'use client';

import React, { useState, useEffect, useRef } from 'react';
import { Card } from 'primereact/card';
import { Chart } from 'primereact/chart';
import { DataTable } from 'primereact/datatable';
import { Column } from 'primereact/column';
import { Button } from 'primereact/button';
import { Calendar } from 'primereact/calendar';
import { Dropdown } from 'primereact/dropdown';
import { Tag } from 'primereact/tag';
import { ProgressBar } from 'primereact/progressbar';
import { Toast } from 'primereact/toast';
import { Toolbar } from 'primereact/toolbar';
import { Badge } from 'primereact/badge';
import { factureService } from '../../../../services/api';
import { formatCurrency, formatDate } from '../../../../utils/formatters';

interface FactureStats {
    totalFactures: number;
    chiffreAffaires: number;
    montantEnAttente: number;
    montantEnRetard: number;
    tauxRecouvrement: number;
    delaiMoyenPaiement: number;
    repartitionStatuts: { [key: string]: number };
    evolutionMensuelle: Array<{ mois: string; emises: number; payees: number; montantEmis: number; montantPaye: number }>;
    topClients: Array<{ client: string; nombre: number; montant: number; montantPaye: number }>;
    retardsParClient: Array<{ client: string; factures: number; montant: number; retardMoyen: number }>;
}

const FactureStatsPage = () => {
    const toast = useRef<Toast>(null);
    
    const [stats, setStats] = useState<FactureStats>({
        totalFactures: 0,
        chiffreAffaires: 0,
        montantEnAttente: 0,
        montantEnRetard: 0,
        tauxRecouvrement: 0,
        delaiMoyenPaiement: 0,
        repartitionStatuts: {},
        evolutionMensuelle: [],
        topClients: [],
        retardsParClient: []
    });
    
    const [loading, setLoading] = useState(true);
    const [dateDebut, setDateDebut] = useState<Date>(new Date(new Date().getFullYear(), 0, 1));
    const [dateFin, setDateFin] = useState<Date>(new Date());
    const [periodeSelectionnee, setPeriodeSelectionnee] = useState('annee');

    const periodeOptions = [
        { label: 'Cette année', value: 'annee' },
        { label: 'Ce trimestre', value: 'trimestre' },
        { label: 'Ce mois', value: 'mois' },
        { label: 'Personnalisée', value: 'custom' }
    ];

    useEffect(() => {
        loadStats();
    }, [dateDebut, dateFin]);

    const loadStats = async () => {
        try {
            setLoading(true);
            
            // TODO: Remplacer par un vrai appel API
            // const response = await factureService.getStatistiques(dateDebut, dateFin);
            
            // Données simulées pour la démonstration
            const mockStats: FactureStats = {
                totalFactures: 234,
                chiffreAffaires: 3250000,
                montantEnAttente: 485000,
                montantEnRetard: 125000,
                tauxRecouvrement: 87.5,
                delaiMoyenPaiement: 28.5,
                repartitionStatuts: {
                    'PAYEE': 156,
                    'ENVOYEE': 45,
                    'EN_RETARD': 18,
                    'PARTIELLEMENT_PAYEE': 12,
                    'BROUILLON': 3
                },
                evolutionMensuelle: [
                    { mois: 'Jan', emises: 18, payees: 15, montantEmis: 285000, montantPaye: 240000 },
                    { mois: 'Fév', emises: 22, payees: 19, montantEmis: 340000, montantPaye: 295000 },
                    { mois: 'Mar', emises: 25, payees: 22, montantEmis: 395000, montantPaye: 350000 },
                    { mois: 'Avr', emises: 20, payees: 18, montantEmis: 315000, montantPaye: 285000 },
                    { mois: 'Mai', emises: 28, payees: 24, montantEmis: 445000, montantPaye: 380000 },
                    { mois: 'Jun', emises: 24, payees: 21, montantEmis: 375000, montantPaye: 320000 },
                    { mois: 'Jul', emises: 30, payees: 26, montantEmis: 485000, montantPaye: 420000 },
                    { mois: 'Aoû', emises: 26, payees: 23, montantEmis: 410000, montantPaye: 365000 },
                    { mois: 'Sep', emises: 29, payees: 25, montantEmis: 465000, montantPaye: 395000 }
                ],
                topClients: [
                    { client: 'Bouygues Construction', nombre: 12, montant: 680000, montantPaye: 620000 },
                    { client: 'Vinci Construction', nombre: 9, montant: 520000, montantPaye: 485000 },
                    { client: 'Eiffage', nombre: 8, montant: 445000, montantPaye: 445000 },
                    { client: 'Spie Batignolles', nombre: 6, montant: 385000, montantPaye: 320000 },
                    { client: 'GTM Bâtiment', nombre: 5, montant: 295000, montantPaye: 295000 }
                ],
                retardsParClient: [
                    { client: 'Constructa SARL', factures: 3, montant: 85000, retardMoyen: 45 },
                    { client: 'Bâti Plus', factures: 2, montant: 65000, retardMoyen: 38 },
                    { client: 'Rénov Express', factures: 4, montant: 125000, retardMoyen: 32 },
                    { client: 'Maisons du Sud', factures: 1, montant: 35000, retardMoyen: 28 }
                ]
            };
            
            setStats(mockStats);
            
