//! Assorted functions shared by several assists.

use ra_syntax::{
    ast::{self, make},
    T,
};

pub(crate) fn invert_boolean_expression(expr: ast::Expr) -> ast::Expr {
    if let Some(expr) = invert_special_case(&expr) {
        return expr;
    }
    make::expr_prefix(T![!], expr)
}

fn invert_special_case(expr: &ast::Expr) -> Option<ast::Expr> {
    match expr {
        ast::Expr::BinExpr(bin) => match bin.op_kind()? {
            ast::BinOp::NegatedEqualityTest => bin.replace_op(T![==]).map(|it| it.into()),
            ast::BinOp::EqualityTest => bin.replace_op(T![!=]).map(|it| it.into()),
            _ => None,
        },
        ast::Expr::PrefixExpr(pe) if pe.op_kind()? == ast::PrefixOp::Not => pe.expr(),
        // FIXME:
        // ast::Expr::Literal(true | false )
        _ => None,
    }
}