extern crate modelica_parser;

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

pub trait TranspileJS {
    fn transpile_js(&self) -> Result<String>;
}

pub trait TranspileJSODE {
    fn transpile_js_ode(&self) -> Result<String>;
}


impl TranspileJS for ModelicaModel {
    fn transpile_js(&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!("var {} = {};", c, try!(v.transpile_js())));
            } 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!("var {} = {};", symb, try!(eq.rhs.transpile_js())));
                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#"function ({args}) {{
    {constants}
    {binds}
    return [{outputs}];
}};"#,
                   args = args.join(", "),
                   constants = constants.join("\n    "),
                   binds = binds.join("\n    "),
                   outputs = outputs.join(", ")))
    }

}

impl TranspileJSODE for ModelicaModel {

    fn transpile_js_ode(&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!("var {} = {};", c, try!(v.transpile_js())));
            } else {
                params.push(c);
            }
        }
        // HashMaps are unsorted, so we need to re-sort here
        constants.sort();
        params.sort();
        let mut exprs = vec![];
        for eq in self.equations.iter() {
            if let Expr::Der(ref der_of) = eq.lhs {
                if let &Expr::Ident(_) = der_of.as_ref() {
                    // Ok
                } else {
                    bail!("Non-trivial derivatives not supported (aka, of non-variable expressions)");
                }
                exprs.push(try!(eq.rhs.transpile_js()));
            } else {
                bail!("Not a simple set of ODEs (aka, all derivatives on LHS of equations)");
            }
        }
        let mut args: Vec<String> = self.get_free_vars().iter().map(|s| s.clone()).collect();
        args.sort();
        Ok(format!(
r#"function ({params}) {{
  return function({args}) {{
    {constants}
    return [
      {expressions}
    ];
  }};
}};"#,
                   params = params.join(", "),
                   args = args.join(", "),
                   constants = constants.join("\n    "), // NB: whitespace
                   expressions = exprs.join(",\n      "))) // NB: whitespace
    }
}

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