use crate::changelog::Changelog;

use crate::config::{Config, ConfigError, ConfigParseError};

use crate::dirstate::DirstateParents;

use crate::dirstate_tree::on_disk::Docket as DirstateDocket;

use crate::dirstate_tree::owning::OwningDirstateMap;

use crate::errors::HgResultExt;

use crate::errors::{HgError, IoResultExt};

use crate::lock::{try_with_lock_no_wait, LockError};

use crate::manifest::{Manifest, Manifestlog};

use crate::revlog::filelog::Filelog;

use crate::revlog::revlog::RevlogError;

use crate::utils::files::get_path_from_bytes;

use crate::utils::hg_path::HgPath;

use crate::utils::SliceExt;

use crate::vfs::{is_dir, is_file, Vfs};

use crate::{requirements, NodePrefix};

use crate::{DirstateError, Revision};

use std::cell::{Ref, RefCell, RefMut};

use std::collections::HashSet;

use std::io::Seek;

use std::io::SeekFrom;

use std::io::Write as IoWrite;

use std::path::{Path, PathBuf};

/// A repository on disk

pub struct Repo {

    working_directory: PathBuf,

    dot_hg: PathBuf,

    store: PathBuf,

    requirements: HashSet<String>,

    config: Config,

    dirstate_parents: LazyCell<DirstateParents>,

    dirstate_data_file_uuid: LazyCell<Option<Vec<u8>>>,

    dirstate_map: LazyCell<OwningDirstateMap>,

    changelog: LazyCell<Changelog>,

    manifestlog: LazyCell<Manifestlog>,

}

#[derive(Debug, derive_more::From)]

pub enum RepoError {

    NotFound {

        at: PathBuf,

    },

    #[from]

    ConfigParseError(ConfigParseError),

    #[from]

    Other(HgError),

}

impl From<ConfigError> for RepoError {

    fn from(error: ConfigError) -> Self {

        match error {

            ConfigError::Parse(error) => error.into(),

            ConfigError::Other(error) => error.into(),

        }

    }

}

impl Repo {

    /// tries to find nearest repository root in current working directory or

    /// its ancestors

    pub fn find_repo_root() -> Result<PathBuf, RepoError> {

        let current_directory = crate::utils::current_dir()?;

        // ancestors() is inclusive: it first yields `current_directory`

        // as-is.

        for ancestor in current_directory.ancestors() {

            if is_dir(ancestor.join(".hg"))? {

                return Ok(ancestor.to_path_buf());

            }

        }

            at: current_directory,

    }

    /// Find a repository, either at the given path (which must contain a `.hg`

    /// sub-directory) or by searching the current directory and its

    /// ancestors.

    ///

    /// A method with two very different "modes" like this usually a code smell

    /// to make two methods instead, but in this case an `Option` is what rhg

    /// sub-commands get from Clap for the `-R` / `--repository` CLI argument.

    /// Having two methods would just move that `if` to almost all callers.

    pub fn find(

        config: &Config,

        explicit_path: Option<PathBuf>,

    ) -> Result<Self, RepoError> {

        if let Some(root) = explicit_path {

            if is_dir(root.join(".hg"))? {

            } else if is_file(&root)? {

                Err(HgError::unsupported("bundle repository").into())

            } else {

            }

        } else {

            let root = Self::find_repo_root()?;

            Self::new_at_path(root, config)

        }

    }

    /// To be called after checking that `.hg` is a sub-directory

    fn new_at_path(

        working_directory: PathBuf,

        config: &Config,

    ) -> Result<Self, RepoError> {

        let dot_hg = working_directory.join(".hg");

        let hg_vfs = Vfs { base: &dot_hg };

        let mut reqs = requirements::load_if_exists(hg_vfs)?;

        let relative =

            reqs.contains(requirements::RELATIVE_SHARED_REQUIREMENT);

        let shared =

            reqs.contains(requirements::SHARED_REQUIREMENT) || relative;

        // From `mercurial/localrepo.py`:

