<?php

namespace App\Services\Otp;

use App\Models\OtpCode;
use App\Models\User;
use App\Services\Sms\SmsService;
use Illuminate\Support\Facades\Hash;

class OtpService
{
    public function __construct(private readonly SmsService $sms) {}

    public function issue(
        string $destination,
        string $purpose,
        ?User $user = null,
        string $channel = OtpCode::CHANNEL_SMS,
    ): OtpIssueResult {
        $cooldown = (int) config('services.otp.resend_cooldown_seconds', 60);
        $latest = OtpCode::query()
            ->where('destination', $destination)
            ->where('purpose', $purpose)
            ->latest('id')
            ->first();

        if ($latest && $latest->created_at->diffInSeconds(now()) < $cooldown && ! $latest->isConsumed()) {
            $retryAfter = $cooldown - (int) $latest->created_at->diffInSeconds(now());

            return OtpIssueResult::throttled(max(1, $retryAfter));
        }

        $code = $this->generateCode();
        $ttl = (int) config('services.otp.ttl_minutes', 10);

        $otp = OtpCode::create([
            'user_id' => $user?->id,
            'channel' => $channel,
            'destination' => $destination,
            'purpose' => $purpose,
            'code_hash' => Hash::make($code),
            'attempts' => 0,
            'expires_at' => now()->addMinutes($ttl),
        ]);

        $message = $this->renderMessage($purpose, $code, $ttl);
        $sendResult = $channel === OtpCode::CHANNEL_SMS
            ? $this->sms->send($destination, $message)
            : null;

        return OtpIssueResult::issued($otp, $code, $sendResult);
    }

    public function verify(string $destination, string $purpose, string $code): OtpVerifyResult
    {
        $otp = OtpCode::query()
            ->where('destination', $destination)
            ->where('purpose', $purpose)
            ->whereNull('consumed_at')
            ->latest('id')
            ->first();

        if (! $otp) {
            return OtpVerifyResult::notFound();
        }

        if ($otp->isExpired()) {
            return OtpVerifyResult::expired();
        }

        if ($otp->isExhausted()) {
            return OtpVerifyResult::exhausted();
        }

        $otp->increment('attempts');

        if (! Hash::check($code, $otp->code_hash)) {
            return OtpVerifyResult::invalid($otp->fresh());
        }

        $otp->forceFill(['consumed_at' => now()])->save();

        return OtpVerifyResult::ok($otp);
    }

    private function generateCode(): string
    {
        $length = max(4, (int) config('services.otp.length', 6));
        $max = (10 ** $length) - 1;

        return str_pad((string) random_int(0, $max), $length, '0', STR_PAD_LEFT);
    }

    private function renderMessage(string $purpose, string $code, int $ttlMinutes): string
    {
        $reason = match ($purpose) {
            OtpCode::PURPOSE_REGISTER => 'verify your Verde registration',
            OtpCode::PURPOSE_LOGIN => 'log in to Verde',
            OtpCode::PURPOSE_PASSWORD_RESET => 'reset your Verde password',
            OtpCode::PURPOSE_PHONE_VERIFY => 'verify your Verde phone number',
            default => 'continue with Verde',
        };

        return "Your Verde code is {$code} (valid {$ttlMinutes} min). Use to {$reason}. Do not share.";
    }
}