//! Define different restrictions that can be applied to relays.

#[cfg(feature = "geoip")]

use tor_geoip::HasCountryCode;

use tor_linkspec::{ChanTarget, HasAddrs, HasRelayIds, RelayIdSet};

use tor_netdir::{FamilyRules, NetDir, Relay, SubnetConfig};

use tor_netdoc::types::policy::AddrPortPattern;

use crate::{LowLevelRelayPredicate, RelaySelectionConfig, RelayUsage};

use std::{fmt, net::IpAddr};

/// A restriction that we use when picking relays.

///

/// Differs from [`RelayUsage`] in that it does not say what

/// the relay is _used for_;

/// instead, it describes an additional set of requirements that a relay must

/// satisfy.

#[derive(Clone, Debug)]

pub struct RelayRestriction<'a> {

    /// The actual restriction object.

    inner: RestrictionInner<'a>,

}

/// Enumeration of possible [`RelayRestriction`]s.

///

/// This is a separate type so that we can hide its variants.

///

// TODO: I'm not sure about having this be relative to `'a``,

// but that is the only way to hold a `Relay<'a>`

//

// NOTE: Any time that you are extending this type, make sure that you are not

// describing a new _mandatory_ restriction that all `RelaySelector` users

// need to consider adding (or not).  If you *are* describing such a restriction,

// then it should have its own type, and it should become a new argument to

// RelaySelector::new().

#[derive(Clone, Debug)]

enum RestrictionInner<'a> {

    /// Do not restrict any relays.

    ///

    /// This is present so that we can construct a no-op restriction when

    /// relaxing a selector.

    NoRestriction,

    /// Require a given usage.

    SupportsUsage(crate::RelayUsage),

    /// Exclude a set of relays explicitly, by family, or by identity.

    Exclude(RelayExclusion<'a>),

    /// Require that, if the relay's contact method uses addresses, the relay

    /// has at least one address matching one of the provided patterns.

    HasAddrInSet(Vec<AddrPortPattern>),

    /// Require that the relay has a given country code.

    #[cfg(feature = "geoip")]

    RequireCountry(tor_geoip::CountryCode),

}

impl<'a> RelayRestriction<'a> {

    /// Create a restriction that allows every relay.

    /// Convert a usage into a restriction.

    ///

    /// This is crate-internal since we never want to support requiring a relay

    /// to provide multiple usages.

    /// Require a relay that appears to be in the provided country,

    /// according ot our geoip subsystem.

    #[cfg(feature = "geoip")]

    /// Require that a relay has at least one address

    /// listed in `addr_patterns`.

    /// Return a restriction that represents having "relaxed" this restriction.

    ///

    /// (Relaxing a restriction replaces it with a no-op, or with an almost-no-op.)

        use RestrictionInner::*;

            // We must always have a usage, so relaxing a usage must always

            // return a usage.

            // Relaxing any other restriction returns a no-op

        }

    /// If this restriction represents a usage, return a reference to that usage.

        use RestrictionInner::*;

        }

    /// Return a string describing why we rejected the relays that _don't_ match

    /// this restriction.

        use RestrictionInner::*;

            #[cfg(feature = "geoip")]

        }

}

impl<'a> LowLevelRelayPredicate for RelayRestriction<'a> {

        use RestrictionInner::*;

            #[cfg(feature = "geoip")]

        }

}

impl<'a> From<RelayExclusion<'a>> for RelayRestriction<'a> {

}

/// Return true if `relay` has at least one address matching at least one member

/// of `patterns`.

/// A set of relays that we must not use when picking a given

/// relays.

///

/// Exclusions are generally used to make sure that we obey

/// family-based path-selection rules,

/// that we avoid putting the same relay into a set more than once,

/// or similar purposes.

///

/// (This is a separate type from [`RelayRestriction`] so that we can

/// enforce our rule that every [`RelaySelector`](crate::RelaySelector) must

/// have a `RelayExclusion`.)

#[derive(Clone, Debug)]

pub struct RelayExclusion<'a> {

    /// A list of identities to exclude.

    ///

    /// Any relay with any one of these identities is rejecteed.

    exclude_ids: RelayIdSet,

    /// A list of subnets from which to exclude addresses.

    ///

    /// The side of the subnet is determined by subnet_config.

    exclude_subnets: Vec<IpAddr>,

    /// A list of relays to exclude, along with their families.

    exclude_relay_families: RelayList<'a>,

    /// The configuration to use when deciding whether two addresses are in the

    /// same subnet.

    subnet_config: SubnetConfig,

    /// The rules to use when deciding whether two relays are in the same family.

    family_rules: FamilyRules,

}

/// Helper: wraps `Vec[Relay]`, but implements Debug.

