hdfs_native/

client.rs

use std::collections::{HashMap, VecDeque};
use std::sync::{Arc, OnceLock};
use std::time::{SystemTime, UNIX_EPOCH};

use futures::stream::BoxStream;
use futures::{StreamExt, stream};
use tokio::runtime::{Handle, Runtime};
use url::Url;

use crate::acl::{AclEntry, AclStatus};
use crate::common::config::{self, Configuration};
use crate::ec::resolve_ec_policy;
use crate::error::{HdfsError, Result};
use crate::file::{FileReader, FileWriter};
use crate::hdfs::crypto::FileCryptoCodec;
use crate::hdfs::protocol::NamenodeProtocol;
use crate::hdfs::proxy::NameServiceProxy;
use crate::proto::hdfs::hdfs_file_status_proto::FileType;
#[cfg(feature = "kms")]
use crate::security::kms::KmsClient;
use crate::security::user::User;

use crate::glob::{GlobPattern, expand_glob, get_path_components, unescape_component};
use crate::proto::hdfs::{ContentSummaryProto, FileEncryptionInfoProto, HdfsFileStatusProto};

const TRASH_ROOT_DIR: &str = ".Trash";
const TRASH_CURRENT_DIR: &str = "Current";
const TRASH_DIR_PERMISSION: u32 = 0o700;

#[derive(Clone)]
pub struct WriteOptions {
    /// Block size. Default is retrieved from the server.
    pub block_size: Option<u64>,
    /// Replication factor. Default is retrieved from the server.
    pub replication: Option<u32>,
    /// Unix file permission, defaults to 0o644, which is "rw-r--r--" as a Unix permission.
    /// This is the raw octal value represented in base 10.
    pub permission: u32,
    /// Whether to overwrite the file, defaults to false. If true and the
    /// file does not exist, it will result in an error.
    pub overwrite: bool,
    /// Whether to create any missing parent directories, defaults to true. If false
    /// and the parent directory does not exist, an error will be returned.
    pub create_parent: bool,
}

impl Default for WriteOptions {
    fn default() -> Self {
        Self {
            block_size: None,
            replication: None,
            permission: 0o644,
            overwrite: false,
            create_parent: true,
        }
    }
}

impl AsRef<WriteOptions> for WriteOptions {
    fn as_ref(&self) -> &WriteOptions {
        self
    }
}

impl WriteOptions {
    /// Set the block_size for the new file
    pub fn block_size(mut self, block_size: u64) -> Self {
        self.block_size = Some(block_size);
        self
    }

    /// Set the replication for the new file
    pub fn replication(mut self, replication: u32) -> Self {
        self.replication = Some(replication);
        self
    }

    /// Set the raw octal permission value for the new file
    pub fn permission(mut self, permission: u32) -> Self {
        self.permission = permission;
        self
    }

    /// Set whether to overwrite an existing file
    pub fn overwrite(mut self, overwrite: bool) -> Self {
        self.overwrite = overwrite;
        self
    }

    /// Set whether to create all missing parent directories
    pub fn create_parent(mut self, create_parent: bool) -> Self {
        self.create_parent = create_parent;
        self
    }
}

#[derive(Debug, Clone)]
struct MountLink {
    viewfs_path: String,
    hdfs_path: String,
    protocol: Arc<NamenodeProtocol>,
}

impl MountLink {
    fn new(viewfs_path: &str, hdfs_path: &str, protocol: Arc<NamenodeProtocol>) -> Self {
        // We should never have an empty path, we always want things mounted at root ("/") by default.
        Self {
            viewfs_path: viewfs_path.trim_end_matches("/").to_string(),
            hdfs_path: hdfs_path.trim_end_matches("/").to_string(),
            protocol,
        }
    }
    /// Convert a viewfs path into a name service path if it matches this link
    fn resolve(&self, path: &str) -> Option<String> {
        // Make sure we don't partially match the last component. It either needs to be an exact
        // match to a viewfs path, or needs to match with a trailing slash
        if path == self.viewfs_path {
            Some(self.hdfs_path.clone())
        } else {
            path.strip_prefix(&format!("{}/", self.viewfs_path))
                .map(|relative_path| format!("{}/{}", self.hdfs_path, relative_path))
        }
    }
}

#[derive(Debug)]
struct MountTable {
    mounts: Vec<MountLink>,
    fallback: MountLink,
    home_dir: String,
}

impl MountTable {
    fn resolve(&self, src: &str) -> (&MountLink, String) {
        let path = if src.starts_with('/') {
            src.to_string()
        } else {
            format!("{}/{}", self.home_dir, src)
        };

        for link in self.mounts.iter() {
            if let Some(resolved) = link.resolve(&path) {
                return (link, resolved);
            }
        }
        (&self.fallback, self.fallback.resolve(&path).unwrap())
    }
}

fn build_home_dir(
    scheme: &str,
    host: Option<&str>,
    config: &Configuration,
    username: &str,
) -> String {
    let prefix = match scheme {
        "hdfs" => config.get("dfs.user.home.dir.prefix"),
        "viewfs" => {
            host.and_then(|host| config.get(&format!("fs.viewfs.mounttable.{host}.homedir")))
        }
        _ => None,
    }
    .unwrap_or("/user");

    let prefix = prefix.trim_end_matches('/');
    if prefix.is_empty() {
        format!("/{username}")
    } else {
        format!("{prefix}/{username}")
    }
}

/// Holds either a [Runtime] or a [Handle] to an existing runtime for IO tasks
#[derive(Debug)]
pub enum IORuntime {
    Runtime(Runtime),
    Handle(Handle),
}

impl From<Runtime> for IORuntime {
    fn from(value: Runtime) -> Self {
        Self::Runtime(value)
    }
}

impl From<Handle> for IORuntime {
    fn from(value: Handle) -> Self {
        Self::Handle(value)
    }
}

impl IORuntime {
    fn handle(&self) -> Handle {
        match self {
            Self::Runtime(runtime) => runtime.handle().clone(),
            Self::Handle(handle) => handle.clone(),
        }
    }
}

