extern crate serde;
#[macro_use]
extern crate serde_derive;
extern crate serde_json;

use serde::Deserialize;
use serde::de::Deserializer;

static INPUT: &str = r#"{
	"post" : {
		"id" : "123",
		"comments" : [{
			"body" : "test body",
			"comments": [{
			    "body": "test body 2",
			    "comments": ""
			}]
		}]
	}
}"#;

#[derive(Serialize, Deserialize, Debug)]
struct InputObject {
    post: Post
}

#[derive(Serialize, Deserialize, Debug)]
struct Post {
    id: String,
    comments: Vec<Comments>
}

#[derive(Serialize, Deserialize, Debug)]
struct Comments {
    body: String,
    #[serde(deserialize_with="parse_listing")]
    comments: Option<Vec<Comments>>
}


fn parse_listing<'de, D>(d: D) -> Result<Option<Vec<Comments>>, D::Error>
    where D: Deserializer<'de>
{
    match Deserialize::deserialize(d) {
        Ok(comments) => Ok(Some(comments)),
        Err(e) => {
            println!("{:?}", e);
            Ok(None)
        }
    }
}


fn main() {
    let input: InputObject = serde_json::from_str(INPUT).unwrap();
    println!("{:?}", input);
}