use std::collections::BTreeMap;

use eyre::{bail, Context};
use serde::Serialize;
use serde_json::{Map, Value};

#[derive(Default)]
pub struct Output {
    elements: BTreeMap<&'static str, Value>,
}

impl Output {
    pub fn write(&mut self, key: &'static str, v: &impl Serialize) -> eyre::Result<()> {
        let v = serde_json::to_value(v).wrap_err("failed to serialize output")?;
        if self.elements.insert(key, v).is_some() {
            bail!("duplicated output key {key:?}");
        }
        Ok(())
    }

    pub fn write_append(&mut self, key: &'static str, v: &impl Serialize) -> eyre::Result<()> {
        let Value::Object(mut v) =
            serde_json::to_value(v).wrap_err("failed to serialize output")?
        else {
            bail!("tried to append non-object");
        };

        let Value::Object(entry) = self.elements.entry(key).or_insert(Map::new().into()) else {
            bail!("tried to append to non-object");
        };

        entry.append(&mut v);

        Ok(())
    }
}

impl Drop for Output {
    fn drop(&mut self) {
        let out =
            serde_json::to_string_pretty(&self.elements).expect("can serialize output as json");
        println!("{out}",);
    }
}