/**
 * @license
 * SPDX-License-Identifier: Apache-2.0
 */

import React, { useState } from 'react';
import { motion } from 'motion/react';
import { 
  TrendingUp, 
  Package, 
  AlertTriangle, 
  FileText, 
  UserCheck, 
  Currency,
  ArrowRight,
  Plus,
  RefreshCw,
  Search,
  ShoppingCart
} from 'lucide-react';
import { TireProduct, Invoice, StaffUser, SystemSettings } from '../types';

interface DashboardProps {
  products: TireProduct[];
  invoices: Invoice[];
  currentStaff: StaffUser;
  settings: SystemSettings;
  setActiveTab: (tab: string) => void;
  onQuickAddStock: (productId: string, amount: number) => void;
  setSelectedInvoiceForView: (invoice: Invoice | null) => void;
}

export default function Dashboard({
  products,
  invoices,
  currentStaff,
  settings,
  setActiveTab,
  onQuickAddStock,
  setSelectedInvoiceForView
}: DashboardProps) {
  const [replenishAmount, setReplenishAmount] = useState<{ [key: string]: number }>({});
  const [searchTerm, setSearchTerm] = useState('');

  // 1. Calculate general statistics
  const totalInvoiced = invoices.reduce((sum, inv) => sum + (inv.paymentStatus === 'PAID' ? inv.total : 0), 0);
  const totalActiveItems = products.reduce((sum, p) => sum + p.stock, 0);
  const lowStockItems = products.filter(p => p.stock <= p.minStock);
  const totalInvoicesCount = invoices.length;

  const currentMonthName = "June 2026";
  const juneInvoices = invoices.filter(inv => {
    // Basic date checking
    return inv.dateTime.includes('-06-') || inv.dateTime.includes('/06/') || inv.dateTime.startsWith('02-06-') || inv.dateTime.startsWith('03-06-');
  });
  const juneSalesTotal = juneInvoices.reduce((sum, inv) => sum + (inv.paymentStatus === 'PAID' ? inv.total : 0), 0);

  // 2. Generate custom monthly line metrics for our 2026 sales chart
  // Group invoices by month
  const monthlyData = [
    { label: 'Jan', value: invoices.filter(i => i.dateTime.includes('-01-')).reduce((sum, i) => sum + i.total, 0) },
    { label: 'Feb', value: invoices.filter(i => i.dateTime.includes('-02-')).reduce((sum, i) => sum + i.total, 0) },
    { label: 'Mar', value: invoices.filter(i => i.dateTime.includes('-03-')).reduce((sum, i) => sum + i.total, 0) },
    { label: 'Apr', value: invoices.filter(i => i.dateTime.includes('-04-')).reduce((sum, i) => sum + i.total, 0) },
    { label: 'May', value: invoices.filter(i => i.dateTime.includes('-05-')).reduce((sum, i) => sum + i.total, 0) },
    { label: 'Jun', value: invoices.filter(i => i.dateTime.includes('-06-')).reduce((sum, i) => sum + i.total, 0) },
  ];

  const maxMonthlyVal = Math.max(...monthlyData.map(d => d.value), 100000);

  // 3. Category distribution
  const categories = ['Passenger', 'SUV', 'Commercial', 'Light Truck', 'Truck/Bus'] as const;
  const categoryStats = categories.map(cat => {
    const items = products.filter(p => p.category === cat);
    const count = items.reduce((sum, p) => sum + p.stock, 0);
    const totalValue = items.reduce((sum, p) => sum + (p.stock * p.price), 0);
    return { name: cat, count, value: totalValue };
  });

  const handleQuickAddClick = (productId: string) => {
    const amt = replenishAmount[productId] || 10;
    onQuickAddStock(productId, amt);
    // Reset counter
    setReplenishAmount(prev => ({ ...prev, [productId]: 10 }));
  };

