<?php

declare(strict_types=1);

namespace App\Repositories;

use Illuminate\Support\Facades\DB;

class FinancialStatisticsRepository implements FinancialStatisticsRepositoryInterface
{
    /**
     * Statuses considered as actual revenue (exclude drafts & cancelled).
     */
    private const REVENUE_STATUSES = ['emise', 'envoyee', 'partiellement_payee', 'payee', 'echue'];

    /**
     * Statuses representing open receivables (unpaid, overdue).
     */
    private const RECEIVABLE_STATUSES = ['emise', 'envoyee', 'partiellement_payee', 'echue'];

    /**
     * Avoir statuses that count as effectively emitted.
     */
    private const AVOIR_EMITTED_STATUSES = ['emis', 'applique'];

    public function getStatistics(): array
    {
        return [
            'revenue'              => $this->revenueStats(),
            'quote_conversion'     => $this->quoteConversionRate(),
            'avg_amount_per_case'  => $this->avgAmountPerCase(),
            'avg_payment_delay'    => $this->avgPaymentDelay(),
            'avoirs'               => $this->avoirsStats(),
            'receivables'          => $this->receivablesStats(),
        ];
    }

    // ─── 1. Chiffre d'affaires mensuel & annuel ───────────────────────────────

    private function revenueStats(): array
    {
        $currentYear = now()->year;

        // Monthly CA for current year
        $monthly = DB::table('invoices')
            ->selectRaw('MONTH(invoice_date) as month, SUM(total_ttc) as total_ttc, SUM(total_ht) as total_ht, COUNT(*) as count')
            ->whereIn('status', self::REVENUE_STATUSES)
            ->whereYear('invoice_date', $currentYear)
            ->groupByRaw('MONTH(invoice_date)')
            ->orderByRaw('MONTH(invoice_date)')
            ->get()
            ->keyBy('month');

        // Build a full 12-month array (0 for missing months)
        $monthlyFull = [];
        for ($m = 1; $m <= 12; $m++) {
            $row = $monthly->get($m);
            $monthlyFull[] = [
                'month'      => $m,
                'total_ttc'  => $row ? (float) $row->total_ttc : 0.0,
                'total_ht'   => $row ? (float) $row->total_ht  : 0.0,
                'count'      => $row ? (int)   $row->count     : 0,
            ];
        }

        // Annual CA — current and previous year for comparison
        $annualRows = DB::table('invoices')
            ->selectRaw('YEAR(invoice_date) as year, SUM(total_ttc) as total_ttc, SUM(total_ht) as total_ht, COUNT(*) as count')
            ->whereIn('status', self::REVENUE_STATUSES)
            ->whereYear('invoice_date', '>=', $currentYear - 1)
            ->groupByRaw('YEAR(invoice_date)')
            ->orderByRaw('YEAR(invoice_date)')
            ->get()
            ->keyBy('year');

        $yearCurrent  = $annualRows->get($currentYear);
        $yearPrevious = $annualRows->get($currentYear - 1);

        $annualCurrentTtc  = $yearCurrent  ? (float) $yearCurrent->total_ttc  : 0.0;
        $annualPreviousTtc = $yearPrevious ? (float) $yearPrevious->total_ttc : 0.0;

        $annualGrowthPct = $annualPreviousTtc > 0
            ? round((($annualCurrentTtc - $annualPreviousTtc) / $annualPreviousTtc) * 100, 2)
            : null;

        return [
            'current_year'      => $currentYear,
            'annual_current'    => [
                'total_ttc' => $annualCurrentTtc,
                'total_ht'  => $yearCurrent ? (float) $yearCurrent->total_ht : 0.0,
                'count'     => $yearCurrent ? (int)   $yearCurrent->count    : 0,
            ],
            'annual_previous'   => [
                'total_ttc' => $annualPreviousTtc,
                'total_ht'  => $yearPrevious ? (float) $yearPrevious->total_ht : 0.0,
                'count'     => $yearPrevious ? (int)   $yearPrevious->count    : 0,
            ],
            'annual_growth_pct' => $annualGrowthPct,
            'monthly'           => $monthlyFull,
        ];
    }

