<?php

namespace App\Services;

use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Log;

/**
 * ارسال آرام همهٔ سندهای جاافتاده به ته‌حساب — بدون schedule.
 * استارت از API؛ حلقه با artisan در پس‌زمینه یا یک تیک روی pending-summary.
 */
class TahesabDocSyncService
{
    public const CACHE_KEY = 'tahesab_doc_sync_job';

    /** فاصله بین دو سند تا ته‌حساب بن نکند (ثانیه) */
    public const GAP_SECONDS = 2.5;

    private const STALE_SECONDS = 8;

    private const TTL_RUNNING = 21600;

    private const TTL_DONE = 7200;

    /** @var resource|null */
    private $lockHandle;

    public function snapshot(): array
    {
        $job = $this->read();

        return $this->publicSnapshot($job);
    }

    /**
     * @return array{ok:bool,message:string,doc_sync:array}
     */
    public function start(): array
    {
        $sync = app(TahesabSyncService::class);
        if (! $sync->isSyncEnabled()) {
            return [
                'ok' => false,
                'message' => 'همگام‌سازی ته‌حساب فعال نیست یا تنظیمات ناقص است',
                'doc_sync' => $this->snapshot(),
            ];
        }

        $current = $this->read();
        if (($current['running'] ?? false) === true) {
            return [
                'ok' => true,
                'message' => 'ارسال سندها از قبل در جریان است',
                'doc_sync' => $this->publicSnapshot($current),
            ];
        }

        $totals = $sync->pendingTotals();
        $total = (int) ($totals['total'] ?? 0);
        if ($total <= 0) {
            return [
                'ok' => false,
                'message' => 'سند جاافتاده‌ای برای ارسال نیست',
                'doc_sync' => $this->emptySnapshot(),
            ];
        }

        $job = [
            'running' => true,
            'stop' => false,
            'stopped' => false,
            'finished' => false,
            'total' => $total,
            'processed' => 0,
            'success' => 0,
            'failed' => 0,
            'current' => '',
            'errors' => [],
            'skip' => ['row' => [], 'withdraw' => [], 'order' => []],
            'started_at' => now()->toDateTimeString(),
            'finished_at' => null,
            'beat_at' => now()->toDateTimeString(),
        ];
        $this->write($job, self::TTL_RUNNING);
        $this->spawnPump();

        return [
            'ok' => true,
            'message' => 'ارسال سندها شروع شد',
            'doc_sync' => $this->publicSnapshot($job),
        ];
    }

    /**
     * @return array{ok:bool,message:string,doc_sync:array}
     */
    public function stop(): array
    {
        $job = $this->read();
        if (($job['running'] ?? false) !== true) {
            return [
                'ok' => true,
                'message' => 'ارسال در جریان نیست',
                'doc_sync' => $this->publicSnapshot($job),
            ];
        }

        $job['stop'] = true;
        $this->write($job, self::TTL_RUNNING);

        return [
            'ok' => true,
            'message' => 'درخواست توقف ثبت شد',
            'doc_sync' => $this->publicSnapshot($job),
        ];
    }

    public function tickIfStale(): void
    {
        $job = $this->read();
        if (($job['running'] ?? false) !== true) {
            return;
        }

        $beat = $job['beat_at'] ?? null;
        if ($beat && now()->diffInSeconds(\Illuminate\Support\Carbon::parse($beat)) < self::STALE_SECONDS) {
            return;
        }

        $this->pumpOnce();
    }

    public function runLoop(): int
    {
        $done = 0;
        while (true) {
            if (! $this->tryLock()) {
                return $done;
            }
            try {
                $cont = $this->pumpOnceUnlocked();
            } finally {
                $this->releaseLock();
            }
            if (! $cont) {
                break;
            }
            $done++;
            usleep((int) (self::GAP_SECONDS * 1_000_000));
        }

        return $done;
    }

    public function pumpOnce(): bool
    {
        if (! $this->tryLock()) {
            return true;
        }
        try {
            return $this->pumpOnceUnlocked();
        } finally {
            $this->releaseLock();
        }
    }

    private function pumpOnceUnlocked(): bool
    {
        $job = $this->read();
        if (($job['running'] ?? false) !== true) {
            return false;
        }

        if (($job['stop'] ?? false) === true) {
            $this->finish($job, true);

            return false;
        }

        $sync = app(TahesabSyncService::class);
        $next = $sync->peekNextPending($job['skip'] ?? []);
        if ($next === null) {
            $this->finish($job, false);

            return false;
        }

        $job['current'] = (string) ($next['label'] ?? '');
        $job['beat_at'] = now()->toDateTimeString();
        $this->write($job, self::TTL_RUNNING);

