<?php

namespace Modules\EcommerceFinance\Services;

use Illuminate\Http\UploadedFile;
use Illuminate\Support\Facades\File;
use Illuminate\Validation\ValidationException;
use Throwable;

/**
 * 大文件导入（20 万行级）：上传时把工作簿转成紧凑的行缓存（jsonl.gz），
 * 之后由前端按片调用 process()，每片控制行数与耗时，避免超时与内存爆掉。
 */
class PayablesFinalImportRunner
{
    /** 单次导入的行数上限。 */
    public const MAX_ROWS = 200000;

    /** 每片默认处理的行数。 */
    private const SLICE_ROWS = 20000;

    /** 每累计多少行落一次库。 */
    private const FLUSH_ROWS = 2000;

    /** 单片的时间预算（秒），到点就返回让前端继续下一片。 */
    private const SLICE_SECONDS = 25.0;

    /** 未完成任务的保留时间（小时），过期自动清理。 */
    private const STALE_HOURS = 24;

    public function __construct(
        private readonly PayablesFieldNormalizer $normalizer,
        private readonly SupplierPayableOverrideStore $store,
    ) {
    }

    public function storagePath(): string
    {
        return storage_path('app/payables-final-imports');
    }

    /**
     * 上传文件 → 建立行缓存。
     *
     * @param  array<string,array{label:string,type:string}>  $fields
     * @return array{token:string,total:int}
     */
    public function prepare(UploadedFile $file, array $fields, string $storeDataset, int $companyId, ?int $userId): array
    {
        $this->cleanupStale();

        $token = bin2hex(random_bytes(16));
        $directory = $this->directory($token);
        if (! is_dir($directory) && ! mkdir($directory, 0770, true)) {
            throw ValidationException::withMessages(['import' => '无法创建导入任务目录。']);
        }

        $extension = strtolower((string) $file->getClientOriginalExtension());
        $source = (string) $file->getRealPath();

        $headerRow = 0;

        try {
            $reader = PayablesWorkbookStreamReader::forFile($source, $extension);
            $header = $this->locateHeader($reader, $fields);
            if ($header === null) {
                throw ValidationException::withMessages([
                    'import' => '没有识别到表头，请先下载本页面的导入模板，按模板列填写后重试。',
                ]);
            }

            [$sheetIndex, $headerRow, $columns] = $header;

            $rows = 0;
            $handle = gzopen($directory . '/rows.jsonl.gz', 'wb1');
            if ($handle === false) {
                throw ValidationException::withMessages(['import' => '无法写入导入缓存。']);
            }

            try {
                foreach ($reader->rows($sheetIndex, $headerRow) as $row) {
                    $values = [];
                    foreach ($columns as $columnIndex => $field) {
                        $values[$field] = $row[$columnIndex] ?? null;
                    }

                    $rows++;
                    if ($rows > self::MAX_ROWS) {
                        throw ValidationException::withMessages([
                            'import' => '单次最多导入 200,000 条记录，请拆分文件后重试。',
                        ]);
                    }

                    gzwrite($handle, (string) json_encode($values, JSON_UNESCAPED_UNICODE | JSON_INVALID_UTF8_SUBSTITUTE) . "\n");
                }
            } finally {
                gzclose($handle);
            }

            if ($rows === 0) {
                throw ValidationException::withMessages(['import' => '表格中没有可导入的数据行。']);
            }
        } catch (Throwable $exception) {
            $this->delete($token);
            if ($exception instanceof ValidationException) {
                throw $exception;
            }

            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。',
            ]);
        }

