use fidc_core::factor_events::{self, Expr, Frame};
use serde::Deserialize;
use serde_json::{Value, json};
use std::io::{self, Read};

#[derive(Deserialize)]
#[serde(deny_unknown_fields)]
struct Request {
    expressions: std::collections::BTreeMap<String, Expr>,
    frame: Frame,
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut input = String::new();
    io::stdin().read_to_string(&mut input)?;
    let output = if input.trim().is_empty() {
        factor_events::catalog()
    } else {
        let request: Request = serde_json::from_str(&input)?;
        let results = request
            .expressions
            .iter()
            .map(|(id, expr)| {
                let result = match factor_events::evaluate(expr, &request.frame) {
                    Ok(v) => json!({"result":v}),
                    Err(e) => json!({"error":e}),
                };
                (id.clone(), result)
            })
            .collect::<std::collections::BTreeMap<String, Value>>();
        json!({"contract":factor_events::CONTRACT,"results":results,"read_only":true})
    };
    println!("{}", serde_json::to_string(&output)?);
    Ok(())
}