<?php

namespace Modules\EcommerceFinance\Services;

use Generator;
use PhpOffice\PhpSpreadsheet\IOFactory;
use PhpOffice\PhpSpreadsheet\Shared\Date as ExcelDate;
use RuntimeException;
use SplFixedArray;
use XMLReader;
use ZipArchive;

/**
 * 逐行读取导入工作簿，内存有界（20 万行级文件也能跑）：
 * - xlsx：ZipArchive + XMLReader 流式解析，共享字符串用「拼接串 + 偏移索引」紧凑存放；
 * - csv：逐行 fgetcsv（自动去 BOM、非 UTF-8 按 GBK 转换）；
 * - xls：退回 PhpSpreadsheet（老格式少见）。
 * 日期格式的单元格按 Y-m-d（含时分秒时为 Y-m-d H:i:s）输出，其余保持原值。
 */
class PayablesWorkbookStreamReader
{
    /** @var array<int,string>|null 工作表内部路径（xlsx） */
    private ?array $sheetPaths = null;

    /** @var list<int>|null 日期样式的 style 索引 */
    private ?array $dateStyles = null;

    /** @var string|null 共享字符串拼接串 */
    private ?string $sharedStrings = null;

    /** @var SplFixedArray<int>|null 共享字符串偏移（第 i 个字符串的起始位置） */
    private ?SplFixedArray $sharedStringOffsets = null;

    public function __construct(
        private readonly string $path,
        private readonly string $extension,
    ) {
    }

    /** 新建读取器（按扩展名）。 */
    public static function forFile(string $path, string $extension): self
    {
        return new self($path, strtolower($extension));
    }

    /** @return list<string> 工作表名称（xls 走 PhpSpreadsheet，仅取名称） */
    public function sheetNames(): array
    {
        if ($this->extension === 'xlsx') {
            return array_map(
                static fn (array $sheet): string => $sheet['name'],
                $this->xlsxSheets(),
            );
        }

        if ($this->extension === 'csv') {
            return ['Sheet1'];
        }

        $spreadsheet = IOFactory::createReader('Xls')->load($this->path);
        try {
            return $spreadsheet->getSheetNames();
        } finally {
            $spreadsheet->disconnectWorksheets();
        }
    }

    /**
     * 逐行读取指定工作表。
     *
     * @param  int|null  $skipUntilRow  跳过该行号之前的行（含），用于分片续读
     * @param  int|null  $stopAfterRow  读到该行号后停止
     * @return Generator<int,array<int,mixed>> 行号（1 基）=> 列序号（0 基）=> 值
     */
    public function rows(int $sheetIndex = 0, ?int $skipUntilRow = null, ?int $stopAfterRow = null): Generator
    {
        yield from match ($this->extension) {
            'xlsx' => $this->xlsxRows($sheetIndex, $skipUntilRow, $stopAfterRow),
            'csv' => $this->csvRows($skipUntilRow, $stopAfterRow),
            default => $this->xlsRows($sheetIndex, $skipUntilRow, $stopAfterRow),
        };
    }

    /** @return Generator<int,array<int,mixed>> */
    private function xlsxRows(int $sheetIndex, ?int $skipUntilRow, ?int $stopAfterRow): Generator
    {
        $path = $this->sheetPaths()[$sheetIndex] ?? null;
        if ($path === null) {
            return;
        }

        $reader = new XMLReader();
        if (! $reader->open('zip://' . $this->path . '#' . $path, null, LIBXML_NONET)) {
            throw new RuntimeException('无法打开工作表。');
        }

        try {
            $dictionary = $this->xlsxSharedStrings();
            $rowNumber = 0;

            while ($reader->read()) {
                if ($reader->nodeType !== XMLReader::ELEMENT || $reader->localName !== 'row') {
                    continue;
                }

                $rowNumber = (int) ($reader->getAttribute('r') ?: $rowNumber + 1);
                if ($stopAfterRow !== null && $rowNumber > $stopAfterRow) {
                    return;
                }

                if ($skipUntilRow !== null && $rowNumber <= $skipUntilRow) {
                    $reader->next(); // 跳过整行
                    continue;
                }

                yield $rowNumber => $this->readRow($reader, $dictionary);
            }
        } finally {
            $reader->close();
        }
    }

