<?php

namespace app\common\traits;

use Illuminate\Pagination\LengthAwarePaginator;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Collection;

trait DataTransformer
{
    /**
     * 核心方法：对任意数据进行转换并返回数组
     *
     * @param mixed         $rawData        原始数据，可为 Paginator / Model / Collection / array 等
     * @param callable|null $postProcessor  可选的后置处理回调，接受处理完的数组再返回新的数组
     * @param callable|null $fieldFormatter 可选的字段命名转换回调，如 snake_case
     *
     * @return array
     */
    protected function transformData(
        mixed $rawData,
        ?callable $postProcessor = null,
        ?callable $fieldFormatter = null
    ): array {
        try {
            $fieldFormatter = $fieldFormatter ?: fn($field) => $field;

            if ($rawData instanceof LengthAwarePaginator) {
                $formatted = $this->formatPaginated($rawData, $postProcessor, $fieldFormatter);
            } elseif ($rawData instanceof Model) {
                $formatted = $this->formatModel($rawData, $fieldFormatter);
            } elseif ($rawData instanceof Collection) {
                $formatted = $this->formatCollection($rawData, $fieldFormatter);
            } elseif (is_array($rawData)) {
                $formatted = $this->formatArray($rawData, $fieldFormatter);
            } else {
                $formatted = (array) $rawData;
            }

            if (is_callable($postProcessor)) {
                $formatted = $postProcessor($formatted);
            }

            return $formatted;
        } catch (\Throwable $e) {
            return [
                'error'   => true,
                'message' => $e->getMessage(),
                'code'    => $e->getCode(),
            ];
        }
    }

    /**
     * 格式化分页数据：将每条记录也进行 transformData 递归处理
     *
     * @param LengthAwarePaginator $paginator
     * @param callable|null        $postProcessor
     * @param callable             $fieldFormatter
     * @return array
     */
    protected function formatPaginated(
        LengthAwarePaginator $paginator,
        ?callable $postProcessor,
        callable $fieldFormatter
    ): array {
        $list = $paginator->getCollection()->map(function ($item) use ($postProcessor, $fieldFormatter) {
            return $this->transformData($item, $postProcessor, $fieldFormatter);
        })->toArray();

        return [
            'records'   => $list,
            'total'     => $paginator->total(),
            'current'   => $paginator->currentPage(),
            'size'      => $paginator->perPage()
        ];
    }

    /**
     * 格式化 Eloquent 模型：递归嵌套关联
     *
     * @param Model    $model
     * @param callable $fieldFormatter
     * @return array
     */
    protected function formatModel(Model $model, callable $fieldFormatter): array
    {
        $formatted = [];

        // 主表字段
        foreach ($model->getAttributes() as $key => $value) {
            $formatted[$fieldFormatter($key)] = $value;
        }

        // 关联数据，递归嵌套
        foreach ($model->getRelations() as $relation => $relationData) {
            if ($relationData instanceof Model) {
                // 单个关联模型
                $formatted[$relation] = $this->formatModel($relationData, $fieldFormatter);
            } elseif ($relationData instanceof Collection) {
                // 关联集合
                $formatted[$relation] = $relationData
                    ->map(fn($item) => $this->transformData($item, null, $fieldFormatter))
                    ->toArray();
            }
        }

        return $formatted;
    }

    /**
     * 格式化集合
     *
     * @param Collection $collection
     * @param callable   $fieldFormatter
     * @return array
     */
    protected function formatCollection(Collection $collection, callable $fieldFormatter): array
    {
        return $collection->map(fn($item) => $this->transformData($item, null, $fieldFormatter))
                          ->toArray();
    }

    /**
     * 格式化普通数组
     *
     * @param array    $array
     * @param callable $fieldFormatter
     * @return array
     */
    protected function formatArray(array $array, callable $fieldFormatter): array
    {
        return array_map(fn($item) => $this->transformData($item, null, $fieldFormatter), $array);
    }
}