<?php

namespace Modules\EcommerceFinance\Services;

use Illuminate\Http\UploadedFile;
use Illuminate\Validation\ValidationException;
use Modules\EcommerceFinance\Repositories\ProductPriceMirrorRepository;
use PhpOffice\PhpSpreadsheet\IOFactory;
use RuntimeException;
use Throwable;

class ProductPriceWorkbookImporter
{
    /** @var array<string,string> */
    private const HEADERS = [
        '记录标识' => 'upstream_key',
        '商品编码' => 'barcode',
        'SPU' => 'spu',
        '商品名称' => 'product_name',
        '类目' => 'category',
        '生产状态' => 'production_status',
        '最低售价' => 'minimum_price',
        '计算限价' => 'price_limit',
        '采购价' => 'purchase_price',
        '运费' => 'shipping_fee',
        '京喜限价' => 'jingxi_limit_price',
    ];

    /** @var array<string,int> */
    private const TEXT_LIMITS = [
        'barcode' => 191,
        'spu' => 191,
        'product_name' => 5000,
        'category' => 255,
        'production_status' => 120,
    ];

    public function __construct(private readonly ProductPriceMirrorRepository $repository)
    {
    }

    /** @return array<string,array{label:string,type:string}> */
    public function templateFields(): array
    {
        $fields = [];

        foreach (self::HEADERS as $label => $field) {
            if ($field === 'upstream_key') {
                continue;
            }

            $fields[$field] = [
                'label' => $label,
                'type' => isset(self::TEXT_LIMITS[$field]) ? 'text' : 'number',
            ];
        }

        return $fields;
    }

    /** @return array{created:int,updated:int,rows:int} */
    public function import(UploadedFile $file, int $companyId, ?int $userId): array
    {
        try {
            $spreadsheet = IOFactory::load($file->getRealPath());
            [$rows, $headerRow, $columns] = $this->bestMatchingSheet($spreadsheet);
        } catch (Throwable) {
            throw ValidationException::withMessages([
                'import' => '无法读取导入文件，请确认文件未损坏且格式为 xlsx、xls 或 csv。',
            ]);
        } finally {
            if (isset($spreadsheet)) {
                $spreadsheet->disconnectWorksheets();
            }
        }

        if ($rows === null || ! in_array('upstream_key', $columns, true)) {
            throw ValidationException::withMessages([
                'import' => '未找到“记录标识”列，请先导出当前数据，再使用导出的表格进行修改。',
            ]);
        }

        if (count(array_intersect($columns, ProductPriceMirrorRepository::EDITABLE_FIELDS)) === 0) {
            throw ValidationException::withMessages([
                'import' => '表格中没有可导入的商品价格字段。',
            ]);
        }

        $records = [];

        foreach (array_slice($rows, $headerRow + 1, null, true) as $rowIndex => $row) {
            $line = $rowIndex + 1;
            $upstreamKey = '';
            $changes = [];

            foreach ($columns as $columnIndex => $field) {
                $value = $row[$columnIndex] ?? null;

                if ($field === 'upstream_key') {
                    $upstreamKey = strtolower(trim((string) $value));
                    continue;
                }

                $changes[$field] = $this->normalizeValue($field, $value, $line);
            }

            if ($upstreamKey === '' && collect($changes)->every(
                static fn (mixed $value): bool => $value === null || $value === ''
            )) {
                continue;
            }

            if (preg_match('/^[a-f0-9]{64}$/', $upstreamKey) !== 1) {
                throw ValidationException::withMessages([
                    'import' => "第 {$line} 行“记录标识”无效，请勿修改导出文件中的该列。",
                ]);
            }

            if (array_key_exists($upstreamKey, $records)) {
                throw ValidationException::withMessages([
                    'import' => "第 {$line} 行“记录标识”重复。",
                ]);
            }

            if (array_key_exists('barcode', $changes) && trim((string) $changes['barcode']) === '') {
                throw ValidationException::withMessages([
                    'import' => "第 {$line} 行“商品编码”不能为空。",
                ]);
            }

            if (collect($changes)->every(static fn (mixed $value): bool => $value === null || $value === '')) {
                continue;
            }

            $records[$upstreamKey] = $changes;

            if (count($records) > 10000) {
                throw ValidationException::withMessages([
                    'import' => '单次最多导入 10,000 条商品价格记录，请拆分文件后重试。',
                ]);
            }
        }

        if ($records === []) {
            throw ValidationException::withMessages(['import' => '表格中没有可导入的数据行。']);
        }

        try {
            $result = $this->repository->applyOverrides($records, $companyId, $userId, 'import');
        } catch (RuntimeException $exception) {
            if (str_starts_with($exception->getMessage(), 'product_price_record_not_found:')) {
                throw ValidationException::withMessages([
                    'import' => '导入文件包含当前商品价格镜像中不存在的记录，请重新导出后再导入。',
                ]);
            }

            if ($exception->getMessage() === 'product_price_maintenance_schema_missing') {
                throw ValidationException::withMessages([
                    'import' => '商品价格维护功能尚未完成初始化，请稍后重试。',
                ]);
            }

            throw $exception;
        }

        return $result + ['rows' => count($records)];
    }

    private function bestMatchingSheet($spreadsheet): array
    {
        $lookup = [];

        foreach (self::HEADERS as $label => $field) {
            $lookup[$this->normalizeHeader($label)] = $field;
            $lookup[$this->normalizeHeader($field)] = $field;
        }

        $best = [null, null, []];
        $bestScore = 0;

        foreach ($spreadsheet->getWorksheetIterator() as $worksheet) {
            $rows = $worksheet->toArray(null, false, false, false);

            foreach (array_slice($rows, 0, 20, true) as $rowIndex => $row) {
                $columns = [];

                foreach ($row as $columnIndex => $heading) {
                    $key = $this->normalizeHeader($heading);

                    if ($key !== '' && isset($lookup[$key])) {
                        $columns[$columnIndex] = $lookup[$key];
                    }
                }

                if (count($columns) > $bestScore) {
                    $best = [$rows, $rowIndex, $columns];
                    $bestScore = count($columns);
                }
            }
        }

        return $best;
    }

    private function normalizeHeader(mixed $value): string
    {
        return mb_strtolower(preg_replace('/[\s\x{FEFF}_\-（）()]+/u', '', trim((string) $value)));
    }

    private function normalizeValue(string $field, mixed $value, int $line): mixed
    {
        if ($value === null || trim((string) $value) === '') {
            return null;
        }

        if (isset(self::TEXT_LIMITS[$field])) {
            $text = trim((string) $value);

            if (mb_strlen($text) > self::TEXT_LIMITS[$field]) {
                $label = array_search($field, self::HEADERS, true) ?: $field;
                throw ValidationException::withMessages([
                    'import' => "第 {$line} 行“{$label}”内容过长。",
                ]);
            }

            return $text;
        }

        $number = str_replace([',', '，', '￥', '¥'], '', trim((string) $value));

        if (preg_match('/^(?:\d+(?:\.\d{1,4})?|\.\d{1,4})$/', $number) !== 1
            || bccomp($number, '9999999999999999.9999', 4) === 1) {
            $label = array_search($field, self::HEADERS, true) ?: $field;
            throw ValidationException::withMessages([
                'import' => "第 {$line} 行“{$label}”必须是大于或等于 0、最多 4 位小数的有效金额。",
            ]);
        }

        return ltrim($number, '+');
    }
}