/// Builds a new [Client] instance. Configs will be loaded with the following precedence:
///
/// - If method `ClientBuilder::with_config_dir` is invoked, configs will be loaded from `${config_dir}/{core,hdfs}-site.xml`
/// - If the `HADOOP_CONF_DIR` environment variable is defined, configs will be loaded from `${HADOOP_CONF_DIR}/{core,hdfs}-site.xml`
/// - If the `HADOOP_HOME` environment variable is defined, configs will be loaded from `${HADOOP_HOME}/etc/hadoop/{core,hdfs}-site.xml`
/// - Otherwise no configs are defined
///
/// Finally, configs set by `with_config` will override the configs loaded above.
///
/// If no URL is defined, the `fs.defaultFS` config must be defined and is used as the URL.
///
/// # Examples
///
/// Create a new client with given config directory
///
/// ```rust,no_run
/// # use hdfs_native::ClientBuilder;
/// let client = ClientBuilder::new()
///     .with_config_dir("/opt/hadoop/etc/hadoop")
///     .build()
///     .unwrap();
/// ```
///
/// Create a client that acquires credentials directly from a keytab:
///
/// An explicit principal is required. A keytab without a supplied cache uses
/// a native `MEMORY:` credential cache.
///
/// ```rust,no_run
/// # use hdfs_native::ClientBuilder;
/// let client = ClientBuilder::new()
///     .with_url("hdfs://namenode.example.com:9000")
///     .with_kerberos_principal("client@EXAMPLE.COM")
///     .with_kerberos_keytab("/run/secrets/client.keytab")
///     .build()
///     .unwrap();
/// ```
///
/// Create a new client with the environment variable
///
/// ```rust,no_run
/// # use hdfs_native::ClientBuilder;
/// unsafe { std::env::set_var("HADOOP_CONF_DIR", "/opt/hadoop/etc/hadoop") };
/// let client = ClientBuilder::new()
///     .build()
///     .unwrap();
/// ```
///
/// Create a new client using the fs.defaultFS config
///
/// ```rust
/// # use hdfs_native::ClientBuilder;
/// let client = ClientBuilder::new()
///     .with_config(vec![("fs.defaultFS", "hdfs://127.0.0.1:9000")])
///     .build()
///     .unwrap();
/// ```
///
/// Create a new client connecting to a specific URL:
///
/// ```rust
/// # use hdfs_native::ClientBuilder;
/// let client = ClientBuilder::new()
///     .with_url("hdfs://127.0.0.1:9000")
///     .build()
///     .unwrap();
/// ```
///
/// Create a new client using a dedicated tokio runtime for spawned tasks and IO operations
///
/// ```rust
/// # use hdfs_native::ClientBuilder;
/// let client = ClientBuilder::new()
///     .with_url("hdfs://127.0.0.1:9000")
///     .with_io_runtime(tokio::runtime::Runtime::new().unwrap())
///     .build()
///     .unwrap();
/// ```
///
/// Create a client with an explicit Kerberos credential cache:
///
/// ```rust,no_run
/// # use hdfs_native::ClientBuilder;
/// let client = ClientBuilder::new()
///     .with_url("hdfs://namenode.example.com:9000")
///     .with_kerberos_principal("client@EXAMPLE.COM")
///     .with_kerberos_cache("FILE:/run/krb5/client.ccache")
///     .build()
///     .unwrap();
/// ```
#[derive(Default)]
pub struct ClientBuilder {
    url: Option<String>,
    config: Option<HashMap<String, String>>,
    config_dir: Option<String>,
    runtime: Option<IORuntime>,
    user: Option<String>,
    kerberos_principal: Option<String>,
    kerberos_keytab: Option<String>,
    kerberos_cache: Option<String>,
}

impl ClientBuilder {
    /// Create a new [ClientBuilder]
    pub fn new() -> Self {
        Self::default()
    }

    /// Set the URL to connect to. Can be the address of a single NameNode, or a logical NameService
    pub fn with_url(mut self, url: impl Into<String>) -> Self {
        self.url = Some(url.into());
        self
    }

    /// Set configs to use for the client. The provided configs will override any found in the config files loaded
    pub fn with_config(
        mut self,
        config: impl IntoIterator<Item = (impl Into<String>, impl Into<String>)>,
    ) -> Self {
        self.config = Some(
            config
                .into_iter()
                .map(|(k, v)| (k.into(), v.into()))
                .collect(),
        );
        self
    }

    /// Set the configration directory path to read from. The provided path will override the one provided by environment variable.
    pub fn with_config_dir(mut self, config_dir: impl Into<String>) -> Self {
        self.config_dir = Some(config_dir.into());
        self
    }

    /// Use a dedicated tokio runtime for spawned tasks and IO operations. Can either take ownership of a whole [Runtime]
    /// or take a [Handle] to an externally owned runtime.
    pub fn with_io_runtime(mut self, runtime: impl Into<IORuntime>) -> Self {
        self.runtime = Some(runtime.into());
        self
    }

    /// Set the effective user for the client. If not set, the client will detect user from environment variables `HADOOP_USER_NAME` or `HADOOP_PROXY_USER`.
    pub fn with_user(mut self, user: impl Into<String>) -> Self {
        self.user = Some(user.into());
        self
    }

    /// Set the Kerberos principal used by this client.
    pub fn with_kerberos_principal(mut self, principal: impl Into<String>) -> Self {
        self.kerberos_principal = Some(principal.into());
        self
    }

    /// Set the Kerberos keytab used by this client.
    pub fn with_kerberos_keytab(mut self, keytab: impl Into<String>) -> Self {
        self.kerberos_keytab = Some(keytab.into());
        self
    }

    /// Set the Kerberos credential cache used by this client.
    pub fn with_kerberos_cache(mut self, cache: impl Into<String>) -> Self {
        self.kerberos_cache = Some(cache.into());
        self
    }

    /// Create the [Client] instance from the provided settings
    pub fn build(self) -> Result<Client> {
        let config = Configuration::new(self.config_dir, self.config)?;
        let url = if let Some(url) = self.url {
            Url::parse(&url)?
        } else {
            Client::default_fs(&config)?
        };

        let kerberos_credentials = crate::security::KerberosCredentials::new(
            self.kerberos_principal,
            self.kerberos_keytab,
            self.kerberos_cache,
        )?
        .map(crate::security::ClientAuth::new);

        Client::build(&url, config, self.runtime, self.user, kerberos_credentials)
    }
}

#[derive(Clone, Debug)]
enum RuntimeHolder {
    Custom(Arc<IORuntime>),
    Default(Arc<OnceLock<Runtime>>),
}

impl RuntimeHolder {
    fn new(rt: Option<IORuntime>) -> Self {
        if let Some(rt) = rt {
            Self::Custom(Arc::new(rt))
        } else {
            Self::Default(Arc::new(OnceLock::new()))
        }
    }

    fn get_handle(&self) -> Handle {
        match self {
            Self::Custom(rt) => rt.handle().clone(),
            Self::Default(rt) => match Handle::try_current() {
                Ok(handle) => handle,
                Err(_) => rt
                    .get_or_init(|| Runtime::new().expect("Failed to create tokio runtime"))
                    .handle()
                    .clone(),
            },
        }
    }
}

