use crate::complex::Complex;

pub struct FunctionArgument {
    args : Vec<Complex>,
}

impl FunctionArgument {
    pub fn new(args: Vec<Complex>) -> Self {
        Self { args }
    }

    pub fn get(&self, i : usize) -> Complex {
        self.args[i]
    }

    pub fn len(&self) -> usize {
        self.args.len()
    }
}

pub trait Function {
    fn eval(&self, args: FunctionArgument) -> Result<Complex, String>;
}

#[macro_export]
macro_rules! functions {
    ({$($x:expr => $y:expr), *}) => {
        {
            let mut h : HashMap<String, Box<dyn Function>> = HashMap::new();
            $(
                h.insert($x.to_string(), Box::new($y));
            )*
            h
        }
    };
}


// Some default implementations
impl<T> Function for T
where
    T: Fn(Complex) -> Complex,
{
    fn eval(&self, args: FunctionArgument) -> Result<Complex, String> {
        if args.len() == 1 {
            Ok(self(args.get(0)))
        } else {
            Err("too many arguments".to_string())
        }
    }
}