// dirs_multiset.rs

//

// Copyright 2019 Raphaël Gomès <rgomes@octobus.net>

//

// This software may be used and distributed according to the terms of the

// GNU General Public License version 2 or any later version.

//! A multiset of directory names.

//!

//! Used to counts the references to directories in a manifest or dirstate.

use crate::{

    dirstate::EntryState,

    utils::{

        files,

        hg_path::{HgPath, HgPathBuf, HgPathError},

    },

};

use std::collections::{hash_map, hash_map::Entry, HashMap, HashSet};

// could be encapsulated if we care API stability more seriously

pub type DirsMultisetIter<'a> = hash_map::Keys<'a, HgPathBuf, u32>;

#[derive(PartialEq, Debug)]

pub struct DirsMultiset {

    inner: FastHashMap<HgPathBuf, u32>,

}

impl DirsMultiset {

    /// Initializes the multiset from a dirstate.

    ///

    /// If `skip_state` is provided, skips dirstate entries with equal state.

    pub fn from_dirstate(

        skip_state: Option<EntryState>,

    ) -> Result<Self, DirstateMapError> {

        let mut multiset = DirsMultiset {

            inner: FastHashMap::default(),

        };

            // This `if` is optimized out of the loop

            if let Some(skip) = skip_state {

                if skip != *state {

                    multiset.add_path(filename)?;

                }

            } else {

                multiset.add_path(filename)?;

            }

        }

        Ok(multiset)

    }

    /// Initializes the multiset from a manifest.

    pub fn from_manifest(

        manifest: &[impl AsRef<HgPath>],

    ) -> Result<Self, DirstateMapError> {

        let mut multiset = DirsMultiset {

            inner: FastHashMap::default(),

        };

        for filename in manifest {

            multiset.add_path(filename.as_ref())?;

        }

        Ok(multiset)

    }

    /// Increases the count of deepest directory contained in the path.

    ///

    /// If the directory is not yet in the map, adds its parents.

    pub fn add_path(

        &mut self,

        path: impl AsRef<HgPath>,

    ) -> Result<(), DirstateMapError> {

        for subpath in files::find_dirs(path.as_ref()) {

            if subpath.as_bytes().last() == Some(&b'/') {

                // TODO Remove this once PathAuditor is certified

                // as the only entrypoint for path data

                let second_slash_index = subpath.len() - 1;

                return Err(DirstateMapError::InvalidPath(

                    HgPathError::ConsecutiveSlashes {

                        bytes: path.as_ref().as_bytes().to_owned(),

                        second_slash_index,

                    },

                ));

            }

            if let Some(val) = self.inner.get_mut(subpath) {

                *val += 1;

                break;

            }

            self.inner.insert(subpath.to_owned(), 1);

        }

        Ok(())

    }

    /// Decreases the count of deepest directory contained in the path.

    ///

    /// If it is the only reference, decreases all parents until one is

    /// removed.

    /// If the directory is not in the map, something horrible has happened.

    pub fn delete_path(

        &mut self,

        path: impl AsRef<HgPath>,

    ) -> Result<(), DirstateMapError> {

        for subpath in files::find_dirs(path.as_ref()) {

            match self.inner.entry(subpath.to_owned()) {

                Entry::Occupied(mut entry) => {

                    let val = *entry.get();

                    if val > 1 {

                        entry.insert(val - 1);

                        break;

                    }

                    entry.remove();

                }

                Entry::Vacant(_) => {

                    return Err(DirstateMapError::PathNotFound(

                        path.as_ref().to_owned(),

                    ))

                }

            };

        }

        Ok(())

    }

    pub fn contains(&self, key: impl AsRef<HgPath>) -> bool {

        self.inner.contains_key(key.as_ref())

    }

    pub fn iter(&self) -> DirsMultisetIter {

        self.inner.keys()

    }

    pub fn len(&self) -> usize {

        self.inner.len()

    }

    pub fn is_empty(&self) -> bool {

        self.len() == 0

    }

}

/// This is basically a reimplementation of `DirsMultiset` that stores the

/// children instead of just a count of them, plus a small optional

/// optimization to avoid some directories we don't need.

#[derive(PartialEq, Debug)]

pub struct DirsChildrenMultiset<'a> {

    inner: FastHashMap<&'a HgPath, HashSet<&'a HgPath>>,

    only_include: Option<HashSet<&'a HgPath>>,

}

impl<'a> DirsChildrenMultiset<'a> {

    pub fn new(

        paths: impl Iterator<Item = &'a HgPathBuf>,

        only_include: Option<&'a HashSet<impl AsRef<HgPath> + 'a>>,

    ) -> Self {

        let mut new = Self {

            inner: HashMap::default(),

            only_include: only_include

                .map(|s| s.iter().map(AsRef::as_ref).collect()),

        };

        for path in paths {

            new.add_path(path)

        }

        new

    }

    fn add_path(&mut self, path: &'a (impl AsRef<HgPath> + 'a)) {

        if path.as_ref().is_empty() {

            return;

        }

        for (directory, basename) in files::find_dirs_with_base(path.as_ref())

        {

            if !self.is_dir_included(directory) {

                continue;