  // Filter products for low stock alert segment
  const filteredAlertProducts = lowStockItems.filter(p => 
    p.brand.toLowerCase().includes(searchTerm.toLowerCase()) ||
    p.model.toLowerCase().includes(searchTerm.toLowerCase()) ||
    p.size.toLowerCase().includes(searchTerm.toLowerCase())
  );

  return (
    <div className="space-y-6" id="dashboard-container">
      {/* Welcome Banner */}
      <div className="bg-white border border-slate-200 rounded-xl p-6 md:p-8 text-slate-900 relative overflow-hidden flex flex-col md:flex-row justify-between items-start md:items-center gap-6 shadow-sm">
        <div className="relative z-10 space-y-2.5">
          <span className="bg-slate-100 text-slate-700 text-[10px] font-bold tracking-wider uppercase px-2.5 py-1 rounded-md border border-slate-200/60 inline-block font-sans">
            ★ Active Session — {currentStaff.role.toUpperCase()} MODE
          </span>
          <h1 className="text-2xl font-bold tracking-tight text-slate-900">
            {settings.shopName}
          </h1>
          <p className="text-slate-500 text-xs max-w-xl leading-relaxed">
            Direct invoicing, tax calculations, dynamic offline persistence, and real-time stock alerts. Welcomed operator: <span className="font-semibold text-slate-900">{currentStaff.name}</span>.
          </p>
        </div>
        <div className="flex gap-2.5 relative z-10">
          <button 
            onClick={() => setActiveTab('invoices')} 
            className="bg-slate-900 hover:bg-slate-800 text-white text-xs font-medium px-4 py-2.5 rounded-lg transition duration-150 flex items-center gap-2 cursor-pointer shadow-sm"
          >
            <ShoppingCart className="w-3.5 h-3.5" />
            New Invoice
          </button>
          <button 
            onClick={() => setActiveTab('inventory')} 
            className="bg-white hover:bg-slate-50 text-slate-700 text-xs font-medium px-4 py-2.5 rounded-lg border border-slate-200 transition duration-150 flex items-center gap-2 cursor-pointer"
          >
            <Package className="w-3.5 h-3.5 text-slate-400" />
            Manage Tires
          </button>
        </div>
        {/* Abstract tire background shadow */}
        <div className="absolute right-[-40px] bottom-[-40px] opacity-5 pointer-events-none transform rotate-12">
          <div className="w-64 h-64 rounded-full border-[24px] border-slate-900 flex items-center justify-center">
            <div className="w-40 h-40 rounded-full border-[12px] border-slate-900 border-dashed"></div>
          </div>
        </div>
      </div>

      {/* Main Core KPI Cards */}
      <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-4 gap-5" id="kpi-grid">
        {/* Metric 1 */}
        <div className="bg-white border border-slate-200 rounded-xl p-5 shadow-sm flex items-center justify-between">
          <div className="space-y-1">
            <p className="text-[10px] uppercase font-semibold text-slate-400 tracking-wider">Mtd Cash Flow ({currentMonthName})</p>
            <p className="text-xl font-bold tracking-tight text-slate-900">
              {settings.currencySymbol} {juneSalesTotal.toLocaleString()}
            </p>
            <p className="text-[11px] text-slate-500 flex items-center gap-1">
              <span className="text-emerald-600 font-semibold flex items-center gap-0.5">
                <TrendingUp className="w-3 h-3" />
                +14.2%
              </span>
              <span>vs last month</span>
            </p>
          </div>
          <div className="p-2.5 bg-slate-50 text-slate-800 border border-slate-150 rounded-lg">
            <TrendingUp className="w-4 h-4 text-slate-500" />
          </div>
        </div>

        {/* Metric 2 */}
        <div className="bg-white border border-slate-200 rounded-xl p-5 shadow-sm flex items-center justify-between">
          <div className="space-y-1">
            <p className="text-[10px] uppercase font-semibold text-slate-400 tracking-wider">Total Warehouse Stock</p>
            <p className="text-xl font-bold tracking-tight text-slate-900">
              {totalActiveItems} pcs
            </p>
            <p className="text-[11px] text-slate-500">
              Across {products.length} distinct models
            </p>
          </div>
          <div className="p-2.5 bg-slate-50 text-slate-800 border border-slate-150 rounded-lg">
            <Package className="w-4 h-4 text-slate-500" />
          </div>
        </div>