    // ─── 2. Taux de conversion devis → facture ────────────────────────────────

    private function quoteConversionRate(): array
    {
        $totalQuotes = (int) DB::table('quotes')
            ->whereNotIn('status', ['annule'])
            ->count();

        // A quote is "converted" when at least one invoice references it
        $convertedQuotes = (int) DB::table('quotes')
            ->join('invoices', 'invoices.source_quote_id', '=', 'quotes.id')
            ->whereNotIn('quotes.status', ['annule'])
            ->distinct('quotes.id')
            ->count('quotes.id');

        $rate = $totalQuotes > 0
            ? round(($convertedQuotes / $totalQuotes) * 100, 2)
            : 0.0;

        // Breakdown by quote status
        $byStatus = DB::table('quotes')
            ->selectRaw('status, COUNT(*) as total')
            ->groupBy('status')
            ->get();

        return [
            'total_quotes'     => $totalQuotes,
            'converted_quotes' => $convertedQuotes,
            'conversion_rate'  => $rate,
            'by_status'        => $byStatus,
        ];
    }

    // ─── 3. Montant moyen par dossier (panier moyen) ─────────────────────────

    private function avgAmountPerCase(): array
    {
        $row = DB::table('invoices')
            ->selectRaw('AVG(total_ttc) as avg_ttc, AVG(total_ht) as avg_ht, COUNT(*) as total_count, SUM(total_ttc) as sum_ttc')
            ->whereIn('status', self::REVENUE_STATUSES)
            ->first();

        return [
            'avg_ttc'     => $row && $row->avg_ttc !== null ? round((float) $row->avg_ttc, 2) : null,
            'avg_ht'      => $row && $row->avg_ht  !== null ? round((float) $row->avg_ht,  2) : null,
            'total_count' => $row ? (int) $row->total_count : 0,
            'total_ttc'   => $row ? (float) $row->sum_ttc   : 0.0,
        ];
    }

    // ─── 4. Délai moyen de paiement ───────────────────────────────────────────

    private function avgPaymentDelay(): array
    {
        // Use document_status_history to find the exact moment status became 'payee'
        $avgFromHistory = DB::table('invoices')
            ->join('document_status_history as dsh', function ($join) {
                $join->on('dsh.document_id', '=', 'invoices.id')
                     ->where('dsh.document_type', '=', 'invoice')
                     ->where('dsh.new_status', '=', 'payee');
            })
            ->selectRaw('AVG(DATEDIFF(dsh.changed_at, invoices.invoice_date)) as avg_days')
            ->where('invoices.status', 'payee')
            ->value('avg_days');

        // Fallback: avg delay between invoice_date and due_date for paid invoices
        $avgFromDueDate = DB::table('invoices')
            ->selectRaw('AVG(DATEDIFF(due_date, invoice_date)) as avg_days')
            ->where('status', 'payee')
            ->whereNotNull('due_date')
            ->value('avg_days');

        // Count overdue invoices (echue = past due_date, still unpaid)
        $overdueCount = (int) DB::table('invoices')
            ->where('status', 'echue')
            ->count();

        $overdueTotal = (float) DB::table('invoices')
            ->where('status', 'echue')
            ->sum('total_ttc');

        return [
            'avg_days_to_payment'          => $avgFromHistory !== null
                ? round((float) $avgFromHistory, 1)
                : ($avgFromDueDate !== null ? round((float) $avgFromDueDate, 1) : null),
            'avg_days_invoice_to_due'       => $avgFromDueDate !== null
                ? round((float) $avgFromDueDate, 1)
                : null,
            'overdue_invoices_count'        => $overdueCount,
            'overdue_invoices_total_ttc'    => $overdueTotal,
        ];
    }

