴金屬
          </button>
          <button
            onClick={() => onViewChange('oil')}
            className={`flex items-center gap-1.5 px-3 py-1.5 rounded-lg text-sm font-medium transition-colors ${
              view === 'oil' ? 'bg-cyan-500/20 text-cyan-300' : 'text-slate-400 hover:text-white hover:bg-slate-800'
            }`}
          >
            <Droplets size={14} />
            石油
          </button>
          <button
            onClick={() => onViewChange('recommend')}
            className={`flex items-center gap-1.5 px-3 py-1.5 rounded-lg text-sm font-medium transition-colors ${
              view === 'recommend' ? 'bg-blue-600/20 text-blue-400' : 'text-slate-400 hover:text-white hover:bg-slate-800'
            }`}
          >
            <ScanLine size={14} />
            Market Scan
          </button>
        </nav>

        {/* Market tabs + search (only on main view) */}
        {view === 'main' && (
          <div className="flex items-center gap-2 flex-1">
            {/* Market tabs */}
            <div className="flex items-center bg-slate-800 rounded-lg p-0.5 flex-shrink-0">
              {MARKET_TABS.map(tab => (
                <button
                  key={tab.key}
                  onClick={() => handleMarketChange(tab.key)}
                  className={`flex items-center gap-1 px-2.5 py-1 rounded-md text-xs font-medium transition-colors ${
                    market === tab.key
                      ? 'bg-slate-700 text-white shadow-sm'
                      : 'text-slate-400 hover:text-white'
                  }`}
                >
                  <span>{tab.flag}</span>
                  <span className="hidden sm:inline">{tab.label}</span>
                </button>
              ))}
            </div>

            {/* Search with autocomplete */}
            <form onSubmit={handleFormSubmit} className="flex items-center gap-2 flex-1">
              <div className="relative flex-1 sm:flex-none" ref={wrapperRef}>
                <Search size={14} className="absolute left-2.5 top-1/2 -translate-y-1/2 text-slate-400 pointer-events-none z-10" />
                <input
                  type="text"
                  value={input}
                  onChange={(e) => handleInputChange(e.target.value)}
                  onFocus={() => suggestions.length > 0 && setShowDrop(true)}
                  placeholder={MARKET_PLACEHOLDER[market]}
                  className="bg-slate-800 border border-slate-600 rounded-lg pl-8 pr-7 py-2 text-sm w-full sm:w-52 focus:outline-none focus:border-blue-500 focus:ring-1 focus:ring-blue-500 text-white placeholder-slate-500"
                />
                {input && (
                  <button
                    type="button"
                    onClick={() => { setInput(''); setSuggestions([]); setShowDrop(false) }}
                    className="absolute right-2 top-1/2 -translate-y-1/2 text-slate-500 hover:text-white"
                  >
                    <X size={12} />
                  </button>
                )}

                {/* Autocomplete dropdown */}
                {showDrop && (
                  <div className="absolute top-full left-0 right-0 mt-1 bg-slate-800 border border-slate-700 rounded-lg shadow-xl z-50 max-h-64 overflow-y-auto">
                    {searching && (
                      <div className="px-3 py-2 text-xs text-slate-500 flex items-center gap-2">
                        <Loader2 size={12} className="animate-spin" /> 搜尋中...
                      </div>
                    )}
                    {suggestions.map((s) => (
                      <button
                        key={s.stock_no}
                        type="button"
                        onClick={() => handleSelect(s.stock_no)}
                        className="w-full px-3 py-2 text-left hover:bg-slate-700 flex items-center justify-between gap-2 transition-colors"
                      >
                        <div className="flex items-center gap-2 min-w-0">
                          <span className="font-mono font-bold text-white text-sm flex-shrink-0">{s.stock_no}</span>
                          <span className="text-slate-300 text-xs truncate">{s.name}</span>
                        </div>
                        <span className={`text-[10px] font-medium flex-shrink-0 ${exchangeColor[s.exchange] ?? 'text-slate-400'}`}>
                          {s.exchange}
                        </span>
                      </button>
                    ))}
                  </div>
                )}
              </div>

              <select
                value={months}
                onChange={(e) => setMonths(Number(e.target.value))}
                className="bg-slate-800 border border-slate-600 rounded-lg px-2 py-2 text-sm focus:outline-none focus:border-blue-500 text-white flex-shrink-0"
              >
                <option value={3}>3個月</option>
                <option value={6}>6個月</option>
                <option value={12}>12個月</option>
                <option value={24}>24個月</option>
              </select>

              <button
                type="submit"
                disabled={loading}
                className="flex items-center gap-1.5 bg-blue-600 hover:bg-blue-500 disabled:bg-blue-800 disabled:cursor-not-allowed text-white rounded-lg px-4 py-2 text-sm font-medium transition-colors flex-shrink-0"
              >
                {loading ? <Loader2 size={14} className="animate-spin" /> : <Search size={14} />}
                <span className="hidden sm:inline">查詢</span>
              </button>
            </form>
          </div>
        )}

        {/* User avatar + logout */}
        <div className="flex items-center gap-2 sm:ml-auto flex-shrink-0">
          {userPhotoURL ? (
            <img src={userPhotoURL} alt={currentUser} className="w-7 h-7 rounded-full border border-slate-600 object-cover" referrerPolicy="no-referrer" />
          ) : (
            <div className="w-7 h-7 rounded-full bg-slate-700 flex items-center justify-center">
              <User size={14} className="text-slate-400" />
            </div>
          )}
          <span className="hidden sm:inline text-xs font-medium text-slate-300 max-w-[100px] truncate">{currentUser}</span>
          <button
            onClick={onLogout}
            className="p-2 text-slate-400 hover:text-white transition-colors rounded-lg hover:bg-slate-800"
            title="登出"
            type="button"
          >
            <LogOut size={18} />
          </button>
        </div>
      </div>
    </header>
  )
}