        //

        // if .hg/requires contains the sharesafe requirement, it means

        // there exists a `.hg/store/requires` too and we should read it

        // NOTE: presence of SHARESAFE_REQUIREMENT imply that store requirement

        // is present. We never write SHARESAFE_REQUIREMENT for a repo if store

        // is not present, refer checkrequirementscompat() for that

        //

        // However, if SHARESAFE_REQUIREMENT is not present, it means that the

        // repository was shared the old way. We check the share source

        // .hg/requires for SHARESAFE_REQUIREMENT to detect whether the

        // current repository needs to be reshared

        let share_safe = reqs.contains(requirements::SHARESAFE_REQUIREMENT);

        let store_path;

        if !shared {

            store_path = dot_hg.join("store");

        } else {

            let bytes = hg_vfs.read("sharedpath")?;

            let mut shared_path =

                get_path_from_bytes(bytes.trim_end_matches(|b| b == b'\n'))

                    .to_owned();

            if relative {

                shared_path = dot_hg.join(shared_path)

            }

            if !is_dir(&shared_path)? {

                return Err(HgError::corrupted(format!(

                    ".hg/sharedpath points to nonexistent directory {}",

                    shared_path.display()

                ))

                .into());

            }

            store_path = shared_path.join("store");

            let source_is_share_safe =

                requirements::load(Vfs { base: &shared_path })?

                    .contains(requirements::SHARESAFE_REQUIREMENT);

            if share_safe != source_is_share_safe {

                return Err(HgError::unsupported("share-safe mismatch").into());

            }

            if share_safe {

                repo_config_files.insert(0, shared_path.join("hgrc"))

            }

        }

        if share_safe {

            reqs.extend(requirements::load(Vfs { base: &store_path })?);

        }

        let repo_config = if std::env::var_os("HGRCSKIPREPO").is_none() {

            config.combine_with_repo(&repo_config_files)?

        } else {

            config.clone()

        };

        let repo = Self {

            requirements: reqs,

            working_directory,

            store: store_path,

            dot_hg,

            config: repo_config,

            dirstate_parents: LazyCell::new(),

            dirstate_data_file_uuid: LazyCell::new(),

            dirstate_map: LazyCell::new(),

            changelog: LazyCell::new(),

            manifestlog: LazyCell::new(),

        };

        requirements::check(&repo)?;

        Ok(repo)

    }

    pub fn working_directory_path(&self) -> &Path {

        &self.working_directory

    }

    pub fn requirements(&self) -> &HashSet<String> {

        &self.requirements

    }

    pub fn config(&self) -> &Config {

        &self.config

    }

    /// For accessing repository files (in `.hg`), except for the store

    /// (`.hg/store`).

    pub fn hg_vfs(&self) -> Vfs<'_> {

        Vfs { base: &self.dot_hg }

    }

    /// For accessing repository store files (in `.hg/store`)

    pub fn store_vfs(&self) -> Vfs<'_> {

        Vfs { base: &self.store }

    }

    /// For accessing the working copy

    pub fn working_directory_vfs(&self) -> Vfs<'_> {

        Vfs {

            base: &self.working_directory,

        }

    }

    pub fn try_with_wlock_no_wait<R>(

        &self,

        f: impl FnOnce() -> R,

    ) -> Result<R, LockError> {

        try_with_lock_no_wait(self.hg_vfs(), "wlock", f)

    }

    pub fn has_dirstate_v2(&self) -> bool {

        self.requirements

            .contains(requirements::DIRSTATE_V2_REQUIREMENT)

    }

    pub fn has_sparse(&self) -> bool {

        self.requirements.contains(requirements::SPARSE_REQUIREMENT)

    }

    pub fn has_narrow(&self) -> bool {

        self.requirements.contains(requirements::NARROW_REQUIREMENT)

    }

    pub fn has_nodemap(&self) -> bool {

        self.requirements

            .contains(requirements::NODEMAP_REQUIREMENT)

    }

    fn dirstate_file_contents(&self) -> Result<Vec<u8>, HgError> {

        Ok(self

            .hg_vfs()

            .read("dirstate")

            .io_not_found_as_none()?

