<?php

namespace App\Services\Jackpot;

use App\Lottery\DrawStatus;
use App\Models\Draw;
use App\Models\JackpotPayoutLog;
use App\Models\JackpotPool;
use App\Models\TicketItem;
use Illuminate\Support\Collection;

/**
 * 产品文档 §5.11.2–5.11.3：中头奖且满足阈值或连续未爆期数 → 按比例释放奖池，按注项 `total_bet_amount` 比例分配。
 */
final class JackpotBurstAllocator
{
    /**
     * @param  Collection<int, array{item: TicketItem, matched_tier: ?string, gross_win: int}>  $results
     * @return array{allocations: array<int, int>, pool_payout: int, trigger: ?string}
     */
    public function allocate(Draw $draw, JackpotPool $pool, Collection $results): array
    {
        $winners = $results->filter(
            fn (array $r) => ($r['matched_tier'] ?? null) === 'first' && (int) $r['gross_win'] > 0,
        );

        if ($winners->isEmpty()) {
            return ['allocations' => [], 'pool_payout' => 0, 'trigger' => null];
        }

        $thresholdOk = (int) $pool->current_amount >= (int) $pool->trigger_threshold;
        $gapOk = $this->gapTriggerMet($pool);
        if (! $thresholdOk && ! $gapOk) {
            return ['allocations' => [], 'pool_payout' => 0, 'trigger' => null];
        }

        $trigger = $thresholdOk ? 'threshold' : 'forced_gap';

        $poolBefore = (int) $pool->current_amount;
        $poolPayout = (int) floor($poolBefore * (float) $pool->payout_rate);
        if ($poolPayout <= 0) {
            return ['allocations' => [], 'pool_payout' => 0, 'trigger' => null];
        }

        $list = $winners->values()->all();
        $weightTotal = 0;
        foreach ($list as $r) {
            $weightTotal += (int) $r['item']->total_bet_amount;
        }
        if ($weightTotal <= 0) {
            return ['allocations' => [], 'pool_payout' => 0, 'trigger' => null];
        }

        $allocations = [];
        $remaining = $poolPayout;
        $n = count($list);
        foreach ($list as $idx => $r) {
            /** @var TicketItem $item */
            $item = $r['item'];
            $w = (int) $item->total_bet_amount;
            if ($idx === $n - 1) {
                $share = max(0, $remaining);
            } else {
                $share = (int) floor($poolPayout * $w / $weightTotal);
                $remaining -= $share;
            }
            $allocations[(int) $item->id] = $share;
        }

        $pool->forceFill([
            'current_amount' => max(0, $poolBefore - $poolPayout),
            'last_trigger_draw_id' => $draw->id,
        ])->save();

        JackpotPayoutLog::query()->create([
            'draw_id' => $draw->id,
            'jackpot_pool_id' => $pool->id,
            'trigger_type' => $trigger,
            'total_payout_amount' => $poolPayout,
            'winner_count' => count($allocations),
            'trigger_snapshot_json' => [
                'threshold_ok' => $thresholdOk,
                'gap_ok' => $gapOk,
                'pool_amount_before' => $poolBefore,
                'payout_rate' => (string) $pool->payout_rate,
            ],
        ]);

        return ['allocations' => $allocations, 'pool_payout' => $poolPayout, 'trigger' => $trigger];
    }

    private function gapTriggerMet(JackpotPool $pool): bool
    {
        $gap = (int) $pool->force_trigger_draw_gap;
        if ($gap <= 0) {
            return false;
        }

        $lastId = (int) ($pool->last_trigger_draw_id ?? 0);
        $count = Draw::query()
            ->where('status', DrawStatus::Settled->value)
            ->when($lastId > 0, fn ($q) => $q->where('id', '>', $lastId))
            ->count();

        return $count >= $gap;
    }
}