/// A client to a speicific NameNode, NameService, or Viewfs mount table
#[derive(Clone, Debug)]
pub struct Client {
    mount_table: Arc<MountTable>,
    config: Arc<Configuration>,
    // Store the runtime used for spawning all internal tasks. If we are not created
    // inside a tokio runtime, we will create our own to use.
    rt_holder: RuntimeHolder,
    // Built once at client construction from `hadoop.security.key.provider.path`.
    // `None` means TDE is not configured; reads of encrypted files will error.
    #[cfg(feature = "kms")]
    kms_client: Option<Arc<KmsClient>>,
}

impl Client {
    fn default_fs(config: &Configuration) -> Result<Url> {
        let url = config
            .get(config::DEFAULT_FS)
            .ok_or(HdfsError::InvalidArgument(format!(
                "No {} setting found",
                config::DEFAULT_FS
            )))?;
        Ok(Url::parse(url)?)
    }

    fn build(
        url: &Url,
        config: Configuration,
        rt: Option<IORuntime>,
        user: Option<String>,
        auth: Option<Arc<crate::security::ClientAuth>>,
    ) -> Result<Self> {
        let resolved_url = if !url.has_host() {
            let default_url = Self::default_fs(&config)?;
            if url.scheme() != default_url.scheme() || !default_url.has_host() {
                return Err(HdfsError::InvalidArgument(
                    "URL must contain a host".to_string(),
                ));
            }
            default_url
        } else {
            url.clone()
        };

        let config = Arc::new(config);

        let rt_holder = RuntimeHolder::new(rt);

        let user_info = if config.security_enabled()
            && let Some(principal) = auth
                .as_deref()
                .and_then(|auth| auth.credentials())
                .and_then(|credentials| credentials.principal.as_deref())
        {
            User::get_user_info_from_principal(principal, user.clone())
        } else {
            User::get_user_info(user.clone(), config.security_enabled())
        };
        let username = user_info
            .effective_user
            .as_deref()
            .or(user_info.real_user.as_deref())
            .expect("User info must include a username");
        let home_dir = build_home_dir(
            resolved_url.scheme(),
            resolved_url.host_str(),
            config.as_ref(),
            username,
        );

        let mount_table = match url.scheme() {
            "hdfs" => {
                let proxy = NameServiceProxy::new(
                    &resolved_url,
                    Arc::clone(&config),
                    rt_holder.get_handle(),
                    user.clone(),
                    auth.clone(),
                )?;
                let protocol = Arc::new(NamenodeProtocol::new(proxy, rt_holder.get_handle()));

                MountTable {
                    mounts: Vec::new(),
                    fallback: MountLink::new("/", "/", protocol),
                    home_dir,
                }
            }
            "viewfs" => Self::build_mount_table(
                // Host is guaranteed to be present.
                resolved_url.host_str().expect("URL must have a host"),
                Arc::clone(&config),
                rt_holder.get_handle(),
                user.clone(),
                auth.clone(),
                home_dir,
            )?,
            _ => {
                return Err(HdfsError::InvalidArgument(
                    "Only `hdfs` and `viewfs` schemes are supported".to_string(),
                ));
            }
        };

        #[cfg(feature = "kms")]
        let kms_client =
            KmsClient::from_config(config.as_ref(), None, username.to_string(), auth.clone())?;

        Ok(Self {
            mount_table: Arc::new(mount_table),
            config,
            rt_holder,
            #[cfg(feature = "kms")]
            kms_client,
        })
    }

    fn build_mount_table(
        host: &str,
        config: Arc<Configuration>,
        handle: Handle,
        effective_user: Option<String>,
        auth: Option<Arc<crate::security::ClientAuth>>,
        home_dir: String,
    ) -> Result<MountTable> {
        let mut mounts: Vec<MountLink> = Vec::new();
        let mut fallback: Option<MountLink> = None;

        for (viewfs_path, hdfs_url) in config.get_mount_table(host).iter() {
            let url = Url::parse(hdfs_url)?;
            if !url.has_host() {
                return Err(HdfsError::InvalidArgument(
                    "URL must contain a host".to_string(),
                ));
            }
            if url.scheme() != "hdfs" {
                return Err(HdfsError::InvalidArgument(
                    "Only hdfs mounts are supported for viewfs".to_string(),
                ));
            }
            let proxy = NameServiceProxy::new(
                &url,
                Arc::clone(&config),
                handle.clone(),
                effective_user.clone(),
                auth.clone(),
            )?;
            let protocol = Arc::new(NamenodeProtocol::new(proxy, handle.clone()));

            if let Some(prefix) = viewfs_path {
                mounts.push(MountLink::new(prefix, url.path(), protocol));
            } else {
                if fallback.is_some() {
                    return Err(HdfsError::InvalidArgument(
                        "Multiple viewfs fallback links found".to_string(),
                    ));
                }
                fallback = Some(MountLink::new("/", url.path(), protocol));
            }
        }

        if let Some(fallback) = fallback {
            // Sort the mount table from longest viewfs path to shortest. This makes sure more specific paths are considered first.
            mounts.sort_by_key(|m| m.viewfs_path.chars().filter(|c| *c == '/').count());
            mounts.reverse();

            Ok(MountTable {
                mounts,
                fallback,
                home_dir,
            })
        } else {
            Err(HdfsError::InvalidArgument(
                "No viewfs fallback mount found".to_string(),
            ))
        }
    }

    fn normalize_path(path: &str) -> String {
        let mut normalized = if path.is_empty() {
            "/".to_string()
        } else {
            path.to_string()
        };
        if !normalized.starts_with('/') {
            normalized.insert(0, '/');
        }
        while normalized.len() > 1 && normalized.ends_with('/') {
            normalized.pop();
        }
        normalized
    }

    fn join_paths(base: &str, suffix: &str) -> String {
        if suffix.is_empty() {
            return base.to_string();
        }
        let trimmed_base = if base.is_empty() { "/" } else { base };
        let suffix = suffix.trim_start_matches('/');
        if trimmed_base == "/" {
            format!("/{suffix}")
        } else {
            format!("{}/{}", trimmed_base.trim_end_matches('/'), suffix)
        }
    }

    fn is_prefix_path(parent: &str, child: &str) -> bool {
        if parent == "/" {
            return true;
        }
        child == parent || child.starts_with(&format!("{parent}/"))
    }

    fn current_time_millis() -> u64 {
        SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap_or_default()
            .as_millis() as u64
    }

    fn absolute_path(&self, path: &str) -> String {
        if path.starts_with('/') {
            Self::normalize_path(path)
        } else {
            let home = self.mount_table.home_dir.trim_end_matches('/');
            Self::normalize_path(&format!("{home}/{path}"))
        }
    }

