//! Code for building paths to an exit relay.

use std::time::SystemTime;

use rand::Rng;

use tracing::instrument;

use super::{AnonymousPathBuilder, TorPath};

use crate::path::pick_path;

use crate::{DirInfo, Error, PathConfig, Result, TargetPort};

use tor_guardmgr::{GuardMgr, GuardMonitor, GuardUsable};

use tor_linkspec::OwnedChanTarget;

use tor_netdir::{NetDir, Relay};

use tor_relay_selection::{RelayExclusion, RelaySelectionConfig, RelaySelector, RelayUsage};

use tor_rtcompat::Runtime;

#[cfg(feature = "geoip")]

use {tor_geoip::CountryCode, tor_relay_selection::RelayRestriction};

/// Internal representation of PathBuilder.

enum ExitPathBuilderInner {

    /// Request a path that allows exit to the given `TargetPort`s.

    WantsPorts(Vec<TargetPort>),

    /// Request a path that allows exit with a relay in the given country.

    // TODO GEOIP: refactor this builder to allow conjunction!

    // See discussion here:

    // https://gitlab.torproject.org/tpo/core/arti/-/merge_requests/1537#note_2942218

    #[cfg(feature = "geoip")]

    ExitInCountry {

        /// The country to exit in.

        country: CountryCode,

        /// Some target ports to use (works like `WantsPorts`).

        ///

        /// HACK(eta): This is a horrible hack to work around the lack of conjunction.

        ports: Vec<TargetPort>,

    },

    /// Request a path that allows exit to _any_ port.

    AnyExit {

        /// If false, then we fall back to non-exit nodes if we can't find an

        /// exit.

        strict: bool,

    },

}

/// A PathBuilder that builds a path to an exit relay supporting a given

/// set of ports.

///

/// NOTE: The name of this type is no longer completely apt: given some circuits,

/// it is happy to build a circuit ending at a non-exit.

pub(crate) struct ExitPathBuilder {

    /// The inner ExitPathBuilder state.

    inner: ExitPathBuilderInner,

    /// If present, a "target" that every chosen relay must be able to share a circuit with with.

    compatible_with: Option<OwnedChanTarget>,

    /// If true, all relays on this path must be Stable.

    require_stability: bool,

}

impl ExitPathBuilder {

    /// Create a new builder that will try to get an exit relay

    /// containing all the ports in `ports`.

    ///

    /// If the list of ports is empty, tries to get any exit relay at all.

    #[cfg(feature = "geoip")]

    /// Create a new builder that will try to get an exit relay in `country`,

    /// containing all the ports in `ports`.

    ///

    /// If the list of ports is empty, it is disregarded.

    // TODO GEOIP: this method is hacky, and should be refactored.

    /// Create a new builder that will try to get any exit relay at all.

    /// Try to create and return a path corresponding to the requirements of

    /// this builder.

    #[instrument(skip_all, level = "trace")]

    /// Create a new builder that will try to get an exit relay, but which

    /// will be satisfied with a non-exit relay.

    /// Indicate that middle and exit relays on this circuit need (or do not

    /// need) to have the Stable flag.

}

impl AnonymousPathBuilder for ExitPathBuilder {

            }

            #[cfg(feature = "geoip")]

                );

            }

            ),

        };

            role: "final hop",

        use ExitPathBuilderInner::*;

            #[cfg(feature = "geoip")]

        }

}

#[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_time_subtraction)]

    #![allow(clippy::useless_vec)]

    #![allow(clippy::needless_pass_by_value)]

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

    use super::*;

    use crate::path::{

        MaybeOwnedRelay, OwnedPath, TorPath, TorPathInner, assert_same_path_when_owned,

    };

    use std::collections::HashSet;

    use tor_basic_utils::test_rng::testing_rng;

    use tor_guardmgr::TestConfig;

    use tor_linkspec::{HasRelayIds, RelayIds};

    use tor_netdir::{FamilyRules, SubnetConfig, testnet};

    use tor_persist::TestingStateMgr;

    use tor_relay_selection::LowLevelRelayPredicate;

    use tor_rtcompat::SleepProvider;

    use web_time_compat::SystemTimeExt;

    impl<'a> MaybeOwnedRelay<'a> {

        fn can_share_circuit(

            &self,

            other: &MaybeOwnedRelay<'_>,

            subnet_config: SubnetConfig,

            family_rules: FamilyRules,

        ) -> bool {

            use MaybeOwnedRelay as M;

            match (self, other) {

                (M::Relay(a), M::Relay(b)) => {

                    let ports = Default::default();

                    let cfg = RelaySelectionConfig {

                        long_lived_ports: &ports,

                        subnet_config,

                    };

                    // This use of "low_level_predicate_permits_relay" is okay because

                    // because we're in tests.