    }

    pub fn dirstate_parents(&self) -> Result<DirstateParents, HgError> {

        Ok(*self

            .dirstate_parents

            .get_or_init(|| self.read_dirstate_parents())?)

    }

    fn read_dirstate_parents(&self) -> Result<DirstateParents, HgError> {

        let dirstate = self.dirstate_file_contents()?;

        let parents = if dirstate.is_empty() {

            if self.has_dirstate_v2() {

                self.dirstate_data_file_uuid.set(None);

            }

            DirstateParents::NULL

        } else if self.has_dirstate_v2() {

            let docket =

                crate::dirstate_tree::on_disk::read_docket(&dirstate)?;

            self.dirstate_data_file_uuid

                .set(Some(docket.uuid.to_owned()));

            docket.parents()

        } else {

        };

        self.dirstate_parents.set(parents);

        Ok(parents)

    }

    fn read_dirstate_data_file_uuid(

        &self,

    ) -> Result<Option<Vec<u8>>, HgError> {

        assert!(

            self.has_dirstate_v2(),

            "accessing dirstate data file ID without dirstate-v2"

        );

        let dirstate = self.dirstate_file_contents()?;

        if dirstate.is_empty() {

            self.dirstate_parents.set(DirstateParents::NULL);

            Ok(None)

        } else {

            let docket =

                crate::dirstate_tree::on_disk::read_docket(&dirstate)?;

            self.dirstate_parents.set(docket.parents());

            Ok(Some(docket.uuid.to_owned()))

        }

    }

    fn new_dirstate_map(&self) -> Result<OwningDirstateMap, DirstateError> {

        let dirstate_file_contents = self.dirstate_file_contents()?;

        if dirstate_file_contents.is_empty() {

            self.dirstate_parents.set(DirstateParents::NULL);

            if self.has_dirstate_v2() {

                self.dirstate_data_file_uuid.set(None);

            }

            Ok(OwningDirstateMap::new_empty(Vec::new()))

        } else if self.has_dirstate_v2() {

            let docket = crate::dirstate_tree::on_disk::read_docket(

                &dirstate_file_contents,

            )?;

            self.dirstate_parents.set(docket.parents());

            self.dirstate_data_file_uuid

                .set(Some(docket.uuid.to_owned()));

            let data_size = docket.data_size();

            let metadata = docket.tree_metadata();

            if let Some(data_mmap) = self

                .hg_vfs()

                .mmap_open(docket.data_filename())

                .io_not_found_as_none()?

            {

                OwningDirstateMap::new_v2(data_mmap, data_size, metadata)

            } else {

                OwningDirstateMap::new_v2(Vec::new(), data_size, metadata)

            }

        } else {

            let (map, parents) =

                OwningDirstateMap::new_v1(dirstate_file_contents)?;

            self.dirstate_parents.set(parents);

            Ok(map)

        }

    }

    pub fn dirstate_map(

        &self,

    ) -> Result<Ref<OwningDirstateMap>, DirstateError> {

        self.dirstate_map.get_or_init(|| self.new_dirstate_map())

    }

    pub fn dirstate_map_mut(

        &self,

    ) -> Result<RefMut<OwningDirstateMap>, DirstateError> {

        self.dirstate_map

            .get_mut_or_init(|| self.new_dirstate_map())

    }

    fn new_changelog(&self) -> Result<Changelog, HgError> {

        Changelog::open(&self.store_vfs(), self.has_nodemap())

    }

    pub fn changelog(&self) -> Result<Ref<Changelog>, HgError> {

        self.changelog.get_or_init(|| self.new_changelog())

    }

    pub fn changelog_mut(&self) -> Result<RefMut<Changelog>, HgError> {

        self.changelog.get_mut_or_init(|| self.new_changelog())

    }

    fn new_manifestlog(&self) -> Result<Manifestlog, HgError> {

        Manifestlog::open(&self.store_vfs(), self.has_nodemap())

    }

    pub fn manifestlog(&self) -> Result<Ref<Manifestlog>, HgError> {

        self.manifestlog.get_or_init(|| self.new_manifestlog())

    }

    pub fn manifestlog_mut(&self) -> Result<RefMut<Manifestlog>, HgError> {

        self.manifestlog.get_mut_or_init(|| self.new_manifestlog())

    }

    /// Returns the manifest of the *changeset* with the given node ID

    pub fn manifest_for_node(

        &self,

        node: impl Into<NodePrefix>,

    ) -> Result<Manifest, RevlogError> {

        self.manifestlog()?.data_for_node(

            self.changelog()?