    fn trash_root_path(&self) -> String {
        let home = Self::normalize_path(&self.mount_table.home_dir);
        Self::join_paths(&home, TRASH_ROOT_DIR)
    }

    async fn trash_enabled(&self, path: &str) -> Result<bool> {
        let (link, _) = self.mount_table.resolve(path);
        let server_defaults = link.protocol.get_cached_server_defaults().await?;
        Ok(server_defaults.trash_interval.unwrap_or_default() > 0)
    }

    fn split_parent_name(path: &str) -> Result<(String, String)> {
        let normalized = Self::normalize_path(path);
        if normalized == "/" {
            return Err(HdfsError::InvalidArgument(
                "Cannot move the root directory to trash".to_string(),
            ));
        }
        let (parent, name) = normalized
            .rsplit_once('/')
            .expect("Normalized path always contains '/'");
        let parent = if parent.is_empty() {
            "/".to_string()
        } else {
            parent.to_string()
        };
        Ok((parent, name.to_string()))
    }

    async fn non_dir_ancestor(&self, path: &str) -> Result<Option<String>> {
        let normalized = Self::normalize_path(path);
        let mut current = "/".to_string();
        for component in normalized.trim_start_matches('/').split('/') {
            if component.is_empty() {
                continue;
            }
            current = Self::join_paths(&current, component);
            match self.get_file_info(&current).await {
                Ok(status) => {
                    if !status.isdir {
                        return Ok(Some(current));
                    }
                }
                Err(HdfsError::FileNotFound(_)) => return Ok(None),
                Err(err) => return Err(err),
            }
        }
        Ok(None)
    }

    async fn ensure_unique_trash_path(&self, path: String) -> Result<String> {
        let base = path.clone();
        let mut candidate = path;
        loop {
            match self.get_file_info(&candidate).await {
                Ok(_) => {
                    candidate = format!("{}{}", base, Self::current_time_millis());
                }
                Err(HdfsError::FileNotFound(_)) => return Ok(candidate),
                Err(err) => return Err(err),
            }
        }
    }

    /// Retrieve the file status for the file at `path`.
    pub async fn get_file_info(&self, path: &str) -> Result<FileStatus> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        match link.protocol.get_file_info(&resolved_path).await?.fs {
            Some(status) => Ok(FileStatus::from(status, path)),
            None => Err(HdfsError::FileNotFound(path.to_string())),
        }
    }

    /// Retrives a list of all files in directories located at `path`. Wrapper around `list_status_iter` that
    /// returns Err if any part of the stream fails, or Ok if all file statuses were found successfully.
    pub async fn list_status(&self, path: &str, recursive: bool) -> Result<Vec<FileStatus>> {
        let iter = self.list_status_iter(path, recursive);
        let statuses = iter
            .into_stream()
            .collect::<Vec<Result<FileStatus>>>()
            .await;

        let mut resolved_statues = Vec::<FileStatus>::with_capacity(statuses.len());
        for status in statuses.into_iter() {
            resolved_statues.push(status?);
        }

        Ok(resolved_statues)
    }

    /// Retrives an iterator of all files in directories located at `path`.
    pub fn list_status_iter(&self, path: &str, recursive: bool) -> ListStatusIterator {
        ListStatusIterator::new(path.to_string(), Arc::clone(&self.mount_table), recursive)
    }

    /// Opens a file reader for the file at `path`. Path should not include a scheme.
    pub async fn read(&self, path: &str) -> Result<FileReader> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        // Get all block locations. Length is actually a signed value, but the proto uses an unsigned value
        let located_info = link
            .protocol
            .get_block_locations(&resolved_path, 0, i64::MAX as u64)
            .await?;

        if let Some(locations) = located_info.locations {
            let ec_schema = if let Some(ec_policy) = locations.ec_policy.as_ref() {
                Some(resolve_ec_policy(ec_policy)?)
            } else {
                None
            };

            let crypto = self
                .build_crypto_codec(locations.file_encryption_info.as_ref())
                .await?;

            Ok(FileReader::new(
                Arc::clone(&link.protocol),
                locations,
                ec_schema,
                Arc::clone(&self.config),
                self.rt_holder.get_handle(),
                crypto,
            ))
        } else {
            Err(HdfsError::FileNotFound(path.to_string()))
        }
    }

    /// Build a [`FileCryptoCodec`] for a file in an HDFS encryption zone.
    /// Returns `None` for files outside any zone. Returns an error if the file
    /// is encrypted but no KMS is configured for this client.
    async fn build_crypto_codec(
        &self,
        info: Option<&FileEncryptionInfoProto>,
    ) -> Result<Option<Arc<FileCryptoCodec>>> {
        let Some(info) = info else {
            return Ok(None);
        };
        #[cfg(feature = "kms")]
        {
            let kms = self.kms_client.as_ref().ok_or_else(|| {
                HdfsError::OperationFailed(
                    "File is in an HDFS encryption zone but no KMS provider is configured \
                     (set `hadoop.security.key.provider.path` in core-site.xml)"
                        .to_string(),
                )
            })?;
            let dek = kms.decrypt_edek(info).await?;
            Ok(Some(Arc::new(FileCryptoCodec::new(info, dek)?)))
        }
        #[cfg(not(feature = "kms"))]
        {
            let _ = info;
            Err(HdfsError::UnsupportedFeature(
                "file is in an HDFS encryption zone; reading or writing it requires \
                 building hdfs-native with the `kms` cargo feature"
                    .to_string(),
            ))
        }
    }

    /// Opens a new file for writing. See [WriteOptions] for options and behavior for different
    /// scenarios.
    pub async fn create(
        &self,
        src: &str,
        write_options: impl AsRef<WriteOptions>,
    ) -> Result<FileWriter> {
        let write_options = write_options.as_ref();

        let (link, resolved_path) = self.mount_table.resolve(src);

        let create_response = link
            .protocol
            .create(
                &resolved_path,
                write_options.permission,
                write_options.overwrite,
                write_options.create_parent,
                write_options.replication,
                write_options.block_size,
            )
            .await?;

        match create_response.fs {
            Some(status) => {
                let crypto = match self
                    .build_crypto_codec(status.file_encryption_info.as_ref())
                    .await
                {
                    Ok(c) => c,
                    Err(e) => {
                        // The file already exists on the namenode but we can't
                        // build a codec to write to it. Clean it up so the
                        // caller doesn't see a zero-byte stub.
                        let _ = self.delete(src, false).await;
                        return Err(e);
                    }
                };

                Ok(FileWriter::new(
                    Arc::clone(&link.protocol),
                    resolved_path,
                    status,
                    Arc::clone(&self.config),
                    self.rt_holder.get_handle(),
                    None,
                    crypto,
                ))
            }
            None => Err(HdfsError::FileNotFound(src.to_string())),
        }
    }

    fn needs_new_block(class: &str, msg: &str) -> bool {
        class == "java.lang.UnsupportedOperationException" && msg.contains("NEW_BLOCK")
    }

