<?php

namespace App\Business;

use Illuminate\Http\UploadedFile;
use Illuminate\Validation\ValidationException;
use PhpOffice\PhpSpreadsheet\IOFactory;
use Throwable;

class LaborExpenseWorkbookImporter
{
    private const MAX_DATA_ROWS = 2000;

    /**
     * @return array{rows: array<int, array<string, mixed>>, row_count: int, blank_count: int}
     */
    public function import(UploadedFile $file): array
    {
        $fields = collect(config('labor_expense_table.fields', []))
            ->filter(static fn (array $field): bool => ($field['kind'] ?? null) !== 'sequence'
                && blank($field['formula'] ?? null));

        if ($fields->isEmpty()) {
            throw ValidationException::withMessages([
                'import' => '人工费用表没有可导入的录入列。',
            ]);
        }

        $lookup = [];
        foreach ($fields as $field) {
            $lookup[$this->normalizeHeader($field['key'])] = $field['key'];
            $lookup[$this->normalizeHeader($field['label'])] = $field['key'];
        }

        $spreadsheet = null;

        try {
            $readerType = match (mb_strtolower($file->getClientOriginalExtension())) {
                'xlsx' => 'Xlsx',
                'xls' => 'Xls',
                'csv' => 'Csv',
                default => throw new \RuntimeException('Unsupported workbook format.'),
            };
            $reader = IOFactory::createReader($readerType);
            if (method_exists($reader, 'setReadDataOnly')) {
                $reader->setReadDataOnly(true);
            }
            $spreadsheet = $reader->load($file->getRealPath());
            [$sheetRows, $headerRow, $columns] = $this->bestSheet($spreadsheet, $lookup);
        } catch (Throwable) {
            throw ValidationException::withMessages([
                'import' => '无法读取导入文件，请确认文件未损坏且格式为 xlsx、xls 或 csv。',
            ]);
        } finally {
            if ($spreadsheet) {
                $spreadsheet->disconnectWorksheets();
            }
        }

        if ($sheetRows === null || $columns === []) {
            throw ValidationException::withMessages([
                'import' => '未找到当前人工费用表的可录入列，请使用页面“导出全部字段”生成的文件作为模板。',
            ]);
        }

        $fieldMap = $fields->keyBy('key');
        $rows = [];
        $blankCount = 0;

        foreach (array_slice($sheetRows, $headerRow + 1, null, true) as $rowIndex => $row) {
            $record = [];
            $hasValue = false;

            foreach ($columns as $columnIndex => $fieldKey) {
                $field = $fieldMap[$fieldKey];
                $value = $this->normalizeCell(
                    $row[$columnIndex] ?? null,
                    $field['kind'] ?? 'text',
                    (int) $rowIndex + 1,
                    $field['label'] ?? $fieldKey,
                );
                $record[$fieldKey] = $value;
                $hasValue = $hasValue || $value !== '';
            }

            if (! $hasValue) {
                $blankCount++;
                continue;
            }

            $rows[] = $record;
            if (count($rows) > self::MAX_DATA_ROWS) {
                throw ValidationException::withMessages([
                    'import' => '单次最多导入 ' . number_format(self::MAX_DATA_ROWS) . ' 行，请拆分文件后重试。',
                ]);
            }
        }

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

        return [
            'rows' => $rows,
            'row_count' => count($rows),
            'blank_count' => $blankCount,
        ];
    }

    /**
     * @return array{0: array<int, array<int, mixed>>|null, 1: int|null, 2: array<int, string>}
     */
    private function bestSheet(mixed $spreadsheet, array $lookup): array
    {
        $best = [null, null, []];
        $bestScore = 0;

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

            foreach (array_slice($rows, 0, 30, true) as $rowIndex => $row) {
                $columns = [];

                foreach ($row as $columnIndex => $heading) {
                    $key = $this->normalizeHeader($heading);
                    if ($key !== '' && isset($lookup[$key])) {
                        $columns[$columnIndex] = $lookup[$key];
                    }
                }

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

        return $best;
    }

    private function normalizeCell(mixed $value, string $kind, int $line, string $label): mixed
    {
        if ($value === null) {
            return '';
        }

        $text = trim((string) $value);
        if ($text === '') {
            return '';
        }

        if (! in_array($kind, ['number', 'percent'], true)) {
            return $text;
        }

        $isPercentText = $kind === 'percent' && str_ends_with($text, '%');
        $number = str_replace([',', '，', '¥', '￥', '%'], '', $text);

        if (! is_numeric($number)) {
            throw ValidationException::withMessages([
                'import' => "第 {$line} 行“{$label}”不是有效数字。",
            ]);
        }

        $normalized = (float) $number;

        return $isPercentText ? $normalized / 100 : $normalized;
    }

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