#[derive(Clone)]

struct RelayList<'a>(Vec<Relay<'a>>);

impl<'a> fmt::Debug for RelayList<'a> {

        }

}

impl<'a> RelayExclusion<'a> {

    /// Exclude no relays at all.

    ///

    /// This kind of restriction is useful when picking the first relay for

    /// something,

    ///

    // (Note that this is _not_ Default::default, since we don't want people

    // picking it by mistake.)

    /// Exclude every relay that has an identity in `ids`.

    /// Exclude every relay that appears in `relays`.

    /// Try to exclude every relay in the same family as the [`ChanTarget`]

    /// `ct`.

    ///

    /// # Limitations

    ///

    /// A ChanTarget does not have a listed family.  Thus, if it does not correspond

    /// to a relay listed in `netdir`, we can only exclude relays that share the

    /// same identity, or relays that are in the same subnet.

    ///

    /// Whenever possible, it's better to use exclude_relays_in_same_family.

    /// Exclude every relay that is in the same family as any member of

    /// `relays`.

    ///

    /// (Remember that every relay is considered to be in the same family as

    /// itself, so you don't typically need to use `exclude_specific_relays`

    /// along with this.)

    ///

    /// Considers relays that are in the same subnets (according to `cfg`) to

    /// belong to the same family.

    /// Modify this `RelayExclusion` by adding every exclusion from `other`.

    ///

    /// (Any subnet configuration becomes the _union_ of previous subnet

    /// configurations.)

    /// Return a string describing why we rejected the relays that _don't_ match

    /// this exclusion.

            } else {

            }

        } else {

        }

}

impl<'a> LowLevelRelayPredicate for RelayExclusion<'a> {

}

/// Return true if `r1` and `r2` are in the same "extended" family,

/// considering both explicitly declared families

/// and subnet-based extended families.

#[cfg(test)]

mod test {

    // @@ begin test lint list maintained by maint/add_warning @@

    #![allow(clippy::bool_assert_comparison)]

    #![allow(clippy::clone_on_copy)]

    #![allow(clippy::dbg_macro)]

    #![allow(clippy::mixed_attributes_style)]

    #![allow(clippy::print_stderr)]

    #![allow(clippy::print_stdout)]

    #![allow(clippy::single_char_pattern)]

    #![allow(clippy::unwrap_used)]

    #![allow(clippy::unchecked_duration_subtraction)]

    #![allow(clippy::useless_vec)]

    #![allow(clippy::needless_pass_by_value)]

    //! <!-- @@ end test lint list maintained by maint/add_warning @@ -->

    use tor_linkspec::RelayId;

    use tor_netdir::testnet::construct_custom_netdir;

    use super::*;

    use crate::testing::{cfg, split_netdir, testnet};

    #[test]

    fn exclude_nothing() {

        let nd = testnet();

        let usage = RelayExclusion::no_relays_excluded();

        assert!(nd

            .relays()

            .all(|r| usage.low_level_predicate_permits_relay(&r)));

    }

    #[test]

    fn exclude_ids() {

        let nd = testnet();

        let id_0 = "$0000000000000000000000000000000000000000".parse().unwrap();

        let id_5 = "ed25519:BQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQU"

            .parse()

            .unwrap();

        let ids: RelayIdSet = [id_0, id_5].into_iter().collect();

        let (yes, no) = split_netdir(&nd, &RelayExclusion::exclude_identities(ids));

        let p = |r: &Relay<'_>| !(r.has_identity(id_0.as_ref()) || r.has_identity(id_5.as_ref()));

        assert_eq!(yes.len(), 38);

        assert_eq!(no.len(), 2);

        assert!(yes.iter().all(p));

        assert!(no.iter().all(|r| !p(r)));

    }

    #[test]

    fn exclude_relays() {

        let nd = testnet();

        let id_0: RelayId = "$0000000000000000000000000000000000000000".parse().unwrap();

        let id_5: RelayId = "ed25519:BQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQU"

            .parse()

            .unwrap();

        let relay_0 = nd.by_id(&id_0).unwrap();

        let relay_5 = nd.by_id(&id_5).unwrap();

        let (yes, no) = split_netdir(

            &nd,

            &RelayExclusion::exclude_specific_relays(&[relay_0.clone(), relay_5.clone()]),

        );

        let p = |r: &Relay<'_>| !(r.same_relay_ids(&relay_0) || r.same_relay_ids(&relay_5));

        assert_eq!(yes.len(), 38);

        assert_eq!(no.len(), 2);

        assert!(yes.iter().all(p));

        assert!(no.iter().all(|r| !p(r)));

    }

    /// Helper for testing family exclusions.  Requires a netdir where,

    /// for every N, relays 2N and 2N+1 are in a family.