    /**
     * 读一行里的单元格（当前节点位于 <row>）。
     *
     * @param  array{0:string,1:SplFixedArray<int>}  $dictionary
     * @return array<int,mixed>
     */
    private function readRow(XMLReader $reader, array $dictionary): array
    {
        $cells = [];
        $depth = $reader->depth;
        $empty = $reader->isEmptyElement;
        if ($empty) {
            return $cells;
        }

        while ($reader->read()) {
            if ($reader->nodeType === XMLReader::END_ELEMENT && $reader->depth === $depth) {
                break;
            }
            if ($reader->nodeType !== XMLReader::ELEMENT || $reader->localName !== 'c' || $reader->isEmptyElement) {
                continue;
            }

            $reference = (string) $reader->getAttribute('r');
            $type = (string) $reader->getAttribute('t');
            $styleIndex = (string) $reader->getAttribute('s');
            $columnIndex = $reference !== '' ? $this->columnIndex($reference) : null;
            $value = $this->readCellValue($reader, $type, $dictionary);
            $columnIndex ??= count($cells);

            if ($value === null || $value === '') {
                continue;
            }

            $cells[$columnIndex] = $this->formatValue($value, $type, $styleIndex);
        }

        return $cells;
    }

    /**
     * @param  array{0:string,1:SplFixedArray<int>}  $dictionary
     */
    private function readCellValue(XMLReader $reader, string $type, array $dictionary): mixed
    {
        $value = null;
        $depth = $reader->depth;

        while ($reader->read()) {
            if ($reader->nodeType === XMLReader::END_ELEMENT && $reader->depth === $depth) {
                break;
            }
            if ($reader->nodeType !== XMLReader::ELEMENT) {
                continue;
            }

            if ($reader->localName === 'v') {
                $value = $reader->isEmptyElement ? '' : $reader->readString();
                continue;
            }

            if ($reader->localName === 'is') {
                $value = $this->readInlineString($reader);
                continue;
            }

            if ($reader->localName === 't' && $type === 'inlineStr') {
                $value = $reader->isEmptyElement ? '' : $reader->readString();
            }
        }

        if ($type === 's') {
            $index = (int) $value;
            [$blob, $offsets] = $dictionary;
            if ($index < 0 || $index + 1 >= $offsets->getSize()) {
                return null;
            }

            return substr($blob, $offsets[$index], $offsets[$index + 1] - $offsets[$index]);
        }

        if ($type === 'str' || $type === 'inlineStr') {
            return $value;
        }

        if ($type === 'b') {
            return $value === '1' ? '1' : '0';
        }

        return $value;
    }

    /** 富文本 <is> 里可能有多个 <t>。 */
    private function readInlineString(XMLReader $reader): string
    {
        $depth = $reader->depth;
        $text = '';

        while ($reader->read()) {
            if ($reader->nodeType === XMLReader::END_ELEMENT && $reader->depth === $depth) {
                break;
            }
            if ($reader->nodeType === XMLReader::ELEMENT && $reader->localName === 't' && ! $reader->isEmptyElement) {
                $text .= $reader->readString();
            }
        }

        return $text;
    }

    /** 日期样式的数字单元格转成日期字符串。 */
    private function formatValue(mixed $value, string $type, string $styleIndex): mixed
    {
        if (! is_string($value) || $value === '' || $styleIndex === '' || ! is_numeric($value)) {
            return $value;
        }

        if (! in_array((int) $styleIndex, $this->dateStyles(), true)) {
            return $value;
        }

        $serial = (float) $value;
        $date = ExcelDate::excelToDateTimeObject($serial);

        return fmod($serial, 1.0) === 0.0 ? $date->format('Y-m-d') : $date->format('Y-m-d H:i:s');
    }

    /** @return Generator<int,array<int,mixed>> */
    private function csvRows(?int $skipUntilRow, ?int $stopAfterRow): Generator
    {
        $handle = fopen($this->path, 'rb');
        if ($handle === false) {
            return;
        }

        try {
            $delimiter = $this->detectDelimiter((string) fgets($handle));
            rewind($handle);

            $line = 0;
            while (($row = fgetcsv($handle, 0, $delimiter)) !== false) {
                $line++;
                if ($stopAfterRow !== null && $line > $stopAfterRow) {
                    return;
                }
                if ($skipUntilRow !== null && $line <= $skipUntilRow) {
                    continue;
                }

