//! The controller's own identity at the swarm's secret store.
//!
//! Two paths log in: writing an agent's credential, and writing the read
//! grant that lets a hive fetch one back. Both present the same certificate
//! under the same role, so the role is named here rather than at each caller.
//! [`AccessStore`] is the subset of calls that give a principal its access, so
//! a test can stand in for the store.

use std::future::Future;

use swarm_secret_client::{Error, SecretStore, client::EntityRef};

/// The cert-auth role the controller logs in under.
///
/// `nix/host-modules/swarm-bao.nix`'s `controllerPolicyName` creates the
/// role and names the policy after it.
///
/// ⚠️ Not the certificate's CN. The role *matches on* the CN
/// (`allowed_common_names`), so the two are deliberately different strings.
pub const CERT_ROLE: &str = "swarm-controller";

/// Log in to the store with this deployment's certificate.
///
/// # Errors
/// Whatever [`SecretStore::from_env`] raises — an unset `BAO_*` variable, an
/// unreadable identity file, or a store that refuses the login.
pub async fn connect() -> Result<SecretStore, Error> {
    SecretStore::from_env(CERT_ROLE).await
}

/// The store calls that give a principal its access: policies, cert-auth roles
/// and identity entities. A test stands in for the store through this trait.
pub(crate) trait AccessStore {
    /// As [`SecretStore::write_policy`].
    fn write_policy(
        &self,
        name: &str,
        policy: &str,
    ) -> impl Future<Output = Result<(), Error>> + Send;

    /// As [`SecretStore::write_cert_role`].
    fn write_cert_role(
        &self,
        mount: &str,
        name: &str,
        certificate: &str,
        common_name: &str,
        policies: &[&str],
    ) -> impl Future<Output = Result<(), Error>> + Send;

    /// As [`SecretStore::auth_mount_accessor`].
    fn auth_mount_accessor(
        &self,
        mount: &str,
    ) -> impl Future<Output = Result<String, Error>> + Send;

    /// As [`SecretStore::entity_by_alias`].
    fn entity_by_alias(
        &self,
        alias_name: &str,
        mount_accessor: &str,
    ) -> impl Future<Output = Result<Option<EntityRef>, Error>> + Send;

    /// As [`SecretStore::entity_id_by_name`].
    fn entity_id_by_name(
        &self,
        name: &str,
    ) -> impl Future<Output = Result<Option<String>, Error>> + Send;

    /// As [`SecretStore::create_entity`].
    fn create_entity(&self, name: &str) -> impl Future<Output = Result<(), Error>> + Send;

    /// As [`SecretStore::rename_entity`].
    fn rename_entity(&self, id: &str, name: &str)
    -> impl Future<Output = Result<(), Error>> + Send;

    /// As [`SecretStore::create_entity_alias`].
    fn create_entity_alias(
        &self,
        alias_name: &str,
        mount_accessor: &str,
        entity_id: &str,
    ) -> impl Future<Output = Result<(), Error>> + Send;
}

impl AccessStore for SecretStore {
    async fn write_policy(&self, name: &str, policy: &str) -> Result<(), Error> {
        SecretStore::write_policy(self, name, policy).await
    }

    async fn write_cert_role(
        &self,
        mount: &str,
        name: &str,
        certificate: &str,
        common_name: &str,
        policies: &[&str],
    ) -> Result<(), Error> {
        SecretStore::write_cert_role(self, mount, name, certificate, common_name, policies).await
    }

    async fn auth_mount_accessor(&self, mount: &str) -> Result<String, Error> {
        SecretStore::auth_mount_accessor(self, mount).await
    }

    async fn entity_by_alias(
        &self,
        alias_name: &str,
        mount_accessor: &str,
    ) -> Result<Option<EntityRef>, Error> {
        SecretStore::entity_by_alias(self, alias_name, mount_accessor).await
    }

    async fn entity_id_by_name(&self, name: &str) -> Result<Option<String>, Error> {
        SecretStore::entity_id_by_name(self, name).await
    }

    async fn create_entity(&self, name: &str) -> Result<(), Error> {
        SecretStore::create_entity(self, name).await
    }

    async fn rename_entity(&self, id: &str, name: &str) -> Result<(), Error> {
        SecretStore::rename_entity(self, id, name).await
    }

    async fn create_entity_alias(
        &self,
        alias_name: &str,
        mount_accessor: &str,
        entity_id: &str,
    ) -> Result<(), Error> {
        SecretStore::create_entity_alias(self, alias_name, mount_accessor, entity_id).await
    }
}

