// files.rs

//

// Copyright 2019

// Raphaël Gomès <rgomes@octobus.net>,

// Yuya Nishihara <yuya@tcha.org>

//

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

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

//! Functions for fiddling with files.

use crate::utils::{

    hg_path::{path_to_hg_path_buf, HgPath, HgPathBuf, HgPathError},

    path_auditor::PathAuditor,

    replace_slice,

};

use lazy_static::lazy_static;

use same_file::is_same_file;

use std::borrow::{Cow, ToOwned};

use std::fs::Metadata;

use std::iter::FusedIterator;

use std::ops::Deref;

use std::path::{Path, PathBuf};

pub fn get_os_str_from_bytes(bytes: &[u8]) -> &OsStr {

    let os_str;

    #[cfg(unix)]

    {

        use std::os::unix::ffi::OsStrExt;

        os_str = std::ffi::OsStr::from_bytes(bytes);

    }

    // TODO Handle other platforms

    // TODO: convert from WTF8 to Windows MBCS (ANSI encoding).

    // Perhaps, the return type would have to be Result<PathBuf>.

    os_str

}

pub fn get_path_from_bytes(bytes: &[u8]) -> &Path {

    Path::new(get_os_str_from_bytes(bytes))

}

// TODO: need to convert from WTF8 to MBCS bytes on Windows.

// that's why Vec<u8> is returned.

#[cfg(unix)]

pub fn get_bytes_from_path(path: impl AsRef<Path>) -> Vec<u8> {

    get_bytes_from_os_str(path.as_ref())

}

#[cfg(unix)]

pub fn get_bytes_from_os_str(str: impl AsRef<OsStr>) -> Vec<u8> {

    use std::os::unix::ffi::OsStrExt;

    str.as_ref().as_bytes().to_vec()

}

/// An iterator over repository path yielding itself and its ancestors.

#[derive(Copy, Clone, Debug)]

pub struct Ancestors<'a> {

    next: Option<&'a HgPath>,

}

impl<'a> Iterator for Ancestors<'a> {

    type Item = &'a HgPath;

    fn next(&mut self) -> Option<Self::Item> {

        let next = self.next;

        self.next = match self.next {

            Some(s) if s.is_empty() => None,

            Some(s) => {

                let p = s.bytes().rposition(|c| *c == b'/').unwrap_or(0);

                Some(HgPath::new(&s.as_bytes()[..p]))

            }

            None => None,

        };

        next

    }

}

impl<'a> FusedIterator for Ancestors<'a> {}

/// An iterator over repository path yielding itself and its ancestors.

#[derive(Copy, Clone, Debug)]

pub(crate) struct AncestorsWithBase<'a> {

    next: Option<(&'a HgPath, &'a HgPath)>,

}

impl<'a> Iterator for AncestorsWithBase<'a> {

    type Item = (&'a HgPath, &'a HgPath);

    fn next(&mut self) -> Option<Self::Item> {

        let next = self.next;

        self.next = match self.next {

            Some((s, _)) if s.is_empty() => None,

            Some((s, _)) => Some(s.split_filename()),

            None => None,

        };

        next

    }

}

impl<'a> FusedIterator for AncestorsWithBase<'a> {}

/// Returns an iterator yielding ancestor directories of the given repository

/// path.

///

/// The path is separated by '/', and must not start with '/'.

///

/// The path itself isn't included unless it is b"" (meaning the root

/// directory.)

pub fn find_dirs(path: &HgPath) -> Ancestors {

    let mut dirs = Ancestors { next: Some(path) };

    if !path.is_empty() {

        dirs.next(); // skip itself

    }

    dirs

}

/// Returns an iterator yielding ancestor directories of the given repository

/// path.

///

/// The path is separated by '/', and must not start with '/'.

///

/// The path itself isn't included unless it is b"" (meaning the root

/// directory.)

pub(crate) fn find_dirs_with_base(path: &HgPath) -> AncestorsWithBase {

    let mut dirs = AncestorsWithBase {

        next: Some((path, HgPath::new(b""))),

    };

    if !path.is_empty() {

        dirs.next(); // skip itself

    }

    dirs

}

/// TODO more than ASCII?

pub fn normalize_case(path: &HgPath) -> HgPathBuf {

    #[cfg(windows)] // NTFS compares via upper()

    return path.to_ascii_uppercase();

    #[cfg(unix)]

    path.to_ascii_lowercase()

}

lazy_static! {

    static ref IGNORED_CHARS: Vec<Vec<u8>> = {

        [

            0x200c, 0x200d, 0x200e, 0x200f, 0x202a, 0x202b, 0x202c, 0x202d,

            0x202e, 0x206a, 0x206b, 0x206c, 0x206d, 0x206e, 0x206f, 0xfeff,

        ]

        .iter()

        .map(|code| {

            std::char::from_u32(*code)

                .unwrap()

                .encode_utf8(&mut [0; 3])

                .bytes()

                .collect()

        })

        .collect()

    };

}

fn hfs_ignore_clean(bytes: &[u8]) -> Vec<u8> {

    let mut buf = bytes.to_owned();

    let needs_escaping = bytes.iter().any(|b| *b == b'\xe2' || *b == b'\xef');

    if needs_escaping {

        for forbidden in IGNORED_CHARS.iter() {

            replace_slice(&mut buf, forbidden, &[])

        }

        buf

    } else {

        buf

    }

}

pub fn lower_clean(bytes: &[u8]) -> Vec<u8> {

    hfs_ignore_clean(&bytes.to_ascii_lowercase())

