<?php
declare(strict_types=1);

function game_special_definitions(array $settings): array
{
    $definitions = [
        ['key'=>'xsy','name'=>'小三元','type'=>1,'positions'=>[2,14,24]],
        ['key'=>'dsy','name'=>'大三元','type'=>2,'positions'=>[5,6,11,17,23]],
        ['key'=>'dsx','name'=>'大四喜','type'=>3,'positions'=>[10,23,11,5,17]],
        ['key'=>'tnsh','name'=>'天女散花','type'=>4,'positions'=>[1,7,13,19]],
        ['key'=>'tlbb','name'=>'天龙八部','type'=>5,'positions'=>[12,16,20,24]],
        ['key'=>'shuaidao','name'=>'甩刀','type'=>6,'positions'=>[8,9,20,21]],
        ['key'=>'huoche','name'=>'开火车','type'=>7,'positions'=>[3,4,15,16]],
        ['key'=>'dmg','name'=>'大满贯','type'=>8,'positions'=>range(1,24)],
    ];
    foreach ($definitions as &$definition) {
        $key = $definition['key'];
        $definition['rate'] = max(0.0, (float)($settings['special_'.$key.'_rate'] ?? 0));
        $definition['odds'] = max(0.0, (float)($settings['special_'.$key.'_odds'] ?? 0));
    }
    unset($definition);
    return $definitions;
}

function game_board(array $settings): array
{
    $odds = static fn(string $key, string $level, float $fallback): float => max(0.0, (float)($settings['odds_'.$key.'_'.$level] ?? $fallback));
    return [
        1=>['fruit'=>13,'name'=>'橘子','multiplier'=>$odds('jz','high',10)],
        2=>['fruit'=>2,'name'=>'铃铛','multiplier'=>$odds('ld','high',10)],
        3=>['fruit'=>4,'name'=>'BAR','multiplier'=>$odds('bar','low',50)],
        4=>['fruit'=>4,'name'=>'BAR','multiplier'=>$odds('bar','high',100)],
        5=>['fruit'=>5,'name'=>'苹果','multiplier'=>$odds('pg','high',5)],
        6=>['fruit'=>5,'name'=>'苹果','multiplier'=>$odds('pg','low',2)],
        7=>['fruit'=>19,'name'=>'柠檬','multiplier'=>$odds('nm','high',10)],
        8=>['fruit'=>8,'name'=>'西瓜','multiplier'=>$odds('xg','high',20)],
        9=>['fruit'=>8,'name'=>'西瓜','multiplier'=>$odds('xg','low',2)],
        10=>['fruit'=>0,'name'=>'LUCKY','multiplier'=>0],
        11=>['fruit'=>5,'name'=>'苹果','multiplier'=>$odds('pg','high',5)],
        12=>['fruit'=>13,'name'=>'橘子','multiplier'=>$odds('jz','low',2)],
        13=>['fruit'=>13,'name'=>'橘子','multiplier'=>$odds('jz','high',10)],
        14=>['fruit'=>2,'name'=>'铃铛','multiplier'=>$odds('ld','high',10)],
        15=>['fruit'=>16,'name'=>'77','multiplier'=>$odds('77','low',2)],
        16=>['fruit'=>16,'name'=>'77','multiplier'=>$odds('77','high',20)],
        17=>['fruit'=>5,'name'=>'苹果','multiplier'=>$odds('pg','high',5)],
        18=>['fruit'=>19,'name'=>'柠檬','multiplier'=>$odds('nm','low',2)],
        19=>['fruit'=>19,'name'=>'柠檬','multiplier'=>$odds('nm','high',10)],
        20=>['fruit'=>20,'name'=>'双星','multiplier'=>$odds('xx','high',20)],
        21=>['fruit'=>20,'name'=>'双星','multiplier'=>$odds('xx','low',2)],
        22=>['fruit'=>0,'name'=>'LUCKY','multiplier'=>0],
        23=>['fruit'=>5,'name'=>'苹果','multiplier'=>$odds('pg','high',5)],
        24=>['fruit'=>2,'name'=>'铃铛','multiplier'=>$odds('ld','low',2)],
    ];
}