        } catch (error) {
            console.error('Erreur lors du chargement des statistiques:', error);
            toast.current?.show({
                severity: 'error',
                summary: 'Erreur',
                detail: 'Impossible de charger les statistiques'
            });
        } finally {
            setLoading(false);
        }
    };

    const handlePeriodeChange = (periode: string) => {
        setPeriodeSelectionnee(periode);
        const now = new Date();
        
        switch (periode) {
            case 'annee':
                setDateDebut(new Date(now.getFullYear(), 0, 1));
                setDateFin(new Date());
                break;
            case 'trimestre':
                const trimestre = Math.floor(now.getMonth() / 3);
                setDateDebut(new Date(now.getFullYear(), trimestre * 3, 1));
                setDateFin(new Date());
                break;
            case 'mois':
                setDateDebut(new Date(now.getFullYear(), now.getMonth(), 1));
                setDateFin(new Date());
                break;
        }
    };

    // Configuration des graphiques
    const chartOptions = {
        responsive: true,
        maintainAspectRatio: false,
        plugins: {
            legend: {
                position: 'bottom' as const
            }
        },
        scales: {
            y: {
                beginAtZero: true
            }
        }
    };

    const evolutionData = {
        labels: stats.evolutionMensuelle.map(item => item.mois),
        datasets: [
            {
                label: 'Factures émises',
                data: stats.evolutionMensuelle.map(item => item.emises),
                borderColor: '#3B82F6',
                backgroundColor: 'rgba(59, 130, 246, 0.1)',
                yAxisID: 'y'
            },
            {
                label: 'Factures payées',
                data: stats.evolutionMensuelle.map(item => item.payees),
                borderColor: '#10B981',
                backgroundColor: 'rgba(16, 185, 129, 0.1)',
                yAxisID: 'y'
            }
        ]
    };

    const chiffreAffairesData = {
        labels: stats.evolutionMensuelle.map(item => item.mois),
        datasets: [
            {
                label: 'CA émis (k€)',
                data: stats.evolutionMensuelle.map(item => item.montantEmis / 1000),
                backgroundColor: 'rgba(59, 130, 246, 0.8)'
            },
            {
                label: 'CA encaissé (k€)',
                data: stats.evolutionMensuelle.map(item => item.montantPaye / 1000),
                backgroundColor: 'rgba(16, 185, 129, 0.8)'
            }
        ]
    };

    const repartitionData = {
        labels: Object.keys(stats.repartitionStatuts),
        datasets: [{
            data: Object.values(stats.repartitionStatuts),
            backgroundColor: [
                '#10B981', // PAYEE - vert
                '#3B82F6', // ENVOYEE - bleu
                '#EF4444', // EN_RETARD - rouge
                '#F59E0B', // PARTIELLEMENT_PAYEE - orange
                '#6B7280'  // BROUILLON - gris
            ]
        }]
    };

    const getStatutSeverity = (statut: string) => {
        switch (statut) {
            case 'PAYEE': return 'success';
            case 'EN_RETARD': return 'danger';
            case 'PARTIELLEMENT_PAYEE': return 'warning';
            case 'ENVOYEE': return 'info';
            case 'BROUILLON': return 'secondary';
            default: return 'info';
        }
    };

    const toolbarStartTemplate = () => (
        <div className="flex align-items-center gap-2">
            <h2 className="text-xl font-bold m-0">Statistiques des Factures</h2>
        </div>
    );

    const toolbarEndTemplate = () => (
        <div className="flex align-items-center gap-2">
            <Dropdown
                value={periodeSelectionnee}
                options={periodeOptions}
                onChange={(e) => handlePeriodeChange(e.value)}
                className="w-10rem"
            />
            {periodeSelectionnee === 'custom' && (
                <>
                    <Calendar
                        value={dateDebut}
                        onChange={(e) => setDateDebut(e.value || new Date())}
                        placeholder="Date début"
                        dateFormat="dd/mm/yy"
                    />
                    <Calendar
                        value={dateFin}
                        onChange={(e) => setDateFin(e.value || new Date())}
                        placeholder="Date fin"
                        dateFormat="dd/mm/yy"
                    />
                </>
            )}
            <Button
                icon="pi pi-refresh"
                className="p-button-outlined"
                onClick={loadStats}
                loading={loading}
            />
        </div>
    );

    return (
        <div className="grid">
            <Toast ref={toast} />
            
            <div className="col-12">
                <Toolbar start={toolbarStartTemplate} end={toolbarEndTemplate} />
            </div>

