<?php
namespace app\common\traits;

use app\common\model\VehMoneyValue;
use support\Db;
use Illuminate\Database\Eloquent\Relations\HasMany;

trait HasMoneyJournal
{
    /**
     * 【抽象方法】必须由使用该 trait 的模型实现
     * 返回当前模型对应的金额“业务场景”标识
     *
     * @return string
     */
    abstract protected static function moneyObjectScene(): string;

    /** 所有关联金额记录（append-only 全部历史） */
    public function moneyJournal(): HasMany
    {
        return $this->hasMany(VehMoneyValue::class, 'object_id')
            ->where('object_scene', static::moneyObjectScene());
    }

    /** 取某费项的“最新记录”（按时间/id 倒序） */
    public function moneyLatest(string $field): ?VehMoneyValue
    {
        return $this->moneyJournal()
            ->where('field', $field)
            ->orderByDesc('created_at')
            ->orderByDesc('id')
            ->first();
    }

    /** 追加一行金额 */
    public function addMoney(string $field, string $currency, $amount, ?string $rate = null, ?string $remark = null): VehMoneyValue
    {
        $now = time();
        /** @var VehMoneyValue $row */
        $row = $this->moneyJournal()->create([
            'object_scene'  => static::moneyObjectScene(),
            'object_id'     => $this->id,
            'field'         => $field,
            'currency'      => strtoupper($currency),
            'amount'        => (string)$amount,
            'exchange_rate' => $rate,
            'remark'        => $remark,
            'created_at'    => $now,
            'updated_at'    => $now,
        ]);
        return $row;
    }

    /** 批量追加：['unit_price'=>['currency'=>'USD','amount'=>'2199.00','rate'=>'7.2','remark'=>'...'], ...] */
    public function addMoneyBatch(array $payload): array
    {
        return Db::transaction(function () use ($payload) {
            $out = [];
            foreach ($payload as $field => $cfg) {
                $out[$field] = $this->addMoney(
                    $field,
                    $cfg['currency'] ?? 'CNY',
                    $cfg['amount']   ?? '0.00',
                    $cfg['rate']     ?? null,
                    $cfg['remark']   ?? null
                );
            }
            return $out;
        });
    }

    /** 把若干费项按各自汇率换到结算币并求和（无 rate 的跳过） */
    public function sumToSettlement(array $fields, int $scale = 2): string
    {
        $sum = '0.00';
        foreach ($fields as $f) {
            $row = $this->moneyLatest($f);
            if ($row) {
                $v = $row->amountInSettlement($scale);
                if ($v !== null) $sum = bcadd($sum, $v, $scale);
            }
        }
        return $sum;
    }
}