<?php
/**
 * Scadenzario — Email notification cron script
 * Run daily: 0 7 * * * php /var/www/html/public/userarea/scadenzario/cron/send_notifications.php
 *
 * Sends "approaching" emails N days before due_date (per-deadline notification_days).
 * Sends "overdue" emails when due_date has passed.
 * Skips completed deadlines and already-sent notifications (same deadline+employee+type+date).
 * Email is taken from employees.auth_user_id → auth_users.email.
 */

require_once __DIR__ . '/../../class/db-functions.php';
require_once __DIR__ . '/../../../../vendor/autoload.php';

use Dotenv\Dotenv;
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception;

$dotenv = Dotenv::createImmutable(__DIR__ . '/../../../../');
$dotenv->load();

$db = DBHandlerSelect::getInstance();
$pdo = $db->getConnection();

$today = date('Y-m-d');
$appUrl = rtrim($_ENV['APP_URL'] ?? 'http://localhost:8001', '/');

$sent = 0;
$skipped = 0;
$errors = 0;

// Get active deadlines that are approaching or overdue
$stmt = $pdo->query("
    SELECT d.id, d.topic, s.name AS subject_name, d.due_date, d.notification_days
    FROM scad_deadlines d
    LEFT JOIN scad_subjects s ON s.id = d.subject_id
    WHERE d.status = 'active'
      AND d.due_date <= DATE_ADD(CURDATE(), INTERVAL d.notification_days DAY)
");
$deadlines = $stmt->fetchAll(PDO::FETCH_ASSOC);

if (empty($deadlines)) {
    echo date('Y-m-d H:i:s') . " — Nessuna scadenza da notificare.\n";
    exit(0);
}

// Prepare statements
$getRecipients = $pdo->prepare("
    SELECT DISTINCT e.id as employee_id, au.email, e.first_name, e.last_name
    FROM scad_deadline_employee de
    JOIN employees e ON e.id = de.employee_id
    JOIN auth_users au ON au.id = e.auth_user_id
    WHERE de.deadline_id = ?
      AND e.auth_user_id IS NOT NULL
      AND au.email IS NOT NULL
      AND au.email != ''
");

// Also get employees from assigned departments
$getDeptRecipients = $pdo->prepare("
    SELECT DISTINCT e.id as employee_id, au.email, e.first_name, e.last_name
    FROM employees e
    JOIN auth_users au ON au.id = e.auth_user_id
    WHERE e.department IN (SELECT TRIM(SUBSTRING_INDEX(SUBSTRING_INDEX(d.departments, ',', n.n), ',', -1))
        FROM scad_deadlines d
        CROSS JOIN (SELECT 1 n UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5) n
        WHERE d.id = ?
          AND d.departments IS NOT NULL
          AND n.n <= 1 + LENGTH(d.departments) - LENGTH(REPLACE(d.departments, ',', '')))
      AND e.auth_user_id IS NOT NULL
      AND au.email IS NOT NULL
      AND au.email != ''
");

$checkSent = $pdo->prepare("
    SELECT COUNT(*) FROM scad_deadline_notifications
    WHERE deadline_id = ? AND employee_id = ? AND type = ? AND DATE(sent_at) = CURDATE()
");

$insertNotif = $pdo->prepare("
    INSERT INTO scad_deadline_notifications (deadline_id, employee_id, type) VALUES (?, ?, ?)
");

$insertHistory = $pdo->prepare("
    INSERT INTO scad_deadline_histories (deadline_id, user_id, action, notes) VALUES (?, NULL, 'notification_sent', ?)
");

foreach ($deadlines as $dl) {
    $isOverdue = $dl['due_date'] < $today;
    $type = $isOverdue ? 'overdue' : 'approaching';
    $daysLeft = (int)((strtotime($dl['due_date']) - strtotime($today)) / 86400);

    // Collect all recipients (direct + department)
    $recipients = [];

    $getRecipients->execute([$dl['id']]);
    foreach ($getRecipients->fetchAll(PDO::FETCH_ASSOC) as $r) {
        $recipients[$r['employee_id']] = $r;
    }

    $getDeptRecipients->execute([$dl['id']]);
    foreach ($getDeptRecipients->fetchAll(PDO::FETCH_ASSOC) as $r) {
        $recipients[$r['employee_id']] = $r;
    }

    if (empty($recipients)) {
        continue;
    }

    foreach ($recipients as $emp) {
        // Check if already sent today
        $checkSent->execute([$dl['id'], $emp['employee_id'], $type]);
        if ($checkSent->fetchColumn() > 0) {
            $skipped++;
            continue;
        }

        // Send email
        try {
            $mail = new PHPMailer(true);

