use gc_arena::{Gc, Mutation};
use hashbrown::HashMap;

use crate::env::VmEnv;
use crate::ty::internal::{AttrSet, CoW, PrimOp, Value};
use crate::vm::VM;

pub fn env<'gc>(vm: &VM, mc: &Mutation<'gc>) -> Gc<'gc, VmEnv<'gc>> {
    let primops = [
        PrimOp::new("add", 2, |args, _, mc| {
            let Ok([mut first, second]): Result<[Value; 2], _> = args.try_into() else {
                unreachable!()
            };
            first.add(second, mc);
            first.ok()
        }),
        PrimOp::new("sub", 2, |args, _, mc| {
            let Ok([mut first, mut second]): Result<[Value; 2], _> = args.try_into() else {
                unreachable!()
            };
            second.neg();
            first.add(second, mc);
            first.ok()
        }),
        PrimOp::new("mul", 2, |args, _, _| {
            let Ok([mut first, second]): Result<[Value; 2], _> = args.try_into() else {
                unreachable!()
            };
            first.mul(second);
            first.ok()
        }),
        PrimOp::new("div", 2, |args, _, _| {
            let Ok([mut first, second]): Result<[Value; 2], _> = args.try_into() else {
                unreachable!()
            };
            first.div(second)?;
            first.ok()
        }),
        PrimOp::new("lessThan", 2, |args, _, _| {
            let Ok([mut first, second]): Result<[Value; 2], _> = args.try_into() else {
                unreachable!()
            };
            first.lt(second);
            first.ok()
        }),
        /* PrimOp::new("seq", 2, |args, vm, mc| {
            let Ok([mut first, second]): Result<[_; 2], _> = args.try_into() else {
                unreachable!()
            };
            first.force(vm, mc).unwrap();
            second.ok()
        }),
        PrimOp::new("deepSeq", 2, |args, vm, mc| {
            let Ok([mut first, second]): Result<[_; 2], _> = args.try_into() else {
                unreachable!()
            };
            first.force_deep(vm, mc).unwrap();
            second.ok()
        }), */
    ];

    let mut env_map = HashMap::new();
    env_map.insert(vm.new_sym("true"), Value::Bool(true));
    env_map.insert(vm.new_sym("false"), Value::Bool(false));

    let mut map = HashMap::new();
    for primop in primops {
        let primop = Gc::new(mc, primop);
        env_map.insert(
            vm.new_sym(format!("__{}", primop.name)),
            Value::PrimOp(primop.clone()),
        );
        map.insert(vm.new_sym(primop.name), Value::PrimOp(primop));
    }
    let sym = vm.new_sym("builtins");
    let attrs = CoW::new_cyclic(
        |this| {
            map.insert(sym, Value::AttrSet(this));
            AttrSet::from_inner(map)
        },
        mc,
    );
    let builtins = Value::AttrSet(attrs);

    env_map.insert(sym, builtins);
    VmEnv::new(Gc::new(mc, env_map.into()), mc)
}