<?php

namespace Modules\EcommerceFinance\Services;

use Illuminate\Http\UploadedFile;
use Illuminate\Validation\ValidationException;
use Throwable;

/**
 * 厂家对账单模板：列头、留空规则与严格校验。
 * 按业务要求：不按模板形式上传的一律整份失败（表头列名、顺序、列数必须完全一致）。
 */
class SupplierStatementTemplate
{
    /** 模板列（顺序固定）：前 3 列允许留空，其余必填。 */
    public const COLUMNS = [
        'expressName' => '快递名称',
        'expressNo' => '快递单号',
        'purchaseNo' => '单据编号（采购单号）',
        'createdAt' => '创建时间',
        'supplier' => '供应商',
        'barcode' => '条码',
        'skuName' => '规格名称',
        'qty' => '数量',
        'unitPrice' => '单价',
        'amount' => '金额',
    ];

    private const MAX_ROWS = 200000;

    /** 允许留空的列：快递信息可缺；单价/金额留空时按「金额÷数量」或「数量×单价」补齐，都空按 0。 */
    private const OPTIONAL_COLUMNS = ['expressName', 'expressNo', 'purchaseNo', 'unitPrice', 'amount'];

    /** 必须是数字的列。 */
    private const NUMERIC_COLUMNS = ['qty', 'unitPrice', 'amount'];

    public function path(): string
    {
        return resource_path('templates/supplier-reconciliation/statement-template.xlsx');
    }

    public function filename(): string
    {
        return '供应商对账单模板.xlsx';
    }

    /**
     * 解析并严格校验厂家上传的对账单。
     *
     * @return list<array<string,mixed>> 模块内部键的记录（条码/单价/数量/金额等）
     */
    public function parse(UploadedFile $file, ?string $expectedSupplier = null): array
    {
        $extension = strtolower((string) $file->getClientOriginalExtension());
        if (! in_array($extension, ['xlsx', 'xls', 'csv'], true)) {
            throw ValidationException::withMessages(['import' => '只能上传 Excel（xlsx / xls）或 CSV 文件。']);
        }

        try {
            $reader = PayablesWorkbookStreamReader::forFile((string) $file->getRealPath(), $extension);
            $header = $this->locateHeader($reader);
        } catch (ValidationException $exception) {
            throw $exception;
        } catch (Throwable) {
            throw ValidationException::withMessages(['import' => '无法读取文件，请确认文件未损坏且格式为 xlsx、xls 或 csv。']);
        }

        $records = [];
        $fields = array_keys(self::COLUMNS);
        foreach ($reader->rows($header['sheet'], $header['row']) as $rowNumber => $cells) {
            $values = [];
            foreach ($fields as $index => $field) {
                $value = trim((string) ($cells[$index] ?? ''));
                $values[$field] = $value === '' ? null : $value;
            }

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

            foreach (self::COLUMNS as $field => $label) {
                if ($values[$field] === null) {
                    if (in_array($field, self::OPTIONAL_COLUMNS, true)) {
                        continue;
                    }

                    throw ValidationException::withMessages(['import' => "第 {$rowNumber} 行：「{$label}」不能为空。"]);
                }

                if (in_array($field, self::NUMERIC_COLUMNS, true)) {
                    $normalized = str_replace([' ', ',', '，'], '', (string) $values[$field]);
                    if (preg_match('/^-?\d+(?:\.\d+)?$/', $normalized) !== 1) {
                        throw ValidationException::withMessages(['import' => "第 {$rowNumber} 行：「{$label}」必须是数字。"]);
                    }
                    $values[$field] = $normalized;
                }
            }

            $values = $this->completeAmounts($values);

            if ($expectedSupplier !== null && $values['supplier'] !== $expectedSupplier) {
                throw ValidationException::withMessages([
                    'import' => "第 {$rowNumber} 行：供应商必须填写「{$expectedSupplier}」，不能提交其他厂家的数据。",
                ]);
            }