    /// Opens an existing file for appending. An Err will be returned if the file does not exist. If the
    /// file is replicated, the current block will be appended to until it is full. If the file is erasure
    /// coded, a new block will be created.
    pub async fn append(&self, src: &str) -> Result<FileWriter> {
        let (link, resolved_path) = self.mount_table.resolve(src);

        // Assume the file is replicated and try to append to the current block. If the file is
        // erasure coded, then try again by appending to a new block.
        let append_response = match link.protocol.append(&resolved_path, false).await {
            Err(HdfsError::RPCError(class, msg)) if Self::needs_new_block(&class, &msg) => {
                link.protocol.append(&resolved_path, true).await?
            }
            resp => resp?,
        };

        match append_response.stat {
            Some(status) => {
                let crypto = match self
                    .build_crypto_codec(status.file_encryption_info.as_ref())
                    .await
                {
                    Ok(c) => c,
                    Err(e) => {
                        // Release the open lease the namenode granted for the
                        // append we can no longer fulfill.
                        let _ = link
                            .protocol
                            .complete(
                                src,
                                append_response.block.as_ref().map(|b| b.b.clone()),
                                status.file_id,
                            )
                            .await;
                        return Err(e);
                    }
                };

                Ok(FileWriter::new(
                    Arc::clone(&link.protocol),
                    resolved_path,
                    status,
                    Arc::clone(&self.config),
                    self.rt_holder.get_handle(),
                    append_response.block,
                    crypto,
                ))
            }
            None => Err(HdfsError::FileNotFound(src.to_string())),
        }
    }

    /// Create a new directory at `path` with the given `permission`.
    ///
    /// `permission` is the raw octal value representing the Unix style permission. For example, to
    /// set 755 (`rwxr-x-rx`) permissions, use 0o755.
    ///
    /// If `create_parent` is true, any missing parent directories will be created as well,
    /// otherwise an error will be returned if the parent directory doesn't already exist.
    pub async fn mkdirs(&self, path: &str, permission: u32, create_parent: bool) -> Result<()> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        link.protocol
            .mkdirs(&resolved_path, permission, create_parent)
            .await
            .map(|_| ())
    }

    async fn rename_internal(
        &self,
        src: &str,
        dst: &str,
        overwrite: bool,
        move_to_trash: bool,
    ) -> Result<()> {
        let (src_link, src_resolved_path) = self.mount_table.resolve(src);
        let (dst_link, dst_resolved_path) = self.mount_table.resolve(dst);
        if src_link.viewfs_path == dst_link.viewfs_path {
            src_link
                .protocol
                .rename(
                    &src_resolved_path,
                    &dst_resolved_path,
                    overwrite,
                    move_to_trash,
                )
                .await
                .map(|_| ())
        } else {
            Err(HdfsError::InvalidArgument(
                "Cannot rename across different name services".to_string(),
            ))
        }
    }

    /// Renames `src` to `dst`. Returns Ok(()) on success, and Err otherwise.
    pub async fn rename(&self, src: &str, dst: &str, overwrite: bool) -> Result<()> {
        self.rename_internal(src, dst, overwrite, false).await
    }

    /// Deletes the file or directory at `path`. If `recursive` is false and `path` is a non-empty
    /// directory, this will fail. Returns `Ok(true)` if it was successfully deleted.
    pub async fn delete(&self, path: &str, recursive: bool) -> Result<bool> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        link.protocol
            .delete(&resolved_path, recursive)
            .await
            .map(|r| r.result)
    }

    /// Moves a file or directory at `path` into the user's trash. Returns `Ok(Some(path))` if
    /// moved, where `path` is the new location in the trash, or `Ok(None)` if the path is already
    /// under trash.
    pub async fn trash(&self, path: &str) -> Result<Option<String>> {
        if path.is_empty() {
            return Err(HdfsError::InvalidPath("Empty path".to_string()));
        }

        let src_abs = self.absolute_path(path);
        if !self.trash_enabled(&src_abs).await? {
            return Err(HdfsError::TrashNotEnabled);
        }

        let trash_root = self.trash_root_path();

        if Self::is_prefix_path(&trash_root, &src_abs) {
            return Ok(None);
        }
        if Self::is_prefix_path(&src_abs, &trash_root) {
            return Err(HdfsError::InvalidArgument(
                "Cannot move to trash because it contains the trash".to_string(),
            ));
        }

        let _ = self.get_file_info(&src_abs).await?;

        let (src_parent, src_name) = Self::split_parent_name(&src_abs)?;
        let trash_current = Self::join_paths(&trash_root, TRASH_CURRENT_DIR);
        let src_parent_rel = src_parent.trim_start_matches('/');
        let mut base_trash_path = if src_parent_rel.is_empty() {
            trash_current.clone()
        } else {
            Self::join_paths(&trash_current, src_parent_rel)
        };
        let mut trash_path = Self::join_paths(&base_trash_path, &src_name);

        for attempt in 0..2 {
            let mut mkdirs_error: Option<HdfsError> = None;
            loop {
                match self
                    .mkdirs(&base_trash_path, TRASH_DIR_PERMISSION, true)
                    .await
                {
                    Ok(()) => break,
                    Err(err) => {
                        if let Some(ancestor) = self.non_dir_ancestor(&base_trash_path).await? {
                            let timestamp = Self::current_time_millis();
                            base_trash_path = base_trash_path.replacen(
                                &ancestor,
                                &format!("{ancestor}{timestamp}"),
                                1,
                            );
                            trash_path = Self::join_paths(&base_trash_path, &src_name);
                            continue;
                        }
                        mkdirs_error = Some(err);
                        break;
                    }
                }
            }

            if let Some(err) = mkdirs_error {
                if attempt == 0 {
                    continue;
                }
                return Err(err);
            }

            let unique_trash_path = self.ensure_unique_trash_path(trash_path.clone()).await?;
            match self
                .rename_internal(&src_abs, &unique_trash_path, false, true)
                .await
            {
                Ok(()) => return Ok(Some(unique_trash_path)),
                Err(_) if attempt == 0 => continue,
                Err(err) => return Err(err),
            }
        }

        Err(HdfsError::OperationFailed(
            "Failed to move to trash after retry".to_string(),
        ))
    }

    /// Sets the modified and access times for a file. Times should be in milliseconds from the epoch.
    pub async fn set_times(&self, path: &str, mtime: u64, atime: u64) -> Result<()> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        link.protocol
            .set_times(&resolved_path, mtime, atime)
            .await?;
        Ok(())
    }

