extern crate modelica_parser;

use self::modelica_parser::*;
use errors::Result;

pub trait TranspileScheme {
    fn transpile_scheme(&self) -> Result<String>;
}


impl TranspileScheme for ModelicaModel {
    fn transpile_scheme(&self) -> Result<String> {
        let mut params = vec![];
        let mut constants = vec![];
        for (c, e) in self.get_constant_vars() {
            if let Some(v) = e {
                constants.push(format!("({} {})", c, try!(v.transpile_scheme())));
            } else {
                params.push(c);
            }
        }
        // HashMaps are unsorted, so we need to re-sort here
        constants.sort();
        params.sort();
        let mut binds = vec![];
        let mut outputs = vec![];
        for eq in self.equations.iter() {
            if let Expr::Ident(ref symb) = eq.lhs {
                binds.push(format!("({} {})", symb, try!(eq.rhs.transpile_scheme())));
                outputs.push(symb.to_string());
            } else {
                bail!("Expected an identifier on LHS (in this partial implementation)")
            }
        }
        let mut args: Vec<String> = self.get_free_vars().iter().map(|s| s.clone()).collect();
        args.sort();
        args.extend(params);
        Ok(format!(
r#"(lambda ({args})
  (let ({constants})
    (letrec ({binds})
    (list {outputs}))))"#,
                   args = args.join(" "),
                   constants = constants.join("\n        "), // NB: whitespace
                   binds = binds.join("\n             "), // NB: whitespace
                   outputs = outputs.join(" ")))
    }
}

impl TranspileScheme for Expr {
    fn transpile_scheme(&self) -> Result<String> {
        use modelica_parser::Expr::*;
        match *self {
            Integer(e) => Ok(format!("{}", e)),
            Float(e) => Ok(format!("{:e}", e)),
            Boolean(true) => Ok(format!("#t")),
            Boolean(false) => Ok(format!("#f")),
            StringLiteral(ref s) => Ok(format!("\"{}\"", s)),
            Ident(ref e) => Ok(format!("{}", e)),
            Der(ref e) => Ok(format!("(der {})", try!(e.transpile_scheme()))),
            Sign(ref e) => Ok(format!("(sign {})", try!(e.transpile_scheme()))),
            MathUnaryExpr(func, ref e) => Ok(format!("({:?} {})", func, try!(e.transpile_scheme()))),
            BinExpr(op, ref l, ref r) => {
                Ok(format!("({:?} {} {})",
                           op,
                           try!(l.transpile_scheme()),
                           try!(r.transpile_scheme())))
            }
            Array(_) => unimplemented!(),
        }
    }
}