use talc_lang::{
	exception::{throw, Exception, Result},
	symbol::{SYM_TYPE_ERROR, SYM_VALUE_ERROR},
	value::Value,
	vm::Vm,
};
use talc_macros::native_func;

use crate::unpack_args;

#[native_func(1)]
pub fn throw(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, arg] = unpack_args!(args);
	let exc = match arg {
		Value::Symbol(ty) => Exception::new(ty),
		Value::List(l) => match l.borrow().as_slice() {
			[Value::Symbol(ty)] | [Value::Symbol(ty), Value::Nil] => Exception::new(*ty),
			[Value::Symbol(ty), Value::String(s)] => {
				Exception::new_with_msg(*ty, s.clone())
			}
			[] | [_] | [_, _] => {
				throw!(*SYM_TYPE_ERROR, "wrong argument for throw")
			}
			[_, _, _, ..] => throw!(
				*SYM_VALUE_ERROR,
				"too many elements in list argument for throw"
			),
		},
		_ => throw!(*SYM_TYPE_ERROR, "throw expected symbol or list"),
	};
	Err(exc)
}

#[native_func(1)]
pub fn rethrow(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, table] = unpack_args!(args);
	if let Value::Table(table) = table {
		if let Some(e) = Exception::from_table(&table) {
			return Err(e)
		}
		throw!(*SYM_VALUE_ERROR, "argument not a valid exception")
	}
	throw!(*SYM_TYPE_ERROR, "argument not a valid exception")
}

pub fn load(vm: &mut Vm) {
	vm.set_global_name("throw", throw().into());
	vm.set_global_name("rethrow", rethrow().into());
}