            }

            self.inner

                .entry(directory)

                .and_modify(|e| {

                    e.insert(basename);

                })

                .or_insert_with(|| {

                    let mut set = HashSet::new();

                    set.insert(basename);

                    set

                });

        }

    }

    fn is_dir_included(&self, dir: impl AsRef<HgPath>) -> bool {

        match &self.only_include {

            None => false,

            Some(i) => i.contains(dir.as_ref()),

        }

    }

    pub fn get(

        &self,

        path: impl AsRef<HgPath>,

    ) -> Option<&HashSet<&'a HgPath>> {

        self.inner.get(path.as_ref())

    }

}

#[cfg(test)]

mod tests {

    use super::*;

    #[test]

    fn test_delete_path_path_not_found() {

        let manifest: Vec<HgPathBuf> = vec![];

        let mut map = DirsMultiset::from_manifest(&manifest).unwrap();

        let path = HgPathBuf::from_bytes(b"doesnotexist/");

        assert_eq!(

            Err(DirstateMapError::PathNotFound(path.to_owned())),

            map.delete_path(&path)

        );

    }

    #[test]

    fn test_delete_path_empty_path() {

        let mut map =

            DirsMultiset::from_manifest(&vec![HgPathBuf::new()]).unwrap();

        let path = HgPath::new(b"");

        assert_eq!(Ok(()), map.delete_path(path));

        assert_eq!(

            Err(DirstateMapError::PathNotFound(path.to_owned())),

            map.delete_path(path)

        );

    }

    #[test]

    fn test_delete_path_successful() {

        let mut map = DirsMultiset {

            inner: [("", 5), ("a", 3), ("a/b", 2), ("a/c", 1)]

                .iter()

                .map(|(k, v)| (HgPathBuf::from_bytes(k.as_bytes()), *v))

                .collect(),

        };

        assert_eq!(Ok(()), map.delete_path(HgPath::new(b"a/b/")));

        eprintln!("{:?}", map);

        assert_eq!(Ok(()), map.delete_path(HgPath::new(b"a/b/")));

        eprintln!("{:?}", map);

        assert_eq!(

            Err(DirstateMapError::PathNotFound(HgPathBuf::from_bytes(

                b"a/b/"

            ))),

            map.delete_path(HgPath::new(b"a/b/"))

        );

        assert_eq!(2, *map.inner.get(HgPath::new(b"a")).unwrap());

        assert_eq!(1, *map.inner.get(HgPath::new(b"a/c")).unwrap());

        eprintln!("{:?}", map);

        assert_eq!(Ok(()), map.delete_path(HgPath::new(b"a/")));

        eprintln!("{:?}", map);

        assert_eq!(Ok(()), map.delete_path(HgPath::new(b"a/c/")));

        assert_eq!(

            Err(DirstateMapError::PathNotFound(HgPathBuf::from_bytes(

                b"a/c/"

            ))),

            map.delete_path(HgPath::new(b"a/c/"))

        );

    }

    #[test]

    fn test_add_path_empty_path() {

        let manifest: Vec<HgPathBuf> = vec![];

        let mut map = DirsMultiset::from_manifest(&manifest).unwrap();

        let path = HgPath::new(b"");

        map.add_path(path).unwrap();

        assert_eq!(1, map.len());

    }

    #[test]

    fn test_add_path_successful() {

        let manifest: Vec<HgPathBuf> = vec![];

        let mut map = DirsMultiset::from_manifest(&manifest).unwrap();

        map.add_path(HgPath::new(b"a/")).unwrap();

        assert_eq!(1, *map.inner.get(HgPath::new(b"a")).unwrap());

        assert_eq!(1, *map.inner.get(HgPath::new(b"")).unwrap());

        assert_eq!(2, map.len());

        // Non directory should be ignored

        map.add_path(HgPath::new(b"a")).unwrap();

        assert_eq!(1, *map.inner.get(HgPath::new(b"a")).unwrap());

        assert_eq!(2, map.len());

        // Non directory will still add its base

        map.add_path(HgPath::new(b"a/b")).unwrap();

        assert_eq!(2, *map.inner.get(HgPath::new(b"a")).unwrap());

        assert_eq!(2, map.len());

        // Duplicate path works

        map.add_path(HgPath::new(b"a/")).unwrap();

        assert_eq!(3, *map.inner.get(HgPath::new(b"a")).unwrap());

        // Nested dir adds to its base

        map.add_path(HgPath::new(b"a/b/")).unwrap();

        assert_eq!(4, *map.inner.get(HgPath::new(b"a")).unwrap());

        assert_eq!(1, *map.inner.get(HgPath::new(b"a/b")).unwrap());

        // but not its base's base, because it already existed

        map.add_path(HgPath::new(b"a/b/c/")).unwrap();

        assert_eq!(4, *map.inner.get(HgPath::new(b"a")).unwrap());

        assert_eq!(2, *map.inner.get(HgPath::new(b"a/b")).unwrap());

        map.add_path(HgPath::new(b"a/c/")).unwrap();

        assert_eq!(1, *map.inner.get(HgPath::new(b"a/c")).unwrap());