                $cells = [];
                foreach ($row as $index => $value) {
                    $value = $this->normalizeEncoding((string) $value);
                    if ($index === 0) {
                        $value = preg_replace('/^\x{FEFF}/u', '', $value) ?? $value;
                    }
                    if ($value !== '') {
                        $cells[$index] = $value;
                    }
                }

                yield $line => $cells;
            }
        } finally {
            fclose($handle);
        }
    }

    /** @return Generator<int,array<int,mixed>> */
    private function xlsRows(int $sheetIndex, ?int $skipUntilRow, ?int $stopAfterRow): Generator
    {
        $spreadsheet = IOFactory::createReader('Xls')->load($this->path);
        try {
            $sheet = $spreadsheet->getSheet($sheetIndex);
            foreach ($sheet->getRowIterator() as $row) {
                $line = $row->getRowIndex();
                if ($stopAfterRow !== null && $line > $stopAfterRow) {
                    return;
                }
                if ($skipUntilRow !== null && $line <= $skipUntilRow) {
                    continue;
                }

                $cells = [];
                foreach ($row->getCellIterator() as $cell) {
                    $value = $cell->getValue();
                    if ($value !== null && $value !== '') {
                        $cells[$this->columnIndex($cell->getColumn())] = $value;
                    }
                }

                yield $line => $cells;
            }
        } finally {
            $spreadsheet->disconnectWorksheets();
        }
    }

    /** @return list<int> 日期样式的 style 索引 */
    private function dateStyles(): array
    {
        if ($this->dateStyles !== null) {
            return $this->dateStyles;
        }

        if ($this->extension !== 'xlsx') {
            return $this->dateStyles = [];
        }

        $zip = new ZipArchive();
        if ($zip->open($this->path) !== true) {
            return $this->dateStyles = [];
        }

        $styles = [];
        try {
            $stylesXml = $zip->getFromName('xl/styles.xml');
            if ($stylesXml === false) {
                return $this->dateStyles = [];
            }

            $reader = new XMLReader();
            $reader->XML($stylesXml, null, LIBXML_NONET);

            $customDateFormats = [];
            $cellXfs = [];
            $inCellXfs = false;

            while ($reader->read()) {
                if ($reader->nodeType === XMLReader::ELEMENT && $reader->localName === 'numFmt') {
                    $id = (int) $reader->getAttribute('numFmtId');
                    $code = (string) $reader->getAttribute('formatCode');
                    if ($id >= 164 && $this->looksLikeDateFormat($code)) {
                        $customDateFormats[$id] = true;
                    }
                    continue;
                }

                if ($reader->nodeType === XMLReader::ELEMENT && $reader->localName === 'cellXfs') {
                    $inCellXfs = true;
                    continue;
                }

                if ($reader->nodeType === XMLReader::END_ELEMENT && $reader->localName === 'cellXfs') {
                    $inCellXfs = false;
                    continue;
                }

                if ($inCellXfs && $reader->nodeType === XMLReader::ELEMENT && $reader->localName === 'xf') {
                    $cellXfs[] = (int) $reader->getAttribute('numFmtId');
                }
            }

            foreach ($cellXfs as $index => $numFmtId) {
                if (($numFmtId >= 14 && $numFmtId <= 22) || ($numFmtId >= 45 && $numFmtId <= 47) || isset($customDateFormats[$numFmtId])) {
                    $styles[] = $index;
                }
            }

            $reader->close();
        } finally {
            $zip->close();
        }

        return $this->dateStyles = $styles;
    }

    private function looksLikeDateFormat(string $code): bool
    {
        $code = preg_replace('/"[^"]*"/', '', $code) ?? $code;
        $code = preg_replace('/\[[^\]]*\]/', '', $code) ?? $code;

        return (bool) preg_match('/[ymdhs]/i', str_replace(['AM/PM', 'am/pm'], '', $code));
    }

    /** @return list<array{name:string,path:string}> */
    private function xlsxSheets(): array
    {
        if ($this->sheetPaths !== null) {
            return $this->sheetPaths;
        }

        $zip = new ZipArchive();
        if ($zip->open($this->path) !== true) {
            throw new RuntimeException('无法打开工作簿。');
        }

