use std::{cmp::Eq, collections::HashMap, hash::Hash};

#[derive(Default, Debug)]
pub struct ScopeStack<'a, T: 'a, V: 'a, N = String>
where T: Hash + Eq
{
    parent: Option<&'a ScopeStack<'a, T, V, N>>,
    values: HashMap<T, V>,
    scope_name: Option<N>,
}

impl<'a, T, V, N> ScopeStack<'a, T, V, N>
where T: Hash + Eq
{
    pub fn new(scope_name: Option<N>) -> Self
    where T: Hash + Eq {
        ScopeStack { parent: None, values: HashMap::new(), scope_name }
    }
    pub fn insert(&mut self, key: T, value: V)
    where T: Hash + Eq {
        self.values.insert(key, value);
    }
    pub fn lookup(&self, key: &T) -> Option<&V>
    where T: Hash + Eq {
        match (self.values.get(key), self.parent) {
            (None, None) => None,
            (None, Some(parent)) => parent.lookup(key),
            (Some(value), _) => Some(value),
        }
    }

    pub fn new_scope(&'a self, scope_name: Option<N>) -> Self
    where T: Hash + Eq {
        ScopeStack { parent: Some(self), values: HashMap::default(), scope_name }
    }

    #[allow(dead_code)]
    pub fn lookup_with_scope(&self, key: &T) -> Option<(&V, Option<&N>)>
    where T: Hash + Eq {
        match (self.values.get(key), self.parent) {
            (None, None) => None,
            (None, Some(parent)) => parent.lookup_with_scope(key),
            (Some(value), _) => Some((value, self.scope_name.as_ref())),
        }
    }

    pub fn get_name(&self) -> Option<&N> {
        self.scope_name.as_ref()
    }
}

/// Quickly create an AST from a string, with no error checking. For test use only
#[cfg(test)]
pub fn quick_ast(input: &str) -> crate::ast::AST {
    let mut parser = crate::parsing::new::Parser::new();
    let output = parser.parse(input);
    output.unwrap()
}

#[allow(unused_macros)]
macro_rules! rc {
    ($string:tt) => {
        Rc::new(stringify!($string).to_string())
    };
}