use bytes_cast::BytesCast;

use micro_timer::timed;

use std::borrow::Cow;

use std::convert::TryInto;

use std::path::PathBuf;

use super::on_disk;

use super::path_with_basename::WithBasename;

use crate::dirstate::parsers::pack_entry;

use crate::dirstate::parsers::packed_entry_size;

use crate::dirstate::parsers::parse_dirstate_entries;

use crate::dirstate::parsers::Timestamp;

use crate::matchers::Matcher;

use crate::utils::hg_path::{HgPath, HgPathBuf};

use crate::CopyMapIter;

use crate::DirstateEntry;

use crate::DirstateError;

use crate::DirstateMapError;

use crate::DirstateParents;

use crate::DirstateStatus;

use crate::EntryState;

use crate::FastHashMap;

use crate::PatternFileWarning;

use crate::StateMapIter;

use crate::StatusError;

use crate::StatusOptions;

pub struct DirstateMap<'on_disk> {

    /// Contents of the `.hg/dirstate` file

    pub(super) on_disk: &'on_disk [u8],

    pub(super) root: ChildNodes<'on_disk>,

    /// Number of nodes anywhere in the tree that have `.entry.is_some()`.

    pub(super) nodes_with_entry_count: u32,

    /// Number of nodes anywhere in the tree that have

    /// `.copy_source.is_some()`.

    pub(super) nodes_with_copy_source_count: u32,

}

/// Using a plain `HgPathBuf` of the full path from the repository root as a

/// map key would also work: all paths in a given map have the same parent

/// path, so comparing full paths gives the same result as comparing base

/// names. However `HashMap` would waste time always re-hashing the same

/// string prefix.

pub(super) type NodeKey<'on_disk> = WithBasename<Cow<'on_disk, HgPath>>;

pub(super) enum ChildNodes<'on_disk> {

    InMemory(FastHashMap<NodeKey<'on_disk>, Node<'on_disk>>),

}

pub(super) enum ChildNodesRef<'tree, 'on_disk> {

    InMemory(&'tree FastHashMap<NodeKey<'on_disk>, Node<'on_disk>>),

}

pub(super) enum NodeRef<'tree, 'on_disk> {

    InMemory(&'tree NodeKey<'on_disk>, &'tree Node<'on_disk>),

}

impl Default for ChildNodes<'_> {

    fn default() -> Self {

        ChildNodes::InMemory(Default::default())

    }

}

impl<'on_disk> ChildNodes<'on_disk> {

    pub(super) fn as_ref<'tree>(

        &'tree self,

    ) -> ChildNodesRef<'tree, 'on_disk> {

        match self {

            ChildNodes::InMemory(nodes) => ChildNodesRef::InMemory(nodes),

        }

    }

    pub(super) fn is_empty(&self) -> bool {

        match self {

            ChildNodes::InMemory(nodes) => nodes.is_empty(),

        }

    }

    pub(super) fn make_mut(

        &mut self,

    ) -> &mut FastHashMap<NodeKey<'on_disk>, Node<'on_disk>> {

        match self {

            ChildNodes::InMemory(nodes) => nodes,

        }

    }

}

impl<'tree, 'on_disk> ChildNodesRef<'tree, 'on_disk> {

    pub(super) fn get(

        &self,

        base_name: &HgPath,

    ) -> Option<NodeRef<'tree, 'on_disk>> {

        match self {

            ChildNodesRef::InMemory(nodes) => nodes

                .get_key_value(base_name)

                .map(|(k, v)| NodeRef::InMemory(k, v)),

        }

    }

    /// Iterate in undefined order

    pub(super) fn iter(

        &self,

    ) -> impl Iterator<Item = NodeRef<'tree, 'on_disk>> {

        match self {

            ChildNodesRef::InMemory(nodes) => {

                nodes.iter().map(|(k, v)| NodeRef::InMemory(k, v))

            }

        }

    }

    /// Iterate in parallel in undefined order

    pub(super) fn par_iter(

        &self,

    ) -> impl rayon::iter::ParallelIterator<Item = NodeRef<'tree, 'on_disk>>

    {

        use rayon::prelude::*;

        match self {

            ChildNodesRef::InMemory(nodes) => {

                nodes.par_iter().map(|(k, v)| NodeRef::InMemory(k, v))

            }

        }

    }

    pub(super) fn sorted(&self) -> Vec<NodeRef<'tree, 'on_disk>> {

        match self {

            ChildNodesRef::InMemory(nodes) => {

                let mut vec: Vec<_> = nodes

                    .iter()

                    .map(|(k, v)| NodeRef::InMemory(k, v))

                    .collect();