        {/* Metric 3 */}
        <div className="bg-white border border-slate-200 rounded-xl p-5 shadow-sm flex items-center justify-between">
          <div className="space-y-1">
            <p className="text-[10px] uppercase font-semibold text-slate-400 tracking-wider">Critical Alerts</p>
            <p className="text-xl font-bold tracking-tight text-red-600">
              {lowStockItems.length} items
            </p>
            <p className="text-[11px] text-red-500 flex items-center gap-1 font-medium">
              <AlertTriangle className="w-3 h-3" />
              Urgent restock alert
            </p>
          </div>
          <div className="p-2.5 bg-red-50 text-red-600 border border-red-100 rounded-lg">
            <AlertTriangle className="w-4 h-4 text-red-500" />
          </div>
        </div>

        {/* Metric 4 */}
        <div className="bg-white border border-slate-200 rounded-xl p-5 shadow-sm flex items-center justify-between">
          <div className="space-y-1">
            <p className="text-[10px] uppercase font-semibold text-slate-400 tracking-wider">Total Sales Invoices</p>
            <p className="text-xl font-bold tracking-tight text-slate-900">
              {totalInvoicesCount} sales
            </p>
            <p className="text-[11px] text-slate-500">
              Invoiced: {settings.currencySymbol}{totalInvoiced.toLocaleString()}
            </p>
          </div>
          <div className="p-2.5 bg-slate-50 text-slate-850 border border-slate-150 rounded-lg">
            <FileText className="w-4 h-4 text-slate-500" />
          </div>
        </div>
      </div>

      {/* Analytics SVG Graph Row */}
      <div className="grid grid-cols-1 lg:grid-cols-3 gap-6" id="dashboard-analytics">
        {/* Core SVG Revenue Chart */}
        <div className="bg-white border border-slate-200 rounded-xl p-5 shadow-sm lg:col-span-2 flex flex-col justify-between">
          <div className="flex justify-between items-center mb-6">
            <div>
              <h3 className="text-sm font-bold text-slate-900 uppercase tracking-wide">Monthly Sales Reporting</h3>
              <p className="text-xs text-slate-400">Telemetry of invoice turnover for year 2026</p>
            </div>
            <div className="bg-slate-50 text-slate-700 text-xs font-semibold px-2.5 py-1 rounded-md border border-slate-200">
              Year {new Date().getFullYear()}
            </div>
          </div>

          {/* SVG Animated Chart */}
          <div className="relative h-64 w-full">
            <svg viewBox="0 0 600 240" className="w-full h-full overflow-visible">
              {/* Grid Lines */}
              <line x1="40" y1="20" x2="580" y2="20" stroke="#f1f5f9" strokeWidth="1" />
              <line x1="40" y1="70" x2="580" y2="70" stroke="#f1f5f9" strokeWidth="1" />
              <line x1="40" y1="120" x2="580" y2="120" stroke="#f1f5f9" strokeWidth="1" />
              <line x1="40" y1="170" x2="580" y2="170" stroke="#f1f5f9" strokeWidth="1" />
              <line x1="40" y1="210" x2="580" y2="210" stroke="#e2e8f0" strokeWidth="1.5" />

              {/* Chart line plotting */}
              {(() => {
                const getCoords = () => {
                  const xSpacing = 540 / 5;
                  return monthlyData.map((d, index) => {
                    const x = 40 + index * xSpacing;
                    // Scale value from 210 (bottom) to 20 (top)
                    const y = 210 - (d.value / maxMonthlyVal) * 180;
                    return { x, y, label: d.label, val: d.value };
                  });
                };

                const coords = getCoords();
                const pathD = coords.reduce((acc, c, idx) => {
                  return acc + (idx === 0 ? `M ${c.x} ${c.y}` : ` L ${c.x} ${c.y}`);
                }, "");

                const areaD = coords.reduce((acc, c, idx) => {
                  if (idx === 0) return `M ${c.x} 210 L ${c.x} ${c.y}`;
                  let ret = acc + ` L ${c.x} ${c.y}`;
                  if (idx === coords.length - 1) ret += ` L ${c.x} 210 Z`;
                  return ret;
                }, "");

                return (
                  <>
                    {/* Shaded Area */}
                    <path d={areaD} fill="url(#blue-gradient)" opacity="0.1" />
                    