    /// Optionally sets the owner and group for a file.
    pub async fn set_owner(
        &self,
        path: &str,
        owner: Option<&str>,
        group: Option<&str>,
    ) -> Result<()> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        link.protocol
            .set_owner(&resolved_path, owner, group)
            .await?;
        Ok(())
    }

    /// Sets permissions for a file. Permission should be an octal number reprenting the Unix style
    /// permission.
    ///
    /// For example, to set permissions to rwxr-xr-x, use 0o755.
    pub async fn set_permission(&self, path: &str, permission: u32) -> Result<()> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        link.protocol
            .set_permission(&resolved_path, permission)
            .await?;
        Ok(())
    }

    /// Sets the replication for a file.
    pub async fn set_replication(&self, path: &str, replication: u32) -> Result<bool> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        let result = link
            .protocol
            .set_replication(&resolved_path, replication)
            .await?
            .result;

        Ok(result)
    }

    /// Gets a content summary for a file or directory rooted at `path`.
    pub async fn get_content_summary(&self, path: &str) -> Result<ContentSummary> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        let result = link
            .protocol
            .get_content_summary(&resolved_path)
            .await?
            .summary;

        Ok(result.into())
    }

    /// Update ACL entries for file or directory at `path`. Existing entries will remain.
    pub async fn modify_acl_entries(&self, path: &str, acl_spec: Vec<AclEntry>) -> Result<()> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        link.protocol
            .modify_acl_entries(&resolved_path, acl_spec)
            .await?;

        Ok(())
    }

    /// Remove specific ACL entries for file or directory at `path`.
    pub async fn remove_acl_entries(&self, path: &str, acl_spec: Vec<AclEntry>) -> Result<()> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        link.protocol
            .remove_acl_entries(&resolved_path, acl_spec)
            .await?;

        Ok(())
    }

    /// Remove all default ACLs for file or directory at `path`.
    pub async fn remove_default_acl(&self, path: &str) -> Result<()> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        link.protocol.remove_default_acl(&resolved_path).await?;

        Ok(())
    }

    /// Remove all ACL entries for file or directory at `path`.
    pub async fn remove_acl(&self, path: &str) -> Result<()> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        link.protocol.remove_acl(&resolved_path).await?;

        Ok(())
    }

    /// Override all ACL entries for file or directory at `path`. If only access ACLs are provided,
    /// default ACLs are maintained. Likewise if only default ACLs are provided, access ACLs are
    /// maintained.
    pub async fn set_acl(&self, path: &str, acl_spec: Vec<AclEntry>) -> Result<()> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        link.protocol.set_acl(&resolved_path, acl_spec).await?;

        Ok(())
    }

    /// Get the ACL status for the file or directory at `path`.
    pub async fn get_acl_status(&self, path: &str) -> Result<AclStatus> {
        let (link, resolved_path) = self.mount_table.resolve(path);
        Ok(link
            .protocol
            .get_acl_status(&resolved_path)
            .await?
            .result
            .into())
    }

    /// Get all file statuses matching the glob `pattern`. Supports Hadoop-style globbing
    /// which only applies to individual components of a path.
    pub async fn glob_status(&self, pattern: &str) -> Result<Vec<FileStatus>> {
        // Expand any brace groups first
        let flattened = expand_glob(pattern.to_string())?;

        let mut results: Vec<FileStatus> = Vec::new();

        for flat in flattened.into_iter() {
            // Make the pattern absolute-ish. We keep the pattern as-is; components
            // will be split on '/'. An empty pattern yields no results.
            if flat.is_empty() {
                continue;
            }

            let components = get_path_components(&flat);

            // Candidate holds a path (fully built so far) and optionally a resolved FileStatus
            #[derive(Clone, Debug)]
            struct Candidate {
                path: String,
                status: Option<FileStatus>,
            }

            // Start from the root placeholder
            let mut candidates: Vec<Candidate> = vec![Candidate {
                path: "/".to_string(),
                status: None,
            }];

            for (idx, comp) in components.iter().enumerate() {
                if candidates.is_empty() {
                    break;
                }

                let is_last = idx == components.len() - 1;

                let unescaped = unescape_component(comp);
                let glob_pat = GlobPattern::new(comp)?;

                if !is_last && !glob_pat.has_wildcard() {
                    // Optimization: just append the literal component to each candidate
                    for cand in candidates.iter_mut() {
                        if !cand.path.ends_with('/') {
                            cand.path.push('/');
                        }
                        cand.path.push_str(&unescaped);
                        // keep status as None (we'll resolve later if needed)
                    }
                    continue;
                }

                let mut new_candidates: Vec<Candidate> = Vec::new();

                for cand in candidates.into_iter() {
                    if glob_pat.has_wildcard() {
                        // List the directory represented by cand.path
                        let listing = match self.list_status(&cand.path, false).await {
                            Ok(listing) => listing,
                            Err(HdfsError::FileNotFound(_)) => continue,
                            Err(e) => return Err(e),
                        };
                        if listing.len() == 1 && listing[0].path == cand.path {
                            // listing corresponds to the candidate itself (file), skip
                            continue;
                        }

                        for child in listing.into_iter() {
                            // If this is not the terminal component, only recurse into directories
                            if !is_last && !child.isdir {
                                continue;
                            }

                            // child.path already contains the full path
                            // Extract the name portion to match against the glob pattern
                            let name = child
                                .path
                                .rsplit_once('/')
                                .map(|(_, n)| n)
                                .unwrap_or(child.path.as_str());

                            if glob_pat.matches(name) {
                                new_candidates.push(Candidate {
                                    path: child.path.clone(),
                                    status: Some(child),
                                });
                            }
                        }
                    } else {
                        // Non-glob component: use get_file_info for exact path
                        let mut next_path = cand.path.clone();
                        if !next_path.ends_with('/') {
                            next_path.push('/');
                        }
                        next_path.push_str(&unescaped);