            {/* KPIs principaux */}
            <div className="col-12 lg:col-3 md:col-6">
                <Card className="h-full">
                    <div className="flex justify-content-between mb-3">
                        <div>
                            <span className="block text-500 font-medium mb-3">Total Factures</span>
                            <div className="text-900 font-medium text-xl">{stats.totalFactures}</div>
                        </div>
                        <div className="flex align-items-center justify-content-center bg-blue-100 border-round" style={{ width: '2.5rem', height: '2.5rem' }}>
                            <i className="pi pi-file text-blue-500 text-xl"></i>
                        </div>
                    </div>
                    <span className="text-green-500 font-medium">+15% </span>
                    <span className="text-500">vs période précédente</span>
                </Card>
            </div>

            <div className="col-12 lg:col-3 md:col-6">
                <Card className="h-full">
                    <div className="flex justify-content-between mb-3">
                        <div>
                            <span className="block text-500 font-medium mb-3">Chiffre d'Affaires</span>
                            <div className="text-900 font-medium text-xl">{formatCurrency(stats.chiffreAffaires)}</div>
                        </div>
                        <div className="flex align-items-center justify-content-center bg-green-100 border-round" style={{ width: '2.5rem', height: '2.5rem' }}>
                            <i className="pi pi-euro text-green-500 text-xl"></i>
                        </div>
                    </div>
                    <span className="text-green-500 font-medium">+12% </span>
                    <span className="text-500">vs période précédente</span>
                </Card>
            </div>

            <div className="col-12 lg:col-3 md:col-6">
                <Card className="h-full">
                    <div className="flex justify-content-between mb-3">
                        <div>
                            <span className="block text-500 font-medium mb-3">Taux de Recouvrement</span>
                            <div className="text-900 font-medium text-xl">{stats.tauxRecouvrement}%</div>
                        </div>
                        <div className="flex align-items-center justify-content-center bg-orange-100 border-round" style={{ width: '2.5rem', height: '2.5rem' }}>
                            <i className="pi pi-chart-line text-orange-500 text-xl"></i>
                        </div>
                    </div>
                    <ProgressBar value={stats.tauxRecouvrement} className="mt-2" style={{ height: '6px' }} />
                </Card>
            </div>

            <div className="col-12 lg:col-3 md:col-6">
                <Card className="h-full">
                    <div className="flex justify-content-between mb-3">
                        <div>
                            <span className="block text-500 font-medium mb-3">Délai Moyen Paiement</span>
                            <div className="text-900 font-medium text-xl">{stats.delaiMoyenPaiement} jours</div>
                        </div>
                        <div className="flex align-items-center justify-content-center bg-cyan-100 border-round" style={{ width: '2.5rem', height: '2.5rem' }}>
                            <i className="pi pi-clock text-cyan-500 text-xl"></i>
                        </div>
                    </div>
                    <span className="text-red-500 font-medium">+2.5j </span>
                    <span className="text-500">vs période précédente</span>
                </Card>
            </div>

            {/* Alertes financières */}
            <div className="col-12 lg:col-6">
                <Card className="h-full">
                    <div className="flex justify-content-between align-items-center mb-4">
                        <h5 className="m-0">Alertes Financières</h5>
                        <Badge value="2" severity="danger" />
                    </div>
                    
                    <div className="grid">
                        <div className="col-12">
                            <div className="p-3 border-round bg-red-50 border-left-3 border-red-500">
                                <div className="flex justify-content-between align-items-center">
                                    <div>
                                        <h6 className="text-red-900 mb-1">Factures en retard</h6>
                                        <p className="text-red-800 text-sm m-0">{formatCurrency(stats.montantEnRetard)} à recouvrer</p>
                                    </div>
                                    <Badge value={stats.repartitionStatuts['EN_RETARD'] || 0} severity="danger" />
                                </div>
                            </div>
                        </div>
                        
                        <div className="col-12">
                            <div className="p-3 border-round bg-orange-50 border-left-3 border-orange-500">
                                <div className="flex justify-content-between align-items-center">
                                    <div>
                                        <h6 className="text-orange-900 mb-1">En attente de paiement</h6>
                                        <p className="text-orange-800 text-sm m-0">{formatCurrency(stats.montantEnAttente)} en cours</p>
                                    </div>
                                    <Badge value={stats.repartitionStatuts['ENVOYEE'] || 0} severity="warning" />
                                </div>
                            </div>
                        </div>
                    </div>
                </Card>
            </div>

            <div className="col-12 lg:col-6">
                <Card title="Répartition par statut" className="h-full">
                    <Chart 
                        type="doughnut" 
                        data={repartitionData} 
                        options={chartOptions}
                        height="250px"
                    />
                </Card>
            </div>