function game_window_stats(PDO $pdo, int $window): array
{
    $window = min(100000, max(100, $window));
    $sql = "SELECT COALESCE(SUM(bet_amount),0) AS bets, COALESCE(SUM(win_amount),0) AS wins, COUNT(*) AS rounds FROM (SELECT bet_amount, win_amount FROM game_logs WHERE game_type='spin' ORDER BY id DESC LIMIT ".$window.') recent';
    $row = $pdo->query($sql)->fetch() ?: [];
    $bets = (float)($row['bets'] ?? 0);
    $wins = (float)($row['wins'] ?? 0);
    return ['bets'=>$bets,'wins'=>$wins,'rounds'=>(int)($row['rounds'] ?? 0),'rtp'=>$bets > 0 ? $wins / $bets : null];
}

function game_weighted_pick(array $items, string $weightKey = 'weight'): array
{
    $total = array_sum(array_map(static fn(array $item): float => max(0.0, (float)$item[$weightKey]), $items));
    if ($total <= 0 || !$items) {
        throw new RuntimeException('无可用的开奖结果。');
    }
    $roll = random_int(1, 1000000000) / 1000000000 * $total;
    foreach ($items as $item) {
        $roll -= max(0.0, (float)$item[$weightKey]);
        if ($roll <= 0) return $item;
    }
    return $items[array_key_last($items)];
}

function game_position_weight(array $settings, int $position): float
{
    return min(1000.0, max(0.01, (float)($settings['normal_weight_'.$position] ?? 1)));
}

function game_lucky_pick(array $settings): int
{
    return (int)game_weighted_pick([
        ['position'=>10, 'weight'=>game_position_weight($settings, 10)],
        ['position'=>22, 'weight'=>game_position_weight($settings, 22)],
    ])['position'];
}

function game_calibrated_ordinary_positions(array $groups, float $normalReturn, float $ordinaryProbability): array
{
    $modelAtTilt = static function (float $tilt) use ($groups, $normalReturn): array {
        $positions = [];
        $total = 0.0;
        foreach ($groups as $group) {
            $maxMultiplier = max(array_column($group['positions'], 'multiplier'));
            $logs = [];
            foreach ($group['positions'] as $position => $entry) {
                $logs[$position] = log($entry['weight']) - $tilt * ($entry['multiplier'] / $maxMultiplier);
            }
            $maxLog = max($logs);
            $denominator = 0.0;
            $scores = [];
            foreach ($group['positions'] as $position => $entry) {
                $scores[$position] = exp($logs[$position] - $maxLog);
                $denominator += $scores[$position] * $entry['multiplier'];
            }
            if ($denominator <= 0) {
                throw new RuntimeException('每种普通图案至少需要一个大于 0 的赔率。');
            }
            foreach ($group['positions'] as $position => $entry) {
                $probability = $normalReturn * $scores[$position] / $denominator;
                $positions[$position] = ['probability'=>$probability, 'weight'=>$entry['weight']];
                $total += $probability;
            }
        }
        return ['positions'=>$positions, 'total'=>$total];
    };

    $low = -100.0;
    $high = 100.0;
    $lowModel = $modelAtTilt($low);
    $highModel = $modelAtTilt($high);
    if ($ordinaryProbability < $lowModel['total'] - 0.0000001 || $ordinaryProbability > $highModel['total'] + 0.0000001) {
        throw new RuntimeException('当前赔率无法同时满足目标 RTP 和 LUCKY 通吃率。');
    }
    for ($iteration = 0; $iteration < 100; $iteration++) {
        $mid = ($low + $high) / 2;
        $model = $modelAtTilt($mid);
        if ($model['total'] < $ordinaryProbability) $low = $mid;
        else $high = $mid;
    }
    $tilt = ($low + $high) / 2;
    $model = $modelAtTilt($tilt);
    $model['tilt'] = $tilt;
    return $model;
}