        $this->writeMeta($token, [
            'dataset' => $storeDataset,
            'company_id' => $companyId,
            'user_id' => $userId,
            'fields' => $fields,
            'first_row' => $headerRow + 1,
            'rows' => $rows,
            'offset' => 0,
            'created' => 0,
            'updated' => 0,
            'status' => 'ready',
            'error' => null,
            'started_at' => now()->toIso8601String(),
        ]);

        return ['token' => $token, 'total' => $rows];
    }

    /**
     * 处理一片；返回最新进度。
     *
     * @return array{offset:int,total:int,created:int,updated:int,done:bool}
     */
    public function process(string $token, int $offset, ?int $maxRows = null, ?int $companyId = null): array
    {
        $meta = $this->readMeta($token);
        if ($meta === null) {
            throw ValidationException::withMessages(['import' => '导入任务不存在或已过期，请重新上传文件。']);
        }

        if ($companyId !== null && (int) $meta['company_id'] !== $companyId) {
            throw ValidationException::withMessages(['import' => '导入任务不存在或已过期，请重新上传文件。']);
        }

        if (($meta['status'] ?? '') === 'done') {
            return $this->progress($meta);
        }

        $total = (int) $meta['rows'];
        $firstRow = (int) ($meta['first_row'] ?? 2);
        $dataset = (string) $meta['dataset'];
        $companyId = (int) $meta['company_id'];
        $userId = isset($meta['user_id']) ? (int) $meta['user_id'] : null;
        $fields = is_array($meta['fields'] ?? null) ? $meta['fields'] : [];
        $sliceRows = max(1, $maxRows ?? self::SLICE_ROWS);
        $deadline = microtime(true) + self::SLICE_SECONDS;

        $created = (int) $meta['created'];
        $updated = (int) $meta['updated'];
        $line = 0;
        $processed = 0;
        $records = [];
        $offset = min(max($offset, 0), $total);

        $handle = gzopen($this->directory($token) . '/rows.jsonl.gz', 'rb');
        if ($handle === false) {
            throw ValidationException::withMessages(['import' => '导入任务数据已损坏，请重新上传文件。']);
        }

        try {
            while ($line < $total && $processed < $sliceRows) {
                $raw = gzgets($handle);
                if ($raw === false) {
                    break;
                }
                $line++;

                if ($line <= $offset) {
                    continue;
                }

                $values = json_decode((string) rtrim($raw, "\r\n"), true);
                if (! is_array($values)) {
                    $values = [];
                }

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

                try {
                    $normalized = $this->normalizer->normalize($fields, $values);
                } catch (ValidationException $exception) {
                    $this->fail($meta, $line - 1, $created, $updated, $this->rowMessage($firstRow, $line, $exception));
                    throw ValidationException::withMessages([
                        'import' => $this->rowMessage($firstRow, $line, $exception),
                    ]);
                }

                $key = $this->store->key($dataset, $normalized);
                if (isset($records[$key])) {
                    $message = '第 ' . ($firstRow + $line - 1) . ' 行与前一行内容重复。';
                    $this->fail($meta, $line - 1, $created, $updated, $message);
                    throw ValidationException::withMessages(['import' => $message]);
                }

                $records[$key] = $normalized;
                $processed++;

                if (count($records) >= self::FLUSH_ROWS) {
                    $counts = $this->store->saveBatch($dataset, $records, $companyId, $userId, 'import');
                    $created += $counts['created'];
                    $updated += $counts['updated'];
                    $records = [];

                    if (microtime(true) >= $deadline || $processed >= $sliceRows) {
                        break;
                    }
                }
            }

            if ($records !== []) {
                $counts = $this->store->saveBatch($dataset, $records, $companyId, $userId, 'import');
                $created += $counts['created'];
                $updated += $counts['updated'];
            }
        } finally {
            gzclose($handle);
        }

