<?php

namespace App\Services;

use App\Enums\ReviewState;
use App\Enums\ShipmentStatus;
use App\Models\Shipment;
use App\Models\ShipmentReview;
use App\Models\ShipmentStatusHistory;
use App\Models\User;
use Illuminate\Support\Facades\DB;
use RuntimeException;

class ShipmentReviewService
{
    /**
     * درخواست اصلاح سفارش توسط کارمند.
     *
     * این عملیات یک Review Revision جدید ایجاد می‌کند،
     * چون یک submission جدید برای بررسی ثبت شده است.
     */
    public function requestChanges(
        Shipment $shipment,
        User $user,
        string $reason,
        ?string $notes = null
    ): Shipment {
        return DB::transaction(function () use ($shipment, $user, $reason, $notes) {

            $shipment = Shipment::query()
                ->lockForUpdate()
                ->findOrFail($shipment->id);

            $this->assertPendingReview(
                $shipment,
                'این سفارش در وضعیت قابل درخواست اصلاح نیست.'
            );

            $revisionNo = $this->nextReviewRevision($shipment);

            $shipment->update([
                'review_state' => ReviewState::ChangesRequested,
            ]);

            ShipmentReview::create([
                'shipment_id' => $shipment->id,
                'revision_no' => $revisionNo,
                'decision' => ReviewState::ChangesRequested->value,
                'reason' => $reason,
                'notes' => $notes,
                'reviewed_by' => $user->id,
                'reviewed_at' => now(),
            ]);

            return $shipment->fresh();
        });
    }

    /**
     * تأیید سفارش توسط کارمند.
     *
     * تأیید، Review جدید ایجاد نمی‌کند.
     * آخرین revision با وضعیت pending را finalize می‌کند.
     */
    public function approve(
        Shipment $shipment,
        User $user,
        ?string $notes = null
    ): Shipment {
        return DB::transaction(function () use ($shipment, $user, $notes) {

            $shipment = Shipment::query()
                ->lockForUpdate()
                ->findOrFail($shipment->id);

            $this->assertPendingReview(
                $shipment,
                'این سفارش در وضعیت قابل تأیید نیست.'
            );

            $review = $this->getPendingReview($shipment);

            $oldStatus = $shipment->status;

            $shipment->update([
                'status' => ShipmentStatus::Approved,
                'review_state' => ReviewState::Approved,
            ]);

            ShipmentStatusHistory::create([
                'shipment_id' => $shipment->id,
                'from_status' => $oldStatus->value,
                'to_status' => ShipmentStatus::Approved->value,
                'reason' => $notes ?: 'تأیید توسط کارمند',
                'changed_by' => $user->id,
            ]);

            $review->update([
                'decision' => ReviewState::Approved->value,
                'reason' => null,
                'notes' => $notes,
                'reviewed_by' => $user->id,
                'reviewed_at' => now(),
            ]);

            return $shipment->fresh();
        });
    }

    /**
     * رد سفارش توسط کارمند.
     *
     * رد، Review جدید ایجاد نمی‌کند.
     * آخرین revision با وضعیت pending را finalize می‌کند.
     */
    public function reject(
        Shipment $shipment,
        User $user,
        string $reason
    ): Shipment {
        return DB::transaction(function () use ($shipment, $user, $reason) {

            $shipment = Shipment::query()
                ->lockForUpdate()
                ->findOrFail($shipment->id);

            $this->assertPendingReview(
                $shipment,
                'این سفارش در وضعیت قابل رد نیست.'
            );

            $review = $this->getPendingReview($shipment);

            $oldStatus = $shipment->status;

            $shipment->update([
                'status' => ShipmentStatus::Cancelled,
                'review_state' => ReviewState::Rejected,
            ]);

            ShipmentStatusHistory::create([
                'shipment_id' => $shipment->id,
                'from_status' => $oldStatus->value,
                'to_status' => ShipmentStatus::Cancelled->value,
                'reason' => 'رد شده: ' . $reason,
                'changed_by' => $user->id,
            ]);

            $review->update([
                'decision' => ReviewState::Rejected->value,
                'reason' => $reason,
                'notes' => null,
                'reviewed_by' => $user->id,
                'reviewed_at' => now(),
            ]);

            return $shipment->fresh();
        });
    }

    /**
     * بررسی وضعیت فعلی Shipment برای عملیات Review.
     */
    private function assertPendingReview(
        Shipment $shipment,
        string $message
    ): void {
        if (
            $shipment->status !== ShipmentStatus::PendingApproval ||
            $shipment->review_state !== ReviewState::Pending
        ) {
            throw new RuntimeException($message);
        }
    }

    /**
     * پیدا کردن Review فعلی که منتظر تصمیم کارمند است.
     *
     * بعد از resubmit باید دقیقاً یک revision با decision=pending
     * وجود داشته باشد.
     */
    private function getPendingReview(Shipment $shipment): ShipmentReview
    {
        $review = $shipment->reviews()
            ->where('decision', ReviewState::Pending->value)
            ->orderByDesc('revision_no')
            ->first();

        if (!$review) {
            throw new RuntimeException(
                'برای این سفارش هیچ Review در وضعیت pending پیدا نشد.'
            );
        }

        return $review;
    }

    /**
     * تعیین شماره revision بعدی.
     *
     * هر resubmission یک revision جدید ایجاد می‌کند.
     */
    private function nextReviewRevision(Shipment $shipment): int
    {
        return ((int) $shipment->reviews()->max('revision_no')) + 1;
    }
}