use std::path::PathBuf;

use bstr::BStr;

/// Common knowledge about the worktree that is needed across most interactions with the work tree
#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
#[derive(PartialEq, Eq, Debug, Hash, Ord, PartialOrd, Clone, Copy)]
pub struct Capabilities {
    /// If true, the filesystem will store paths as decomposed unicode, i.e. `ä` becomes `"a\u{308}"`, which means that
    /// we have to turn these forms back from decomposed to precomposed unicode before storing it in the index or generally
    /// using it. This also applies to input received from the command-line, so callers may have to be aware of this and
    /// perform conversions accordingly.
    /// If false, no conversions will be performed.
    pub precompose_unicode: bool,
    /// If true, the filesystem ignores the case of input, which makes `A` the same file as `a`.
    /// This is also called case-folding.
    pub ignore_case: bool,
    /// If true, we assume the the executable bit is honored as part of the files mode. If false, we assume the file system
    /// ignores the executable bit, hence it will be reported as 'off' even though we just tried to set it to be on.
    pub executable_bit: bool,
    /// If true, the file system supports symbolic links and we should try to create them. Otherwise symbolic links will be checked
    /// out as files which contain the link as text.
    pub symlink: bool,
}

/// A stack of path components with the delegation of side-effects as the currently set path changes, component by component.
#[derive(Clone)]
pub struct Stack {
    /// The prefix/root for all paths we handle.
    root: PathBuf,
    /// the most recent known cached that we know is valid.
    current: PathBuf,
    /// The relative portion of `valid` that was added previously.
    current_relative: PathBuf,
    /// The amount of path components of 'current' beyond the roots components.
    valid_components: usize,
    /// If set, we assume the `current` element is a directory to affect calls to `(push|pop)_directory()`.
    current_is_directory: bool,
}

/// A cache for efficiently executing operations on directories and files which are encountered in sorted order.
/// That way, these operations can be re-used for subsequent invocations in the same directory.
///
/// This cache can be configured to create directories efficiently, read git-ignore files and git-attribute files,
/// in any combination.
///
/// A cache for directory creation to reduce the amount of stat calls when creating
/// directories safely, that is without following symlinks that might be on the way.
///
/// As a special case, it offers a 'prefix' which (by itself) is assumed to exist and may contain symlinks.
/// Everything past that prefix boundary must not contain a symlink. We do this by allowing any input path.
///
/// Another added benefit is its ability to store the path of full path of the entry to which leading directories
/// are to be created to avoid allocating memory.
///
/// For this to work, it remembers the last 'good' path to a directory and assumes that all components of it
/// are still valid, too.
/// As directories are created, the cache will be adjusted to reflect the latest seen directory.
///
/// The caching is only useful if consecutive calls to create a directory are using a sorted list of entries.
#[derive(Clone)]
pub struct Cache<'paths> {
    stack: Stack,
    /// tells us what to do as we change paths.
    state: cache::State,
    /// A buffer used when reading attribute or ignore files or their respective objects from the object database.
    buf: Vec<u8>,
    /// If case folding should happen when looking up attributes or exclusions.
    case: git_glob::pattern::Case,
    /// A lookup table for object ids to read from in some situations when looking up attributes or exclusions.
    attribute_files_in_index: Vec<PathOidMapping<'paths>>,
}

pub(crate) type PathOidMapping<'paths> = (&'paths BStr, git_hash::ObjectId);

///
pub mod cache;
///
pub mod stack;

mod capabilities;