//! Manipulating the internal representation of files and directories
//! tracked by Pijul (i.e. adding files, removing files, getting file
//! names…).

use backend;
use backend::*;
use {ErrorKind, Result};

use rand;
use std;
use std::collections::BTreeMap;
use std::iter::Iterator;
use std::path::{Path, PathBuf};

impl<'env, R: rand::Rng> MutTxn<'env, R> {
    pub fn mark_inode_moved(&mut self, inode: Inode) {
        let mut header = None;
        if let Some(h) = self.get_inodes(inode) {
            header = Some(h.clone())
        }
        if let Some(mut h) = header {
            h.status = FileStatus::Moved;
            self.replace_inodes(inode, h).unwrap();
        }
    }

    /// Create an inode that doesn't exist in the repository, but
    /// doesn't put it into the repository.
    pub fn create_new_inode(&self) -> Inode {
        let mut already_taken = true;
        let mut inode: Inode = ROOT_INODE.clone();
        while already_taken {
            for i in inode.iter_mut() {
                *i = rand::random()
            }
            already_taken = self.get_revtree(inode).is_some();
        }
        inode
    }

    /// Record the information that `parent_inode` is now a parent of
    /// file `filename`, and `filename` has inode `child_inode`.
    fn make_new_child(
        &mut self,
        parent_inode: Inode,
        filename: &str,
        is_dir: bool,
        child_inode: Option<Inode>,
    ) -> Result<Inode> {
        let parent_id = OwnedFileId {
            parent_inode: parent_inode.clone(),
            basename: SmallString::from_str(filename),
        };
        if let Some(inode) = self.get_tree(&parent_id.as_file_id()) {
            // If we already have the file, make sure the file status
            // is Ok (i.e. not zombie, not deleted).
            let mut header = if let Some(header) = self.get_inodes(inode) {
                header.to_owned()
            } else {
                return Err(ErrorKind::AlreadyAdded.into());
            };
            if let FileStatus::Ok = header.status {
            } else {
                header.status = FileStatus::Ok;
                self.replace_inodes(inode, header)?;
            }
            Ok(inode)
        } else {
            // Else, add a new file.

            let child_inode = match child_inode {
                None => self.create_new_inode(),
                Some(i) => i.clone(),
            };
            self.put_tree(&parent_id.as_file_id(), child_inode)?;
            self.put_revtree(child_inode, &parent_id.as_file_id())?;

            if is_dir {
                // If this new file is a directory, add a name-less
                // file id without a reverse in revtree.
                let dir_id = OwnedFileId {
                    parent_inode: child_inode.clone(),
                    basename: SmallString::from_str(""),
                };
                self.put_tree(&dir_id.as_file_id(), child_inode)?;
            };
            Ok(child_inode)
        }
    }

    pub fn add_inode(
        &mut self,
        inode: Option<Inode>,
        path: &std::path::Path,
        is_dir: bool,
    ) -> Result<()> {
        if let Some(parent) = path.parent() {
            let (mut current_inode, unrecorded_path) =
                self.closest_in_repo_ancestor(&parent).unwrap();

            for c in unrecorded_path {
                current_inode =
                    self.make_new_child(current_inode, c.as_os_str().to_str().unwrap(), true, None)?
            }

            self.make_new_child(
                current_inode,
                path.file_name().unwrap().to_str().unwrap(),
                is_dir,
                inode,
            )?;
        }
        Ok(())
    }

    pub fn inode_is_ancestor_of(&self, a: Inode, mut b: Inode) -> bool {
        loop {
            if a == b {
                return true;
            }
            if let Some(b_parent) = self.get_revtree(b) {
                b = b_parent.parent_inode
            } else {
                return false;
            }
        }
    }

