use std::{collections::HashMap, rc::Rc};

use crate::{
    exec::{DeBrujinAst as DBAst, builtin_definitions::AddOp},
    parse::{Ast, Constant},
    types::{PrimitiveType, Type},
};

use super::builtins::Builtin;

#[test]
fn to_de_brujin_ast_simple() {
    let input = Ast::Abstraction(
        "x".to_string(),
        Some(Type::Primitive(PrimitiveType::Nat).into()),
        Box::new(Ast::Abstraction(
            "x".to_string(),
            Some(Type::Primitive(PrimitiveType::Nat).into()),
            Box::new(Ast::Variable("x".to_string())),
        )),
    );
    let de_brujin: DBAst = input.into();
    assert_eq!(
        de_brujin,
        DBAst::Abstraction(
            "x".to_string(),
            Some(Type::Primitive(PrimitiveType::Nat).into()),
            Box::new(DBAst::Abstraction(
                "x".to_string(),
                Some(Type::Primitive(PrimitiveType::Nat).into()),
                Box::new(DBAst::BoundVariable(1))
            ))
        )
    )
}

#[test]
fn de_brujin_beta_reduce() {
    let input = Ast::Application(
        Box::new(Ast::Abstraction(
            "x".to_string(),
            Some(Type::arrow(PrimitiveType::Nat, PrimitiveType::Nat).into()),
            Box::new(Ast::Application(
                Box::new(Ast::Variable("x".to_string())),
                Box::new(Ast::Constant(Constant::Nat(5))),
            )),
        )),
        Box::new(Ast::Variable("y".to_string())),
    );
    let dbast: DBAst = input.into();
    let reduced = dbast.beta_reduce();
    assert_eq!(
        reduced,
        DBAst::Application(
            Box::new(DBAst::FreeVariable("y".to_string())),
            Box::new(DBAst::Constant(Constant::Nat(5))),
        ),
    )
}

#[test]
fn to_and_from_de_brujin_is_id() {
    let input = Ast::Application(
        Box::new(Ast::Abstraction(
            "x".to_string(),
            Some(Type::arrow(PrimitiveType::Nat, PrimitiveType::Nat).into()),
            Box::new(Ast::Application(
                Box::new(Ast::Variable("x".to_string())),
                Box::new(Ast::Constant(Constant::Nat(5))),
            )),
        )),
        Box::new(Ast::Variable("y".to_string())),
    );
    let dbast: DBAst = input.clone().into();
    let output: Ast = dbast.into();
    assert_eq!(input, output);
}

#[test]
fn reduce_add() {
    let input: DBAst = Ast::Application(
        Box::new(Ast::Application(
            Box::new(Ast::Variable("add".to_string())),
            Box::new(Ast::Constant(Constant::Nat(5))),
        )),
        Box::new(Ast::Constant(Constant::Nat(5))),
    )
    .into();
    let mut builtins: HashMap<String, Rc<dyn Builtin>> = HashMap::new();
    builtins.insert("add".to_string(), Rc::new(AddOp));
    let output = input.reduce_builtins(&builtins);
    assert_eq!(output, DBAst::Constant(Constant::Nat(10)));
}