                    {/* Connective Line */}
                    <path d={pathD} fill="none" stroke="#2563eb" strokeWidth="3" strokeLinecap="round" strokeLinejoin="round" />
                    
                    {/* Dots and Labels */}
                    {coords.map((c, i) => (
                      <g key={i} className="group cursor-pointer">
                        {/* Hidden interactive target block */}
                        <circle cx={c.x} cy={c.y} r="14" fill="transparent" />
                        <circle cx={c.x} cy={c.y} r="6" fill="#2563eb" stroke="#ffffff" strokeWidth="2" className="transition-all group-hover:scale-150 duration-100" />
                        <text x={c.x} y="230" textAnchor="middle" className="text-[11px] font-medium fill-slate-500 font-sans">{c.label}</text>
                        {/* Turnover Value Overlay on Hover */}
                        <g className="opacity-0 group-hover:opacity-100 transition-opacity duration-150 pointer-events-none">
                          <rect x={c.x - 55} y={c.y - 36} width="110" height="26" rx="6" fill="#0f172a" />
                          <text x={c.x} y={c.y - 19} textAnchor="middle" className="text-[10px] font-semibold fill-white font-sans">
                            {settings.currencySymbol}{Math.round(c.val).toLocaleString()}
                          </text>
                        </g>
                      </g>
                    ))}
                    
                    {/* Gradiant definitions */}
                    <defs>
                      <linearGradient id="blue-gradient" x1="0" y1="0" x2="0" y2="1">
                        <stop offset="0%" stopColor="#2563eb" />
                        <stop offset="100%" stopColor="#2563eb" stopOpacity="0" />
                      </linearGradient>
                    </defs>
                  </>
                );
              })()}
            </svg>
          </div>
          
          <div className="border-t border-slate-50 pt-4 flex justify-between text-xs text-slate-400">
            <span>Graph starts: Jan 2026</span>
            <span>Real-time custom math calculation engine active</span>
            <span>Graph terminal: June 2026</span>
          </div>
        </div>

        {/* Category Breakdown list */}
        <div className="bg-white border border-slate-200 rounded-xl p-5 shadow-sm flex flex-col justify-between">
          <div>
            <h3 className="text-sm font-bold text-slate-900 uppercase tracking-wide">Tire Category Audit</h3>
            <p className="text-xs text-slate-400">Warehouse composition and valuation</p>
          </div>

          <div className="space-y-4 my-6">
            {categoryStats.map((stat, i) => {
              const maxCount = Math.max(...categoryStats.map(s => s.count), 1);
              const percentage = Math.round((stat.count / maxCount) * 100);
              
              return (
                <div key={i} className="space-y-1">
                  <div className="flex justify-between text-xs">
                    <span className="font-semibold text-slate-700">{stat.name}</span>
                    <span className="text-slate-500">{stat.count} pcs — <span className="font-medium text-slate-800">{settings.currencySymbol}{stat.value.toLocaleString()}</span></span>
                  </div>
                  <div className="w-full bg-slate-100 h-2 rounded-full overflow-hidden">
                    <div 
                      className={`h-full rounded-full ${
                        stat.name === 'Passenger' ? 'bg-blue-600' :
                        stat.name === 'SUV' ? 'bg-indigo-500' :
                        stat.name === 'Commercial' ? 'bg-emerald-500' :
                        stat.name === 'Light Truck' ? 'bg-amber-500' : 'bg-red-500'
                      }`} 
                      style={{ width: `${percentage}%` }}
                    />
                  </div>
                </div>
              );
            })}
          </div>

