// Copyright 2021 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

use {
    crate::{
        errors::FxfsError,
        object_handle::ObjectHandle,
        object_store::{
            self,
            transaction::{LockKey, Transaction},
        },
        server::{errors::map_to_status, file::FxFile, node::FxNode, volume::FxVolume},
    },
    anyhow::{bail, Error},
    async_trait::async_trait,
    either::{Left, Right},
    fidl::endpoints::ServerEnd,
    fidl_fuchsia_io::{
        self as fio, NodeAttributes, NodeMarker, MODE_TYPE_DIRECTORY, OPEN_FLAG_CREATE,
        OPEN_FLAG_CREATE_IF_ABSENT,
    },
    fuchsia_async as fasync,
    fuchsia_zircon::Status,
    std::{any::Any, sync::Arc},
    vfs::{
        common::send_on_open_with_error,
        directory::{
            connection::{io1::DerivedConnection, util::OpenDirectory},
            dirents_sink::{self, Sink},
            entry::{DirectoryEntry, EntryInfo},
            entry_container::{AsyncGetEntry, Directory, MutableDirectory},
            mutable::connection::io1::MutableConnection,
            traversal_position::TraversalPosition,
        },
        execution_scope::ExecutionScope,
        filesystem::Filesystem,
        path::Path,
    },
};

pub struct FxDirectory {
    volume: Arc<FxVolume>,
    directory: object_store::Directory,
}

impl FxDirectory {
    pub(crate) fn new(volume: Arc<FxVolume>, directory: object_store::Directory) -> Self {
        Self { volume, directory }
    }

    async fn lookup(
        self: &Arc<Self>,
        flags: u32,
        mode: u32,
        mut path: Path,
    ) -> Result<Arc<dyn FxNode>, Error> {
        // TODO(csuter): There are races to fix here where a direectory or file could be removed
        // whilst a lookup is taking place. The transaction locks only protect against multiple
        // writers, but the readers don't have any locks, so there needs to be checks that nodes
        // still exist at some point.
        let fs = self.volume.store().filesystem();
        let mut current_node = self.clone() as Arc<dyn FxNode>;
        while !path.is_empty() {
            let last_segment = path.is_single_component();
            let current_dir =
                current_node.into_any().downcast::<FxDirectory>().map_err(|_| FxfsError::NotDir)?;
            let name = path.next().unwrap();
            // Create the transaction here if we might need to create the object so that we have a
            // lock in place.
            let store = self.volume.store();
            let transaction_or_guard = if last_segment && flags & OPEN_FLAG_CREATE != 0 {
                Left(
                    fs.clone()
                        .new_transaction(&[LockKey::object(
                            store.store_object_id(),
                            current_dir.directory.object_id(),
                        )])
                        .await?,
                )
            } else {
                // When child objects are created, the object is created along with the directory
                // entry in the same transaction, and so we need to hold a read lock over the lookup
                // and open calls.

                // TODO(csuter): I think that this cannot be tested easily at the moment because it
                // would only result in open_or_load_node returning NotFound, which is what we would
                // want to return anyway.  When we add unlink support, we might be able to use this
                // same lock to guard against the race mentioned above.
                Right(
                    fs.read_lock(&[LockKey::object(
                        store.store_object_id(),
                        current_dir.directory.object_id(),
                    )])
                    .await,
                )
            };
            match current_dir.directory.lookup(name).await {
                Ok((object_id, object_descriptor)) => {
                    if last_segment
                        && flags & OPEN_FLAG_CREATE != 0
                        && flags & OPEN_FLAG_CREATE_IF_ABSENT != 0
                    {
                        bail!(FxfsError::AlreadyExists);
                    }
                    current_node =
                        self.volume.open_or_load_node(object_id, object_descriptor).await?;
                }
                Err(e) if FxfsError::NotFound.matches(&e) => {
                    if let Left(transaction) = transaction_or_guard {
                        return self.create_child(transaction, &current_dir, name, mode).await;
                    } else {
                        return Err(e);
                    }
                }
                Err(e) => return Err(e),
            };
        }
        Ok(current_node)
    }