            $records[] = $values;
            if (count($records) > self::MAX_ROWS) {
                throw ValidationException::withMessages(['import' => '单次最多上传 200,000 行，请拆分文件后重试。']);
            }
        }

        if ($records === []) {
            throw ValidationException::withMessages(['import' => '表格里没有数据行，请按模板填写后重新上传。']);
        }

        return $records;
    }

    /**
     * 找出模板表头：列名、顺序、起始列必须与模板完全一致。
     *
     * @return array{sheet:int,row:int}
     */
    private function locateHeader(PayablesWorkbookStreamReader $reader): array
    {
        $expected = array_values(self::COLUMNS);
        $expectedNormalized = array_map($this->normalizeLabel(...), $expected);
        $bestLabels = null;
        $bestScore = -1;

        foreach (array_keys($reader->sheetNames()) as $sheetIndex) {
            foreach ($reader->rows($sheetIndex, null, 20) as $rowNumber => $row) {
                $labels = [];
                foreach ($row as $columnIndex => $value) {
                    $label = $this->normalizeLabel((string) $value);
                    if ($label !== '') {
                        $labels[$columnIndex] = $label;
                    }
                }
                ksort($labels);

                if (array_values($labels) === $expectedNormalized && array_keys($labels) === range(0, count($expected) - 1)) {
                    return ['sheet' => $sheetIndex, 'row' => $rowNumber];
                }

                $score = count(array_intersect(array_values($labels), $expectedNormalized));
                if ($score > $bestScore) {
                    $bestScore = $score;
                    $bestLabels = array_values($labels);
                }
            }
        }

        throw ValidationException::withMessages([
            'import' => '表头与模板不一致：' . $this->describeHeader($bestLabels, $expectedNormalized) . '请下载最新模板填写，不要增删或修改列（列名、顺序必须与模板完全相同）。',
        ]);
    }

    /** @param  list<string>|null  $actual  标准化后的实际表头；@param  list<string>  $expected  标准化后的模板表头 */
    private function describeHeader(?array $actual, array $expected): string
    {
        if ($actual === null) {
            return '';
        }

        $display = [];
        foreach (self::COLUMNS as $label) {
            $display[$this->normalizeLabel($label)] = $label;
        }

        $missing = array_map(static fn (string $key): string => $display[$key] ?? $key, array_values(array_diff($expected, $actual)));
        $extra = array_map(static fn (string $key): string => $display[$key] ?? $key, array_values(array_diff($actual, $expected)));

        $parts = [];
        if ($missing !== []) {
            $parts[] = '缺少「' . implode('」「', $missing) . '」';
        }
        if ($extra !== []) {
            $parts[] = '多出「' . implode('」「', $extra) . '」';
        }
        $commonActual = array_values(array_filter($actual, static fn (string $key): bool => in_array($key, $expected, true)));
        $commonExpected = array_values(array_filter($expected, static fn (string $key): bool => in_array($key, $actual, true)));
        if ($commonActual !== $commonExpected) {
            $parts[] = '列顺序与模板不同';
        }

        return $parts === [] ? '' : implode('，', $parts) . '；';
    }

    /** 比较表头时忽略空白与全半角括号差异。 */
    private function normalizeLabel(string $label): string
    {
        $label = preg_replace('/\s+/u', '', trim($label)) ?? '';
        $label = str_replace(['（', '）'], ['(', ')'], $label);

        return mb_strtolower($label);
    }

    /** 单价/金额留空时互相补算；两者都空按 0（未定价行厂家直接导出时会出现）。 */
    private function completeAmounts(array $values): array
    {
        $qty = (float) ($values['qty'] ?? 0);
        $unitPrice = $values['unitPrice'] === null ? null : (float) $values['unitPrice'];
        $amount = $values['amount'] === null ? null : (float) $values['amount'];

        if ($unitPrice === null && $amount !== null && $qty != 0.0) {
            $values['unitPrice'] = (string) round($amount / $qty, 4);
        } elseif ($unitPrice === null) {
            $values['unitPrice'] = '0';
        }

        if ($amount === null) {
            $values['amount'] = (string) round($qty * (float) $values['unitPrice'], 2);
        }

        return $values;
    }
}