            // SMTP config from .env
            $mailer = $_ENV['MAIL_MAILER'] ?? 'mail';
            if ($mailer === 'smtp') {
                $mail->isSMTP();
                $mail->Host = $_ENV['MAIL_HOST'] ?? 'localhost';
                $mail->Port = (int)($_ENV['MAIL_PORT'] ?? 587);
                if (!empty($_ENV['MAIL_USERNAME']) && $_ENV['MAIL_USERNAME'] !== 'null') {
                    $mail->SMTPAuth = true;
                    $mail->Username = $_ENV['MAIL_USERNAME'];
                    $mail->Password = $_ENV['MAIL_PASSWORD'] ?? '';
                }
                $enc = $_ENV['MAIL_ENCRYPTION'] ?? '';
                if ($enc && $enc !== 'null') {
                    $mail->SMTPSecure = $enc;
                }
            }

            $mail->CharSet = 'UTF-8';
            $mail->setFrom(
                $_ENV['MAIL_FROM_ADDRESS'] ?? 'noreply@zibogomma.it',
                $_ENV['MAIL_FROM_NAME'] ?? 'Scadenzario ZIBOGOMMA'
            );
            $mail->addAddress($emp['email'], trim($emp['first_name'] . ' ' . $emp['last_name']));

            $detailUrl = $appUrl . '/userarea/scadenzario/detail.php?id=' . $dl['id'];
            $topicText = (!empty($dl['subject_name']) ? $dl['subject_name'] . ' — ' : '') . $dl['topic'];

            if ($isOverdue) {
                $mail->Subject = '⚠️ Scadenza superata: ' . $dl['topic'];
                $mail->Body = buildHtml(
                    'Scadenza superata',
                    $topicText,
                    'La scadenza era prevista per il <strong>' . date('d/m/Y', strtotime($dl['due_date'])) . '</strong> ed è stata superata da <strong>' . abs($daysLeft) . ' giorni</strong>.',
                    '#dc3545',
                    $detailUrl
                );
            } else {
                $mail->Subject = '📅 Scadenza in arrivo: ' . $dl['topic'];
                $daysText = $daysLeft === 0 ? 'oggi' : 'tra <strong>' . $daysLeft . ' giorni</strong>';
                $mail->Body = buildHtml(
                    'Scadenza in arrivo',
                    $topicText,
                    'La scadenza è prevista per il <strong>' . date('d/m/Y', strtotime($dl['due_date'])) . '</strong> (' . $daysText . ').',
                    '#e8930c',
                    $detailUrl
                );
            }

            $mail->isHTML(true);
            $mail->AltBody = strip_tags(str_replace('<br>', "\n", $mail->Body));

            $mail->send();

            // Record notification
            $insertNotif->execute([$dl['id'], $emp['employee_id'], $type]);
            $sent++;

            echo date('H:i:s') . " ✓ {$type} → {$emp['email']} — {$dl['topic']}\n";

        } catch (Exception $e) {
            $errors++;
            echo date('H:i:s') . " ✗ Errore {$emp['email']}: {$e->getMessage()}\n";
        }
    }

    // History (one per deadline, not per recipient)
    $recipientNames = implode(', ', array_map(fn($r) => trim($r['first_name'] . ' ' . $r['last_name']), $recipients));
    $insertHistory->execute([$dl['id'], "Notifica {$type} inviata a: {$recipientNames}"]);
}

echo "\n" . date('Y-m-d H:i:s') . " — Completato. Inviate: {$sent}, Saltate: {$skipped}, Errori: {$errors}\n";

// --- HTML email template ---
function buildHtml(string $title, string $topic, string $message, string $accentColor, string $url): string
{
    return '
<!DOCTYPE html>
<html>
<head><meta charset="UTF-8"></head>
<body style="margin:0;padding:0;background:#f4f6f9;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif">
<table width="100%" cellpadding="0" cellspacing="0" style="padding:30px 0">
<tr><td align="center">
<table width="560" cellpadding="0" cellspacing="0" style="background:#fff;border-radius:12px;overflow:hidden;box-shadow:0 2px 8px rgba(0,0,0,0.06)">
    <tr><td style="background:' . $accentColor . ';padding:20px 30px">
        <h1 style="margin:0;color:#fff;font-size:18px">' . htmlspecialchars($title) . '</h1>
    </td></tr>
    <tr><td style="padding:30px">
        <h2 style="margin:0 0 15px;color:#2c3e6b;font-size:16px">' . htmlspecialchars($topic) . '</h2>
        <p style="margin:0 0 20px;color:#444;font-size:14px;line-height:1.6">' . $message . '</p>
        <a href="' . htmlspecialchars($url) . '" style="display:inline-block;background:#5a8fd8;color:#fff;padding:10px 24px;border-radius:6px;text-decoration:none;font-weight:600;font-size:14px">Vai alla scadenza</a>
    </td></tr>
    <tr><td style="padding:15px 30px;background:#f8f9fb;border-top:1px solid #eee">
        <p style="margin:0;color:#999;font-size:11px">ZIBOGOMMA — Scadenzario</p>
    </td></tr>
</table>
</td></tr>
</table>
</body>
</html>';
}