Turn Sqlite into a public, read-only, JSON API

sqlite-api.php

<?php

function json_response(int $code = 200, array $data = null)
{
    // clear the old headers
    header_remove();
    // set the actual code
    http_response_code($code);
    // set the header to make sure cache is forced
    header('Cache-Control: public, max-age=300');
    // treat this as json
    header('Content-Type: application/json');
    // allow CORS
    header('Access-Control-Allow-Origin: *');

    $status = [
        200 => '200 OK',
        204 => '204 No Content',
        400 => '400 Bad Request',
        405 => '405 Method Not Allowed',
        422 => '422 Unprocessable Entity',
        500 => '500 Internal Server Error',
    ];

    // set the status header
    header('Status: ' . $status[$code]);

    // return the encoded json
    return json_encode($data,
        JSON_NUMERIC_CHECK
        |JSON_UNESCAPED_UNICODE
        |JSON_UNESCAPED_SLASHES
        |JSON_PARTIAL_OUTPUT_ON_ERROR
        |JSON_INVALID_UTF8_IGNORE
        |JSON_THROW_ON_ERROR);
}

$method = strtoupper($_SERVER['REQUEST_METHOD']);

if ($method !== 'GET' && $method !== 'POST') {
    echo json_response(405, [
        'error' => "method {$method} is not supported",
        'meta' => [],
    ]);

    return;
}

$query = $_GET['query'] ?? '';

if ($method === 'POST') {
    // if you are doing ajax with application-json headers
    $query = empty($_POST) ? json_decode(
        (string)file_get_contents('php://input'),
        true)['query'] : $_POST['query'] ?? '';
}

if (empty($query)) {
    $wording = [
        'GET' => 'query string',
        'POST' => 'parameter',
    ];

    echo json_response(400, [
        'error' => 'must provide a "query" ' . $wording[$method],
        'meta' => [],
    ]);

    return;
}

// Create (connect to) SQLite database in file
// http://www.sqlitetutorial.net/sqlite-sample-database/
$db = new SQLite3('chinook.sqlite', SQLITE3_OPEN_READONLY);
// throw real exceptions
$db->enableExceptions(true);

try {
    $rows = $db->query($query);

    $results = [
        'data' => [],
        'meta' => [
            'query' => $query,
            'total' => 0,
        ]
    ];

    while ($row = $rows->fetchArray(SQLITE3_ASSOC)) {
        $results['data'][] = $row;
    }

    $results['meta']['total'] = count($results['data']);

    $code = empty($results) ? 404 : 200;

    echo json_response($code, $results);
} catch (Exception $e) {
    echo json_response(500, [
        'message' => $e->getMessage(),
        'trace' => $e->getTrace(),
        'meta' => [],
    ]);
}