<?php

namespace App\Services;

use App\Models\Client;
use App\Models\ClientTier;
use App\Models\ClientTierHistory;

class ClientTierService
{
    /**
     * Calcular y actualizar el tier del cliente basado en sus compras totales
     */
    public function recalculateClientTier(Client $client): ?ClientTier
    {
        // Calcular compras netas (total - devoluciones)
        $netPurchases = $client->total_purchases - $client->lifetime_returns;

        // Buscar el tier apropiado ordenado por monto mínimo descendente
        $newTier = ClientTier::active()
            ->where('min_purchase_amount', '<=', $netPurchases)
            ->where(function ($query) use ($netPurchases) {
                $query->whereNull('max_purchase_amount')
                      ->orWhere('max_purchase_amount', '>=', $netPurchases);
            })
            ->orderBy('min_purchase_amount', 'desc')
            ->first();

        // Si cambió el tier, registrar en historial
        if ($newTier && $client->tier_id !== $newTier->id) {
            $this->recordTierChange($client, $newTier, $netPurchases);

            $client->tier_id = $newTier->id;
            $client->save();
        }

        return $newTier;
    }

    /**
     * Registrar cambio de tier en el historial
     */
    protected function recordTierChange(Client $client, ClientTier $newTier, float $totalAtChange): void
    {
        ClientTierHistory::create([
            'client_id' => $client->id,
            'old_tier_id' => $client->tier_id,
            'new_tier_id' => $newTier->id,
            'total_at_change' => $totalAtChange,
            'reason' => 'Actualización automática por cambio en compras acumuladas',
        ]);
    }

    /**
     * Obtener descuento aplicable para un cliente
     */
    public function getApplicableDiscount(Client $client): float
    {
        if (!$client->tier) {
            return 0.00;
        }

        return $client->tier->discount_percentage;
    }

    /**
     * Actualizar estadísticas de compra del cliente
     */
    public function updateClientPurchaseStats(Client $client, float $amount, int $quantity = 1): void
    {
        $client->total_purchases += $amount;
        $client->total_transactions += 1;
        $client->last_purchase_at = now();
        $client->save();

        // Recalcular tier después de actualizar stats
        $this->recalculateClientTier($client);
    }

    /**
     * Revertir estadísticas de compra del cliente (para devoluciones)
     */
    public function revertClientPurchaseStats(Client $client, float $amount): void
    {
        $client->lifetime_returns += $amount;
        $client->save();

        // Recalcular tier después de registrar devolución
        $this->recalculateClientTier($client);
    }

    /**
     * Obtener todos los tiers activos
     */
    public function getActiveTiers()
    {
        return ClientTier::active()
            ->orderBy('min_purchase_amount')
            ->get();
    }

    /**
     * Obtener tier apropiado para un monto específico
     */
    public function getTierForAmount(float $amount): ?ClientTier
    {
        return ClientTier::active()
            ->where('min_purchase_amount', '<=', $amount)
            ->where(function ($query) use ($amount) {
                $query->whereNull('max_purchase_amount')
                      ->orWhere('max_purchase_amount', '>=', $amount);
            })
            ->orderBy('min_purchase_amount', 'desc')
            ->first();
    }

    /**
     * Obtener estadísticas del cliente
     */
    public function getClientStats(Client $client): array
    {
        return [
            'client_number' => $client->client_number,
            'total_purchases' => $client->total_purchases,
            'lifetime_returns' => $client->lifetime_returns,
            'net_purchases' => $client->net_purchases,
            'total_transactions' => $client->total_transactions,
            'last_purchase_at' => $client->last_purchase_at,
            'average_purchase' => $client->total_transactions > 0
                ? $client->total_purchases / $client->total_transactions
                : 0,
            'current_tier' => $client->tier ? [
                'id' => $client->tier->id,
                'name' => $client->tier->tier_name,
                'discount' => $client->tier->discount_percentage,
            ] : null,
            'next_tier' => $this->getNextTier($client),
        ];
    }

    /**
     * Obtener información del siguiente tier disponible
     */
    protected function getNextTier(Client $client): ?array
    {
        $currentAmount = $client->net_purchases;
        $currentTierId = $client->tier_id;

        $nextTier = ClientTier::active()
            ->where('min_purchase_amount', '>', $currentAmount)
            ->orderBy('min_purchase_amount')
            ->first();

        if ($nextTier) {
            return [
                'id' => $nextTier->id,
                'name' => $nextTier->tier_name,
                'discount' => $nextTier->discount_percentage,
                'required_amount' => $nextTier->min_purchase_amount,
                'remaining_amount' => $nextTier->min_purchase_amount - $currentAmount,
            ];
        }

        return null;
    }
}