                        match self.get_file_info(&next_path).await {
                            Ok(status) => {
                                if is_last || status.isdir {
                                    new_candidates.push(Candidate {
                                        path: status.path.clone(),
                                        status: Some(status),
                                    });
                                }
                            }
                            Err(HdfsError::FileNotFound(_)) => continue,
                            Err(e) => return Err(e),
                        }
                    }
                }

                candidates = new_candidates;
            }

            // Resolve any placeholder candidates (including root) and collect results
            for cand in candidates.into_iter() {
                let status = if let Some(s) = cand.status {
                    s
                } else {
                    // Try to resolve the path to a real FileStatus
                    match self.get_file_info(&cand.path).await {
                        Ok(s) => s,
                        Err(HdfsError::FileNotFound(_)) => continue,
                        Err(e) => return Err(e),
                    }
                };

                results.push(status);
            }
        }

        Ok(results)
    }
}

impl Default for Client {
    /// Creates a new HDFS Client based on the fs.defaultFS setting. Panics if the config files fail to load,
    /// no defaultFS is defined, or the defaultFS is invalid.
    fn default() -> Self {
        ClientBuilder::new()
            .build()
            .expect("Failed to create default client")
    }
}

pub(crate) struct DirListingIterator {
    path: String,
    resolved_path: String,
    link: MountLink,
    files_only: bool,
    partial_listing: VecDeque<HdfsFileStatusProto>,
    remaining: u32,
    last_seen: Vec<u8>,
}

impl DirListingIterator {
    fn new(path: String, mount_table: &Arc<MountTable>, files_only: bool) -> Self {
        let (link, resolved_path) = mount_table.resolve(&path);

        DirListingIterator {
            path,
            resolved_path,
            link: link.clone(),
            files_only,
            partial_listing: VecDeque::new(),
            remaining: 1,
            last_seen: Vec::new(),
        }
    }

    async fn get_next_batch(&mut self) -> Result<bool> {
        let listing = self
            .link
            .protocol
            .get_listing(&self.resolved_path, self.last_seen.clone(), false)
            .await?;

        if let Some(dir_list) = listing.dir_list {
            self.last_seen = dir_list
                .partial_listing
                .last()
                .map(|p| p.path.clone())
                .unwrap_or(Vec::new());

            self.remaining = dir_list.remaining_entries;

            self.partial_listing = dir_list
                .partial_listing
                .into_iter()
                .filter(|s| !self.files_only || s.file_type() != FileType::IsDir)
                .collect();
            Ok(!self.partial_listing.is_empty())
        } else {
            Err(HdfsError::FileNotFound(self.path.clone()))
        }
    }

    pub async fn next(&mut self) -> Option<Result<FileStatus>> {
        if self.partial_listing.is_empty()
            && self.remaining > 0
            && let Err(error) = self.get_next_batch().await
        {
            self.remaining = 0;
            return Some(Err(error));
        }
        if let Some(next) = self.partial_listing.pop_front() {
            Some(Ok(FileStatus::from(next, &self.path)))
        } else {
            None
        }
    }
}

pub struct ListStatusIterator {
    mount_table: Arc<MountTable>,
    recursive: bool,
    iters: Arc<tokio::sync::Mutex<Vec<DirListingIterator>>>,
}

impl ListStatusIterator {
    fn new(path: String, mount_table: Arc<MountTable>, recursive: bool) -> Self {
        let initial = DirListingIterator::new(path.clone(), &mount_table, false);

        ListStatusIterator {
            mount_table,
            recursive,
            iters: Arc::new(tokio::sync::Mutex::new(vec![initial])),
        }
    }

    pub async fn next(&self) -> Option<Result<FileStatus>> {
        let mut next_file: Option<Result<FileStatus>> = None;
        let mut iters = self.iters.lock().await;
        while next_file.is_none() {
            if let Some(iter) = iters.last_mut() {
                if let Some(file_result) = iter.next().await {
                    if let Ok(file) = file_result {
                        // Return the directory as the next result, but start traversing into that directory
                        // next if we're doing a recursive listing
                        if file.isdir && self.recursive {
                            iters.push(DirListingIterator::new(
                                file.path.clone(),
                                &self.mount_table,
                                false,
                            ))
                        }
                        next_file = Some(Ok(file));
                    } else {
                        // Error, return that as the next element
                        next_file = Some(file_result)
                    }
                } else {
                    // We've exhausted this directory
                    iters.pop();
                }
            } else {
                // There's nothing left, just return None
                break;
            }
        }

        next_file
    }

    pub fn into_stream(self) -> BoxStream<'static, Result<FileStatus>> {
        let listing = stream::unfold(self, |state| async move {
            let next = state.next().await;
            next.map(|n| (n, state))
        });
        Box::pin(listing)
    }
}

#[derive(Debug, Clone)]
pub struct FileStatus {
    pub path: String,
    pub length: usize,
    pub isdir: bool,
    pub permission: u16,
    pub owner: String,
    pub group: String,
    pub modification_time: u64,
    pub access_time: u64,
    pub replication: Option<u32>,
    pub blocksize: Option<u64>,
}

impl FileStatus {
    fn from(value: HdfsFileStatusProto, base_path: &str) -> Self {
        let mut path = base_path.trim_end_matches("/").to_string();
        let relative_path = std::str::from_utf8(&value.path).unwrap();
        if !relative_path.is_empty() {
            path.push('/');
            path.push_str(relative_path);
        }

        // Root path should be a slash
        if path.is_empty() {
            path.push('/');
        }

        FileStatus {
            isdir: value.file_type() == FileType::IsDir,
            path,
            length: value.length as usize,
            permission: value.permission.perm as u16,
            owner: value.owner,
            group: value.group,
            modification_time: value.modification_time,
            access_time: value.access_time,
            replication: value.block_replication,
            blocksize: value.blocksize,
        }
    }
}

#[derive(Debug)]
pub struct ContentSummary {
    pub length: u64,
    pub file_count: u64,
    pub directory_count: u64,
    pub quota: u64,
    pub space_consumed: u64,
    pub space_quota: u64,
}

impl From<ContentSummaryProto> for ContentSummary {
    fn from(value: ContentSummaryProto) -> Self {
        ContentSummary {
            length: value.length,
            file_count: value.file_count,
            directory_count: value.directory_count,
            quota: value.quota,
            space_consumed: value.space_consumed,
            space_quota: value.space_quota,
        }
    }
}

#[cfg(test)]
mod test {
    use std::sync::{Arc, LazyLock};

    use tokio::runtime::Runtime;
    use url::Url;

    use crate::{
        client::ClientBuilder,
        common::config::Configuration,
        hdfs::{protocol::NamenodeProtocol, proxy::NameServiceProxy},
    };

    use super::{MountLink, MountTable};

    static RT: LazyLock<Runtime> = LazyLock::new(|| Runtime::new().unwrap());

    fn create_protocol(url: &str) -> Arc<NamenodeProtocol> {
        let proxy = NameServiceProxy::new(
            &Url::parse(url).unwrap(),
            Arc::new(Configuration::new(None, None).unwrap()),
            RT.handle().clone(),
            None,
            None,
        )
        .unwrap();
        Arc::new(NamenodeProtocol::new(proxy, RT.handle().clone()))
    }