                    RelayExclusion::exclude_relays_in_same_family(

                        &cfg,

                        vec![a.clone()],

                        family_rules,

                    )

                    .low_level_predicate_permits_relay(b)

                }

                (a, b) => !subnet_config.any_addrs_in_same_subnet(a, b),

            }

        }

    }

    fn assert_exit_path_ok(relays: &[MaybeOwnedRelay<'_>], family_rules: FamilyRules) {

        assert_eq!(relays.len(), 3);

        let r1 = &relays[0];

        let r2 = &relays[1];

        let r3 = &relays[2];

        if let MaybeOwnedRelay::Relay(r1) = r1 {

            assert!(r1.low_level_details().is_suitable_as_guard());

        }

        assert!(!r1.same_relay_ids(r2));

        assert!(!r1.same_relay_ids(r3));

        assert!(!r2.same_relay_ids(r3));

        let subnet_config = SubnetConfig::default();

        assert!(r1.can_share_circuit(r2, subnet_config, family_rules));

        assert!(r2.can_share_circuit(r3, subnet_config, family_rules));

        assert!(r1.can_share_circuit(r3, subnet_config, family_rules));

    }

    #[test]

    fn by_ports() {

        tor_rtcompat::test_with_all_runtimes!(|rt| async move {

            let mut rng = testing_rng();

            let family_rules = FamilyRules::all_family_info();

            let netdir = testnet::construct_netdir().unwrap_if_sufficient().unwrap();

            let ports = vec![TargetPort::ipv4(443), TargetPort::ipv4(1119)];

            let dirinfo = (&netdir).into();

            let config = PathConfig::default();

            let statemgr = TestingStateMgr::new();

            let guards =

                tor_guardmgr::GuardMgr::new(rt.clone(), statemgr, &TestConfig::default()).unwrap();

            guards.install_test_netdir(&netdir);

            let now = SystemTime::get();

            for _ in 0..1000 {

                let (path, _, _) = ExitPathBuilder::from_target_ports(ports.clone())

                    .pick_path(&mut rng, dirinfo, &guards, &config, now)

                    .unwrap();

                assert_same_path_when_owned(&path);

                if let TorPathInner::Path(p) = path.inner {

                    assert_exit_path_ok(&p[..], family_rules);

                    let exit = match &p[2] {

                        MaybeOwnedRelay::Relay(r) => r,

                        MaybeOwnedRelay::Owned(_) => panic!("Didn't asked for an owned target!"),

                    };

                    assert!(exit.low_level_details().ipv4_policy().allows_port(1119));

                } else {

                    panic!("Generated the wrong kind of path");

                }

            }

        });

    }

    #[test]

    fn any_exit() {

        tor_rtcompat::test_with_all_runtimes!(|rt| async move {

            let mut rng = testing_rng();

            let family_rules = FamilyRules::all_family_info();

            let netdir = testnet::construct_netdir().unwrap_if_sufficient().unwrap();

            let dirinfo = (&netdir).into();

            let statemgr = TestingStateMgr::new();

            let guards =

                tor_guardmgr::GuardMgr::new(rt.clone(), statemgr, &TestConfig::default()).unwrap();

            guards.install_test_netdir(&netdir);

            let now = SystemTime::get();

            let config = PathConfig::default();

            for _ in 0..1000 {

                let (path, _, _) = ExitPathBuilder::for_any_exit()

                    .pick_path(&mut rng, dirinfo, &guards, &config, now)

                    .unwrap();

                assert_same_path_when_owned(&path);

                if let TorPathInner::Path(p) = path.inner {

                    assert_exit_path_ok(&p[..], family_rules);

                    let exit = match &p[2] {

                        MaybeOwnedRelay::Relay(r) => r,

                        MaybeOwnedRelay::Owned(_) => panic!("Didn't asked for an owned target!"),

                    };

                    assert!(exit.low_level_details().policies_allow_some_port());