    async fn create_child(
        self: &Arc<Self>,
        mut transaction: Transaction<'_>,
        dir: &Arc<FxDirectory>,
        name: &str,
        mode: u32,
    ) -> Result<Arc<dyn FxNode>, Error> {
        let (object_id, node) = if mode & MODE_TYPE_DIRECTORY != 0 {
            let dir = dir.directory.create_child_dir(&mut transaction, name).await?;
            let object_id = dir.object_id();
            let node = Arc::new(FxDirectory { volume: self.volume.clone(), directory: dir })
                as Arc<dyn FxNode>;
            (object_id, node)
        } else {
            let handle = dir.directory.create_child_file(&mut transaction, name).await?;
            let object_id = handle.object_id();
            let node = Arc::new(FxFile::new(handle)) as Arc<dyn FxNode>;
            (object_id, node)
        };
        self.volume.store().filesystem().commit_transaction(transaction).await;
        self.volume.add_node(object_id, Arc::downgrade(&node)).await;
        Ok(node)
    }
}

impl FxNode for FxDirectory {
    fn object_id(&self) -> u64 {
        self.directory.object_id()
    }
    fn into_any(self: Arc<Self>) -> Arc<dyn Any + Send + Sync + 'static> {
        self
    }
}

#[async_trait]
impl MutableDirectory for FxDirectory {
    async fn link(&self, _name: String, _entry: Arc<dyn DirectoryEntry>) -> Result<(), Status> {
        log::error!("link not implemented");
        Err(Status::NOT_SUPPORTED)
    }

    async fn unlink(&self, _path: Path) -> Result<(), Status> {
        log::error!("unlink not implemented");
        Err(Status::NOT_SUPPORTED)
    }

    async fn set_attrs(&self, _flags: u32, _attrs: NodeAttributes) -> Result<(), Status> {
        log::error!("set_attrs not implemented");
        Err(Status::NOT_SUPPORTED)
    }

    fn get_filesystem(&self) -> &dyn Filesystem {
        &*self.volume
    }

    fn into_any(self: Arc<Self>) -> Arc<dyn Any + Sync + Send> {
        self as Arc<dyn Any + Sync + Send>
    }

    async fn sync(&self) -> Result<(), Status> {
        // TODO(csuter): Support sync on root of fxfs volume.
        Ok(())
    }
}

impl DirectoryEntry for FxDirectory {
    fn open(
        self: Arc<Self>,
        scope: ExecutionScope,
        flags: u32,
        mode: u32,
        path: Path,
        server_end: ServerEnd<NodeMarker>,
    ) {
        let cloned_scope = scope.clone();
        scope.spawn(async move {
            // TODO(jfsulliv): Factor this out into a visitor-pattern style method for FxNode, e.g.
            // FxNode::visit(FileFn, DirFn).
            match self.lookup(flags, mode, path).await {
                Err(e) => send_on_open_with_error(flags, server_end, map_to_status(e)),
                Ok(node) => {
                    if let Ok(dir) = node.clone().into_any().downcast::<FxDirectory>() {
                        MutableConnection::create_connection(
                            cloned_scope,
                            OpenDirectory::new(dir),
                            flags,
                            mode,
                            server_end,
                        );
                    } else if let Ok(file) = node.into_any().downcast::<FxFile>() {
                        file.clone().open(cloned_scope, flags, mode, Path::empty(), server_end);
                    } else {
                        panic!("Unknown node type")
                    }
                }
            };
        });
    }

    fn entry_info(&self) -> EntryInfo {
        EntryInfo::new(fio::INO_UNKNOWN, fio::DIRENT_TYPE_DIRECTORY)
    }

    fn can_hardlink(&self) -> bool {
        false
    }
}

#[async_trait]
impl Directory for FxDirectory {
    fn get_entry(self: Arc<Self>, _name: String) -> AsyncGetEntry {
        // TODO(jfsulliv): Implement
        AsyncGetEntry::Immediate(Err(Status::NOT_FOUND))
    }

