<?php

namespace App\Business;

use App\Http\Controllers\Business\Pages;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Schema;

/**
 * 「业绩明细」差额规则的物化状态。
 *
 * 备注分类、有效差额、有/无差额原先都在查询时按同一套规则链逐行现算，整月
 * 30 多万行需要十几到几十秒。store-receipt:materialize-differences 把结果写进
 * store_receipt_order_match_rows 的 difference_reason_index / base_difference /
 * has_difference 三列，页面改读列。
 *
 * 规则表达式始终取自 Pages 的静态方法（唯一口径），这里只负责：
 * - 用规则表达式的指纹判断物化结果是否仍与当前代码一致；
 * - 记录/读取每个月是否已物化。
 */
class StoreReceiptDifferenceMaterialization
{
    public const REASON_INDEX_COLUMN = 'difference_reason_index';

    public const BASE_DIFFERENCE_COLUMN = 'base_difference';

    public const HAS_DIFFERENCE_COLUMN = 'has_difference';

    private const TABLE = 'store_receipt_order_match_rows';

    private const STATE_TABLE = 'store_receipt_order_match_materializations';

    /** @var array<string,bool> */
    private static array $memo = [];

    public static function connection(): string
    {
        return (string) config('upstream_mirrors.connection', 'business_mirror');
    }

    public static function table(): string
    {
        return self::TABLE;
    }

    public static function stateTable(): string
    {
        return self::STATE_TABLE;
    }

    /**
     * 当前规则表达式的指纹。规则改动后指纹变化，旧的物化结果会自动视为过期。
     */
    public static function ruleVersion(): string
    {
        return md5(implode('|', [
            Pages::receiptDefaultDifferenceSql(),
            Pages::receiptDifferenceRemarkIndexSql(),
            Pages::receiptEffectiveDifferenceSql(),
        ]));
    }

    /**
     * 物化列与状态表是否已就绪（迁移是否执行过）。
     *
     * 结果缓存 10 分钟：schema 探测在共享镜像库上每次要 0.3～0.5 秒，
     * 不能放在每个页面请求的热路径上。迁移执行后由 markMaterialized() 主动失效。
     */
    public static function available(bool $fresh = false): bool
    {
        static $memo = null;

        if (! $fresh) {
            if ($memo !== null) {
                return $memo;
            }

            return $memo = (bool) Cache::remember(
                self::availabilityCacheKey(),
                now()->addMinutes(10),
                static fn (): bool => self::detectAvailability(),
            );
        }

        $available = self::detectAvailability();
        if ($available) {
            Cache::put(self::availabilityCacheKey(), true, now()->addMinutes(10));
        }

        return $memo = $available;
    }

    private static function detectAvailability(): bool
    {
        try {
            $schema = Schema::connection(self::connection());

            return $schema->hasTable(self::TABLE)
                && $schema->hasTable(self::STATE_TABLE)
                && $schema->hasColumn(self::TABLE, self::REASON_INDEX_COLUMN)
                && $schema->hasColumn(self::TABLE, self::BASE_DIFFERENCE_COLUMN)
                && $schema->hasColumn(self::TABLE, self::HAS_DIFFERENCE_COLUMN);
        } catch (\Throwable) {
            return false;
        }
    }

    private static function availabilityCacheKey(): string
    {
        return 'store-receipt-materialization-available:v1';
    }

    /**
     * 该账期是否已经按当前规则物化完成。未物化时页面回退到实时规则表达式。
     */
    public static function materialized(string $month): bool
    {
        $month = substr(trim($month), 0, 10);
        if ($month === '' || ! self::available()) {
            return false;
        }

        if (array_key_exists($month, self::$memo)) {
            return self::$memo[$month];
        }

        $cacheKey = 'store-receipt-materialized:' . $month . ':' . self::ruleVersion();

        return self::$memo[$month] = (bool) Cache::remember($cacheKey, now()->addMinutes(10), function () use ($month): bool {
            $row = DB::connection(self::connection())
                ->table(self::STATE_TABLE)
                ->where('report_month', $month)
                ->first();

            if ($row === null || (string) ($row->rule_version ?? '') !== self::ruleVersion()) {
                return false;
            }

            // 过渡期保护：尚未部署新代码的同步任务重刷账期时不会写物化列，
            // 一旦出现 NULL 就回退实时口径，避免页面把未物化的行当成 0 差额。
            return ! DB::connection(self::connection())
                ->table(self::TABLE)
                ->where('report_month', $month)
                ->whereNull(self::HAS_DIFFERENCE_COLUMN)
                ->limit(1)
                ->exists();
        });
    }

    /**
     * 该账期的数据版本：物化后自增，页面聚合/联动统计的缓存键带上它即可精确失效。
     */
    public static function dataVersion(string $month): string
    {
        return (string) Cache::remember(
            self::dataVersionKey($month),
            now()->addDays(30),
            static fn (): int => 1,
        );
    }

    public static function bumpDataVersion(string $month): void
    {
        $key = self::dataVersionKey($month);
        $current = (int) Cache::get($key, 1);
        Cache::put($key, $current + 1, now()->addDays(30));
    }

    private static function dataVersionKey(string $month): string
    {
        return 'store-receipt-data-version:' . substr(trim($month), 0, 10);
    }

    public static function markMaterialized(string $month, int $rowCount): void
    {
        $month = substr(trim($month), 0, 10);
        $connection = self::connection();

        DB::connection($connection)->table(self::STATE_TABLE)->updateOrInsert(
            ['report_month' => $month],
            [
                'rule_version' => self::ruleVersion(),
                'row_count' => $rowCount,
                'materialized_at' => now(),
            ],
        );

        Cache::forget('store-receipt-materialized:' . $month . ':' . self::ruleVersion());
        Cache::forget(self::availabilityCacheKey());
        self::bumpDataVersion($month);
        unset(self::$memo[$month]);
    }

    public static function forget(string $month): void
    {
        $month = substr(trim($month), 0, 10);
        Cache::forget('store-receipt-materialized:' . $month . ':' . self::ruleVersion());
        unset(self::$memo[$month]);
    }

    /**
     * 账期相邻月份（物化跨月备注规则时需要一起重算）。
     *
     * @return list<string>
     */
    public static function adjacentMonths(string $month): array
    {
        $date = \Illuminate\Support\Carbon::parse(substr($month, 0, 10) . ' 00:00:00');

        return [
            $date->copy()->subMonthNoOverflow()->format('Y-m-01'),
            $date->copy()->format('Y-m-01'),
            $date->copy()->addMonthNoOverflow()->format('Y-m-01'),
        ];
    }
}