    pub fn move_file(
        &mut self,
        path: &std::path::Path,
        path_: &std::path::Path,
        is_dir: bool,
    ) -> Result<()> {
        debug!("move_file: {:?},{:?}", path, path_);
        if let Some(parent) = path.parent() {
            let fileref = OwnedFileId {
                parent_inode: self.find_inode(parent)?,
                basename: SmallString::from_str(path.file_name().unwrap().to_str().unwrap()),
            };

            if let Some(inode) = self.get_tree(&fileref.as_file_id()).map(|i| i.clone()) {
                // Now the last inode is in "*inode"
                debug!("txn.del fileref={:?}", fileref);
                self.del_tree(&fileref.as_file_id(), None)?;
                self.del_revtree(inode, None)?;

                debug!("inode={} path_={:?}", inode.to_hex(), path_);
                self.add_inode(Some(inode), path_, is_dir)?;
                self.mark_inode_moved(inode);

                return Ok(());
            }
        }
        Err(ErrorKind::FileNotInRepo(path.to_path_buf()).into())
    }

    // Deletes a directory, given by its inode, recursively.
    pub fn rec_delete(&mut self, key: Inode) -> Result<bool> {
        debug!("rec_delete, key={:?}", key.to_hex());
        let file_id = OwnedFileId {
            parent_inode: key.clone(),
            basename: SmallString::from_str(""),
        };

        let children: Vec<(_, Inode)> = self.iter_tree(Some((&file_id.as_file_id(), None)))
            .take_while(|&(ref k, _)| key == k.parent_inode)
            .filter(|&(ref k, _)| !k.basename.is_empty())
            .map(|(k, v)| (k.to_owned(), v.to_owned()))
            .collect();

        let mut has_recorded_descendants = false;
        for (_, b) in children {
            debug!("deleting from tree {:?}", b);
            has_recorded_descendants |= self.rec_delete(b)?;
        }

        // Now that the directory is empty, mark the corresponding node as deleted (flag '2').
        if let Some(mut header) = self.get_inodes(key).map(|h| h.clone()) {
            // If this is was recorded, mark deleted.
            debug!("key {:?}, header = {:?}", key, header);
            header.status = FileStatus::Deleted;
            self.replace_inodes(key, header)?;
            debug!("after = {:?}", self.get_inodes(key).map(|h| h.clone()));
        } else if !has_recorded_descendants {
            // Else, simply delete from the tree.
            let parent = self.get_revtree(key).unwrap().to_owned();
            debug!("key = {:?}, parent = {:?}", key, parent);
            self.del_tree(&parent.as_file_id(), None)?;
            self.del_revtree(key, None)?;
        }
        Ok(has_recorded_descendants)
    }

    /// Removes a file from the repository.
    pub fn remove_file(&mut self, path: &std::path::Path) -> Result<()> {
        debug!("remove_file");
        let inode = self.find_inode(path)?;
        debug!("rec_delete");
        self.rec_delete(inode)?;
        debug!("/rec_delete");
        Ok(())
    }
}

impl<A: Transaction, R> backend::GenericTxn<A, R> {
    /// Traverses the `tree` base recursively, collecting all descendants of `key`.
    fn collect(
        &self,
        key: Inode,
        pb: &Path,
        basename: &str,
        files: &mut Vec<PathBuf>,
    ) -> Result<()> {
        debug!("collecting {:?},{:?}", key, basename);
        let add = match self.get_inodes(key) {
            Some(inode) => {
                debug!("node = {:?}", inode);
                inode.status != FileStatus::Deleted
            }
            None => true,
        };
        if add {
            debug!("basename = {:?}", basename);
            let next_pb = pb.join(basename);
            let next_pb_ = next_pb.clone();
            if basename.len() > 0 {
                files.push(next_pb)
            }

            debug!("starting iterator, key={:?}", key);
            let fileid = OwnedFileId {
                parent_inode: key.clone(),
                basename: SmallString::from_str(""),
            };
            for (k, v) in self.iter_tree(Some((&fileid.as_file_id(), None)))
                .take_while(|&(ref k, _)| k.parent_inode == key)
            {
                debug!("iter: {:?} {:?}", k, v);
                if k.basename.len() > 0 {
                    self.collect(v.to_owned(), next_pb_.as_path(), k.basename.as_str(), files)?;
                }
            }
            debug!("ending iterator {:?}", {
                let v: Vec<_> = self.iter_tree(Some((&fileid.as_file_id(), None))).collect();
                v
            });
        }
        Ok(())
    }

