use std::collections::HashSet; use git_features::progress::Progress;use git_protocol::transport::client::Transport; use crate::{    bstr,    bstr::{BString, ByteVec},    remote::{connection::HandshakeWithRefs, fetch, Connection, Direction},}; /// The error returned by [`Connection::ref_map()`].#[derive(Debug, thiserror::Error)]#[allow(missing_docs)]pub enum Error {    #[error(transparent)]    Handshake(#[from] git_protocol::fetch::handshake::Error),    #[error("The object format {format:?} as used by the remote is unsupported")]    UnknownObjectFormat { format: BString },    #[error(transparent)]    ListRefs(#[from] git_protocol::fetch::refs::Error),    #[error(transparent)]    Transport(#[from] git_protocol::transport::client::Error),    #[error(transparent)]    ConfigureCredentials(#[from] crate::config::credential_helpers::Error),    #[error(transparent)]    MappingValidation(#[from] git_refspec::match_group::validate::Error),} /// For use in [`Connection::ref_map()`].#[derive(Debug, Clone)]pub struct Options {    /// Use a two-component prefix derived from the ref-spec's source, like `refs/heads/`  to let the server pre-filter refs    /// with great potential for savings in traffic and local CPU time. Defaults to `true`.    pub prefix_from_spec_as_filter_on_remote: bool,    /// Parameters in the form of `(name, optional value)` to add to the handshake.    ///    /// This is useful in case of custom servers.    pub handshake_parameters: Vec<(String, Option<String>)>,} impl Default for Options {    fn default() -> Self {        Options {            prefix_from_spec_as_filter_on_remote: true,            handshake_parameters: Default::default(),        }    }} impl<'remote, 'repo, T, P> Connection<'remote, 'repo, T, P>where    T: Transport,    P: Progress,{    /// List all references on the remote that have been filtered through our remote's [`refspecs`][crate::Remote::refspecs()]    /// for _fetching_.    ///    /// This comes in the form of all matching tips on the remote and the object they point to, along with    /// with the local tracking branch of these tips (if available).    ///    /// Note that this doesn't fetch the objects mentioned in the tips nor does it make any change to underlying repository.    ///    /// # Consumption    ///    /// Due to management of the transport, it's cleanest to only use it for a single interaction. Thus it's consumed along with    /// the connection.    #[allow(clippy::result_large_err)]    #[git_protocol::maybe_async::maybe_async]    pub async fn ref_map(mut self, options: Options) -> Result<fetch::RefMap, Error> {        let res = self.ref_map_inner(options).await;        git_protocol::fetch::indicate_end_of_interaction(&mut self.transport)            .await            .ok();        res    }     #[allow(clippy::result_large_err)]    #[git_protocol::maybe_async::maybe_async]    pub(crate) async fn ref_map_inner(        &mut self,        Options {            prefix_from_spec_as_filter_on_remote,            handshake_parameters,        }: Options,    ) -> Result<fetch::RefMap, Error> {        let null = git_hash::ObjectId::null(git_hash::Kind::Sha1); // OK to hardcode Sha1, it's not supposed to match, ever.        let remote = self            .fetch_refs(prefix_from_spec_as_filter_on_remote, handshake_parameters)            .await?;        let group = git_refspec::MatchGroup::from_fetch_specs(self.remote.fetch_specs.iter().map(|s| s.to_ref()));        let (res, fixes) = group            .match_remotes(remote.refs.iter().map(|r| {                let (full_ref_name, target, object) = r.unpack();                git_refspec::match_group::Item {                    full_ref_name,                    target: target.unwrap_or(&null),                    object,                }            }))            .validated()?;        let mappings = res.mappings;        let mappings = mappings            .into_iter()            .map(|m| fetch::Mapping {                remote: m                    .item_index                    .map(|idx| fetch::Source::Ref(remote.refs[idx].clone()))                    .unwrap_or_else(|| {                        fetch::Source::ObjectId(match m.lhs {                            git_refspec::match_group::SourceRef::ObjectId(id) => id,                            _ => unreachable!("no item index implies having an object id"),                        })                    }),                local: m.rhs.map(|c| c.into_owned()),                spec_index: m.spec_index,            })            .collect();         let object_hash = extract_object_format(self.remote.repo, &remote.outcome)?;        Ok(fetch::RefMap {            mappings,            fixes,            remote_refs: remote.refs,            handshake: remote.outcome,            object_hash,        })    }     #[allow(clippy::result_large_err)]    #[git_protocol::maybe_async::maybe_async]    async fn fetch_refs(        &mut self,        filter_by_prefix: bool,        extra_parameters: Vec<(String, Option<String>)>,    ) -> Result<HandshakeWithRefs, Error> {        let mut credentials_storage;        let authenticate = match self.authenticate.as_mut() {            Some(f) => f,            None => {                let url = self                    .remote                    .url(Direction::Fetch)                    .map(ToOwned::to_owned)                    .unwrap_or_else(|| {                        git_url::parse(self.transport.to_url().as_bytes().into())                            .expect("valid URL to be provided by transport")                    });                credentials_storage = self.configured_credentials(url)?;                &mut credentials_storage            }        };        let mut outcome =            git_protocol::fetch::handshake(&mut self.transport, authenticate, extra_parameters, &mut self.progress)                .await?;        let refs = match outcome.refs.take() {            Some(refs) => refs,            None => {                let specs = &self.remote.fetch_specs;                git_protocol::fetch::refs(                    &mut self.transport,                    outcome.server_protocol_version,                    &outcome.capabilities,                    |_capabilities, arguments, _features| {                        if filter_by_prefix {                            let mut seen = HashSet::new();                            for spec in specs {                                let spec = spec.to_ref();                                if seen.insert(spec.instruction()) {                                    let mut prefixes = Vec::with_capacity(1);                                    spec.expand_prefixes(&mut prefixes);                                    for mut prefix in prefixes {                                        prefix.insert_str(0, "ref-prefix ");                                        arguments.push(prefix);                                    }                                }                            }                        }                        Ok(git_protocol::fetch::delegate::LsRefsAction::Continue)                    },                    &mut self.progress,                )                .await?            }        };        Ok(HandshakeWithRefs { outcome, refs })    }} /// Assume sha1 if server says nothing, otherwise configure anything beyond sha1 in the local repo configuration#[allow(clippy::result_large_err)]fn extract_object_format(    _repo: &crate::Repository,    outcome: &git_protocol::fetch::handshake::Outcome,) -> Result<git_hash::Kind, Error> {    use bstr::ByteSlice;    let object_hash =        if let Some(object_format) = outcome.capabilities.capability("object-format").and_then(|c| c.value()) {            let object_format = object_format.to_str().map_err(|_| Error::UnknownObjectFormat {                format: object_format.into(),            })?;            match object_format {                "sha1" => git_hash::Kind::Sha1,                unknown => return Err(Error::UnknownObjectFormat { format: unknown.into() }),            }        } else {            git_hash::Kind::Sha1        };    Ok(object_hash)}