<?php

namespace Modules\FluxoCaixaPro\Services;

use Modules\FluxoCaixaPro\Models\Transaction;
use Modules\FluxoCaixaPro\Models\CashFlowAnalysis;
use Carbon\Carbon;

/**
 * Class CashFlowPredictionService
 *
 * Handles intelligent predictions and analysis for cash flow.
 *
 * @package Modules\FluxoCaixaPro\Services
 */
class CashFlowPredictionService
{
    /**
     * Generate a new cash flow analysis based on historical data.
     *
     * @return CashFlowAnalysis
     */
    public function generateAnalysis(): CashFlowAnalysis
    {
        $lastSixMonths = Carbon::now()->subMonths(6);

        // Use only business transactions for core metrics
        $transactions = Transaction::where('transaction_date', '>=', $lastSixMonths)
            ->where('is_personal', false)
            ->get();

        $count = $transactions->count();
        $monthlyAvgIncome = $count > 0 ? ($transactions->where('type', 'income')->sum('amount') / 6) : 0;
        $monthlyAvgExpense = $count > 0 ? ($transactions->where('type', 'expense')->sum('amount') / 6) : 0;

        $predictedBalance = $monthlyAvgIncome - $monthlyAvgExpense;

        // Pending items analysis
        $pendingIncome = Transaction::where('type', 'income')->where('status', 'pending')->sum('amount');
        $pendingExpense = Transaction::where('type', 'expense')->where('status', 'pending')->sum('amount');

        // Personal mix analysis
        $personalExpense = Transaction::where('is_personal', true)
            ->where('transaction_date', '>=', $lastSixMonths)
            ->sum('amount');

        $recommendations = $this->generateDetailedRecommendations([
            'income' => $monthlyAvgIncome,
            'expense' => $monthlyAvgExpense,
            'pending_income' => $pendingIncome,
            'pending_expense' => $pendingExpense,
            'personal_expense' => $personalExpense,
            'balance' => $predictedBalance
        ]);

        return CashFlowAnalysis::create([
            'analysis_date' => Carbon::now(),
            'summary_data' => [
                'period_analyzed' => $lastSixMonths->format('Y-m') . ' to ' . Carbon::now()->format('Y-m'),
                'predicted_balance' => $predictedBalance,
                'avg_monthly_income' => $monthlyAvgIncome,
                'avg_monthly_expense' => $monthlyAvgExpense,
                'growth_rate' => $this->calculateGrowthRate(),
                'risk_level' => $this->calculateRiskLevel($predictedBalance, $pendingExpense, $pendingIncome),
                'personal_mix_ratio' => $monthlyAvgExpense > 0 ? ($personalExpense / ($monthlyAvgExpense * 6)) : 0
            ],
            'recommendations' => $recommendations,
            'projections' => $this->getProjections()
        ]);
    }

    /**
     * Generate detailed recommendations based on financial management principles.
     */
    private function generateDetailedRecommendations(array $data): string
    {
        $rec = [];

        // 1. Separation of accounts (Core management principle)
        if ($data['personal_expense'] > 0) {
            $rec[] = "⚠️ SEPARAÇÃO DE CONTAS: Identificamos gastos pessoais misturados aos da empresa. Recomenda-se que o empresário tenha um 'Pró-labore' fixo e nunca use o caixa da empresa para despesas pessoais.";
        }

        // 2. Operational Health
        if ($data['balance'] < 0) {
            $rec[] = "🔴 DÉFICIT OPERACIONAL: Suas despesas empresariais superam as receitas. Revise seus custos fixos e tente aumentar o volume de vendas ou reajustar preços.";
        } elseif ($data['balance'] < ($data['income'] * 0.15)) {
            $rec[] = "🟡 MARGEM ESTREITA: Seu saldo operacional está muito próximo de zero. Qualquer imprevisto pode gerar necessidade de capital de giro externo (empréstimos).";
        }

        // 3. Accounts Payable vs Receivable
        if ($data['pending_expense'] > $data['pending_income']) {
            $gap = $data['pending_expense'] - $data['pending_income'];
            $rec[] = "📉 GAP DE CAIXA: Você tem R$ " . number_format($gap, 2, ',', '.') . " a mais em contas a pagar do que a receber nos próximos períodos. Antecipe recebíveis ou renegocie prazos com fornecedores.";
        }

        // 4. Working Capital Reserve
        $reserveNeeded = $data['expense'] * 3; // 3 months of reserve
        $rec[] = "🏦 RESERVA DE EMERGÊNCIA: Recomenda-se manter uma reserva de 3 a 6 meses de despesas. Sua meta de reserva deve ser de aproximadamente R$ " . number_format($reserveNeeded, 2, ',', '.') . ".";

        if (empty($rec)) {
            $rec[] = "✅ SAÚDE FINANCEIRA: Seu fluxo de caixa está equilibrado. Continue registrando todas as movimentações diariamente para manter a precisão das projeções.";
        }

        return implode("\n\n", $rec);
    }

    /**
     * Calculate risk level.
     */
    private function calculateRiskLevel(float $balance, float $pendingExp, float $pendingInc): string
    {
        if ($balance < 0 || ($pendingExp > $pendingInc * 1.5)) {
            return 'High';
        }
        if ($balance < 500 || $pendingExp > $pendingInc) {
            return 'Medium';
        }
        return 'Low';
    }

    /**
     * Calculate growth rate based on last two months.
     *
     * @return float
     */
    /**
     * Calculate growth rate based on last two months.
     *
     * @return float
     */
    private function calculateGrowthRate(): float
    {
        $currentMonth = Carbon::now()->startOfMonth();
        $lastMonth = Carbon::now()->subMonth()->startOfMonth();

        $currentIncome = Transaction::where('type', 'income')
            ->whereBetween('transaction_date', [$currentMonth, Carbon::now()])
            ->sum('amount');

        $lastMonthIncome = Transaction::where('type', 'income')
            ->whereBetween('transaction_date', [$lastMonth, $currentMonth->subDay()])
            ->sum('amount');

        if ($lastMonthIncome == 0) {
            return 0;
        }

        return (($currentIncome - $lastMonthIncome) / $lastMonthIncome) * 100;
    }

    /**
     * getProjections - Generate basic future projections for the analysis
     *
     * @return array
     */
    private function getProjections(): array
    {
        $lastSixMonths = Carbon::now()->subMonths(6);
        $transactions = Transaction::where('transaction_date', '>=', $lastSixMonths)
            ->where('is_personal', false)
            ->get();

        $monthlyAvgIncome = $transactions->where('type', 'income')->sum('amount') / 6;
        $monthlyAvgExpense = $transactions->where('type', 'expense')->sum('amount') / 6;

        $projections = [];
        for ($i = 1; $i <= 3; $i++) {
            $month = Carbon::now()->addMonths($i)->format('Y-m');
            $projections[] = [
                'month' => $month,
                'predicted_income' => round($monthlyAvgIncome, 2),
                'predicted_expense' => round($monthlyAvgExpense, 2),
                'predicted_balance' => round($monthlyAvgIncome - $monthlyAvgExpense, 2)
            ];
        }

        return $projections;
    }
}