    /// Returns a vector containing all files in the repository.
    pub fn list_files(&self, inode: Inode) -> Result<Vec<PathBuf>> {
        debug!("list_files {:?}", inode);
        let mut files = Vec::new();
        let mut pathbuf = PathBuf::new();
        self.collect(inode, &mut pathbuf, "", &mut files)?;
        Ok(files)
    }

    /// Returns a list of files under the given inode.
    pub fn list_files_under_inode(
        &self,
        inode: Inode,
    ) -> Vec<(SmallString, Option<Key<PatchId>>, Inode)> {
        let mut result = Vec::new();

        let file_id = OwnedFileId {
            parent_inode: inode,
            basename: SmallString::from_str(""),
        };
        for (k, v) in self.iter_tree(Some((&file_id.as_file_id(), None)))
            .take_while(|&(ref k, _)| k.parent_inode == inode)
        {
            let header = self.get_inodes(k.parent_inode).map(|x| x.clone());
            // add: checking that this file has neither been moved nor deleted.
            println!("============= {:?} {:?}", k, v);
            let add = match header {
                Some(ref h) => h.status == FileStatus::Ok,
                None => true,
            };
            if add && k.basename.len() > 0 {
                result.push((
                    k.basename.to_owned(),
                    header.map(|h| h.key.clone()),
                    v.clone(),
                ))
            }
        }

        result
    }

    /// Returns a list of files under the given inode.
    pub fn list_files_under_node(
        &self,
        branch: &Branch,
        key: Key<PatchId>,
    ) -> BTreeMap<Key<PatchId>, Vec<(FileMetadata, &str)>> {
        let mut result = BTreeMap::new();

        let e = Edge::zero(EdgeFlags::FOLDER_EDGE);
        for (_, child) in self.iter_nodes(branch, Some((key, Some(&e)))).take_while(
            |&(k, ref v)| k == key && v.flag <= EdgeFlags::FOLDER_EDGE | EdgeFlags::PSEUDO_EDGE,
        ) {
            let name = self.get_contents(child.dest).unwrap();
            // This is supposed to be a small string anyway.
            let (perms, basename) = name.as_slice().split_at(2);
            let perms = FileMetadata::from_contents(perms);
            let basename = std::str::from_utf8(basename).unwrap();

            for (_, grandchild) in self.iter_nodes(branch, Some((child.dest, Some(&e))))
                .take_while(|&(k, ref v)| {
                    k == child.dest && v.flag <= EdgeFlags::FOLDER_EDGE | EdgeFlags::PSEUDO_EDGE
                }) {
                let names = result.entry(grandchild.dest.to_owned()).or_insert(vec![]);
                names.push((perms, basename))
            }
        }
        result
    }

    pub fn is_directory(&self, inode: &Inode) -> bool {
        let file_id = OwnedFileId {
            parent_inode: inode.clone(),
            basename: SmallString::from_str(""),
        };
        inode == &ROOT_INODE || self.get_tree(&file_id.as_file_id()).is_some()
    }