    #[test]
    fn test_default_fs() {
        assert!(
            ClientBuilder::new()
                .with_config(vec![("fs.defaultFS", "hdfs://test:9000")])
                .build()
                .is_ok()
        );

        assert!(
            ClientBuilder::new()
                .with_config(vec![("fs.defaultFS", "hdfs://")])
                .build()
                .is_err()
        );

        assert!(
            ClientBuilder::new()
                .with_url("hdfs://")
                .with_config(vec![("fs.defaultFS", "hdfs://test:9000")])
                .build()
                .is_ok()
        );

        assert!(
            ClientBuilder::new()
                .with_url("hdfs://")
                .with_config(vec![("fs.defaultFS", "hdfs://")])
                .build()
                .is_err()
        );

        assert!(
            ClientBuilder::new()
                .with_url("hdfs://")
                .with_config(vec![("fs.defaultFS", "viewfs://test")])
                .build()
                .is_err()
        );
    }

    #[test]
    fn test_mount_link_resolve() {
        let protocol = create_protocol("hdfs://127.0.0.1:9000");
        let link = MountLink::new("/view", "/hdfs", protocol);

        assert_eq!(link.resolve("/view/dir/file").unwrap(), "/hdfs/dir/file");
        assert_eq!(link.resolve("/view").unwrap(), "/hdfs");
        assert!(link.resolve("/hdfs/path").is_none());
    }

    #[test]
    fn test_fallback_link() {
        let protocol = create_protocol("hdfs://127.0.0.1:9000");
        let link = MountLink::new("", "/hdfs", Arc::clone(&protocol));

        assert_eq!(link.resolve("/path/to/file").unwrap(), "/hdfs/path/to/file");
        assert_eq!(link.resolve("/").unwrap(), "/hdfs/");
        assert_eq!(link.resolve("/hdfs/path").unwrap(), "/hdfs/hdfs/path");

        let link = MountLink::new("", "", protocol);
        assert_eq!(link.resolve("/").unwrap(), "/");
    }

    #[test]
    fn test_mount_table_resolve() {
        let link1 = MountLink::new(
            "/mount1",
            "/path1/nested",
            create_protocol("hdfs://127.0.0.1:9000"),
        );
        let link2 = MountLink::new(
            "/mount2",
            "/path2",
            create_protocol("hdfs://127.0.0.1:9001"),
        );
        let link3 = MountLink::new(
            "/mount3/nested",
            "/path3",
            create_protocol("hdfs://127.0.0.1:9002"),
        );
        let fallback = MountLink::new("/", "/path4", create_protocol("hdfs://127.0.0.1:9003"));

        let mount_table = MountTable {
            mounts: vec![link1, link2, link3],
            fallback,
            home_dir: "/user/test".to_string(),
        };

        // Exact mount path resolves to the exact HDFS path
        let (link, resolved) = mount_table.resolve("/mount1");
        assert_eq!(link.viewfs_path, "/mount1");
        assert_eq!(resolved, "/path1/nested");

        // Trailing slash is treated the same
        let (link, resolved) = mount_table.resolve("/mount1/");
        assert_eq!(link.viewfs_path, "/mount1");
        assert_eq!(resolved, "/path1/nested/");

        // Doesn't do partial matches on a directory name
        let (link, resolved) = mount_table.resolve("/mount12");
        assert_eq!(link.viewfs_path, "");
        assert_eq!(resolved, "/path4/mount12");

        let (link, resolved) = mount_table.resolve("/mount3/file");
        assert_eq!(link.viewfs_path, "");
        assert_eq!(resolved, "/path4/mount3/file");

        let (link, resolved) = mount_table.resolve("/mount3/nested/file");
        assert_eq!(link.viewfs_path, "/mount3/nested");
        assert_eq!(resolved, "/path3/file");

        let (link, resolved) = mount_table.resolve("file");
        assert_eq!(link.viewfs_path, "");
        assert_eq!(resolved, "/path4/user/test/file");

        let (link, resolved) = mount_table.resolve("dir/subdir");
        assert_eq!(link.viewfs_path, "");
        assert_eq!(resolved, "/path4/user/test/dir/subdir");

        let mount_table = MountTable {
            mounts: vec![
                MountLink::new(
                    "/mount1",
                    "/path1/nested",
                    create_protocol("hdfs://127.0.0.1:9000"),
                ),
                MountLink::new(
                    "/mount2",
                    "/path2",
                    create_protocol("hdfs://127.0.0.1:9001"),
                ),
            ],
            fallback: MountLink::new("/", "/path4", create_protocol("hdfs://127.0.0.1:9003")),
            home_dir: "/mount1/user".to_string(),
        };

        let (link, resolved) = mount_table.resolve("file");
        assert_eq!(link.viewfs_path, "/mount1");
        assert_eq!(resolved, "/path1/nested/user/file");

        let (link, resolved) = mount_table.resolve("dir/subdir");
        assert_eq!(link.viewfs_path, "/mount1");
        assert_eq!(resolved, "/path1/nested/user/dir/subdir");
    }

    #[test]
    fn test_io_runtime() {
        assert!(
            ClientBuilder::new()
                .with_url("hdfs://127.0.0.1:9000")
                .with_io_runtime(Runtime::new().unwrap())
                .build()
                .is_ok()
        );

        let rt = Runtime::new().unwrap();
        assert!(
            ClientBuilder::new()
                .with_url("hdfs://127.0.0.1:9000")
                .with_io_runtime(rt.handle().clone())
                .build()
                .is_ok()
        );
    }

    #[test]
    fn test_with_user_sets_relative_path_home_dir() {
        let client = ClientBuilder::new()
            .with_url("hdfs://127.0.0.1:9000")
            .with_user("alice")
            .build()
            .unwrap();

        let (_, resolved) = client.mount_table.resolve("file");
        assert_eq!(resolved, "/user/alice/file");
    }

    #[test]
    fn test_kerberos_credentials_set_principal_home_dir() {
        let client = ClientBuilder::new()
            .with_url("hdfs://127.0.0.1:9000")
            .with_config([("hadoop.security.authentication", "kerberos")])
            .with_kerberos_principal("alice@EXAMPLE.COM")
            .with_kerberos_cache("FILE:/run/krb5/alice.ccache")
            .build()
            .unwrap();

        let (_, resolved) = client.mount_table.resolve("file");
        assert_eq!(resolved, "/user/alice/file");
    }

    #[test]
    fn test_explicit_kerberos_credentials_require_principal() {
        let error = ClientBuilder::new()
            .with_url("hdfs://127.0.0.1:9000")
            .with_kerberos_keytab("client.keytab")
            .build()
            .unwrap_err();

        assert!(error.to_string().contains("principal is required"));
    }

    #[test]
    fn test_set_conf_dir() {
        assert!(
            ClientBuilder::new()
                .with_url("hdfs://127.0.0.1:9000")
                .with_config_dir("target/test")
                .build()
                .is_ok()
        )
    }
}