    async fn read_dirents<'a>(
        &'a self,
        _pos: &'a TraversalPosition,
        sink: Box<dyn Sink>,
    ) -> Result<(TraversalPosition, Box<dyn dirents_sink::Sealed>), Status> {
        // TODO(jfsulliv): Implement
        Ok((TraversalPosition::End, sink.seal()))
    }

    fn register_watcher(
        self: Arc<Self>,
        _scope: ExecutionScope,
        _mask: u32,
        _channel: fasync::Channel,
    ) -> Result<(), Status> {
        // TODO(jfsulliv): Implement
        Err(Status::NOT_SUPPORTED)
    }

    fn unregister_watcher(self: Arc<Self>, _key: usize) {
        // TODO(jfsulliv): Implement
    }

    async fn get_attrs(&self) -> Result<NodeAttributes, Status> {
        Err(Status::NOT_SUPPORTED)
    }

    fn close(&self) -> Result<(), Status> {
        // TODO(jfsulliv): Implement
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use {
        crate::{
            object_store::{filesystem::SyncOptions, FxFilesystem},
            server::{
                testing::{open_dir_validating, open_file, open_file_validating},
                volume::FxVolumeAndRoot,
            },
            testing::fake_device::FakeDevice,
            volume::root_volume,
        },
        anyhow::Error,
        fidl::endpoints::ServerEnd,
        fidl_fuchsia_io::{
            DirectoryMarker, MODE_TYPE_DIRECTORY, MODE_TYPE_FILE, OPEN_FLAG_CREATE,
            OPEN_FLAG_CREATE_IF_ABSENT, OPEN_FLAG_DIRECTORY, OPEN_RIGHT_READABLE,
            OPEN_RIGHT_WRITABLE,
        },
        fuchsia_async as fasync,
        fuchsia_zircon::Status,
        matches::assert_matches,
        std::sync::Arc,
        vfs::{directory::entry::DirectoryEntry, execution_scope::ExecutionScope, path::Path},
    };

    #[fasync::run_singlethreaded(test)]
    async fn test_lifecycle() -> Result<(), Error> {
        let device = Arc::new(FakeDevice::new(2048, 512));
        let filesystem = FxFilesystem::new_empty(device.clone()).await?;
        let root_volume = root_volume(&filesystem).await?;
        let vol = FxVolumeAndRoot::new(root_volume.new_volume("vol").await?).await;
        {
            let (dir_proxy, dir_server_end) = fidl::endpoints::create_proxy::<DirectoryMarker>()
                .expect("Create proxy to succeed");

            vol.root().clone().open(
                ExecutionScope::new(),
                OPEN_FLAG_DIRECTORY | OPEN_RIGHT_READABLE | OPEN_RIGHT_WRITABLE,
                MODE_TYPE_DIRECTORY,
                Path::empty(),
                ServerEnd::new(dir_server_end.into_channel()),
            );

            open_dir_validating(
                &dir_proxy,
                OPEN_FLAG_CREATE | OPEN_RIGHT_READABLE,
                MODE_TYPE_DIRECTORY,
                "foo",
            )
            .await
            .expect("Create dir failed");

            open_file_validating(
                &dir_proxy,
                OPEN_FLAG_CREATE | OPEN_RIGHT_READABLE,
                MODE_TYPE_FILE,
                "bar",
            )
            .await
            .expect("Create file failed");

            dir_proxy.close().await?;
        }

        // Ensure that there's no remaining references to |vol|, which would indicate a reference
        // cycle or other leak.
        Arc::try_unwrap(vol.into_volume()).map_err(|_| "References to vol still exist").unwrap();