function game_probability_model(array $settings, ?float $targetRtpPercent = null): array
{
    $specials = game_special_definitions($settings);
    $specialRate = array_sum(array_column($specials, 'rate')) / 100;
    $luckyProbability = min(1.0, max(0.0, (float)($settings['lucky_eat_rate'] ?? 2) / 100));
    if ($specialRate + $luckyProbability >= 1) {
        throw new RuntimeException('LUCKY 通吃率与特殊玩法总触发率之和必须小于 100%。');
    }

    $specialExpected = 0.0;
    foreach ($specials as $special) {
        $specialExpected += ($special['rate'] / 100) * $special['odds'];
    }

    $target = min(2.0, max(0.01, ($targetRtpPercent ?? (float)($settings['target_rtp'] ?? 92)) / 100));
    if ($target <= $specialExpected + 0.0000001) {
        throw new RuntimeException('目标 RTP 必须高于特殊玩法理论 RTP。');
    }

    $board = game_board($settings);
    $groups = [];
    $luckyPositions = [];
    foreach ($board as $position => $cell) {
        $weight = game_position_weight($settings, $position);
        if ((int)$cell['fruit'] === 0) {
            $luckyPositions[$position] = $weight;
            continue;
        }
        $fruit = (int)$cell['fruit'];
        $groups[$fruit]['positions'][$position] = ['weight'=>$weight, 'multiplier'=>(float)$cell['multiplier']];
    }

    if (!$luckyPositions) {
        throw new RuntimeException('游戏盘面缺少未中奖格。');
    }

    $minCoefficient = 0.0;
    $maxCoefficient = 0.0;
    foreach ($groups as $group) {
        $multipliers = array_column($group['positions'], 'multiplier');
        $positiveMultipliers = array_values(array_filter($multipliers, static fn(float $value): bool => $value > 0));
        if (!$positiveMultipliers) {
            throw new RuntimeException('每种普通图案至少需要一个大于 0 的赔率。');
        }
        $minCoefficient += 1 / max($positiveMultipliers);
        $minimum = min($multipliers);
        $maxCoefficient = $minimum <= 0 ? INF : $maxCoefficient + 1 / $minimum;
    }

    $normalProbability = 1 - $specialRate;
    $ordinaryProbability = $normalProbability - $luckyProbability;
    $minTarget = $specialExpected + (is_infinite($maxCoefficient) ? 0 : $ordinaryProbability / $maxCoefficient);
    $maxTarget = $specialExpected + $ordinaryProbability / $minCoefficient;
    if ($target < $minTarget - 0.0000001 || $target > $maxTarget + 0.0000001) {
        throw new RuntimeException('当前赔率和通吃率可支持的目标 RTP 范围为 '.number_format($minTarget * 100, 2).'% - '.number_format($maxTarget * 100, 2).'%。');
    }
    $normalReturn = $target - $specialExpected;
    $calibrated = game_calibrated_ordinary_positions($groups, $normalReturn, $ordinaryProbability);
    $positions = $calibrated['positions'];
    $luckyWeightTotal = array_sum($luckyPositions);
    foreach ($luckyPositions as $position => $weight) {
        $positions[$position] = [
            'probability'=>$luckyProbability * $weight / $luckyWeightTotal,
            'weight'=>$weight,
        ];
    }
    ksort($positions);

    return [
        'positions'=>$positions,
        'target_rtp'=>$target,
        'min_rtp'=>$minTarget,
        'max_rtp'=>$maxTarget,
        'special_rate'=>$specialRate,
        'special_expected'=>$specialExpected,
        'normal_probability'=>$normalProbability,
        'ordinary_probability'=>$ordinaryProbability,
        'lucky_probability'=>$luckyProbability,
        'calibration_tilt'=>$calibrated['tilt'],
    ];
}

