import React, { useEffect, useState, useMemo } from 'react';
import { CondoService } from '../services/mockDb';
import { Payment, Family, Condo } from '../types';
import { PieChart, Download, Calendar, Search, CreditCard, Banknote, Filter, ArrowUpRight } from 'lucide-react';
import { useNavigate } from 'react-router-dom';

const MONTH_NAMES = [
  "Gennaio", "Febbraio", "Marzo", "Aprile", "Maggio", "Giugno",
  "Luglio", "Agosto", "Settembre", "Ottobre", "Novembre", "Dicembre"
];

export const ReportsPage: React.FC = () => {
  const navigate = useNavigate();
  const [loading, setLoading] = useState(true);
  const [payments, setPayments] = useState<Payment[]>([]);
  const [families, setFamilies] = useState<Family[]>([]);
  const [activeCondo, setActiveCondo] = useState<Condo | undefined>(undefined);
  const [availableYears, setAvailableYears] = useState<number[]>([]);

  // Filters
  const [selectedYear, setSelectedYear] = useState<number>(new Date().getFullYear());
  const [selectedMonth, setSelectedMonth] = useState<number | 'ALL'>('ALL');
  const [searchTerm, setSearchTerm] = useState('');

  useEffect(() => {
    const fetchData = async () => {
      setLoading(true);
      try {
        const settings = await CondoService.getSettings();
        if (!settings.features.reports) {
            navigate('/');
            return;
        }

        const condo = await CondoService.getActiveCondo();
        setActiveCondo(condo);

        if (condo) {
            const [payList, famList, years] = await Promise.all([
                CondoService.getCondoPayments(condo.id),
                CondoService.getFamilies(condo.id),
                CondoService.getAvailableYears()
            ]);
            setPayments(payList);
            setFamilies(famList);
            setAvailableYears(years);
            if (years.length > 0 && !years.includes(selectedYear)) {
                setSelectedYear(years[0]);
            }
        }
      } catch (e) {
        console.error("Error loading reports", e);
      } finally {
        setLoading(false);
      }
    };
    fetchData();
  }, [navigate]);

  // Filter Logic
  const filteredData = useMemo(() => {
    return payments.filter(p => {
        const matchesYear = p.forYear === selectedYear;
        const matchesMonth = selectedMonth === 'ALL' || p.forMonth === selectedMonth;
        
        const familyName = families.find(f => f.id === p.familyId)?.name.toLowerCase() || '';
        const matchesSearch = searchTerm === '' || 
                              familyName.includes(searchTerm.toLowerCase()) || 
                              (p.notes && p.notes.toLowerCase().includes(searchTerm.toLowerCase()));

        return matchesYear && matchesMonth && matchesSearch;
    }).map(p => {
        const isPayPal = p.notes && p.notes.includes("PayPal");
        const family = families.find(f => f.id === p.familyId);
        return {
            ...p,
            familyName: family ? family.name : 'Sconosciuto',
            familyUnit: family ? family.unitNumber : '-',
            method: isPayPal ? 'PayPal' : 'Manuale'
        };
    });
  }, [payments, families, selectedYear, selectedMonth, searchTerm]);

  // Statistics
  const stats = useMemo(() => {
      const totalAmount = filteredData.reduce((acc, curr) => acc + curr.amount, 0);
      const paypalAmount = filteredData.filter(p => p.method === 'PayPal').reduce((acc, curr) => acc + curr.amount, 0);
      const manualAmount = filteredData.filter(p => p.method === 'Manuale').reduce((acc, curr) => acc + curr.amount, 0);
      const count = filteredData.length;

      return { totalAmount, paypalAmount, manualAmount, count };
  }, [filteredData]);

  const handleExportCSV = () => {
      if (!activeCondo) return;
      
      const headers = ["Data Pagamento", "Famiglia", "Interno", "Mese Rif.", "Anno Rif.", "Importo", "Metodo", "Note"];
      const rows = filteredData.map(p => [
          new Date(p.datePaid).toLocaleDateString(),
          p.familyName,
          p.familyUnit,
          MONTH_NAMES[p.forMonth - 1],
          p.forYear,
          p.amount.toFixed(2),
          p.method,
          p.notes ? `"${p.notes.replace(/"/g, '""')}"` : ""
      ]);