}

#[derive(Eq, PartialEq, Ord, PartialOrd, Copy, Clone)]

pub struct HgMetadata {

    pub st_dev: u64,

    pub st_mode: u32,

    pub st_nlink: u64,

    pub st_size: u64,

    pub st_mtime: i64,

    pub st_ctime: i64,

}

// TODO support other plaforms

#[cfg(unix)]

impl HgMetadata {

    pub fn from_metadata(metadata: Metadata) -> Self {

        use std::os::unix::fs::MetadataExt;

        Self {

            st_dev: metadata.dev(),

            st_mode: metadata.mode(),

            st_nlink: metadata.nlink(),

            st_size: metadata.size(),

            st_mtime: metadata.mtime(),

            st_ctime: metadata.ctime(),

        }

    }

    pub fn is_symlink(&self) -> bool {

        // This is way too manual, but `HgMetadata` will go away in the

        // near-future dirstate rewrite anyway.

        self.st_mode & 0170000 == 0120000

    }

}

/// Returns the canonical path of `name`, given `cwd` and `root`

pub fn canonical_path(

    root: impl AsRef<Path>,

    cwd: impl AsRef<Path>,

    name: impl AsRef<Path>,

) -> Result<PathBuf, HgPathError> {

    // TODO add missing normalization for other platforms

    let root = root.as_ref();

    let cwd = cwd.as_ref();

    let name = name.as_ref();

    let name = if !name.is_absolute() {

        root.join(&cwd).join(&name)

    } else {

        name.to_owned()

    };

    let auditor = PathAuditor::new(&root);

    if name != root && name.starts_with(&root) {

        let name = name.strip_prefix(&root).unwrap();

        auditor.audit_path(path_to_hg_path_buf(name)?)?;

        Ok(name.to_owned())

    } else if name == root {

        Ok("".into())

    } else {

        // Determine whether `name' is in the hierarchy at or beneath `root',

        // by iterating name=name.parent() until it returns `None` (can't

        // check name == '/', because that doesn't work on windows).

        let mut name = name.deref();

        let original_name = name.to_owned();

        loop {

            let same = is_same_file(&name, &root).unwrap_or(false);

            if same {

                if name == original_name {

                    // `name` was actually the same as root (maybe a symlink)

                    return Ok("".into());

                }

                // `name` is a symlink to root, so `original_name` is under

                // root

                let rel_path = original_name.strip_prefix(&name).unwrap();

                auditor.audit_path(path_to_hg_path_buf(&rel_path)?)?;

                return Ok(rel_path.to_owned());

            }

            name = match name.parent() {

                None => break,

                Some(p) => p,

            };

        }

        // TODO hint to the user about using --cwd

        // Bubble up the responsibility to Python for now

        Err(HgPathError::NotUnderRoot {

            path: original_name.to_owned(),

            root: root.to_owned(),

        })

    }

}

/// Returns the representation of the path relative to the current working

/// directory for display purposes.

///

/// `cwd` is a `HgPath`, so it is considered relative to the root directory

/// of the repository.

///

/// # Examples

///

/// ```

/// use hg::utils::hg_path::HgPath;

/// use hg::utils::files::relativize_path;

/// use std::borrow::Cow;

///

/// let file = HgPath::new(b"nested/file");

/// let cwd = HgPath::new(b"");

/// assert_eq!(relativize_path(file, cwd), Cow::Borrowed(b"nested/file"));

///

/// let cwd = HgPath::new(b"nested");

/// assert_eq!(relativize_path(file, cwd), Cow::Borrowed(b"file"));

///

/// let cwd = HgPath::new(b"other");

/// assert_eq!(relativize_path(file, cwd), Cow::Borrowed(b"../nested/file"));

/// ```

pub fn relativize_path(path: &HgPath, cwd: impl AsRef<HgPath>) -> Cow<[u8]> {

    if cwd.as_ref().is_empty() {

        Cow::Borrowed(path.as_bytes())

    } else {

        // This is not all accurate as to how large `res` will actually be, but

        // profiling `rhg files` on a large-ish repo shows it’s better than

        // starting from a zero-capacity `Vec` and letting `extend` reallocate

        // repeatedly.

        let guesstimate = path.as_bytes().len();

        let mut res: Vec<u8> = Vec::with_capacity(guesstimate);

        let mut path_iter = path.as_bytes().split(|b| *b == b'/').peekable();

        let mut cwd_iter =

            cwd.as_ref().as_bytes().split(|b| *b == b'/').peekable();

        loop {

            match (path_iter.peek(), cwd_iter.peek()) {

                (Some(a), Some(b)) if a == b => (),

                _ => break,

            }

            path_iter.next();

            cwd_iter.next();

        }

        let mut need_sep = false;

        for _ in cwd_iter {

            if need_sep {

                res.extend(b"/")

            } else {

                need_sep = true

            };

            res.extend(b"..");

        }

        for c in path_iter {

            if need_sep {

                res.extend(b"/")

            } else {

                need_sep = true

            };

            res.extend(c);

        }

        Cow::Owned(res)

    }

}

#[cfg(test)]

mod tests {

    use super::*;

    use pretty_assertions::assert_eq;

    #[test]

    fn find_dirs_some() {

        let mut dirs = super::find_dirs(HgPath::new(b"foo/bar/baz"));

        assert_eq!(dirs.next(), Some(HgPath::new(b"foo/bar")));

        assert_eq!(dirs.next(), Some(HgPath::new(b"foo")));

        assert_eq!(dirs.next(), Some(HgPath::new(b"")));