use std::{borrow::Cow, path::Path};

use bstr::{BStr, ByteSlice};

use crate::{MagicSignature, Pattern, Search};

/// Describes a matching pattern within a search for ignored paths.

#[derive(PartialEq, Eq, Debug, Hash, Ord, PartialOrd, Clone)]

pub struct Match<'a> {

    /// The matching search specification, which contains the pathspec as well.

    pub pattern: &'a Pattern,

    /// The number of the sequence the matching pathspec was in, or the line of pathspec file it was read from if [Search::source] is not `None`.

    pub sequence_number: usize,

    /// How the pattern matched.

    pub kind: MatchKind,

}

/// Describe how a pathspec pattern matched.

#[derive(Copy, Clone, PartialEq, Eq, Debug, Hash, Ord, PartialOrd)]

pub enum MatchKind {

    /// The match happened because there wasn't any pattern, which matches all, or because there was a nil pattern or one with an empty path.

    /// Thus this is not a match by merit.

    Always,

    /// The first part of a pathspec matches, like `dir/` that matches `dir/a`.

    Prefix,

    /// The whole pathspec matched and used a wildcard match, like `a/*` matching `a/file`.

    WildcardMatch,

    /// The entire pathspec matched, letter by letter, e.g. `a/file` matching `a/file`.

    Verbatim,

}

mod init;

impl Match<'_> {

    /// Return `true` if the pathspec that matched was negative, which excludes this item from the set.

    pub fn is_excluded(&self) -> bool {

        self.pattern.is_excluded()

    }

}

/// Access

impl Search {

    /// Return an iterator over the patterns that participate in the search.

    pub fn patterns(&self) -> impl ExactSizeIterator<Item = &Pattern> + '_ {

        self.patterns.iter().map(|m| &m.value.pattern)

    }

    /// Return the portion of the prefix among all of the pathspecs involved in this search, or an empty string if

    /// there is none. It doesn't have to end at a directory boundary though, nor does it denote a directory.

    ///

    /// Note that the common_prefix is always matched case-sensitively, and it is useful to skip large portions of input.

    /// Further, excluded pathspecs don't participate which makes this common prefix inclusive. To work correctly though,

    /// one will have to additionally match paths that have the common prefix with that pathspec itself to assure it is

    /// not excluded.

    pub fn common_prefix(&self) -> &BStr {

        self.patterns

            .iter()

            .find(|p| !p.value.pattern.is_excluded())

            .map_or("".into(), |m| m.value.pattern.path[..self.common_prefix_len].as_bstr())

    }

    /// Returns a guaranteed-to-be-directory that is shared across all pathspecs, in its repository-relative form.

    /// Thus to be valid, it must be joined with the worktree root.

    /// The prefix is the CWD within a worktree passed when [normalizing](crate::Pattern::normalize) the pathspecs.

    ///

    /// Note that it may well be that the directory isn't available even though there is a [`common_prefix()`](Self::common_prefix),

    /// as they are not quire the same.

    ///

    /// See also: [`maybe_prefix_directory()`](Self::longest_common_directory).

    pub fn prefix_directory(&self) -> Cow<'_, Path> {

        gix_path::from_bstr(

            self.patterns

                .iter()

                .find(|p| !p.value.pattern.is_excluded())

                .map_or("".into(), |m| m.value.pattern.prefix_directory()),

        )

    }

    /// Return the longest possible common directory that is shared across all non-exclusive pathspecs.

    /// It must be tested for existence by joining it with a suitable root before being able to use it.

    /// Note that if it is returned, it's guaranteed to be longer than the [prefix-directory](Self::prefix_directory).

    ///

    /// Returns `None` if the returned directory would be empty, or if all pathspecs are exclusive.

    pub fn longest_common_directory(&self) -> Option<Cow<'_, Path>> {

        let first_non_excluded = self.patterns.iter().find(|p| !p.value.pattern.is_excluded())?;

        let common_prefix = first_non_excluded.value.pattern.path[..self.common_prefix_len].as_bstr();

        let stripped_prefix = if first_non_excluded

            .value

            .pattern

            .signature

            .contains(MagicSignature::MUST_BE_DIR)

        {

            common_prefix

        } else {

            common_prefix[..common_prefix.rfind_byte(b'/')?].as_bstr()

        };

        Some(gix_path::from_bstr(stripped_prefix))

    }

}

#[derive(Default, Clone, Debug)]

pub(crate) struct Spec {

    pub pattern: Pattern,

    pub attrs_match: Option<gix_attributes::search::Outcome>,

}

mod matching;