use sexp::{Atom, Sexp, SourcePosition};

use crate::asm::error::CrsnError;

pub fn expect_list(expr: Sexp, allow_empty: bool) -> Result<(Vec<Sexp>, SourcePosition), CrsnError> {
    match expr {
        Sexp::Atom(_, pos) => {
            return Err(CrsnError::Parse("Expected a list".into(), pos));
        }
        Sexp::List(list, pos) => {
            if !allow_empty && list.is_empty() {
                return Err(CrsnError::Parse("Routine: Empty list".into(), pos));
            }

            Ok((list, pos))
        }
    }
}

pub fn expect_atom(expr: Sexp) -> Result<(Atom, SourcePosition), CrsnError> {
    match expr {
        Sexp::Atom(a, pos) => {
            Ok((a, pos))
        }
        Sexp::List(_, pos) => {
            return Err(CrsnError::Parse("Expected atom got list".into(), pos));
        }
    }
}

pub fn expect_string_atom(expr: Sexp) -> Result<(String, SourcePosition), CrsnError> {
    match expect_atom(expr) {
        Ok((Atom::S(s), pos)) => Ok((s, pos)),
        Ok((_, pos)) => Err(CrsnError::Parse("Expected string atom".into(), pos)),
        Err(e) => Err(e),
    }
}

pub fn expect_quoted_string_atom(expr: Sexp) -> Result<(String, SourcePosition), CrsnError> {
    match expect_atom(expr) {
        Ok((Atom::QS(s), pos)) => Ok((s, pos)),
        Ok((_, pos)) => Err(CrsnError::Parse("Expected quoted string atom".into(), pos)),
        Err(e) => Err(e),
    }
}

/// Quoted or simple string
pub fn expect_any_string_atom(expr: Sexp) -> Result<(String, SourcePosition), CrsnError> {
    match expect_atom(expr) {
        Ok((Atom::S(s), pos)) => Ok((s, pos)),
        Ok((Atom::QS(s), pos)) => Ok((s, pos)),
        Ok((_, pos)) => Err(CrsnError::Parse("Expected quoted string atom".into(), pos)),
        Err(e) => Err(e),
    }
}