            {/* Graphiques d'évolution */}
            <div className="col-12 lg:col-6">
                <Card title="Évolution du nombre de factures">
                    <Chart 
                        type="line" 
                        data={evolutionData} 
                        options={chartOptions}
                        height="300px"
                    />
                </Card>
            </div>

            <div className="col-12 lg:col-6">
                <Card title="Évolution du chiffre d'affaires">
                    <Chart 
                        type="bar" 
                        data={chiffreAffairesData} 
                        options={chartOptions}
                        height="300px"
                    />
                </Card>
            </div>

            {/* Top clients */}
            <div className="col-12 lg:col-6">
                <Card title="Top 5 Clients par CA">
                    <DataTable value={stats.topClients} responsiveLayout="scroll">
                        <Column 
                            field="client" 
                            header="Client"
                            body={(rowData, options) => (
                                <div className="flex align-items-center">
                                    <Badge value={options.rowIndex + 1} className="mr-2" />
                                    {rowData.client}
                                </div>
                            )}
                        />
                        <Column 
                            field="nombre" 
                            header="Nb Factures" 
                            style={{ width: '100px' }}
                        />
                        <Column 
                            field="montant" 
                            header="CA Total" 
                            style={{ width: '120px' }}
                            body={(rowData) => formatCurrency(rowData.montant)}
                        />
                        <Column 
                            header="Taux Paiement" 
                            style={{ width: '120px' }}
                            body={(rowData) => (
                                <Tag 
                                    value={`${Math.round((rowData.montantPaye / rowData.montant) * 100)}%`}
                                    severity={rowData.montantPaye / rowData.montant > 0.9 ? 'success' : 'warning'}
                                />
                            )}
                        />
                    </DataTable>
                </Card>
            </div>

            {/* Clients en retard */}
            <div className="col-12 lg:col-6">
                <Card title="Clients avec retards de paiement">
                    <DataTable value={stats.retardsParClient} responsiveLayout="scroll">
                        <Column field="client" header="Client" />
                        <Column 
                            field="factures" 
                            header="Nb Factures" 
                            style={{ width: '100px' }}
                        />
                        <Column 
                            field="montant" 
                            header="Montant" 
                            style={{ width: '120px' }}
                            body={(rowData) => formatCurrency(rowData.montant)}
                        />
                        <Column 
                            field="retardMoyen" 
                            header="Retard Moyen" 
                            style={{ width: '120px' }}
                            body={(rowData) => (
                                <Tag 
                                    value={`${rowData.retardMoyen}j`}
                                    severity={rowData.retardMoyen > 30 ? 'danger' : 'warning'}
                                />
                            )}
                        />
                    </DataTable>
                </Card>
            </div>

            {/* Analyse et recommandations */}
            <div className="col-12">
                <Card title="Analyse et Recommandations">
                    <div className="grid">
                        <div className="col-12 md:col-4">
                            <div className="p-3 border-round bg-blue-50">
                                <h6 className="text-blue-900 mb-2">
                                    <i className="pi pi-chart-line mr-2"></i>
                                    Performance
                                </h6>
                                <ul className="text-sm text-blue-800 list-none p-0 m-0">
                                    <li className="mb-1">• CA en croissance de 12%</li>
                                    <li className="mb-1">• Taux de recouvrement à 87.5%</li>
                                    <li className="mb-1">• 234 factures émises</li>
                                </ul>
                            </div>
                        </div>
                        
                        <div className="col-12 md:col-4">
                            <div className="p-3 border-round bg-orange-50">
                                <h6 className="text-orange-900 mb-2">
                                    <i className="pi pi-exclamation-triangle mr-2"></i>
                                    Points d'attention
                                </h6>
                                <ul className="text-sm text-orange-800 list-none p-0 m-0">
                                    <li className="mb-1">• {formatCurrency(stats.montantEnRetard)} en retard</li>
                                    <li className="mb-1">• Délai moyen en hausse (+2.5j)</li>
                                    <li className="mb-1">• 18 factures en retard</li>
                                </ul>
                            </div>
                        </div>
                        
                        <div className="col-12 md:col-4">
                            <div className="p-3 border-round bg-green-50">
                                <h6 className="text-green-900 mb-2">
                                    <i className="pi pi-lightbulb mr-2"></i>
                                    Actions recommandées
                                </h6>
                                <ul className="text-sm text-green-800 list-none p-0 m-0">
                                    <li className="mb-1">• Relancer les impayés</li>
                                    <li className="mb-1">• Revoir les conditions de paiement</li>
                                    <li className="mb-1">• Mettre en place des acomptes</li>
                                </ul>
                            </div>
                        </div>
                    </div>
                </Card>
            </div>
        </div>
    );
};

export default FactureStatsPage;