<?php

namespace App\Services;

use App\Game\GlobalUserInfo;
use App\Game\Services\OuroGameService;
use App\Http\helper\NumConfig;
use App\Models\RewardCode;
use App\Models\RewardCodeClaim;
use Carbon\Carbon;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Str;

class RewardCodeService
{
    const STATUS_ACTIVE = 1;
    const STATUS_INACTIVE = 0;

    /**
     * Generate a unique 4-char alphanumeric reward code.
     */
    public static function generateUniqueCode(int $maxRetry = 5): string
    {
        for ($i = 0; $i < $maxRetry; $i++) {
            $code = strtoupper(Str::random(4));
            if (!RewardCode::where('code', $code)->exists()) {
                return $code;
            }
        }
        throw new \RuntimeException('Failed to generate unique reward code');
    }

    /**
     * Redeem reward by code.
     */
    public static function redeem(string $code, string $GlobalUID, string $clientIp = '', int $UserID = 0): array
    {
        $code = strtoupper($code);
        $now = Carbon::now();
        if (!$UserID) {
            $user = GlobalUserInfo::getGameUserInfo('GlobalUID', $GlobalUID);
            if (!$user) {
                throw new \InvalidArgumentException('user_not_exist');
            }
            $UserID = $user->UserID;
        }

        return DB::connection('write')->transaction(function () use ($code, $UserID, $GlobalUID, $clientIp, $now) {
            $rewardCode = RewardCode::where('code', $code)->lockForUpdate()->first();
            if (!$rewardCode || $rewardCode->status != self::STATUS_ACTIVE) {
                throw new \InvalidArgumentException('code_not_found');
            }
            if ($rewardCode->expire_at && $now->gt(Carbon::parse($rewardCode->expire_at))) {
                throw new \InvalidArgumentException('code_expired');
            }
            if ($rewardCode->claimed_count >= $rewardCode->total_count) {
                throw new \InvalidArgumentException('code_limit_reached');
            }
            if ($rewardCode->claimed_amount >= $rewardCode->total_amount) {
                throw new \InvalidArgumentException('code_amount_exhausted');
            }
            if (RewardCodeClaim::where('reward_code_id', $rewardCode->id)->where('UserID', $UserID)->exists()) {
                throw new \InvalidArgumentException('already_claimed');
            }

            $remainingCount = $rewardCode->total_count - $rewardCode->claimed_count;
            $remainingAmount = $rewardCode->total_amount - $rewardCode->claimed_amount;

            if ($remainingAmount < $rewardCode->min_amount) {
                throw new \InvalidArgumentException('code_amount_exhausted');
            }

            // fixed-point to support decimals (<1)
            $scale = 100;
            $min = (int)round($rewardCode->min_amount * $scale);
            $max = (int)round($rewardCode->max_amount * $scale);
            $remainingScaled = (int)floor($remainingAmount * $scale);

            $minReserve = ($remainingCount - 1) * $min;
            $maxPossible = $remainingScaled - $minReserve;
            $maxPossible = max($min, min($max, $maxPossible));
            $reward = mt_rand($min, $maxPossible) / $scale;
            $reward = round($reward, 2);

            $rewardCode->claimed_count += 1;
            $rewardCode->claimed_amount = round($rewardCode->claimed_amount + $reward, 2);
            $rewardCode->save();

            RewardCodeClaim::create([
                'reward_code_id' => $rewardCode->id,
                'code' => $rewardCode->code,
                'UserID' => $UserID,
                'GlobalUID' => $GlobalUID,
                'amount' => $reward,
                'client_ip' => $clientIp,
            ]);

            $scoreAmount = (int)round($reward * NumConfig::NUM_VALUE);
            OuroGameService::AddScore($UserID, $scoreAmount, OuroGameService::REASON_RewardCode,false);

            return [
                'code' => $rewardCode->code,
                'amount' => $reward,
                'claimed_count' => $rewardCode->claimed_count,
                'claimed_amount' => $rewardCode->claimed_amount,
                'total_count' => $rewardCode->total_count,
                'total_amount' => $rewardCode->total_amount,
                'expire_at' => $rewardCode->expire_at,
            ];
        });
    }
}