      const csvContent = "data:text/csv;charset=utf-8," 
          + headers.join(",") + "\n" 
          + rows.map(e => e.join(",")).join("\n");

      const encodedUri = encodeURI(csvContent);
      const link = document.createElement("a");
      link.setAttribute("href", encodedUri);
      link.setAttribute("download", `Report_Pagamenti_${activeCondo.name}_${selectedYear}.csv`);
      document.body.appendChild(link);
      link.click();
      document.body.removeChild(link);
  };

  if (loading) return <div className="p-8 text-center text-slate-400">Caricamento report...</div>;

  return (
    <div className="space-y-8 pb-20 animate-fade-in">
        <div className="flex flex-col md:flex-row justify-between md:items-end gap-4">
            <div>
                <h2 className="text-2xl font-bold text-slate-800 flex items-center gap-2">
                    <PieChart className="w-6 h-6 text-blue-600"/> Reportistica & Transazioni
                </h2>
                <p className="text-slate-500 text-sm">Analisi incassi per {activeCondo?.name}</p>
            </div>
            
            <div className="flex gap-2">
                <button onClick={handleExportCSV} className="bg-slate-800 text-white px-4 py-2 rounded-lg font-medium flex items-center gap-2 hover:bg-slate-900 transition-colors">
                    <Download className="w-4 h-4"/> Export CSV
                </button>
            </div>
        </div>

        {/* Filters Bar */}
        <div className="bg-white p-4 rounded-xl border border-slate-200 shadow-sm flex flex-col md:flex-row gap-4">
            <div className="flex-1 grid grid-cols-2 md:grid-cols-4 gap-4">
                <div>
                    <label className="text-xs font-bold text-slate-500 uppercase mb-1 block">Anno</label>
                    <select 
                        value={selectedYear} 
                        onChange={e => setSelectedYear(parseInt(e.target.value))}
                        className="w-full border p-2 rounded-lg text-slate-700 bg-slate-50 font-medium"
                    >
                        {availableYears.map(y => <option key={y} value={y}>{y}</option>)}
                    </select>
                </div>
                <div>
                    <label className="text-xs font-bold text-slate-500 uppercase mb-1 block">Mese</label>
                    <select 
                        value={selectedMonth} 
                        onChange={e => setSelectedMonth(e.target.value === 'ALL' ? 'ALL' : parseInt(e.target.value))}
                        className="w-full border p-2 rounded-lg text-slate-700 bg-slate-50 font-medium"
                    >
                        <option value="ALL">Tutti</option>
                        {MONTH_NAMES.map((m, i) => <option key={i} value={i+1}>{m}</option>)}
                    </select>
                </div>
                <div className="col-span-2">
                    <label className="text-xs font-bold text-slate-500 uppercase mb-1 block">Cerca Famiglia/ID</label>
                    <div className="relative">
                        <input 
                            type="text" 
                            placeholder="Cerca..." 
                            value={searchTerm}
                            onChange={e => setSearchTerm(e.target.value)}
                            className="w-full border p-2 pl-9 rounded-lg text-slate-700 bg-slate-50"
                        />
                        <Search className="w-4 h-4 text-slate-400 absolute left-3 top-2.5"/>
                    </div>
                </div>
            </div>
        </div>

        {/* Stats Cards */}
        <div className="grid grid-cols-1 md:grid-cols-3 gap-4">
            <div className="bg-blue-600 text-white p-6 rounded-xl shadow-lg shadow-blue-200">
                <p className="text-blue-100 text-sm font-medium mb-1">Incasso Totale</p>
                <h3 className="text-3xl font-bold">€ {stats.totalAmount.toLocaleString('it-IT', { minimumFractionDigits: 2 })}</h3>
                <p className="text-blue-200 text-xs mt-2 flex items-center gap-1">
                    <ArrowUpRight className="w-3 h-3"/> su {stats.count} transazioni
                </p>
            </div>
            
            <div className="bg-white p-6 rounded-xl border border-slate-200 shadow-sm flex items-center justify-between">
                <div>
                    <p className="text-slate-500 text-xs font-bold uppercase mb-1 flex items-center gap-1"><CreditCard className="w-3 h-3"/> PayPal / Online</p>
                    <h3 className="text-2xl font-bold text-slate-800">€ {stats.paypalAmount.toLocaleString('it-IT', { minimumFractionDigits: 2 })}</h3>
                </div>
                <div className="h-10 w-10 bg-blue-50 text-blue-600 rounded-full flex items-center justify-center font-bold text-xs">
                    {stats.count > 0 ? Math.round((stats.paypalAmount / stats.totalAmount) * 100) : 0}%
                </div>
            </div>

