<?php
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

include('include/headscript.php');

header('Content-Type: application/json');

// Read JSON payload
$data = json_decode(file_get_contents('php://input'), true);

$template_id = intval($data['template_id'] ?? 0);
$mapping_id  = intval($data['mapping_id'] ?? 0);
$value       = intval($data['value'] ?? 0);

if ($template_id <= 0 || $mapping_id <= 0) {
    echo json_encode(['success' => false, 'message' => 'Invalid IDs']);
    exit;
}

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

try {
    $pdo->beginTransaction();

    // If user is trying to activate a Main field, check current number of active Main fields
    if ($value === 1) {
        $stmt = $pdo->prepare("
            SELECT COUNT(*) 
            FROM template_mapping 
            WHERE template_id = ? 
              AND main_field = 1 
              AND id <> ?
        ");
        $stmt->execute([$template_id, $mapping_id]);
        $currentMainCount = (int)$stmt->fetchColumn();

        if ($currentMainCount >= 2) {
            $pdo->rollBack();
            echo json_encode([
                'success' => false,
                'message' => 'Maximum 2 Main fields allowed'
            ]);
            exit;
        }
    }

    // Update only this mapping
    $stmt = $pdo->prepare("
        UPDATE template_mapping 
        SET main_field = ? 
        WHERE id = ? 
          AND template_id = ?
    ");
    $stmt->execute([$value, $mapping_id, $template_id]);

    $pdo->commit();

    echo json_encode(['success' => true]);
} catch (Exception $e) {
    if ($pdo->inTransaction()) {
        $pdo->rollBack();
    }

    echo json_encode([
        'success' => false,
        'message' => $e->getMessage()
    ]);
}