function game_effective_probability_model(array $settings, array $windowStats): array
{
    $configuredTarget = min(2.0, max(0.01, (float)($settings['target_rtp'] ?? 92) / 100));
    $baseModel = game_probability_model($settings);
    $effectiveTarget = $configuredTarget;
    if (($windowStats['rtp'] ?? null) !== null && (int)($windowStats['rounds'] ?? 0) >= 20) {
        $drift = max(-0.15, min(0.15, ($configuredTarget - (float)$windowStats['rtp']) * 0.5));
        $effectiveTarget += $drift;
    }
    $effectiveTarget = max($baseModel['min_rtp'], min($baseModel['max_rtp'], $effectiveTarget));
    $model = game_probability_model($settings, $effectiveTarget * 100);
    $model['configured_target_rtp'] = $configuredTarget;
    return $model;
}

function game_select_outcome(PDO $pdo, float $stake, array $bets, array $settings, ?array $windowStats = null): array
{
    $specials = game_special_definitions($settings);
    $stats = $windowStats ?? game_window_stats($pdo, (int)($settings['rtp_window'] ?? 1000));
    $model = game_effective_probability_model($settings, $stats);

    $specialRoll = random_int(1, 1000000) / 10000;
    $cursor = 0.0;
    foreach ($specials as $special) {
        $cursor += $special['rate'];
        if ($special['rate'] > 0 && $specialRoll <= $cursor) {
            if ($special['key'] === 'dsx' && random_int(0,1) === 1) {
                $special['positions'] = [22,11,23,17,5];
            }
            return [
                'kind'=>'special','name'=>$special['name'],'type'=>$special['type'],
                'position'=>game_lucky_pick($settings),'positions'=>$special['positions'],
                'payout'=>round($stake * $special['odds'], 2),'multiplier'=>$special['odds'],
                'special_rate'=>$special['rate'],'special_expected'=>$model['special_expected'],
                'probability_model'=>'fixed_position_v2_lucky',
            ];
        }
    }

    $board = game_board($settings);
    $candidates = [];
    foreach ($board as $position => $cell) {
        $bet = (float)($bets[$cell['fruit']] ?? 0);
        $payout = round($bet * (float)$cell['multiplier'], 2);
        $candidates[] = [
            'position'=>$position,'payout'=>$payout,'multiplier'=>(float)$cell['multiplier'],
            'fruit'=>(int)$cell['fruit'],'name'=>$cell['name'],
            'weight'=>$model['positions'][$position]['probability'],
        ];
    }
    $choice = game_weighted_pick($candidates);

    if ($choice['fruit'] === 0) {
        return [
            'kind'=>'lucky_eat','name'=>'LUCKY通吃','type'=>9,
            'position'=>$choice['position'],'positions'=>[],
            'payout'=>0.0,'multiplier'=>0.0,
            'special_expected'=>$model['special_expected'],
            'position_probability'=>$model['positions'][$choice['position']]['probability'],
            'effective_rtp'=>$model['target_rtp'],
            'probability_model'=>'fixed_position_v2_lucky',
        ];
    }

    return [
        'kind'=>'normal','name'=>$choice['name'],'type'=>0,'position'=>$choice['position'],
        'positions'=>[$choice['position']],'payout'=>$choice['payout'],
        'multiplier'=>$choice['multiplier'],'special_expected'=>$model['special_expected'],
        'position_probability'=>$model['positions'][$choice['position']]['probability'],
        'effective_rtp'=>$model['target_rtp'],
        'probability_model'=>'fixed_position_v2_lucky',
    ];
}

function game_theoretical_special_rtp(array $settings): float
{
    $rtp = 0.0;
    foreach (game_special_definitions($settings) as $special) {
        $rtp += ($special['rate'] / 100) * $special['odds'] * 100;
    }
    return $rtp;
}