use serde_json::Value;
use std::error::Error;

// Takes a list of objects from a json string and turns it into a csv.
// You can use different deliminators.
fn convert_object(
    json: &str,
    deliminator: char,
    with_headers: bool,
) -> Result<String, Box<dyn Error>> {
    let mut headers = String::new();
    let mut buffer = String::new();

    let object: Value = serde_json::from_str(&json)?;
    let map = object.as_object().unwrap();

    if with_headers {
        for (x, _) in map {
            headers.push_str(x);
            headers.push(deliminator);
        }
        // Cut of the last ,.
        headers = headers[..headers.len() - 1].parse()?;

        buffer.push_str(&headers);

        buffer.push('\n');
    }

    for (_, y) in map {
        buffer.push_str(y.as_str().unwrap_or(""));
        buffer.push(deliminator);
    }

    buffer = buffer[..buffer.len() - 1].parse()?;
    buffer.push('\n');
    Ok(buffer)
}

#[cfg(test)]
mod tests {
    use crate::convert_object;
    use std::fs::read_to_string;

    #[test]
    fn one_object() {
        assert_eq!(
            convert_object(r#"{"name":"tom","age":"23","dob":"07/22/1989"}"#, ',', true).unwrap(),
            ("age,dob,name\n23,07/22/1989,tom\n")
        );
    }

    #[test]
    fn without_headers() {
        assert_eq!(
            convert_object(
                r#"{"name":"tom","age":"23","dob":"07/22/1989"}"#,
                ',',
                false
            )
            .unwrap(),
            "23,07/22/1989,tom\n"
        );
    }

    #[test]
    fn json_doc() {
        let in_buffer = read_to_string("test").unwrap();
        println!("{}", convert_object(&in_buffer, '|', true).unwrap());
    }

    #[test]
    fn bad_data() {
        assert_eq!(
            convert_object("{asdfasdf,{adsf}}sdf}", ',', true).unwrap(),
            "should fail"
        );
    }
}