// 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::utils::hg_path::{HgPath, HgPathBuf};

use crate::{

    dirstate::EntryState, utils::files, DirstateEntry, DirstateMapError,

};

use std::collections::hash_map::{self, Entry};

use std::collections::HashMap;

// 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: HashMap<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(

        vec: &HashMap<HgPathBuf, DirstateEntry>,

        skip_state: Option<EntryState>,

    ) -> Self {

        let mut multiset = DirsMultiset {

            inner: HashMap::new(),

        };

        for (filename, DirstateEntry { state, .. }) in vec {

            // 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);

            }

        }

        multiset

    }

    /// Initializes the multiset from a manifest.

    pub fn from_manifest(vec: &Vec<HgPathBuf>) -> Self {

        let mut multiset = DirsMultiset {

            inner: HashMap::new(),

        };

        for filename in vec {

            multiset.add_path(filename);

        }

        multiset

    }

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

    ///

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

        for subpath in files::find_dirs(path) {

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

                *val += 1;

                break;

            }

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

        }

    }

    /// 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: &HgPath,

    ) -> Result<(), DirstateMapError> {

        for subpath in files::find_dirs(path) {

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

                Entry::Occupied(mut entry) => {

                    let val = entry.get().clone();

                    if val > 1 {

                        entry.insert(val - 1);

                        break;

                    }

                    entry.remove();

                }

                Entry::Vacant(_) => {

                    return Err(DirstateMapError::PathNotFound(

                        path.to_owned(),

                    ))

                }

            };

        }

        Ok(())

    }

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

        self.inner.contains_key(key)

    }

    pub fn iter(&self) -> DirsMultisetIter {

        self.inner.keys()

    }

    pub fn len(&self) -> usize {

        self.inner.len()

    }

}

#[cfg(test)]

mod tests {

    use super::*;

    use std::collections::HashMap;

    #[test]

    fn test_delete_path_path_not_found() {

        let mut map = DirsMultiset::from_manifest(&vec![]);

        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()]);

        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 mut map = DirsMultiset::from_manifest(&vec![]);

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

        map.add_path(path);

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

    }

    #[test]

    fn test_add_path_successful() {

        let mut map = DirsMultiset::from_manifest(&vec![]);

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

        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"));

        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"));

        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/"));

        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/"));

        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/"));

        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/"));

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

        let expected = DirsMultiset {

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

                .iter()

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

                .collect(),

        };

        assert_eq!(map, expected);

    }

    #[test]

    fn test_dirsmultiset_new_empty() {

        let new = DirsMultiset::from_manifest(&vec![]);

        let expected = DirsMultiset {

            inner: HashMap::new(),

        };

        assert_eq!(expected, new);

        let new = DirsMultiset::from_dirstate(&HashMap::new(), None);

        let expected = DirsMultiset {

            inner: HashMap::new(),

        };

        assert_eq!(expected, new);

    }

    #[test]

    fn test_dirsmultiset_new_no_skip() {

        let input_vec = ["a/", "b/", "a/c", "a/d/"]

            .iter()

            .map(|e| HgPathBuf::from_bytes(e.as_bytes()))

            .collect();

        let expected_inner = [("", 2), ("a", 3), ("b", 1), ("a/d", 1)]

            .iter()

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

            .collect();

        let new = DirsMultiset::from_manifest(&input_vec);

        let expected = DirsMultiset {

            inner: expected_inner,

        };

        assert_eq!(expected, new);

        let input_map = ["a/", "b/", "a/c", "a/d/"]

            .iter()

            .map(|f| {

                (

                    HgPathBuf::from_bytes(f.as_bytes()),

                    DirstateEntry {

                        state: EntryState::Normal,

                        mode: 0,

                        mtime: 0,

                        size: 0,

                    },

                )

            })

            .collect();

        let expected_inner = [("", 2), ("a", 3), ("b", 1), ("a/d", 1)]

            .iter()

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

            .collect();

        let new = DirsMultiset::from_dirstate(&input_map, None);

        let expected = DirsMultiset {

            inner: expected_inner,

        };

        assert_eq!(expected, new);

    }

    #[test]

    fn test_dirsmultiset_new_skip() {

        let input_map = [

            ("a/", EntryState::Normal),

            ("a/b/", EntryState::Normal),

            ("a/c", EntryState::Removed),

            ("a/d/", EntryState::Merged),

        ]

        .iter()

        .map(|(f, state)| {

            (

                HgPathBuf::from_bytes(f.as_bytes()),

                DirstateEntry {

                    state: *state,

                    mode: 0,

                    mtime: 0,

                    size: 0,

                },

            )

        })

        .collect();

        // "a" incremented with "a/c" and "a/d/"

        let expected_inner = [("", 1), ("a", 2), ("a/d", 1)]

            .iter()

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

            .collect();

        let new =

            DirsMultiset::from_dirstate(&input_map, Some(EntryState::Normal));

        let expected = DirsMultiset {

            inner: expected_inner,

        };

        assert_eq!(expected, new);

    }

}