use libc::size_t;
use std::iter::IntoIterator;
use std::marker;
use std::ops::Range;
use std::path::Path;
use std::ptr;

use crate::util::{path_to_repo_path, Binding};
use crate::{raw, Diff, DiffDelta, Error, Index, IntoCString, PathspecFlags, Repository, Tree};

/// Structure representing a compiled pathspec used for matching against various
/// structures.
pub struct Pathspec {
    raw: *mut raw::git_pathspec,
}

/// List of filenames matching a pathspec.
pub struct PathspecMatchList<'ps> {
    raw: *mut raw::git_pathspec_match_list,
    _marker: marker::PhantomData<&'ps Pathspec>,
}

/// Iterator over the matched paths in a pathspec.
pub struct PathspecEntries<'list> {
    range: Range<usize>,
    list: &'list PathspecMatchList<'list>,
}

/// Iterator over the matching diff deltas.
pub struct PathspecDiffEntries<'list> {
    range: Range<usize>,
    list: &'list PathspecMatchList<'list>,
}

/// Iterator over the failed list of pathspec items that did not match.
pub struct PathspecFailedEntries<'list> {
    range: Range<usize>,
    list: &'list PathspecMatchList<'list>,
}

impl Pathspec {
    /// Creates a new pathspec from a list of specs to match against.
    pub fn new<I, T>(specs: I) -> Result<Pathspec, Error>
    where
        T: IntoCString,
        I: IntoIterator<Item = T>,
    {
        crate::init();
        let (_a, _b, arr) = crate::util::iter2cstrs_paths(specs)?;
        unsafe {
            let mut ret = ptr::null_mut();
            try_call!(raw::git_pathspec_new(&mut ret, &arr));
            Ok(Binding::from_raw(ret))
        }
    }

    /// Match a pathspec against files in a diff.
    ///
    /// The list returned contains the list of all matched filenames (unless you
    /// pass `PATHSPEC_FAILURES_ONLY` in the flags) and may also contain the
    /// list of pathspecs with no match if the `PATHSPEC_FIND_FAILURES` flag is
    /// specified.
    pub fn match_diff(
        &self,
        diff: &Diff<'_>,
        flags: PathspecFlags,
    ) -> Result<PathspecMatchList<'_>, Error> {
        let mut ret = ptr::null_mut();
        unsafe {
            try_call!(raw::git_pathspec_match_diff(
                &mut ret,
                diff.raw(),
                flags.bits(),
                self.raw
            ));
            Ok(Binding::from_raw(ret))
        }
    }

    /// Match a pathspec against files in a tree.
    ///
    /// The list returned contains the list of all matched filenames (unless you
    /// pass `PATHSPEC_FAILURES_ONLY` in the flags) and may also contain the
    /// list of pathspecs with no match if the `PATHSPEC_FIND_FAILURES` flag is
    /// specified.
    pub fn match_tree(
        &self,
        tree: &Tree<'_>,
        flags: PathspecFlags,
    ) -> Result<PathspecMatchList<'_>, Error> {
        let mut ret = ptr::null_mut();
        unsafe {
            try_call!(raw::git_pathspec_match_tree(
                &mut ret,
                tree.raw(),
                flags.bits(),
                self.raw
            ));
            Ok(Binding::from_raw(ret))
        }
    }

    /// This matches the pathspec against the files in the repository index.
    ///
    /// The list returned contains the list of all matched filenames (unless you
    /// pass `PATHSPEC_FAILURES_ONLY` in the flags) and may also contain the
    /// list of pathspecs with no match if the `PATHSPEC_FIND_FAILURES` flag is
    /// specified.
    pub fn match_index(
        &self,
        index: &Index,
        flags: PathspecFlags,
    ) -> Result<PathspecMatchList<'_>, Error> {
        let mut ret = ptr::null_mut();
        unsafe {
            try_call!(raw::git_pathspec_match_index(
                &mut ret,
                index.raw(),
                flags.bits(),
                self.raw
            ));
            Ok(Binding::from_raw(ret))
        }
    }

