use std::{
    rc::Rc,
    time::{SystemTime, UNIX_EPOCH},
};

use ordered_float::OrderedFloat;

use crate::{
    callable::{Callable, CallingError},
    interpreter::Interpreter,
    value::{CallableType, Value},
};

struct Clock;

impl Callable for Clock {
    fn name(&self) -> String {
        "clock".into()
    }

    fn arity(&self) -> usize {
        0
    }

    fn call(
        &self,
        _interpreter: &mut Interpreter,
        _args: Vec<crate::value::Value>,
    ) -> Result<Value, CallingError> {
        let start = SystemTime::now();
        let since_the_epoch = start
            .duration_since(UNIX_EPOCH)
            .map_err(|e| CallingError::CallFailed(e.to_string()))?;

        Ok(Value::Number(OrderedFloat(since_the_epoch.as_secs_f64())))
    }
}

pub fn all() -> Vec<(String, Value)> {
    vec![(
        "clock".into(),
        Value::Callable((Rc::new(Clock {}), CallableType::Function)),
    )]
}