<?php
/**
 * Cron Worker for AI Invoice Extraction
 * 
 * Designed to run via cron every minute: * * * * *
 * Processes ALL pending items in the queue, then EXITS.
 * NO infinite loop. NO lock file issues.
 */

declare(strict_types=1);

require_once __DIR__ . '/../bootstrap/init.php';

use App\Core\Database;
use App\Services\InvoiceProcessor;

// Simple lock: prevent overlapping runs
$lockFile = STORAGE_PATH . '/logs/process_batches.lock';

// Check if lock file exists and is stale (older than 5 minutes = dead process)
if (file_exists($lockFile)) {
    $lockAge = time() - filemtime($lockFile);
    if ($lockAge > 300) {
        // Stale lock from a crashed process - remove it
        @unlink($lockFile);
        workerLog("Removed stale lock file (age: {$lockAge}s)");
    } else {
        workerLog("Worker already running (lock age: {$lockAge}s). Exiting.");
        exit(0);
    }
}

// Create lock
file_put_contents($lockFile, getmypid() . "\n" . date('c'));

function workerLog(string $msg): void {
    $line = "[" . date('Y-m-d H:i:s') . "] " . $msg . "\n";
    echo $line;
    // Also write to dedicated log file
    @file_put_contents(STORAGE_PATH . '/logs/worker.log', $line, FILE_APPEND);
}

workerLog("=== Musadaq AI Worker Started ===");

try {
    $db = Database::getInstance();
    $processed = 0;
    $failed = 0;

    // Get pending items whose batch is ready for processing.
    //
    // The b.status <> 'uploading' filter is essential: queue rows are inserted as
    // 'pending' the moment each image lands, while total_images is still growing.
    // Picking them up mid-upload made the batch look complete after the first
    // image, which locked the batch and made every later upload fail with
    // "لا يمكن إضافة صور لدفعة تمت معالجتها".
    $stmt = $db->prepare("
        SELECT q.id
        FROM invoice_processing_queue q
        JOIN invoice_batches b ON q.batch_id = b.id
        WHERE q.status = 'pending'
          AND q.attempts < COALESCE(q.max_attempts, 3)
          AND b.status <> 'uploading'
        ORDER BY q.created_at ASC
        LIMIT 20
    ");
    $stmt->execute();
    $items = $stmt->fetchAll(\PDO::FETCH_COLUMN);

    // Rescue items abandoned in 'processing' by a crashed worker. claimed_at is
    // set at claim time, so "claimed over 10 minutes ago and still processing"
    // reliably means the owning process died mid-flight.
    $rescued = $db->prepare("
        UPDATE invoice_processing_queue
        SET status = 'pending',
            error_message = 'Reclaimed from a stalled worker'
        WHERE status = 'processing'
          AND claimed_at IS NOT NULL
          AND claimed_at < (NOW() - INTERVAL 10 MINUTE)
    ");
    $rescued->execute();
    if ($rescued->rowCount() > 0) {
        workerLog("Reclaimed {$rescued->rowCount()} stalled item(s) back to pending.");
    }

    // Also close out batches whose images all reached a terminal state but whose
    // status was never flipped (e.g. the worker died right after the last item).
    $stuck = $db->query("
        SELECT id FROM invoice_batches
        WHERE status = 'processing'
          AND total_images > 0
          AND (processed_images + failed_images) >= total_images
        LIMIT 50
    ")->fetchAll(\PDO::FETCH_COLUMN);
    foreach ($stuck as $stuckBatchId) {
        workerLog("Closing stuck batch: $stuckBatchId");
        InvoiceProcessor::checkBatchCompletion((string)$stuckBatchId);
    }

    if (empty($items)) {
        workerLog("No pending items. Exiting.");
    } else {
        workerLog("Found " . count($items) . " pending item(s).");

        foreach ($items as $queueId) {
            workerLog("Processing Queue ID: $queueId ...");
            
            try {
                $success = InvoiceProcessor::processQueueItem((int)$queueId);
                if ($success) {
                    $processed++;
                    workerLog("  ✓ Queue ID $queueId processed successfully.");
                } else {
                    $failed++;
                    workerLog("  ✗ Queue ID $queueId failed (returned false).");
                }
            } catch (\Throwable $e) {
                $failed++;
                workerLog("  ✗ Queue ID $queueId EXCEPTION: " . $e->getMessage());
            }
        }

        workerLog("=== Worker Done: $processed success, $failed failed ===");
    }

} catch (\Throwable $e) {
    workerLog("FATAL ERROR: " . $e->getMessage() . "\n" . $e->getTraceAsString());
} finally {
    // ALWAYS remove lock file
    @unlink($lockFile);
}