                .data_for_node(node.into())?

                .manifest_node()?

                .into(),

        )

    }

    /// Returns the manifest of the *changeset* with the given revision number

    pub fn manifest_for_rev(

        &self,

        revision: Revision,

    ) -> Result<Manifest, RevlogError> {

        self.manifestlog()?.data_for_node(

            self.changelog()?

                .data_for_rev(revision)?

                .manifest_node()?

                .into(),

        )

    }

    pub fn has_subrepos(&self) -> Result<bool, DirstateError> {

        if let Some(entry) = self.dirstate_map()?.get(HgPath::new(".hgsub"))? {

            Ok(entry.tracked())

        } else {

            Ok(false)

        }

    }

    pub fn filelog(&self, path: &HgPath) -> Result<Filelog, HgError> {

        Filelog::open(self, path)

    }

    /// Write to disk any updates that were made through `dirstate_map_mut`.

    ///

    /// The "wlock" must be held while calling this.

    /// See for example `try_with_wlock_no_wait`.

    ///

    /// TODO: have a `WritableRepo` type only accessible while holding the

    /// lock?

    pub fn write_dirstate(&self) -> Result<(), DirstateError> {

        let map = self.dirstate_map()?;

        // TODO: Maintain a `DirstateMap::dirty` flag, and return early here if

        // it’s unset

        let parents = self.dirstate_parents()?;

        let (packed_dirstate, old_uuid_to_remove) = if self.has_dirstate_v2() {

            let uuid_opt = self

                .dirstate_data_file_uuid

                .get_or_init(|| self.read_dirstate_data_file_uuid())?;

            let uuid_opt = uuid_opt.as_ref();

            let can_append = uuid_opt.is_some();

            let (data, tree_metadata, append, old_data_size) =

                map.pack_v2(can_append)?;

            // Reuse the uuid, or generate a new one, keeping the old for

            // deletion.

            let (uuid, old_uuid) = match uuid_opt {

                Some(uuid) => {

                    let as_str = std::str::from_utf8(uuid)

                        .map_err(|_| {

                            HgError::corrupted(

                                "non-UTF-8 dirstate data file ID",

                            )

                        })?

                        .to_owned();

                    if append {

                        (as_str, None)

                    } else {

                        (DirstateDocket::new_uid(), Some(as_str))

                    }

                }

                None => (DirstateDocket::new_uid(), None),

            };

            let data_filename = format!("dirstate.{}", uuid);

            let data_filename = self.hg_vfs().join(data_filename);

            let mut options = std::fs::OpenOptions::new();

            options.write(true);

            // Why are we not using the O_APPEND flag when appending?

            //

            // - O_APPEND makes it trickier to deal with garbage at the end of

            //   the file, left by a previous uncommitted transaction. By

            //   starting the write at [old_data_size] we make sure we erase

            //   all such garbage.

            //

            // - O_APPEND requires to special-case 0-byte writes, whereas we

            //   don't need that.

            //

            // - Some OSes have bugs in implementation O_APPEND:

            //   revlog.py talks about a Solaris bug, but we also saw some ZFS

            //   bug: https://github.com/openzfs/zfs/pull/3124,

            //   https://github.com/openzfs/zfs/issues/13370

            //

            if !append {

                options.create_new(true);

            }

            let data_size = (|| {

                // TODO: loop and try another random ID if !append and this

                // returns `ErrorKind::AlreadyExists`? Collision chance of two

                // random IDs is one in 2**32

                let mut file = options.open(&data_filename)?;

                if append {

                    file.seek(SeekFrom::Start(old_data_size as u64))?;

                }

                file.write_all(&data)?;

                file.flush()?;