    // ─── 5. Volume d'avoirs émis ──────────────────────────────────────────────

    private function avoirsStats(): array
    {
        $totals = DB::table('avoirs')
            ->selectRaw('COUNT(*) as count, SUM(total_ttc) as total_ttc, SUM(total_ht) as total_ht')
            ->whereIn('status', self::AVOIR_EMITTED_STATUSES)
            ->first();

        // Breakdown by reason type
        $byReason = DB::table('avoirs')
            ->selectRaw('reason_type, COUNT(*) as count, SUM(total_ttc) as total_ttc')
            ->whereIn('status', self::AVOIR_EMITTED_STATUSES)
            ->groupBy('reason_type')
            ->orderByDesc('count')
            ->get();

        // Monthly trend (current year)
        $monthlyTrend = DB::table('avoirs')
            ->selectRaw('MONTH(avoir_date) as month, COUNT(*) as count, SUM(total_ttc) as total_ttc')
            ->whereIn('status', self::AVOIR_EMITTED_STATUSES)
            ->whereYear('avoir_date', now()->year)
            ->groupByRaw('MONTH(avoir_date)')
            ->orderByRaw('MONTH(avoir_date)')
            ->get();

        return [
            'total_count'  => $totals ? (int)   $totals->count     : 0,
            'total_ttc'    => $totals ? (float) $totals->total_ttc  : 0.0,
            'total_ht'     => $totals ? (float) $totals->total_ht   : 0.0,
            'by_reason'    => $byReason,
            'monthly_trend' => $monthlyTrend,
        ];
    }

    // ─── 6. Créances en cours (relances prioritaires) ─────────────────────────

    private function receivablesStats(): array
    {
        // Global totals
        $totals = DB::table('invoices')
            ->selectRaw('COUNT(*) as count, SUM(total_ttc) as total_ttc')
            ->whereIn('status', self::RECEIVABLE_STATUSES)
            ->first();

        // Breakdown by status
        $byStatus = DB::table('invoices')
            ->selectRaw('status, COUNT(*) as count, SUM(total_ttc) as total_ttc')
            ->whereIn('status', self::RECEIVABLE_STATUSES)
            ->groupBy('status')
            ->get();

        // Top 10 clients with highest outstanding balance
        $topDebtors = DB::table('invoices')
            ->join('clients', 'invoices.client_id', '=', 'clients.id')
            ->select(
                'clients.id',
                'clients.name',
                DB::raw('COUNT(invoices.id) as invoice_count'),
                DB::raw('SUM(invoices.total_ttc) as total_outstanding')
            )
            ->whereIn('invoices.status', self::RECEIVABLE_STATUSES)
            ->groupBy('clients.id', 'clients.name')
            ->orderByDesc('total_outstanding')
            ->limit(10)
            ->get();

        // Overdue (echue) + near-due (due within 7 days) detail
        $criticalInvoices = DB::table('invoices')
            ->join('clients', 'invoices.client_id', '=', 'clients.id')
            ->select(
                'invoices.id',
                'invoices.invoice_number',
                'invoices.status',
                'invoices.due_date',
                'invoices.total_ttc',
                'clients.name as client_name',
                'clients.id as client_id',
                DB::raw('DATEDIFF(NOW(), invoices.due_date) as days_overdue')
            )
            ->where(function ($q) {
                $q->where('invoices.status', 'echue')
                  ->orWhere(function ($q2) {
                      $q2->whereIn('invoices.status', ['emise', 'envoyee', 'partiellement_payee'])
                         ->whereRaw('invoices.due_date <= DATE_ADD(NOW(), INTERVAL 7 DAY)')
                         ->whereNotNull('invoices.due_date');
                  });
            })
            ->orderByRaw('invoices.due_date ASC')
            ->limit(20)
            ->get();

        return [
            'total_count'       => $totals ? (int)   $totals->count    : 0,
            'total_outstanding' => $totals ? (float) $totals->total_ttc : 0.0,
            'by_status'         => $byStatus,
            'top_debtors'       => $topDebtors,
            'critical_invoices' => $criticalInvoices,
        ];
    }
}