        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn test_open_root_dir() -> Result<(), Error> {
        let device = Arc::new(FakeDevice::new(2048, 512));
        let filesystem = FxFilesystem::new_empty(device.clone()).await?;
        let root_volume = root_volume(&filesystem).await?;
        let vol = FxVolumeAndRoot::new(root_volume.new_volume("vol").await?).await;
        let dir = vol.root().clone();

        let (dir_proxy, dir_server_end) =
            fidl::endpoints::create_proxy::<DirectoryMarker>().expect("Create proxy to succeed");

        dir.open(
            ExecutionScope::new(),
            OPEN_FLAG_DIRECTORY | OPEN_RIGHT_READABLE,
            MODE_TYPE_DIRECTORY,
            Path::empty(),
            ServerEnd::new(dir_server_end.into_channel()),
        );

        dir_proxy.describe().await.expect("Describe to succeed");

        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn test_create_dir_persists() -> Result<(), Error> {
        let device = Arc::new(FakeDevice::new(2048, 512));
        for i in 0..2 {
            let (filesystem, vol) = if i == 0 {
                let filesystem = FxFilesystem::new_empty(device.clone()).await?;
                let root_volume = root_volume(&filesystem).await?;
                let vol = FxVolumeAndRoot::new(root_volume.new_volume("vol").await?).await;
                (filesystem, vol)
            } else {
                let filesystem = FxFilesystem::open(device.clone()).await?;
                let root_volume = root_volume(&filesystem).await?;
                let vol = FxVolumeAndRoot::new(root_volume.volume("vol").await?).await;
                (filesystem, vol)
            };
            let dir = vol.root().clone();
            let (dir_proxy, dir_server_end) = fidl::endpoints::create_proxy::<DirectoryMarker>()
                .expect("Create proxy to succeed");

            dir.open(
                ExecutionScope::new(),
                OPEN_FLAG_DIRECTORY | OPEN_RIGHT_READABLE | OPEN_RIGHT_WRITABLE,
                MODE_TYPE_DIRECTORY,
                Path::empty(),
                ServerEnd::new(dir_server_end.into_channel()),
            );

            let flags =
                if i == 0 { OPEN_FLAG_CREATE | OPEN_RIGHT_READABLE } else { OPEN_RIGHT_READABLE };
            open_dir_validating(&dir_proxy, flags, MODE_TYPE_DIRECTORY, "foo")
                .await
                .expect(&format!("Open dir iter {} failed", i));

            filesystem.sync(SyncOptions::default()).await?;
        }

        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn test_open_nonexistent_file() -> Result<(), Error> {
        let device = Arc::new(FakeDevice::new(2048, 512));
        let filesystem = FxFilesystem::new_empty(device.clone()).await?;
        let root_volume = root_volume(&filesystem).await?;
        let vol = FxVolumeAndRoot::new(root_volume.new_volume("vol").await?).await;
        let dir = vol.root().clone();

        let (dir_proxy, dir_server_end) =
            fidl::endpoints::create_proxy::<DirectoryMarker>().expect("Create proxy to succeed");

        dir.open(
            ExecutionScope::new(),
            OPEN_FLAG_DIRECTORY | OPEN_RIGHT_READABLE,
            MODE_TYPE_DIRECTORY,
            Path::empty(),
            ServerEnd::new(dir_server_end.into_channel()),
        );

        let child_proxy = open_file(&dir_proxy, OPEN_RIGHT_READABLE, MODE_TYPE_FILE, "foo")
            .expect("Create proxy failed");

        // The channel also be closed with a NOT_FOUND epitaph.
        assert_matches!(
            child_proxy.describe().await,
            Err(fidl::Error::ClientChannelClosed {
                status: Status::NOT_FOUND,
                service_name: "(anonymous) File",
            })
        );

        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn test_create_file() -> Result<(), Error> {
        let device = Arc::new(FakeDevice::new(2048, 512));
        let filesystem = FxFilesystem::new_empty(device.clone()).await?;
        let root_volume = root_volume(&filesystem).await?;
        let vol = FxVolumeAndRoot::new(root_volume.new_volume("vol").await?).await;
        let dir = vol.root().clone();

        let (dir_proxy, dir_server_end) =
            fidl::endpoints::create_proxy::<DirectoryMarker>().expect("Create proxy to succeed");