          <div className="bg-slate-50 rounded-xl p-3 text-center border border-slate-100">
            <span className="text-xs font-semibold text-slate-600">Total Inventory Valuation:</span>
            <p className="text-lg font-bold text-slate-900">
              {settings.currencySymbol} {products.reduce((sum, p) => sum + (p.stock * p.price), 0).toLocaleString()}
            </p>
          </div>
        </div>
      </div>

      {/* Stock critical alerts and Quick Add Section */}
      <div className="grid grid-cols-1 lg:grid-cols-2 gap-6" id="dashboard-tables">
        {/* Real-time low stock warnings widget */}
        <div className="bg-white border border-slate-200 rounded-xl p-5 shadow-sm flex flex-col justify-between">
          <div className="space-y-2">
            <div className="flex justify-between items-center">
              <h3 className="text-sm font-bold text-slate-900 flex items-center gap-2 uppercase tracking-wide">
                <AlertTriangle className="w-4 h-4 text-slate-800" />
                Live Replenishment Alerts
              </h3>
              <span className="bg-red-50 text-red-800 text-[10px] font-bold px-2 py-0.5 rounded-md border border-red-100/60 font-sans">
                {lowStockItems.length} Low Stock
              </span>
            </div>
            <p className="text-xs text-slate-500">
              The products listed below are currently equal to or below their alert limit. Top up immediately:
            </p>
          </div>

          {/* Search alerts */}
          <div className="my-4 relative">
            <span className="absolute left-3.5 top-3 text-slate-400">
              <Search className="w-4 h-4" />
            </span>
            <input 
              type="text" 
              placeholder="Search low-stock products..."
              value={searchTerm}
              onChange={(e) => setSearchTerm(e.target.value)}
              className="w-full text-xs border border-slate-200 outline-none focus:border-blue-500 bg-slate-50 hover:bg-slate-100 focus:bg-white rounded-xl pl-10 pr-4 py-2.5 transition duration-150"
            />
          </div>

          <div className="space-y-3 max-h-64 overflow-y-auto pr-1 my-2">
            {filteredAlertProducts.length === 0 ? (
              <div className="text-center py-8 border border-dashed border-slate-200 rounded-xl">
                <p className="text-sm text-slate-400">No matching low stock warnings!</p>
              </div>
            ) : (
              filteredAlertProducts.map((p) => {
                const stockPercent = Math.max(Math.min((p.stock / p.minStock) * 100, 100), 5);
                const currentReplValue = replenishAmount[p.id] || 10;
                
                return (
                  <div key={p.id} className="border border-slate-100 hover:border-slate-200 rounded-xl p-3 flex flex-col sm:flex-row justify-between items-start sm:items-center gap-4 bg-slate-50/50">
                    <div className="space-y-1 col-span-2">
                      <div className="flex items-center gap-2">
                        <span className="text-xs font-bold text-slate-800">{p.brand} {p.model}</span>
                        <span className="text-[10px] bg-slate-200/70 text-slate-600 px-2 py-0.5 rounded font-mono">{p.size}</span>
                      </div>
                      <div className="flex items-center gap-3 text-xs">
                        <span className="text-slate-500">Min. stock threshold: <span className="font-semibold text-slate-700">{p.minStock}</span></span>
                        <span className="text-slate-300">|</span>
                        <span className="text-red-600 font-bold">Qty: {p.stock} remaining</span>
                      </div>
                      
                      {/* Critical line representing the severe level */}
                      <div className="w-52 bg-slate-200 h-1 rounded-full overflow-hidden">
                        <div className="h-full bg-red-500" style={{ width: `${stockPercent}%` }} />
                      </div>
                    </div>

