use serde::{Deserialize, Serialize};
use url; // 1.7.2

fn main() {

let input_query = parse_url_param(Some(vec!["query { human(id: \"1000\") { id, name, appearsIn, homePlanet } }".to_string()]));
   println!("{:?}",input_query);
//let operation_name = parse_url_param(url_query_string.remove("operationName"))?;
let variables = parse_variable_param( Some(vec!["{ \"id\": \"1000\" }".to_string()]));
println!("{:?}",variables);
}


fn parse_url_param(params: Option<Vec<String>>) ->  std::result::Result<Option<String>,()> {
    if let Some(values) = params {
        get_single_value(values).map(Some)
    } else {
        Ok(None)
    }
}

fn get_single_value(mut values: Vec<String>) -> std::result::Result<String,()> {
    if values.len() == 1 {
       return Ok(values.remove(0));
    } else {
    // ошибка дубликат ключа
       return Err(());
   }

}

fn parse_variable_param(params: Option<Vec<String>>) -> std::result::Result<Option<String>,()>
{
    if let Some(values) = params {
       return Ok(
            serde_json::from_str::<String>(get_single_value(values)?.as_ref())
                .map(Some)
                .map_err(|_|())?
        );
    } else {
      return  Ok(None);
    }
}