use crate::errors::{HgError, IoResultExt};

use crate::requirements;

use memmap::{Mmap, MmapOptions};

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

/// A repository on disk

pub struct Repo {

    working_directory: PathBuf,

    dot_hg: PathBuf,

    store: PathBuf,

}

/// Filesystem access abstraction for the contents of a given "base" diretory

#[derive(Clone, Copy)]

pub(crate) struct Vfs<'a> {

    base: &'a Path,

}

impl Repo {

        }

    }

    pub fn working_directory_path(&self) -> &Path {

        &self.working_directory

    }

    /// For accessing repository files (in `.hg`), except for the store

    /// (`.hg/store`).

    pub(crate) fn hg_vfs(&self) -> Vfs<'_> {

        Vfs { base: &self.dot_hg }

    }

    /// For accessing repository store files (in `.hg/store`)

    pub(crate) fn store_vfs(&self) -> Vfs<'_> {

        Vfs { base: &self.store }

    }

    /// For accessing the working copy

    // The undescore prefix silences the "never used" warning. Remove before

    // using.

    pub(crate) fn _working_directory_vfs(&self) -> Vfs<'_> {

        Vfs {

            base: &self.working_directory,

        }

    }

}

impl Vfs<'_> {

    pub(crate) fn read(

        &self,

        relative_path: impl AsRef<Path>,

    ) -> Result<Vec<u8>, HgError> {

        std::fs::read(&path).for_file(&path)

    }

    pub(crate) fn mmap_open(

        &self,

        relative_path: impl AsRef<Path>,

    ) -> Result<Mmap, HgError> {

        let path = self.base.join(relative_path);

        let file = std::fs::File::open(&path).for_file(&path)?;

        // TODO: what are the safety requirements here?

        let mmap = unsafe { MmapOptions::new().map(&file) }.for_file(&path)?;

        Ok(mmap)

    }

}