    /// Match a pathspec against the working directory of a repository.
    ///
    /// This matches the pathspec against the current files in the working
    /// directory of the repository. It is an error to invoke this on a bare
    /// repo. This handles git ignores (i.e. ignored files will not be
    /// considered to match the pathspec unless the file is tracked in the
    /// index).
    ///
    /// The list returned contains the list of all matched filenames (unless you
    /// pass `PATHSPEC_FAILURES_ONLY` in the flags) and may also contain the
    /// list of pathspecs with no match if the `PATHSPEC_FIND_FAILURES` flag is
    /// specified.
    pub fn match_workdir(
        &self,
        repo: &Repository,
        flags: PathspecFlags,
    ) -> Result<PathspecMatchList<'_>, Error> {
        let mut ret = ptr::null_mut();
        unsafe {
            try_call!(raw::git_pathspec_match_workdir(
                &mut ret,
                repo.raw(),
                flags.bits(),
                self.raw
            ));
            Ok(Binding::from_raw(ret))
        }
    }

    /// Try to match a path against a pathspec
    ///
    /// Unlike most of the other pathspec matching functions, this will not fall
    /// back on the native case-sensitivity for your platform. You must
    /// explicitly pass flags to control case sensitivity or else this will fall
    /// back on being case sensitive.
    pub fn matches_path(&self, path: &Path, flags: PathspecFlags) -> bool {
        let path = path_to_repo_path(path).unwrap();
        unsafe { raw::git_pathspec_matches_path(&*self.raw, flags.bits(), path.as_ptr()) == 1 }
    }
}

impl Binding for Pathspec {
    type Raw = *mut raw::git_pathspec;

    unsafe fn from_raw(raw: *mut raw::git_pathspec) -> Pathspec {
        Pathspec { raw }
    }
    fn raw(&self) -> *mut raw::git_pathspec {
        self.raw
    }
}

impl Drop for Pathspec {
    fn drop(&mut self) {
        unsafe { raw::git_pathspec_free(self.raw) }
    }
}

impl<'ps> PathspecMatchList<'ps> {
    fn entrycount(&self) -> usize {
        unsafe { raw::git_pathspec_match_list_entrycount(&*self.raw) as usize }
    }

    fn failed_entrycount(&self) -> usize {
        unsafe { raw::git_pathspec_match_list_failed_entrycount(&*self.raw) as usize }
    }

    /// Returns an iterator over the matching filenames in this list.
    pub fn entries(&self) -> PathspecEntries<'_> {
        let n = self.entrycount();
        let n = if n > 0 && self.entry(0).is_none() {
            0
        } else {
            n
        };
        PathspecEntries {
            range: 0..n,
            list: self,
        }
    }

    /// Get a matching filename by position.
    ///
    /// If this list was generated from a diff, then the return value will
    /// always be `None.
    pub fn entry(&self, i: usize) -> Option<&[u8]> {
        unsafe {
            let ptr = raw::git_pathspec_match_list_entry(&*self.raw, i as size_t);
            crate::opt_bytes(self, ptr)
        }
    }

    /// Returns an iterator over the matching diff entries in this list.
    pub fn diff_entries(&self) -> PathspecDiffEntries<'_> {
        let n = self.entrycount();
        let n = if n > 0 && self.diff_entry(0).is_none() {
            0
        } else {
            n
        };
        PathspecDiffEntries {
            range: 0..n,
            list: self,
        }
    }

    /// Get a matching diff delta by position.
    ///
    /// If the list was not generated from a diff, then the return value will
    /// always be `None`.
    pub fn diff_entry(&self, i: usize) -> Option<DiffDelta<'_>> {
        unsafe {
            let ptr = raw::git_pathspec_match_list_diff_entry(&*self.raw, i as size_t);
            Binding::from_raw_opt(ptr as *mut _)
        }
    }

    /// Returns an iterator over the non-matching entries in this list.
    pub fn failed_entries(&self) -> PathspecFailedEntries<'_> {
        let n = self.failed_entrycount();
        let n = if n > 0 && self.failed_entry(0).is_none() {
            0
        } else {
            n
        };
        PathspecFailedEntries {
            range: 0..n,
            list: self,
        }
    }