        $sheets = [];
        try {
            $workbook = $zip->getFromName('xl/workbook.xml');
            $relationships = $zip->getFromName('xl/_rels/workbook.xml.rels');
            if ($workbook === false || $relationships === false) {
                throw new RuntimeException('工作簿结构不完整。');
            }

            $targets = [];
            $rels = new XMLReader();
            $rels->XML($relationships, null, LIBXML_NONET);
            while ($rels->read()) {
                if ($rels->nodeType === XMLReader::ELEMENT && $rels->localName === 'Relationship') {
                    $targets[(string) $rels->getAttribute('Id')] = ltrim((string) $rels->getAttribute('Target'), '/');
                }
            }
            $rels->close();

            $book = new XMLReader();
            $book->XML($workbook, null, LIBXML_NONET);
            while ($book->read()) {
                if ($book->nodeType !== XMLReader::ELEMENT || $book->localName !== 'sheet') {
                    continue;
                }
                $relId = (string) ($book->getAttributeNs('id', 'http://schemas.openxmlformats.org/officeDocument/2006/relationships') ?? '');
                $target = $targets[$relId] ?? ('worksheets/sheet' . (count($sheets) + 1) . '.xml');
                $sheets[] = [
                    'name' => (string) $book->getAttribute('name'),
                    'path' => str_starts_with($target, 'xl/') ? $target : 'xl/' . $target,
                ];
            }
            $book->close();
        } finally {
            $zip->close();
        }

        return $this->sheetPaths = $sheets;
    }

    /** @return list<string> */
    private function sheetPaths(): array
    {
        return array_column($this->xlsxSheets(), 'path');
    }

    /** @return array{0:string,1:SplFixedArray<int>} */
    private function xlsxSharedStrings(): array
    {
        if ($this->sharedStrings !== null && $this->sharedStringOffsets !== null) {
            return [$this->sharedStrings, $this->sharedStringOffsets];
        }

        $blob = '';
        $reader = new XMLReader();
        if (! @$reader->open('zip://' . $this->path . '#xl/sharedStrings.xml', null, LIBXML_NONET)) {
            return [$this->sharedStrings = '', $this->sharedStringOffsets = new SplFixedArray(1)];
        }

        try {
            $count = 0;
            $offsets = new SplFixedArray(1024);
            $offsets[0] = 0;
            $depth = 0;
            $collect = false;
            $text = '';

            while ($reader->read()) {
                if ($reader->nodeType === XMLReader::ELEMENT && $reader->localName === 'si') {
                    $collect = true;
                    $text = '';
                    $depth = $reader->depth;
                    continue;
                }

                if (! $collect) {
                    continue;
                }

                if ($reader->nodeType === XMLReader::ELEMENT && $reader->localName === 't' && ! $reader->isEmptyElement) {
                    $text .= $reader->readString();
                    continue;
                }

                if ($reader->nodeType === XMLReader::END_ELEMENT && $reader->localName === 'si' && $reader->depth === $depth) {
                    $blob .= $text;
                    $count++;
                    if ($count + 1 > $offsets->getSize()) {
                        $offsets->setSize($offsets->getSize() * 2);
                    }
                    $offsets[$count] = strlen($blob);
                    $collect = false;
                }
            }

            $offsets->setSize($count + 1);
        } finally {
            $reader->close();
        }

        return [$this->sharedStrings = $blob, $this->sharedStringOffsets = $offsets];
    }

    private function detectDelimiter(string $line): string
    {
        $counts = [
            ',' => substr_count($line, ','),
            ';' => substr_count($line, ';'),
            "\t" => substr_count($line, "\t"),
        ];

        arsort($counts);
        $delimiter = (string) array_key_first($counts);

        return $counts[$delimiter] > 0 ? $delimiter : ',';
    }

    private function normalizeEncoding(string $value): string
    {
        if ($value === '' || mb_check_encoding($value, 'UTF-8')) {
            return $value;
        }

        return mb_convert_encoding($value, 'UTF-8', 'GBK');
    }

    private function columnIndex(string $reference): int
    {
        preg_match('/^([A-Z]+)/i', $reference, $matches);

        $letters = strtoupper($matches[1] ?? 'A');
        $index = 0;
        foreach (str_split($letters) as $letter) {
            $index = $index * 26 + (ord($letter) - 64);
        }

        return $index - 1;
    }
}