        dir.open(
            ExecutionScope::new(),
            OPEN_FLAG_DIRECTORY | OPEN_RIGHT_READABLE | OPEN_RIGHT_WRITABLE,
            MODE_TYPE_DIRECTORY,
            Path::empty(),
            ServerEnd::new(dir_server_end.into_channel()),
        );

        open_file_validating(
            &dir_proxy,
            OPEN_FLAG_CREATE | OPEN_RIGHT_READABLE,
            MODE_TYPE_FILE,
            "foo",
        )
        .await
        .expect("Create file failed");

        open_file_validating(&dir_proxy, OPEN_RIGHT_READABLE, MODE_TYPE_FILE, "foo")
            .await
            .expect("Open file failed");

        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn test_create_dir_nested() -> Result<(), Error> {
        let device = Arc::new(FakeDevice::new(2048, 512));
        let filesystem = FxFilesystem::new_empty(device.clone()).await?;
        let root_volume = root_volume(&filesystem).await?;
        let vol = FxVolumeAndRoot::new(root_volume.new_volume("vol").await?).await;
        let dir = vol.root().clone();

        let (dir_proxy, dir_server_end) =
            fidl::endpoints::create_proxy::<DirectoryMarker>().expect("Create proxy to succeed");

        dir.open(
            ExecutionScope::new(),
            OPEN_FLAG_DIRECTORY | OPEN_RIGHT_READABLE | OPEN_RIGHT_WRITABLE,
            MODE_TYPE_DIRECTORY,
            Path::empty(),
            ServerEnd::new(dir_server_end.into_channel()),
        );

        let subdir_proxy = open_dir_validating(
            &dir_proxy,
            OPEN_FLAG_CREATE | OPEN_RIGHT_READABLE | OPEN_RIGHT_WRITABLE,
            MODE_TYPE_DIRECTORY,
            "foo",
        )
        .await
        .expect("Create dir failed");

        open_dir_validating(
            &subdir_proxy,
            OPEN_FLAG_CREATE | OPEN_RIGHT_READABLE,
            MODE_TYPE_DIRECTORY,
            "bar",
        )
        .await
        .expect("Create nested dir failed");

        // Also make sure we can follow the path.
        open_dir_validating(&dir_proxy, OPEN_RIGHT_READABLE, MODE_TYPE_DIRECTORY, "foo/bar")
            .await
            .expect("Open nested dir failed");

        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn test_strict_create_file_fails_if_present() -> Result<(), Error> {
        let device = Arc::new(FakeDevice::new(2048, 512));
        let filesystem = FxFilesystem::new_empty(device.clone()).await?;
        let root_volume = root_volume(&filesystem).await?;
        let vol = FxVolumeAndRoot::new(root_volume.new_volume("vol").await?).await;
        let dir = vol.root().clone();

        let (dir_proxy, dir_server_end) =
            fidl::endpoints::create_proxy::<DirectoryMarker>().expect("Create proxy to succeed");

        dir.open(
            ExecutionScope::new(),
            OPEN_FLAG_DIRECTORY | OPEN_RIGHT_READABLE | OPEN_RIGHT_WRITABLE,
            MODE_TYPE_DIRECTORY,
            Path::empty(),
            ServerEnd::new(dir_server_end.into_channel()),
        );

        open_file_validating(
            &dir_proxy,
            OPEN_FLAG_CREATE | OPEN_FLAG_CREATE_IF_ABSENT | OPEN_RIGHT_READABLE,
            MODE_TYPE_FILE,
            "foo",
        )
        .await
        .expect("Create file failed");

        let file_proxy = open_file(
            &dir_proxy,
            OPEN_FLAG_CREATE | OPEN_FLAG_CREATE_IF_ABSENT | OPEN_RIGHT_READABLE,
            MODE_TYPE_FILE,
            "foo",
        )
        .expect("Open proxy failed");

        assert_matches!(
            file_proxy.describe().await,
            Err(fidl::Error::ClientChannelClosed {
                status: Status::ALREADY_EXISTS,
                service_name: "(anonymous) File",
            })
        );

        Ok(())
    }
}