                    {/* Stock quick load inputs */}
                    {['owner', 'manager'].includes(currentStaff.role) ? (
                      <div className="flex items-center gap-2 w-full sm:w-auto justify-end">
                        <input 
                          type="number"
                          min="1"
                          max="200"
                          value={currentReplValue}
                          onChange={(e) => setReplenishAmount(prev => ({ ...prev, [p.id]: parseInt(e.target.value) || 1 }))}
                          className="w-16 border border-slate-200 focus:border-blue-500 bg-white shadow-inner outline-none rounded-lg text-xs py-1 px-2 font-mono text-center"
                        />
                        <button
                          onClick={() => handleQuickAddClick(p.id)}
                          className="bg-blue-600 hover:bg-blue-700 font-bold text-white p-1.5 rounded-lg text-xs flex items-center gap-1 cursor-pointer transition shadow"
                          title="Restock now"
                        >
                          <Plus className="w-3.5 h-3.5" />
                          Restock
                        </button>
                      </div>
                    ) : (
                      <span className="text-[10px] text-slate-400 italic">Restock restricted to Managers</span>
                    )}
                  </div>
                );
              })
            )}
          </div>
          <div className="pt-2 border-t border-slate-50 text-right">
            <button 
              onClick={() => setActiveTab('inventory')}
              className="text-xs text-blue-600 hover:text-blue-800 flex items-center gap-1 ml-auto font-semibold cursor-pointer"
            >
              Examine full inventory history
              <ArrowRight className="w-3.5 h-3.5" />
            </button>
          </div>
        </div>

        {/* Recent Invoices Table list */}
        <div className="bg-white border border-slate-200 rounded-xl p-5 shadow-sm flex flex-col justify-between">
          <div className="space-y-1">
            <h3 className="text-sm font-bold text-slate-900 uppercase tracking-wide">Recent Transactions</h3>
            <p className="text-xs text-slate-400">Review, query, and print historical customer receipts</p>
          </div>

          <div className="space-y-3 scrollbar-none overflow-y-auto max-h-80 pr-1 my-4">
            {invoices.length === 0 ? (
              <div className="text-center py-12 border border-dashed border-slate-200 rounded-xl">
                <p className="text-sm text-slate-400">No invoices drafted yet!</p>
              </div>
            ) : (
              [...invoices].reverse().slice(0, 5).map((inv) => (
                <div 
                  key={inv.id}
                  onClick={() => setSelectedInvoiceForView(inv)}
                  className="group border border-slate-50 hover:border-blue-100 hover:bg-blue-50/20 rounded-xl p-3 flex justify-between items-center transition cursor-pointer"
                >
                  <div className="space-y-1">
                    <div className="flex items-center gap-2">
                      <span className="font-mono text-xs font-semibold text-slate-900">{inv.invoiceNumber}</span>
                      {inv.isOfflineCreated && (
                        <span className="bg-orange-100 text-orange-800 text-[9px] font-bold px-1.5 py-0.5 rounded-full" title="Saved locally offline. Ready for vault sync.">
                          OFFLINE
                        </span>
                      )}
                    </div>
                    <p className="text-xs font-medium text-slate-700">{inv.customerName}</p>
                    <p className="text-[10px] text-slate-400">{inv.dateTime}</p>
                  </div>

                  <div className="text-right space-y-1">
                    <span className="text-xs font-bold text-slate-900 font-sans">
                      {inv.currencySymbol} {inv.total.toLocaleString()}
                    </span>
                    <div className="flex items-center gap-1 justify-end">
                      <span className={`text-[10px] font-bold px-2 py-0.5 rounded ${
                        inv.paymentStatus === 'PAID' ? 'bg-emerald-100 text-emerald-800' : 'bg-red-100 text-red-800'
                      }`}>
                        {inv.paymentStatus}
                      </span>
                      <span className="text-[9px] text-slate-400 bg-slate-100 px-1.5 rounded uppercase font-mono">
                        {inv.paymentMethod}
                      </span>
                    </div>
                  </div>
                </div>
              ))
            )}
          </div>

          <div className="pt-2 border-t border-slate-50">
            <button 
              onClick={() => setActiveTab('invoices')}
              className="text-xs text-blue-600 hover:text-blue-800 flex items-center gap-1 ml-auto font-semibold cursor-pointer"
            >
              Access complete Invoices terminal
              <ArrowRight className="w-3.5 h-3.5" />
            </button>
          </div>
        </div>
      </div>
    </div>
  );
}