/// A store that records what it is asked to do, for tests of the order and the
/// outcome of the access calls.
#[cfg(test)]
pub(crate) mod fake {
    use std::sync::Mutex;

    use swarm_secret_client::{Error, client::EntityRef};

    use super::AccessStore;

    /// What the fake answers; the default is a store with a readable cert mount
    /// and no entities, which accepts every write.
    #[derive(Default)]
    pub(crate) struct FakeAccess {
        /// The accessor read fails.
        no_accessor: bool,
        /// Every policy write is refused.
        refuse_policy: bool,
        /// The entity that owns each alias, as `(id, name)`.
        alias_owner: Option<(String, String)>,
        entities: Mutex<Vec<String>>,
        calls: Mutex<Vec<String>>,
    }

    impl FakeAccess {
        /// A store whose cert mount accessor cannot be read.
        pub(crate) fn without_accessor() -> Self {
            Self {
                no_accessor: true,
                ..Self::default()
            }
        }

        /// A store that refuses every policy write.
        pub(crate) fn refusing_policies() -> Self {
            Self {
                refuse_policy: true,
                ..Self::default()
            }
        }

        /// A store where the agent alias is already on the entity `name`.
        pub(crate) fn with_alias_on(id: &str, name: &str) -> Self {
            Self {
                alias_owner: Some((id.to_owned(), name.to_owned())),
                ..Self::default()
            }
        }

        /// The calls so far, as `verb name` strings, in order.
        pub(crate) fn calls(&self) -> Vec<String> {
            self.calls.lock().expect("not poisoned").clone()
        }

        /// The `write_cert_role` calls so far, as `write_cert_role <role> <policies>`.
        pub(crate) fn roles_written(&self) -> Vec<String> {
            self.calls()
                .into_iter()
                .filter(|c| c.starts_with("write_cert_role "))
                .collect()
        }

        fn log(&self, call: String) {
            self.calls.lock().expect("not poisoned").push(call);
        }

        fn denied() -> Error {
            Error::Settings("fake store: refused".to_owned())
        }
    }

    impl AccessStore for FakeAccess {
        async fn write_policy(&self, name: &str, _policy: &str) -> Result<(), Error> {
            self.log(format!("write_policy {name}"));
            if self.refuse_policy {
                return Err(Self::denied());
            }
            Ok(())
        }

        async fn write_cert_role(
            &self,
            _mount: &str,
            name: &str,
            _certificate: &str,
            _common_name: &str,
            policies: &[&str],
        ) -> Result<(), Error> {
            self.log(format!("write_cert_role {name} {}", policies.join(",")));
            Ok(())
        }

        async fn auth_mount_accessor(&self, _mount: &str) -> Result<String, Error> {
            self.log("auth_mount_accessor".to_owned());
            if self.no_accessor {
                return Err(Self::denied());
            }
            Ok("auth_cert_test".to_owned())
        }

        async fn entity_by_alias(
            &self,
            alias_name: &str,
            _mount_accessor: &str,
        ) -> Result<Option<EntityRef>, Error> {
            self.log(format!("entity_by_alias {alias_name}"));
            Ok(self.alias_owner.as_ref().map(|(id, name)| EntityRef {
                id: id.clone(),
                name: name.clone(),
            }))
        }

        async fn entity_id_by_name(&self, name: &str) -> Result<Option<String>, Error> {
            self.log(format!("entity_id_by_name {name}"));
            let named = self
                .entities
                .lock()
                .expect("not poisoned")
                .contains(&name.to_owned());
            Ok(named.then(|| format!("id-{name}")))
        }

        async fn create_entity(&self, name: &str) -> Result<(), Error> {
            self.log(format!("create_entity {name}"));
            self.entities
                .lock()
                .expect("not poisoned")
                .push(name.to_owned());
            Ok(())
        }

        async fn rename_entity(&self, id: &str, name: &str) -> Result<(), Error> {
            self.log(format!("rename_entity {id} {name}"));
            Ok(())
        }

        async fn create_entity_alias(
            &self,
            alias_name: &str,
            _mount_accessor: &str,
            _entity_id: &str,
        ) -> Result<(), Error> {
            self.log(format!("create_entity_alias {alias_name}"));
            Ok(())
        }
    }
}