/**
 * 打开一个对话框，让用户选择一个文件，读取
 * 
 */
export async function openFile(): Promise<{ file: File; content: string } | null> {
    return new Promise((resolve) => {
        const input = document.createElement('input');
        input.type = 'file';
        input.onchange = async () => {
            if (input.files && input.files.length > 0) {
                const file = input.files[0];
                const reader = new FileReader();
                reader.onload = () => {
                    resolve({ file, content: reader.result as string });
                };
                reader.onerror = () => {
                    resolve(null);
                };
                reader.readAsText(file);
            } else {
                resolve(null);
            }
        };
        input.click();
    });
}