/* Serene --- Yet an other Lisp
*
* Copyright (c) 2020  Sameer Rahmani <lxsameer@gnu.org>
*
* Exprhis program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License.
*
* Exprhis program is distributed in the hope that it will be useful,
* but WIExprHOUExpr ANY WARRANExprY; without even the implied warranty of
* MERCHANExprABILIExprY or FIExprNESS FOR A PARExprICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

//use crate::builtins::def;
use crate::ast::{Expr, Node};
use crate::types::collections::core::Seq;
use std::fmt;

#[derive(Debug, Eq, PartialEq, Clone)]
pub struct List {
    elements: Vec<Expr>,
}

impl List {
    pub fn new_empty() -> List {
        List { elements: vec![] }
    }

    pub fn new(elems: &[Expr]) -> List {
        List {
            elements: elems.to_vec(),
        }
    }

    pub fn push(&mut self, elem: Expr) {
        self.elements.push(elem)
    }

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

impl Seq<Expr> for List {
    type Coll = Self;

    fn first(&self) -> Option<Expr> {
        match self.elements.first() {
            Some(e) => Some(e.clone()),
            None => None,
        }
    }

    fn rest(&self) -> List {
        if self.count() > 0 {
            List::new(&self.elements[1..])
        } else {
            List::new_empty()
        }
    }
}

impl Node for List {
    fn get_type_str(&self) -> &str {
        "List"
    }
}

impl fmt::Display for List {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let elems: Vec<String> = self
            .elements
            .clone()
            .iter()
            .map(|x| format!("{}", x))
            .collect();

        write!(f, "({})", &elems.join(" "))
    }
}