    /// Get an original pathspec string that had no matches.
    pub fn failed_entry(&self, i: usize) -> Option<&[u8]> {
        unsafe {
            let ptr = raw::git_pathspec_match_list_failed_entry(&*self.raw, i as size_t);
            crate::opt_bytes(self, ptr)
        }
    }
}

impl<'ps> Binding for PathspecMatchList<'ps> {
    type Raw = *mut raw::git_pathspec_match_list;

    unsafe fn from_raw(raw: *mut raw::git_pathspec_match_list) -> PathspecMatchList<'ps> {
        PathspecMatchList {
            raw,
            _marker: marker::PhantomData,
        }
    }
    fn raw(&self) -> *mut raw::git_pathspec_match_list {
        self.raw
    }
}

impl<'ps> Drop for PathspecMatchList<'ps> {
    fn drop(&mut self) {
        unsafe { raw::git_pathspec_match_list_free(self.raw) }
    }
}

impl<'list> Iterator for PathspecEntries<'list> {
    type Item = &'list [u8];
    fn next(&mut self) -> Option<&'list [u8]> {
        self.range.next().and_then(|i| self.list.entry(i))
    }
    fn size_hint(&self) -> (usize, Option<usize>) {
        self.range.size_hint()
    }
}
impl<'list> DoubleEndedIterator for PathspecEntries<'list> {
    fn next_back(&mut self) -> Option<&'list [u8]> {
        self.range.next_back().and_then(|i| self.list.entry(i))
    }
}
impl<'list> ExactSizeIterator for PathspecEntries<'list> {}

impl<'list> Iterator for PathspecDiffEntries<'list> {
    type Item = DiffDelta<'list>;
    fn next(&mut self) -> Option<DiffDelta<'list>> {
        self.range.next().and_then(|i| self.list.diff_entry(i))
    }
    fn size_hint(&self) -> (usize, Option<usize>) {
        self.range.size_hint()
    }
}
impl<'list> DoubleEndedIterator for PathspecDiffEntries<'list> {
    fn next_back(&mut self) -> Option<DiffDelta<'list>> {
        self.range.next_back().and_then(|i| self.list.diff_entry(i))
    }
}
impl<'list> ExactSizeIterator for PathspecDiffEntries<'list> {}

impl<'list> Iterator for PathspecFailedEntries<'list> {
    type Item = &'list [u8];
    fn next(&mut self) -> Option<&'list [u8]> {
        self.range.next().and_then(|i| self.list.failed_entry(i))
    }
    fn size_hint(&self) -> (usize, Option<usize>) {
        self.range.size_hint()
    }
}
impl<'list> DoubleEndedIterator for PathspecFailedEntries<'list> {
    fn next_back(&mut self) -> Option<&'list [u8]> {
        self.range
            .next_back()
            .and_then(|i| self.list.failed_entry(i))
    }
}
impl<'list> ExactSizeIterator for PathspecFailedEntries<'list> {}

#[cfg(test)]
mod tests {
    use super::Pathspec;
    use crate::PathspecFlags;
    use std::fs::File;
    use std::path::Path;

    #[test]
    fn smoke() {
        let ps = Pathspec::new(["a"].iter()).unwrap();
        assert!(ps.matches_path(Path::new("a"), PathspecFlags::DEFAULT));
        assert!(ps.matches_path(Path::new("a/b"), PathspecFlags::DEFAULT));
        assert!(!ps.matches_path(Path::new("b"), PathspecFlags::DEFAULT));
        assert!(!ps.matches_path(Path::new("ab/c"), PathspecFlags::DEFAULT));

        let (td, repo) = crate::test::repo_init();
        let list = ps.match_workdir(&repo, PathspecFlags::DEFAULT).unwrap();
        assert_eq!(list.entries().len(), 0);
        assert_eq!(list.diff_entries().len(), 0);
        assert_eq!(list.failed_entries().len(), 0);

        File::create(&td.path().join("a")).unwrap();

        let list = ps
            .match_workdir(&repo, crate::PathspecFlags::FIND_FAILURES)
            .unwrap();
        assert_eq!(list.entries().len(), 1);
        assert_eq!(list.entries().next(), Some("a".as_bytes()));
    }
}