                // `sort_unstable_by_key` doesn’t allow keys borrowing from the

                // value: https://github.com/rust-lang/rust/issues/34162

                vec.sort_unstable_by(|a, b| a.base_name().cmp(b.base_name()));

                vec

            }

        }

    }

}

impl<'tree, 'on_disk> NodeRef<'tree, 'on_disk> {

    pub(super) fn full_path(&self) -> &'tree HgPath {

        match self {

            NodeRef::InMemory(path, _node) => path.full_path(),

        }

    }

    /// Returns a `Cow` that can borrow 'on_disk but is detached from 'tree

    pub(super) fn full_path_cow(&self) -> Cow<'on_disk, HgPath> {

        match self {

            NodeRef::InMemory(path, _node) => path.full_path().clone(),

        }

    }

    pub(super) fn base_name(&self) -> &'tree HgPath {

        match self {

            NodeRef::InMemory(path, _node) => path.base_name(),

        }

    }

    pub(super) fn children(&self) -> ChildNodesRef<'tree, 'on_disk> {

        match self {

            NodeRef::InMemory(_path, node) => node.children.as_ref(),

        }

    }

    pub(super) fn copy_source(&self) -> Option<&'tree HgPath> {

        match self {

            NodeRef::InMemory(_path, node) => {

                node.copy_source.as_ref().map(|s| &**s)

            }

        }

    }

    pub(super) fn has_entry(&self) -> bool {

        match self {

            NodeRef::InMemory(_path, node) => node.entry.is_some(),

        }

    }

    pub(super) fn entry(&self) -> Option<DirstateEntry> {

        match self {

            NodeRef::InMemory(_path, node) => node.entry,

        }

    }

    pub(super) fn state(&self) -> Option<EntryState> {

        match self {

            NodeRef::InMemory(_path, node) => {

                node.entry.as_ref().map(|entry| entry.state)

            }

        }

    }

    pub(super) fn tracked_descendants_count(&self) -> u32 {

        match self {

            NodeRef::InMemory(_path, node) => node.tracked_descendants_count,

        }

    }

}

/// Represents a file or a directory

#[derive(Default)]

pub(super) struct Node<'on_disk> {

    /// `None` for directories

    pub(super) entry: Option<DirstateEntry>,

    pub(super) copy_source: Option<Cow<'on_disk, HgPath>>,

    pub(super) children: ChildNodes<'on_disk>,

    /// How many (non-inclusive) descendants of this node are tracked files

    pub(super) tracked_descendants_count: u32,

}

impl<'on_disk> DirstateMap<'on_disk> {

    pub(super) fn empty(on_disk: &'on_disk [u8]) -> Self {

        Self {

            on_disk,

            root: ChildNodes::default(),

            nodes_with_entry_count: 0,

            nodes_with_copy_source_count: 0,

        }

    }

    #[timed]

    pub fn new_v2(

        on_disk: &'on_disk [u8],

    ) -> Result<(Self, Option<DirstateParents>), DirstateError> {

    }

    #[timed]

    pub fn new_v1(

        on_disk: &'on_disk [u8],

    ) -> Result<(Self, Option<DirstateParents>), DirstateError> {

        let mut map = Self::empty(on_disk);

        if map.on_disk.is_empty() {

            return Ok((map, None));

        }

        let parents = parse_dirstate_entries(

            map.on_disk,

            |path, entry, copy_source| {

                let tracked = entry.state.is_tracked();

                let node = Self::get_or_insert_node(

                    &mut map.root,

                    path,

                    WithBasename::to_cow_borrowed,

                    |ancestor| {

                        if tracked {

                            ancestor.tracked_descendants_count += 1

                        }

                    },

                );

                assert!(

                    node.entry.is_none(),

                    "duplicate dirstate entry in read"

                );

                assert!(

                    node.copy_source.is_none(),

                    "duplicate dirstate entry in read"

                );

                node.entry = Some(*entry);

                node.copy_source = copy_source.map(Cow::Borrowed);

                map.nodes_with_entry_count += 1;

                if copy_source.is_some() {

                    map.nodes_with_copy_source_count += 1

                }

            },

        )?;

        let parents = Some(parents.clone());

        Ok((map, parents))

    }

    fn get_node<'tree>(

        &'tree self,

        path: &HgPath,

    ) -> Option<NodeRef<'tree, 'on_disk>> {

        let mut children = self.root.as_ref();

        let mut components = path.components();

        let mut component =

            components.next().expect("expected at least one components");

        loop {

            let child = children.get(component)?;

            if let Some(next_component) = components.next() {

                component = next_component;

                children = child.children();

            } else {

                return Some(child);

            }

        }

    }

    /// Returns a mutable reference to the node at `path` if it exists

    ///

    /// This takes `root` instead of `&mut self` so that callers can mutate

    /// other fields while the returned borrow is still valid

    fn get_node_mut<'tree>(

        root: &'tree mut ChildNodes<'on_disk>,

        path: &HgPath,

    ) -> Option<&'tree mut Node<'on_disk>> {

        let mut children = root;

        let mut components = path.components();

        let mut component =

            components.next().expect("expected at least one components");

        loop {

            let child = children.make_mut().get_mut(component)?;

            if let Some(next_component) = components.next() {

                component = next_component;

                children = &mut child.children;

            } else {

                return Some(child);

            }

        }

    }

    fn get_or_insert_node<'tree, 'path>(

        root: &'tree mut ChildNodes<'on_disk>,

        path: &'path HgPath,

        to_cow: impl Fn(

            WithBasename<&'path HgPath>,

        ) -> WithBasename<Cow<'on_disk, HgPath>>,

        mut each_ancestor: impl FnMut(&mut Node),

    ) -> &'tree mut Node<'on_disk> {

        let mut child_nodes = root;

        let mut inclusive_ancestor_paths =

            WithBasename::inclusive_ancestors_of(path);

        let mut ancestor_path = inclusive_ancestor_paths

            .next()