#![allow(dead_code)]

use std::error::Error as StdError;
use std::fmt::{self, Display};
use std::io::{self, Read};
use std::path::{Path, PathBuf};

pub(crate) type Result<T> = std::result::Result<T, Error>;

#[derive(Debug)]
pub(crate) struct Error {
    source: Option<io::Error>,
    message: String,
}

impl Error {
    pub fn kind(&self) -> io::ErrorKind {
        match &self.source {
            Some(io_error) => io_error.kind(),
            None => io::ErrorKind::Other,
        }
    }
}

impl Display for Error {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        formatter.write_str(&self.message)
    }
}

impl StdError for Error {
    fn source(&self) -> Option<&(dyn StdError + 'static)> {
        let source = self.source.as_ref()?;
        Some(source)
    }
}

macro_rules! err {
    ($io_error:expr, $fmt:expr $(, $path:expr)* $(,)?) => {
        Err(Error {
            source: Option::from($io_error),
            message: format!($fmt $(, $path.display())*),
        })
    }
}

pub(crate) fn copy(from: impl AsRef<Path>, to: impl AsRef<Path>) -> Result<u64> {
    let from = from.as_ref();
    let to = to.as_ref();
    match std::fs::copy(from, to) {
        Ok(n) => Ok(n),
        Err(e) => err!(e, "Failed to copy `{}` -> `{}`", from, to),
    }
}

pub(crate) fn create_dir_all(path: impl AsRef<Path>) -> Result<()> {
    let path = path.as_ref();
    match std::fs::create_dir_all(path) {
        Ok(()) => Ok(()),
        Err(e) => err!(e, "Failed to create directory `{}`", path),
    }
}

pub(crate) fn current_dir() -> Result<PathBuf> {
    match std::env::current_dir() {
        Ok(dir) => Ok(dir),
        Err(e) => err!(e, "Failed to determine current directory"),
    }
}

pub(crate) fn exists(path: impl AsRef<Path>) -> bool {
    let path = path.as_ref();
    // If path is a symlink, this returns true, regardless of whether the
    // symlink points to a path that exists.
    std::fs::symlink_metadata(path).is_ok()
}

pub(crate) fn read(path: impl AsRef<Path>) -> Result<Vec<u8>> {
    let path = path.as_ref();
    match std::fs::read(path) {
        Ok(string) => Ok(string),
        Err(e) => err!(e, "Failed to read file `{}`", path),
    }
}

pub(crate) fn read_stdin() -> Result<Vec<u8>> {
    let mut bytes = Vec::new();
    match io::stdin().read_to_end(&mut bytes) {
        Ok(_len) => Ok(bytes),
        Err(e) => err!(e, "Failed to read input from stdin"),
    }
}

pub(crate) fn remove_file(path: impl AsRef<Path>) -> Result<()> {
    let path = path.as_ref();
    match std::fs::remove_file(path) {
        Ok(()) => Ok(()),
        Err(e) => err!(e, "Failed to remove file `{}`", path),
    }
}

pub(crate) fn remove_dir(path: impl AsRef<Path>) -> Result<()> {
    let path = path.as_ref();
    match std::fs::remove_dir(path) {
        Ok(()) => Ok(()),
        Err(e) => err!(e, "Failed to remove directory `{}`", path),
    }
}

fn symlink<'a>(
    original: &'a Path,
    link: &'a Path,
    fun: fn(&'a Path, &'a Path) -> io::Result<()>,
) -> Result<()> {
    match fun(original, link) {
        Ok(()) => Ok(()),
        Err(e) => err!(
            e,
            "Failed to create symlink `{}` pointing to `{}`",
            link,
            original,
        ),
    }
}

pub(crate) fn symlink_fail(original: impl AsRef<Path>, link: impl AsRef<Path>) -> Result<()> {
    err!(
        None,
        "Failed to create symlink `{}` pointing to `{}`",
        link.as_ref(),
        original.as_ref(),
    )
}

#[cfg(unix)]
#[allow(unused_imports)]
pub(crate) use self::symlink_file as symlink_dir;

#[cfg(not(any(unix, windows)))]
#[allow(unused_imports)]
pub(crate) use self::symlink_fail as symlink_dir;

#[cfg(unix)]
pub(crate) fn symlink_file(original: impl AsRef<Path>, link: impl AsRef<Path>) -> Result<()> {
    symlink(original.as_ref(), link.as_ref(), std::os::unix::fs::symlink)
}

#[cfg(windows)]
pub(crate) fn symlink_file(original: impl AsRef<Path>, link: impl AsRef<Path>) -> Result<()> {
    symlink(
        original.as_ref(),
        link.as_ref(),
        std::os::windows::fs::symlink_file,
    )
}

#[cfg(windows)]
pub(crate) fn symlink_dir(original: impl AsRef<Path>, link: impl AsRef<Path>) -> Result<()> {
    symlink(
        original.as_ref(),
        link.as_ref(),
        std::os::windows::fs::symlink_dir,
    )
}

pub(crate) fn write(path: impl AsRef<Path>, contents: impl AsRef<[u8]>) -> Result<()> {
    let path = path.as_ref();
    match std::fs::write(path, contents) {
        Ok(()) => Ok(()),
        Err(e) => err!(e, "Failed to write file `{}`", path),
    }
}