        $done = $line >= $total;
        $meta['offset'] = $line;
        $meta['created'] = $created;
        $meta['updated'] = $updated;
        $meta['status'] = $done ? 'done' : 'running';
        $meta['error'] = null;
        $this->writeMeta($token, $meta);

        if ($done) {
            $this->delete($token);
        }

        return $this->progress($meta);
    }

    /** @return array{offset:int,total:int,created:int,updated:int,done:bool} */
    private function progress(array $meta): array
    {
        return [
            'offset' => (int) ($meta['offset'] ?? 0),
            'total' => (int) ($meta['rows'] ?? 0),
            'created' => (int) ($meta['created'] ?? 0),
            'updated' => (int) ($meta['updated'] ?? 0),
            'done' => ($meta['status'] ?? '') === 'done',
        ];
    }

    private function rowMessage(int $firstRow, int $line, ValidationException $exception): string
    {
        return '第 ' . ($firstRow + $line - 1) . ' 行：' . collect($exception->errors())->flatten()->first();
    }

    private function fail(array $meta, int $offset, int $created, int $updated, string $message): void
    {
        $meta['offset'] = $offset;
        $meta['created'] = $created;
        $meta['updated'] = $updated;
        $meta['status'] = 'failed';
        $meta['error'] = $message;
        $this->writeMeta((string) $meta['token'], $meta);
    }

    /**
     * 前若干行里找出表头（列序号 => 字段），与旧版打分规则一致。
     *
     * @param  array<string,array{label:string,type:string}>  $fields
     * @return array{0:int,1:int,2:array<int,string>}|null
     */
    private function locateHeader(PayablesWorkbookStreamReader $reader, array $fields): ?array
    {
        $lookup = ['记录标识' => '_action_key', 'recordkey' => '_action_key', '_action_key' => '_action_key'];
        foreach ($fields as $field => $definition) {
            $lookup[$this->header($field)] = $field;
            $lookup[$this->header((string) $definition['label'])] = $field;
        }

        $best = null;
        $score = 0;
        foreach (array_keys($reader->sheetNames()) as $sheetIndex) {
            foreach ($reader->rows($sheetIndex, null, 20) as $rowNumber => $row) {
                $columns = [];
                foreach ($row as $columnIndex => $value) {
                    $key = $this->header($value);
                    if ($key !== '' && isset($lookup[$key])) {
                        $columns[$columnIndex] = $lookup[$key];
                    }
                }

                if (count($columns) > $score) {
                    $score = count($columns);
                    $best = [$sheetIndex, $rowNumber, $columns];
                }
            }
        }

        return $best;
    }

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

    private function directory(string $token): string
    {
        return $this->storagePath() . '/' . $token;
    }

    private function metaPath(string $token): string
    {
        return $this->directory($token) . '/meta.json';
    }

    /** @return array<string,mixed>|null */
    private function readMeta(string $token): ?array
    {
        if (preg_match('/^[a-f0-9]{32}$/', $token) !== 1) {
            return null;
        }

        $path = $this->metaPath($token);
        if (! is_file($path)) {
            return null;
        }

        $meta = json_decode((string) file_get_contents($path), true);
        if (! is_array($meta)) {
            return null;
        }

        return $meta + ['token' => $token];
    }

    private function writeMeta(string $token, array $meta): void
    {
        $meta['token'] = $token;
        $meta['updated_at'] = now()->toIso8601String();
        file_put_contents($this->metaPath($token), (string) json_encode($meta, JSON_UNESCAPED_UNICODE));
    }

    public function delete(string $token): void
    {
        if (preg_match('/^[a-f0-9]{32}$/', $token) !== 1) {
            return;
        }

        File::deleteDirectory($this->directory($token));
    }

    /** 清理过期任务（超过 24 小时未完成）。 */
    private function cleanupStale(): void
    {
        $root = $this->storagePath();
        if (! is_dir($root)) {
            return;
        }

        $deadline = time() - self::STALE_HOURS * 3600;
        foreach (File::directories($root) as $directory) {
            $metaPath = $directory . '/meta.json';
            $modified = is_file($metaPath) ? (int) filemtime($metaPath) : (int) filemtime($directory);
            if ($modified < $deadline) {
                $this->delete(basename($directory));
            }
        }
    }
}