use std::{    convert::TryInto,    ops::{Deref, DerefMut},}; use git_actor as actor;use git_hash::ObjectId;use git_lock as lock;use git_ref::{    transaction::{Change, LogChange, PreviousValue, RefEdit, RefLog},    FullName, PartialNameRef, Target,}; use crate::{    bstr::BString,    easy,    easy::{ext::RepositoryAccessExt, reference, Reference},    ext::ReferenceExt,}; const DEFAULT_LOCK_MODE: git_lock::acquire::Fail = git_lock::acquire::Fail::Immediately; /// Obtain and alter references comfortablypub trait ReferenceAccessExt: easy::Access + Sized {    /// Create a lightweight tag with given `name` (and without `refs/tags/` prefix) pointing to the given `target`, and return it as reference.    ///    /// It will be created with `constraint` which is most commonly to [only create it][PreviousValue::MustNotExist]    /// or to [force overwriting a possibly existing tag](PreviousValue::Any).    fn tag_reference(        &self,        name: impl AsRef<str>,        target: impl Into<ObjectId>,        constraint: PreviousValue,    ) -> Result<Reference<'_, Self>, reference::edit::Error> {        let id = target.into();        let mut edits = self.edit_reference(            RefEdit {                change: Change::Update {                    log: Default::default(),                    expected: constraint,                    new: Target::Peeled(id),                },                name: format!("refs/tags/{}", name.as_ref()).try_into()?,                deref: false,            },            DEFAULT_LOCK_MODE,            None,        )?;        assert_eq!(edits.len(), 1, "reference splits should ever happen");        let edit = edits.pop().expect("exactly one item");        Ok(easy::Reference {            inner: git_ref::Reference {                name: edit.name,                target: id.into(),                peeled: None,            },            access: self,        })    }     /// Returns the currently set namespace for references, or `None` if it is not set.    ///    /// Namespaces allow to partition references.    fn namespace(&self) -> Result<Option<git_ref::Namespace>, easy::borrow::repo::Error> {        self.repo().map(|repo| repo.deref().refs.namespace.clone())    }     /// Remove the currently set reference namespace and return it.    fn clear_namespace(&mut self) -> Result<Option<git_ref::Namespace>, easy::borrow::repo::Error> {        self.repo_mut().map(|mut repo| repo.deref_mut().refs.namespace.take())    }     /// Set the reference namespace to the given value, like `"foo"` or `"foo/bar"`.    fn set_namespace<'a, Name, E>(        &mut self,        namespace: Name,    ) -> Result<Option<git_ref::Namespace>, easy::reference::namespace::set::Error>    where        Name: TryInto<PartialNameRef<'a>, Error = E>,        git_validate::refname::Error: From<E>,    {        let namespace = git_ref::namespace::expand(namespace)?;        Ok(self.repo_mut()?.deref_mut().refs.namespace.replace(namespace))    }     // TODO: more tests or usage    /// Create a new reference with `name`, like `refs/heads/branch`, pointing to `target`, adhering to `constraint`    /// during creation and writing `log_message` into the reflog. Note that a ref-log will be written even if `log_message` is empty.    ///    /// The newly created Reference is returned.    fn reference<Name, E>(        &self,        name: Name,        target: impl Into<ObjectId>,        constraint: PreviousValue,        log_message: impl Into<BString>,    ) -> Result<Reference<'_, Self>, reference::edit::Error>    where        Name: TryInto<FullName, Error = E>,        reference::edit::Error: From<E>,    {        let name = name.try_into()?;        let id = target.into();        let mut edits = self.edit_reference(            RefEdit {                change: Change::Update {                    log: LogChange {                        mode: RefLog::AndReference,                        force_create_reflog: false,                        message: log_message.into(),                    },                    expected: constraint,                    new: Target::Peeled(id),                },                name,                deref: false,            },            DEFAULT_LOCK_MODE,            None,        )?;        assert_eq!(            edits.len(),            1,            "only one reference can be created, splits aren't possible"        );         Ok(git_ref::Reference {            name: edits.pop().expect("exactly one edit").name,            target: Target::Peeled(id),            peeled: None,        }        .attach(self))    }     /// Edit a single reference as described in `edit`, handle locks via `lock_mode` and write reference logs as `log_committer`.    ///    /// One or more `RefEdit`s  are returned - symbolic reference splits can cause more edits to be performed. All edits have the previous    /// reference values set to the ones encountered at rest after acquiring the respective reference's lock.    fn edit_reference(        &self,        edit: RefEdit,        lock_mode: lock::acquire::Fail,        log_committer: Option<&actor::Signature>,    ) -> Result<Vec<RefEdit>, reference::edit::Error> {        self.edit_references(Some(edit), lock_mode, log_committer)    }     /// Edit one or more references as described by their `edits`, with `lock_mode` deciding on how to handle competing    /// transactions. `log_committer` is the name appearing in reference logs.    ///    /// Returns all reference edits, which might be more than where provided due the splitting of symbolic references, and    /// whose previous (_old_) values are the ones seen on in storage after the reference was locked.    fn edit_references(        &self,        edits: impl IntoIterator<Item = RefEdit>,        lock_mode: lock::acquire::Fail,        log_committer: Option<&actor::Signature>,    ) -> Result<Vec<RefEdit>, reference::edit::Error> {        let committer_storage;        let committer = match log_committer {            Some(c) => c,            None => {                committer_storage = self.committer()?;                &committer_storage            }        };        let repo = self.repo()?;        repo.refs            .transaction()            .prepare(edits, lock_mode)?            .commit(committer)            .map_err(Into::into)    }     /// Return the repository head, an abstraction to help dealing with the `HEAD` reference.    ///    /// The `HEAD` reference can be in various states, for more information, the documentation of [`Head`][easy::Head].    fn head(&self) -> Result<easy::Head<'_, Self>, reference::find::existing::Error> {        let head = self.find_reference("HEAD")?;        Ok(match head.inner.target {            Target::Symbolic(branch) => match self.find_reference(branch.to_partial()) {                Ok(r) => easy::head::Kind::Symbolic(r.detach()),                Err(reference::find::existing::Error::NotFound) => easy::head::Kind::Unborn(branch),                Err(err) => return Err(err),            },            Target::Peeled(target) => easy::head::Kind::Detached {                target,                peeled: head.inner.peeled,            },        }        .attach(self))    }     /// Find the reference with the given partial or full `name`, like `main`, `HEAD`, `heads/branch` or `origin/other`,    /// or return an error if it wasn't found.    ///    /// Consider [`try_find_reference(…)`][ReferenceAccessExt::try_find_reference()] if the reference might not exist    /// without that being considered an error.    fn find_reference<'a, Name, E>(&self, name: Name) -> Result<Reference<'_, Self>, reference::find::existing::Error>    where        Name: TryInto<PartialNameRef<'a>, Error = E>,        git_ref::file::find::Error: From<E>,    {        self.try_find_reference(name)?            .ok_or(reference::find::existing::Error::NotFound)    }     /// Return a platform for iterating references.    ///    /// Common kinds of iteration are [all][easy::reference::iter::Platform::all()] or [prefixed][easy::reference::iter::Platform::prefixed()]    /// references.    fn references(&self) -> Result<easy::reference::iter::Platform<'_, Self>, easy::reference::iter::Error> {        let state = self.state();        let repo = self.repo()?;        let packed_refs = state.assure_packed_refs_uptodate(&repo.refs)?;        Ok(easy::reference::iter::Platform {            repo,            packed_refs,            access: self,        })    }     /// Try to find the reference named `name`, like `main`, `heads/branch`, `HEAD` or `origin/other`, and return it.    ///    /// Otherwise return `None` if the reference wasn't found.    /// If the reference is expected to exist, use [`find_reference()`][ReferenceAccessExt::find_reference()].    fn try_find_reference<'a, Name, E>(&self, name: Name) -> Result<Option<Reference<'_, Self>>, reference::find::Error>    where        Name: TryInto<PartialNameRef<'a>, Error = E>,        git_ref::file::find::Error: From<E>,    {        let state = self.state();        let repo = self.repo()?;        match repo            .refs            .try_find(name, state.assure_packed_refs_uptodate(&repo.refs)?.buffer.as_ref())        {            Ok(r) => match r {                Some(r) => Ok(Some(Reference::from_ref(r, self))),                None => Ok(None),            },            Err(err) => Err(err.into()),        }    }} impl<A> ReferenceAccessExt for A where A: easy::Access + Sized {}