    fn exclude_families_impl(nd: &NetDir, family_rules: FamilyRules) {

        let id_0: RelayId = "$0000000000000000000000000000000000000000".parse().unwrap();

        let id_5: RelayId = "ed25519:BQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQU"

            .parse()

            .unwrap();

        let relay_0 = nd.by_id(&id_0).unwrap();

        let relay_5 = nd.by_id(&id_5).unwrap();

        let excluding_relays = vec![relay_0, relay_5];

        // in the test netdir, all (2n, 2n+1) pairs are in a family.

        let id_1 = "$0101010101010101010101010101010101010101".parse().unwrap();

        let id_4 = "$0404040404040404040404040404040404040404".parse().unwrap();

        let expect_excluded_ids: RelayIdSet = [id_0, id_1, id_4, id_5].into_iter().collect();

        // Case one: No subnet-based exclusion.

        let cfg_no_subnet = RelaySelectionConfig {

            long_lived_ports: cfg().long_lived_ports,

            subnet_config: SubnetConfig::new(255, 255),

        };

        let (yes, no) = split_netdir(

            nd,

            &RelayExclusion::exclude_relays_in_same_family(

                &cfg_no_subnet,

                excluding_relays.clone(),

                family_rules,

            ),

        );

        let p = |r: &Relay<'_>| !r.identities().any(|id| expect_excluded_ids.contains(id));

        assert_eq!(yes.len(), 36);

        assert_eq!(no.len(), 4);

        assert!(yes.iter().all(p));

        assert!(no.iter().all(|r| !p(r)));

        // Case two: default subnet-based exclusion.

        //

        // In the test network, addresses are x.0.0.3 where x is the index of

        // the relay, modulo 5.  Since the default ipv4 subnet family rule looks at /16

        // prefixes, every one of the 40 relays in the testnet will be in a

        // family with 8 other relays.

        let expect_excluded_ids: RelayIdSet = nd

            .relays()

            .filter_map(|r| {

                let rsa = r.rsa_identity().unwrap();

                let b = rsa.as_bytes()[0];

                if [0, 1, 4, 5].contains(&b) || [0, 5].contains(&(b % 5)) {

                    Some(RelayId::from(*rsa))

                } else {

                    None

                }

            })

            .collect();

        let (yes, no) = split_netdir(

            nd,

            &RelayExclusion::exclude_relays_in_same_family(&cfg(), excluding_relays, family_rules),

        );

        for r in &no {

            dbg!(r.rsa_identity().unwrap());

        }

        dbg!(&expect_excluded_ids);

        dbg!(expect_excluded_ids.len());

        let p = |r: &Relay<'_>| !r.identities().any(|id| expect_excluded_ids.contains(id));

        assert_eq!(yes.len(), 30);

        assert_eq!(no.len(), 10);

        assert!(yes.iter().all(p));

        assert!(no.iter().all(|r| { !p(r) }));

    }

    #[test]

    fn exclude_families_by_list() {

        exclude_families_impl(

            &testnet(),

            *FamilyRules::ignore_declared_families().use_family_lists(true),

        );

    }

    #[test]

    fn exclude_families_by_id() {

        // Here we construct a network that matches our default testnet,

        // but without any family lists.

        // Instead we use "happy family" IDs to match the families from that default testnest.

        let netdir = construct_custom_netdir(|pos, nb, _| {

            // Clear the family list.

            nb.md.family("".parse().unwrap());

            // This will create an "Unrecognized" family id such that

            // pos:N  will be shared by nodes in positions 2N and 2N+1.

            let fam_id = format!("pos:{}", pos / 2);

            nb.md.add_family_id(fam_id.parse().unwrap());

        })

        .unwrap()

        .unwrap_if_sufficient()

        .unwrap();

        exclude_families_impl(

            &netdir,

            *FamilyRules::ignore_declared_families().use_family_ids(true),

        );

    }

    #[test]

    fn filter_addresses() {

        let nd = testnet();

        let reachable = vec![

            "1.0.0.0/8:*".parse().unwrap(),

            "2.0.0.0/8:*".parse().unwrap(),

        ];

        let reachable = RelayRestriction::require_address(reachable);

        let (yes, no) = split_netdir(&nd, &reachable);

        assert_eq!(yes.len(), 16);

        assert_eq!(no.len(), 24);

        let expected = ["1.0.0.3".parse().unwrap(), "2.0.0.3".parse().unwrap()];

        let p = |r: &Relay<'_>| expected.contains(&r.addrs()[0].ip());

        assert!(yes.iter().all(p));

        assert!(no.iter().all(|r| !p(r)));

    }

    // TODO: Write a geoip test?

}