                } else {

                    panic!("Generated the wrong kind of path");

                }

            }

        });

    }

    #[test]

    fn empty_path() {

        // This shouldn't actually be constructable IRL, but let's test to

        // make sure our code can handle it.

        let bogus_path = TorPath {

            inner: TorPathInner::Path(vec![]),

        };

        assert!(bogus_path.exit_relay().is_none());

        assert!(bogus_path.exit_policy().is_none());

        assert_eq!(bogus_path.len(), 0);

        let owned: Result<OwnedPath> = (&bogus_path).try_into();

        assert!(owned.is_err());

    }

    #[test]

    fn no_exits() {

        tor_rtcompat::test_with_all_runtimes!(|rt| async move {

            // Construct a netdir with no exits.

            let netdir = testnet::construct_custom_netdir(|_idx, bld, _| {

                bld.md.parse_ipv4_policy("reject 1-65535").unwrap();

            })

            .unwrap()

            .unwrap_if_sufficient()

            .unwrap();

            let mut rng = testing_rng();

            let dirinfo = (&netdir).into();

            let statemgr = TestingStateMgr::new();

            let guards =

                tor_guardmgr::GuardMgr::new(rt.clone(), statemgr, &TestConfig::default()).unwrap();

            guards.install_test_netdir(&netdir);

            let config = PathConfig::default();

            let now = SystemTime::get();

            // With target ports

            let outcome = ExitPathBuilder::from_target_ports(vec![TargetPort::ipv4(80)])

                .pick_path(&mut rng, dirinfo, &guards, &config, now);

            assert!(outcome.is_err());

            assert!(matches!(outcome, Err(Error::NoRelay { .. })));

            // For any exit

            let outcome =

                ExitPathBuilder::for_any_exit().pick_path(&mut rng, dirinfo, &guards, &config, now);

            assert!(outcome.is_err());

            assert!(matches!(outcome, Err(Error::NoRelay { .. })));

            // For any exit (non-strict, so this will work).

            let outcome = ExitPathBuilder::for_timeout_testing()

                .pick_path(&mut rng, dirinfo, &guards, &config, now);

            assert!(outcome.is_ok());

        });

    }

    #[test]

    fn exitpath_with_guards() {

        use tor_guardmgr::GuardStatus;

        tor_rtcompat::test_with_all_runtimes!(|rt| async move {

            let netdir = testnet::construct_netdir().unwrap_if_sufficient().unwrap();

            let family_rules = FamilyRules::all_family_info();

            let mut rng = testing_rng();

            let dirinfo = (&netdir).into();

            let statemgr = TestingStateMgr::new();

            let guards =

                tor_guardmgr::GuardMgr::new(rt.clone(), statemgr, &TestConfig::default()).unwrap();

            let config = PathConfig::default();

            guards.install_test_netdir(&netdir);

            let port443 = TargetPort::ipv4(443);

            // We're going to just have these all succeed and make sure

            // that they pick the same guard.  We won't test failing

            // cases here, since those are tested in guardmgr.

            let mut distinct_guards = HashSet::new();

            let mut distinct_mid = HashSet::new();

            let mut distinct_exit = HashSet::new();

            for _ in 0..20 {

                let (path, mon, usable) = ExitPathBuilder::from_target_ports(vec![port443])

                    .pick_path(&mut rng, dirinfo, &guards, &config, rt.wallclock())

                    .unwrap();

                assert_eq!(path.len(), 3);

                assert_same_path_when_owned(&path);

                if let TorPathInner::Path(p) = path.inner {

                    assert_exit_path_ok(&p[..], family_rules);

                    distinct_guards.insert(RelayIds::from_relay_ids(&p[0]));

                    distinct_mid.insert(RelayIds::from_relay_ids(&p[1]));

                    distinct_exit.insert(RelayIds::from_relay_ids(&p[2]));

                } else {

                    panic!("Wrong kind of path");

                }

                assert!(matches!(

                    mon.inspect_pending_status(),

                    (GuardStatus::AttemptAbandoned, false)

                ));

                mon.succeeded();

                assert!(usable.await.unwrap());

            }

            assert_eq!(distinct_guards.len(), 1);

            assert_ne!(distinct_mid.len(), 1);

            assert_ne!(distinct_exit.len(), 1);

        });

    }

}