            <div className="bg-white p-6 rounded-xl border border-slate-200 shadow-sm flex items-center justify-between">
                <div>
                    <p className="text-slate-500 text-xs font-bold uppercase mb-1 flex items-center gap-1"><Banknote className="w-3 h-3"/> Manuale / Bonifico</p>
                    <h3 className="text-2xl font-bold text-slate-800">€ {stats.manualAmount.toLocaleString('it-IT', { minimumFractionDigits: 2 })}</h3>
                </div>
                <div className="h-10 w-10 bg-slate-100 text-slate-600 rounded-full flex items-center justify-center font-bold text-xs">
                    {stats.count > 0 ? Math.round((stats.manualAmount / stats.totalAmount) * 100) : 0}%
                </div>
            </div>
        </div>

        {/* Transactions Table */}
        <div className="bg-white rounded-xl shadow-sm border border-slate-200 overflow-hidden">
            <div className="p-4 border-b border-slate-100 bg-slate-50/50 flex justify-between items-center">
                <h3 className="font-bold text-slate-800">Dettaglio Transazioni</h3>
                <span className="text-xs bg-slate-200 text-slate-600 px-2 py-1 rounded-full font-bold">{filteredData.length} risultati</span>
            </div>
            <div className="overflow-x-auto">
                <table className="w-full text-left text-sm text-slate-600">
                    <thead className="bg-slate-50 text-slate-700 font-semibold border-b border-slate-200">
                        <tr>
                            <th className="px-6 py-3 whitespace-nowrap">Data</th>
                            <th className="px-6 py-3">Famiglia</th>
                            <th className="px-6 py-3">Riferimento</th>
                            <th className="px-6 py-3">Metodo</th>
                            <th className="px-6 py-3">Note / ID Transazione</th>
                            <th className="px-6 py-3 text-right">Importo</th>
                        </tr>
                    </thead>
                    <tbody className="divide-y divide-slate-100">
                        {filteredData.length === 0 ? (
                            <tr><td colSpan={6} className="p-8 text-center text-slate-400">Nessuna transazione trovata con i filtri attuali.</td></tr>
                        ) : (
                            filteredData.map((t) => (
                                <tr key={t.id} className="hover:bg-slate-50 transition-colors">
                                    <td className="px-6 py-4 whitespace-nowrap text-slate-500 font-medium">
                                        <div className="flex items-center gap-2">
                                            <Calendar className="w-4 h-4 text-slate-300"/>
                                            {new Date(t.datePaid).toLocaleDateString()}
                                        </div>
                                    </td>
                                    <td className="px-6 py-4">
                                        <div className="font-bold text-slate-700">{t.familyName}</div>
                                        <div className="text-xs text-slate-400">Int. {t.familyUnit}</div>
                                    </td>
                                    <td className="px-6 py-4">
                                        <span className="bg-slate-100 text-slate-600 px-2 py-1 rounded text-xs font-bold uppercase">
                                            {MONTH_NAMES[t.forMonth - 1].substring(0, 3)} {t.forYear}
                                        </span>
                                    </td>
                                    <td className="px-6 py-4">
                                        <span className={`inline-flex items-center gap-1 px-2 py-1 rounded-full text-xs font-bold uppercase ${t.method === 'PayPal' ? 'bg-blue-100 text-blue-700' : 'bg-green-100 text-green-700'}`}>
                                            {t.method === 'PayPal' ? <CreditCard className="w-3 h-3"/> : <Banknote className="w-3 h-3"/>}
                                            {t.method}
                                        </span>
                                    </td>
                                    <td className="px-6 py-4 max-w-xs truncate text-slate-500 text-xs" title={t.notes}>
                                        {t.notes || '-'}
                                    </td>
                                    <td className="px-6 py-4 text-right font-bold text-slate-800">
                                        € {t.amount.toFixed(2)}
                                    </td>
                                </tr>
                            ))
                        )}
                    </tbody>
                </table>
            </div>
        </div>
    </div>
  );
};