<?php
declare(strict_types=1);

require_once __DIR__ . '/db.php';

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    error_out('Method not allowed', 405);
}

// ─── POST /api/send-now.php ───────────────────────────────────────────────────
// Body: {
//   "message": "...",               -- required if template_id is omitted
//   "template_id": 1,               -- optional, overrides message
//   "recipient_scope": "all",       -- "all" (default) or "workshop"
//   "workshop_session_id": 2        -- required when recipient_scope is "workshop"
// }

try {
    require_api_key();

    $body       = json_body();
    $customBody = trim((string) ($body['message'] ?? ''));
    $templateId = isset($body['template_id']) ? (int) $body['template_id'] : null;
    $scope      = (string) ($body['recipient_scope'] ?? 'all');
    $workshopId = isset($body['workshop_session_id']) ? (int) $body['workshop_session_id'] : null;

    if ($customBody === '' && $templateId === null) {
        error_out('Either message or template_id is required');
    }
    if (!in_array($scope, ['all', 'workshop'], true)) {
        error_out('recipient_scope must be "all" or "workshop"');
    }
    if ($scope === 'workshop' && ($workshopId === null || $workshopId <= 0)) {
        error_out('workshop_session_id is required when recipient_scope is "workshop"');
    }
    if ($customBody !== '' && mb_strlen($customBody) > 160) {
        error_out('message must be 160 characters or fewer');
    }

    $db = db();

    // Resolve message text from template if provided
    $messageBody = $customBody;
    if ($templateId !== null) {
        $t = $db->prepare('SELECT body FROM sms_templates WHERE id = :id');
        $t->execute([':id' => $templateId]);
        $tpl = $t->fetch();
        if (!$tpl) {
            error_out('Template not found', 404);
        }
        $messageBody = $tpl['body'];
    }

    // Fetch recipients
    if ($scope === 'all') {
        $recipients = $db->query('SELECT id, mobile_number FROM attendees')->fetchAll();
    } else {
        $stmt = $db->prepare(
            'SELECT a.id, a.mobile_number
             FROM attendees a
             JOIN registrations r ON r.attendee_id = a.id
             WHERE r.workshop_session_id = :ws_id'
        );
        $stmt->execute([':ws_id' => $workshopId]);
        $recipients = $stmt->fetchAll();
    }

    if (empty($recipients)) {
        error_out('No recipients found for the selected scope');
    }

    $db->beginTransaction();

    // Create the send job record (worker will update status once it has sent)
    $jobStmt = $db->prepare(
        'INSERT INTO send_jobs (template_id, custom_body, recipient_scope, workshop_session_id, status)
         VALUES (:template_id, :custom_body, :scope, :ws_id, "pending")'
    );
    $jobStmt->execute([
        ':template_id' => $templateId,
        ':custom_body' => $customBody !== '' ? $customBody : null,
        ':scope'       => $scope,
        ':ws_id'       => $workshopId,
    ]);
    $jobId = (int) $db->lastInsertId();
    $db->commit();

    // Dispatch to Python worker (synchronous — waits for all messages to send)
    $ch = curl_init(WORKER_URL . '/send');
    curl_setopt_array($ch, [
        CURLOPT_POST           => true,
        CURLOPT_POSTFIELDS     => json_encode(['job_id' => $jobId]),
        CURLOPT_HTTPHEADER     => ['Content-Type: application/json'],
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_TIMEOUT        => 120,
    ]);
    $response  = curl_exec($ch);
    $httpCode  = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    $curlError = curl_error($ch);
    curl_close($ch);

    if ($curlError || $httpCode !== 200) {
        $db->prepare("UPDATE send_jobs SET status='failed' WHERE id = :id")
           ->execute([':id' => $jobId]);
        error_out('SMS worker unavailable: ' . ($curlError ?: "HTTP $httpCode"), 503);
    }

    $result = json_decode((string) $response, true) ?? [];

    json_out([
        'job_id'     => $jobId,
        'sent'       => (int) ($result['sent']   ?? 0),
        'failed'     => (int) ($result['failed'] ?? 0),
        'recipients' => count($recipients),
    ]);

} catch (PDOException $e) {
    if (isset($db) && $db->inTransaction()) {
        $db->rollBack();
    }
    error_out('Database error: ' . $e->getMessage(), 500);
}