// Copyright Istio Authors

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//     http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

use hickory_proto::rr::Name;

/// Returns true if the given name ends with the labels provided by the domain iterator.

// TODO(nmittler): Consider upstreaming to TrustDNS.

pub fn has_domain(name: &Name, domain: &Name) -> bool {

    if domain.is_wildcard() || name.num_labels() <= domain.num_labels() {

        return false;

    }

    let name_iter = name.iter();

    let domain_iter = domain.iter();

    // Skip ahead to the start of the domain.

    let num_skip = name_iter.len() - domain_iter.len();

    let name_iter = name_iter.skip(num_skip);

    // Compare the remaining elements.

    name_iter.eq(domain_iter)

}

/// Trims the domain labels from the name. Returns `Some` if the domain was found and removed.

// TODO(nmittler): Consider upstreaming to TrustDNS.

pub fn trim_domain(name: &Name, domain: &Name) -> Option<Name> {

    if has_domain(name, domain) {

        // Create a Name from the labels leading up to the domain.

        let iter = name.iter();

        let num_labels = iter.len() - domain.num_labels() as usize;

        let mut name = Name::from_labels(iter.take(num_labels)).unwrap();

        name.set_fqdn(false);

        Some(name)

    } else {

        None

    }

}

#[cfg(test)]

mod tests {

    use super::*;

    use crate::test_helpers::dns::n;

    use hickory_proto::rr::Name;

    #[test]

    fn test_has_domain() {

        assert!(has_domain(&n("name.ns.svc.cluster.local"), &domain()));

        assert!(!has_domain(&n("name.ns.a.different.domain"), &domain()));

        assert!(!has_domain(&n("cluster.com"), &domain()));

    }

    #[test]

    fn test_trim_domain() {

        assert_eq!(

            Some(n("name.ns")),

            trim_domain(&n("name.ns.svc.cluster.local"), &domain())

        );

        assert_eq!(

            None,

            trim_domain(&n("name.ns.a.different.domain"), &domain())

        );

        // Can't trim if nothing left.

        assert_eq!(None, trim_domain(&n("svc.cluster.local"), &domain()));

    }

    fn domain() -> Name {

        n("svc.cluster.local")

    }

}