use std::path::PathBuf;

pub use gix_worktree::*;

use crate::{
    bstr::{BStr, BString},
    Repository,
};

pub(crate) type IndexStorage = gix_features::threading::OwnShared<gix_fs::SharedFileSnapshotMut<gix_index::File>>;
/// A lazily loaded and auto-updated worktree index.
pub type Index = gix_fs::SharedFileSnapshot<gix_index::File>;

/// A stand-in to a worktree as result of a worktree iteration.
///
/// It provides access to typical worktree state, but may not actually point to a valid checkout as the latter has been moved or
/// deleted.
#[derive(Debug, Clone)]
pub struct Proxy<'repo> {
    pub(crate) parent: &'repo Repository,
    pub(crate) git_dir: PathBuf,
}

/// Access
impl<'repo> crate::Worktree<'repo> {
    /// Read the location of the checkout, the base of the work tree
    pub fn base(&self) -> &'repo std::path::Path {
        self.path
    }

    /// Return true if this worktree is the main worktree associated with a non-bare git repository.
    ///
    /// It cannot be removed.
    pub fn is_main(&self) -> bool {
        self.id().is_none()
    }

    /// Return true if this worktree cannot be pruned, moved or deleted, which is useful if it is located on an external storage device.
    ///
    /// Always false for the main worktree.
    pub fn is_locked(&self) -> bool {
        Proxy::new(self.parent, self.parent.git_dir()).is_locked()
    }

    /// Provide a reason for the locking of this worktree, if it is locked at all.
    ///
    /// Note that we squelch errors in case the file cannot be read in which case the
    /// reason is an empty string.
    pub fn lock_reason(&self) -> Option<BString> {
        Proxy::new(self.parent, self.parent.git_dir()).lock_reason()
    }

    /// Return the ID of the repository worktree, if it is a linked worktree, or `None` if it's a linked worktree.
    pub fn id(&self) -> Option<&BStr> {
        id(self.parent.git_dir(), self.parent.common_dir.is_some())
    }
}

pub(crate) fn id(git_dir: &std::path::Path, has_common_dir: bool) -> Option<&BStr> {
    if !has_common_dir {
        return None;
    }
    let candidate = gix_path::os_str_into_bstr(git_dir.file_name().expect("at least one directory level"))
        .expect("no illformed UTF-8");
    let maybe_worktrees = git_dir.parent()?;
    (maybe_worktrees.file_name()?.to_str()? == "worktrees").then_some(candidate)
}

///
pub mod proxy;

///
pub mod open_index {
    /// The error returned by [`Worktree::open_index()`][crate::Worktree::open_index()].
    #[derive(Debug, thiserror::Error)]
    #[allow(missing_docs)]
    pub enum Error {
        #[error(transparent)]
        ConfigIndexThreads(#[from] crate::config::key::GenericErrorWithValue),
        #[error(transparent)]
        IndexFile(#[from] gix_index::file::init::Error),
    }

    impl<'repo> crate::Worktree<'repo> {
        /// A shortcut to [`crate::Repository::open_index()`].
        pub fn open_index(&self) -> Result<gix_index::File, Error> {
            self.parent.open_index()
        }

        /// A shortcut to [`crate::Repository::index()`].
        pub fn index(&self) -> Result<crate::worktree::Index, Error> {
            self.parent.index()
        }
    }
}

///
pub mod excludes {
    /// The error returned by [`Worktree::excludes()`][crate::Worktree::excludes()].
    #[derive(Debug, thiserror::Error)]
    #[allow(missing_docs)]
    pub enum Error {
        #[error(transparent)]
        OpenIndex(#[from] crate::worktree::open_index::Error),
        #[error(transparent)]
        CreateCache(#[from] crate::config::exclude_stack::Error),
    }

    impl<'repo> crate::Worktree<'repo> {
        /// Configure a file-system cache checking if files below the repository are excluded.
        ///
        /// This takes into consideration all the usual repository configuration, namely:
        ///
        /// * `$XDG_CONFIG_HOME/…/ignore` if `core.excludesFile` is *not* set, otherwise use the configured file.
        /// * `$GIT_DIR/info/exclude` if present.
        ///
        /// When only excludes are desired, this is the most efficient way to obtain them. Otherwise use
        /// [`Worktree::attributes()`][crate::Worktree::attributes()] for accessing both attributes and excludes.
        pub fn excludes(&self, overrides: Option<gix_ignore::Search>) -> Result<gix_worktree::Cache, Error> {
            let index = self.index()?;
            Ok(self.parent.excludes(
                &index,
                overrides,
                gix_worktree::cache::state::ignore::Source::WorktreeThenIdMappingIfNotSkipped,
            )?)
        }
    }
}

///
pub mod attributes {
    /// The error returned by [`Worktree::attributes()`][crate::Worktree::attributes()].
    #[derive(Debug, thiserror::Error)]
    #[allow(missing_docs)]
    pub enum Error {
        #[error(transparent)]
        OpenIndex(#[from] crate::worktree::open_index::Error),
        #[error(transparent)]
        CreateCache(#[from] crate::attributes::Error),
    }

    impl<'repo> crate::Worktree<'repo> {
        /// Configure a file-system cache checking if files below the repository are excluded or for querying their attributes.
        ///
        /// This takes into consideration all the usual repository configuration, namely:
        ///
        /// * `$XDG_CONFIG_HOME/…/ignore|attributes` if `core.excludesFile|attributesFile` is *not* set, otherwise use the configured file.
        /// * `$GIT_DIR/info/exclude|attributes` if present.
        pub fn attributes(&self, overrides: Option<gix_ignore::Search>) -> Result<gix_worktree::Cache, Error> {
            let index = self.index()?;
            Ok(self.parent.attributes(
                &index,
                gix_worktree::cache::state::attributes::Source::WorktreeThenIdMapping,
                gix_worktree::cache::state::ignore::Source::WorktreeThenIdMappingIfNotSkipped,
                overrides,
            )?)
        }
    }
}