    /// Splits a path into (1) the deepest inode from the root that is
    /// an ancestor of the path or the path itself and (2) the
    /// remainder of this path
    fn closest_in_repo_ancestor<'a>(
        &self,
        path: &'a std::path::Path,
    ) -> Result<(Inode, std::iter::Peekable<std::path::Components<'a>>)> {
        let mut components = path.components().peekable();
        let mut fileid = OwnedFileId {
            parent_inode: ROOT_INODE,
            basename: SmallString::from_str(""),
        };

        loop {
            if let Some(c) = components.peek() {
                fileid.basename = SmallString::from_str(c.as_os_str().to_str().unwrap());
                if let Some(v) = self.get_tree(&fileid.as_file_id()) {
                    fileid.parent_inode = v.clone()
                } else {
                    break;
                }
            } else {
                break;
            }
            components.next();
        }
        Ok((fileid.parent_inode.clone(), components))
    }

    /// Find the inode corresponding to that path, or return an error if there's no such inode.
    pub fn find_inode(&self, path: &std::path::Path) -> Result<Inode> {
        let (inode, mut remaining_path_components) = self.closest_in_repo_ancestor(path)?;
        if remaining_path_components.next().is_none() {
            Ok(inode)
        } else {
            Err(ErrorKind::FileNotInRepo(path.to_path_buf()).into())
        }
    }

    pub fn file_names(
        &self,
        branch: &Branch,
        key: Key<PatchId>,
    ) -> Vec<(Key<PatchId>, FileMetadata, &str)> {
        let mut result = Vec::new();
        let e = Edge::zero(EdgeFlags::FOLDER_EDGE | EdgeFlags::PARENT_EDGE);

        debug!("file_names, key {:?}", key);
        for (_, parent) in self.iter_nodes(branch, Some((key, Some(&e))))
            .take_while(|&(k, _)| k == key)
            .filter(|&(_, ref v)| {
                v.flag
                    .contains(EdgeFlags::FOLDER_EDGE | EdgeFlags::PARENT_EDGE)
            }) {
            debug!("file_names, parent {:?}", parent);
            match self.get_contents(parent.dest) {
                Some(ref name) if name.len() >= 2 => {
                    // This is supposed to be a small string anyway.
                    let (perms, basename) = name.as_slice().split_at(2);
                    let perms = FileMetadata::from_contents(perms);
                    let basename = std::str::from_utf8(basename).unwrap();

                    for (_, grandparent) in self.iter_nodes(branch, Some((parent.dest, Some(&e))))
                        .take_while(|&(k, _)| k == parent.dest)
                        .filter(|&(_, ref v)| {
                            v.flag
                                .contains(EdgeFlags::FOLDER_EDGE | EdgeFlags::PARENT_EDGE)
                        }) {
                        result.push((grandparent.dest.to_owned(), perms, basename));
                        break;
                    }
                }
                _ => error!("Key: {:?}, file {}, line {}", key, file!(), line!()),
            }
        }
        result
    }

    pub fn prefix_keys(&self, branch: &Branch, path: &str) -> Result<Vec<Key<PatchId>>> {
        let mut result = Vec::new();
        let e = Edge::zero(EdgeFlags::FOLDER_EDGE);

        let mut current_key = ROOT_KEY;

        for comp in path.split(std::path::MAIN_SEPARATOR) {
            let mut is_first = true;
            let cur = current_key;
            for (_, child) in self.iter_nodes(branch, Some((current_key, Some(&e))))
                .take_while(|&(k, _)| k == cur)
                .filter(|&(_, ref v)| v.flag.contains(EdgeFlags::FOLDER_EDGE))
            {
                let contents = self.get_contents(child.dest).unwrap();
                if contents.into_cow().split_at(2).1 == comp.as_bytes() {
                    if !is_first {
                        return Err(ErrorKind::FileNameCount(current_key).into());
                    }

                    for (_, grandchild) in self.iter_nodes(branch, Some((child.dest, Some(&e))))
                        .take_while(|&(k, _)| k == child.dest)
                        .filter(|&(_, ref v)| v.flag.contains(EdgeFlags::FOLDER_EDGE))
                    {
                        result.push(grandchild.dest);
                        current_key = grandchild.dest;
                    }
                }
            }
        }
        Ok(result)
    }
}