        $type = (string) $next['type'];
        $id = (int) $next['id'];
        $ok = false;
        $message = '';
        try {
            $result = $sync->syncOne($type, $id);
            $ok = (bool) ($result['ok'] ?? false);
            $message = (string) ($result['message'] ?? '');
        } catch (\Throwable $e) {
            $ok = false;
            $message = $e->getMessage();
            Log::warning('Tahesab doc sync item failed', [
                'type' => $type,
                'id' => $id,
                'error' => $e->getMessage(),
            ]);
        }

        if (! $ok && $this->looksRateLimited($message)) {
            $job = $this->read();
            if (($job['running'] ?? false) !== true) {
                return false;
            }
            $job['current'] = 'محدودیت نرخ ته‌حساب — کمی صبر…';
            $job['beat_at'] = now()->toDateTimeString();
            $this->write($job, self::TTL_RUNNING);
            usleep(5_000_000);

            return true;
        }

        $job = $this->read();
        if (($job['running'] ?? false) !== true) {
            return false;
        }

        $job['processed'] = (int) ($job['processed'] ?? 0) + 1;
        if ($ok) {
            $job['success'] = (int) ($job['success'] ?? 0) + 1;
        } else {
            $job['failed'] = (int) ($job['failed'] ?? 0) + 1;
            $errors = is_array($job['errors'] ?? null) ? $job['errors'] : [];
            $errors[] = [
                'label' => $job['current'] ?: ($type.' #'.$id),
                'error' => $message !== '' ? $message : 'ناموفق',
            ];
            $job['errors'] = array_slice($errors, -30);
            $skip = is_array($job['skip'] ?? null) ? $job['skip'] : ['row' => [], 'withdraw' => [], 'order' => []];
            $skip[$type] = array_values(array_unique(array_merge($skip[$type] ?? [], [$id])));
            $job['skip'] = $skip;
        }

        $job['beat_at'] = now()->toDateTimeString();
        $this->write($job, self::TTL_RUNNING);

        return true;
    }

    private function finish(array $job, bool $stopped): void
    {
        $job['running'] = false;
        $job['finished'] = true;
        $job['stopped'] = $stopped;
        $job['stop'] = false;
        $job['current'] = '';
        $job['finished_at'] = now()->toDateTimeString();
        $job['beat_at'] = now()->toDateTimeString();
        $this->write($job, self::TTL_DONE);
    }

    private function spawnPump(): void
    {
        if (\PHP_OS_FAMILY === 'Windows') {
            return;
        }

        $php = PHP_BINARY;
        if (stripos((string) $php, 'fpm') !== false || ! is_executable((string) $php)) {
            $php = 'php';
        }
        $artisan = base_path('artisan');
        $cmd = 'nohup '.escapeshellarg($php).' '.escapeshellarg($artisan)
            .' tahesab:pump-doc-sync >/dev/null 2>&1 &';
        if (! function_exists('exec')) {
            Log::warning('Tahesab doc sync spawn skipped: exec disabled');

            return;
        }
        try {
            exec($cmd);
        } catch (\Throwable $e) {
            Log::warning('Tahesab doc sync spawn failed', ['error' => $e->getMessage()]);
        }
    }

    private function tryLock(): bool
    {
        $path = storage_path('framework/cache/tahesab-doc-sync.lock');
        $dir = dirname($path);
        if (! is_dir($dir)) {
            @mkdir($dir, 0775, true);
        }
        $handle = fopen($path, 'c');
        if ($handle === false) {
            return false;
        }
        if (! flock($handle, LOCK_EX | LOCK_NB)) {
            fclose($handle);

            return false;
        }
        $this->lockHandle = $handle;

        return true;
    }

    private function releaseLock(): void
    {
        if (! is_resource($this->lockHandle)) {
            $this->lockHandle = null;

            return;
        }
        flock($this->lockHandle, LOCK_UN);
        fclose($this->lockHandle);
        $this->lockHandle = null;
    }

    private function looksRateLimited(string $message): bool
    {
        $m = mb_strtolower($message);

        return str_contains($m, '429')
            || str_contains($m, 'too many')
            || str_contains($m, 'rate limit')
            || str_contains($m, 'تعداد درخواست');
    }

    private function read(): array
    {
        $job = Cache::get(self::CACHE_KEY);

        return is_array($job) ? $job : [];
    }

    private function write(array $job, int $ttl): void
    {
        Cache::put(self::CACHE_KEY, $job, $ttl);
    }

    private function emptySnapshot(): array
    {
        return $this->publicSnapshot([]);
    }

    private function publicSnapshot(array $job): array
    {
        $running = (bool) ($job['running'] ?? false);
        $finished = (bool) ($job['finished'] ?? false);
        $total = (int) ($job['total'] ?? 0);
        $processed = (int) ($job['processed'] ?? 0);
        $percent = $total > 0 ? min(100, (int) round(($processed / $total) * 100)) : 0;
        if ($finished && ! ($job['stopped'] ?? false)) {
            $percent = 100;
        }

        return [
            'running' => $running,
            'finished' => $finished,
            'stopped' => (bool) ($job['stopped'] ?? false),
            'percent' => $percent,
            'total' => $total,
            'processed' => $processed,
            'success' => (int) ($job['success'] ?? 0),
            'failed' => (int) ($job['failed'] ?? 0),
            'current' => (string) ($job['current'] ?? ''),
            'errors' => is_array($job['errors'] ?? null) ? $job['errors'] : [],
            'started_at' => $job['started_at'] ?? null,
            'finished_at' => $job['finished_at'] ?? null,
        ];
    }
}