/* Copyright (c) 2018 Garrett Berg, vitiral@gmail.com
 *
 * Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
 * http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
 * http://opensource.org/licenses/MIT>, at your option. This file may not be
 * copied, modified, or distributed except according to those terms.
 */
//! Ergonomic paths and files in rust.
//!
//! This library aims to provide ergonomic path and file operations to rust with reasonable
//! performance.
//!
//! This includes:
//!
//! - Cleaner _absolute_ paths (which is distinct from canonicalized paths).
//! - Improved error messages, see the **Better Errors** section.
//! - Improved type safety. The types specify that a file/dir _once_ existed and was _once_ a certain
//!   type. Obviously a file/dir can be deleted/changed by another process.
//! - More stringent mutability requirements. See the **Differing Method Signatures** section.
//! - Cheap cloning: all path types are `Arc`, which a cheap operation compared to filesystem
//!   operations and allows more flexibility and ergonomics in the library for relatively low cost.
//!
//! ## Better Errors
//!
//! All errors include the **path** and **action** which caused the error, as well as the unaltered
//! `std::io::Error` message. Errors are convertable into `std::io::Error`, giving almost complete
//! compatibility with existing code.
//!
//! ### `set_len` (i.e. truncate a file):
//!
//! - [`/* */ std::fs::File::set_len(0)`][file_set_len]: `Invalid argument (os error 22)`
//! - [`path_abs::FileWrite::set_len(0)`][path_set_len]: `Invalid argument (os error 22) when setting
//!   len for /path/to/example/foo.txt`
//!
//! > The above error is actually impossible because `FileWrite` is always writeable, and
//! > `FileRead` does not implement `set_len`. However, it is kept for demonstration.
//!
//! ### `read` (open file for reading):
//!
//! - [`/**/ std::fs::File::read(path)`][file_read]: `No such file or directory (os error 2)`
//! - [`path_abs::FileRead::read(path)`][path_read]: `No such file or directory (os error 2) when
//!   opening example/foo.txt`
//!
//! And every other method has similarily improved errors. If a method does not have pretty error
//! messages please open a ticket.
//!
//! [file_set_len]: https://doc.rust-lang.org/std/fs/struct.File.html#method.set_len
//! [file_read]: https://doc.rust-lang.org/std/fs/struct.File.html#method.read
//! [path_set_len]: struct.FileWrite.html#method.set_len
//! [path_read]: struct.FileRead.html#method.read
//!
//!
//! ## Exported Path Types
//!
//! These are the exported Path types. All of them are absolute except for `PathArc`, which
//! is just an `Arc<PathBuf>` with methods that have better error reporting.
//!
//! - [`PathArc`](struct.PathArc.html): a reference counted `PathBuf` with methods reimplemented
//!   with better error messages. Use this for a generic serializable path that may or may
//!   not exist.
//! - [`PathAbs`](struct.PathAbs.html): a reference counted absolute (_not necessarily_
//!   canonicalized) path that is not necessarily guaranteed to exist.
//! - [`PathFile`](struct.PathFile.html): a `PathAbs` that is guaranteed (at instantiation) to
//!   exist and be a file, with associated methods.
//! - [`PathDir`](struct.PathDir.html): a `PathAbs` that is guaranteed (at instantiation) to exist
//!   and be a directory, with associated methods.
//! - [`PathType`](struct.PathType.html): an enum containing either a PathFile or a PathDir.
//!   Returned by [`PathDir::list`][dir_list]
//!
//! In addition, all paths are serializable through serde (even on windows!) by using the crate
//! [`stfu8`](https://crates.io/crates/stfu8) to encode/decode, allowing ill-formed UTF-16. See
//! that crate for more details on how the resulting encoding can be edited (by hand) even in the
//! case of what *would be* ill-formed UTF-16.
//!
//! [dir_list]: struct.PathDir.html#method.list
//!
//!
//! ## Exported File Types
//!
//! All File types provide _type safe_ access to their relevant traits. For instance, you can't
//! `read` with a `FileWrite` and you can't `write` with a `FileRead`.
//!
//! - [`FileRead`](struct.FileRead.html): a read-only file handle with `path()` attached and
//!   improved error messages. Contains only the methods and trait implementations which are
//!   allowed by a read-only file.
//! - [`FileWrite`](struct.FileWrite.html): a write-only file handle with `path()` attached and
//!   improved error messages. Contains only the methods and trait implementations which are
//!   allowed by a write-only file.
//! - [`FileEdit`](struct.FileEdit.html): a read/write file handle with `path()` attached and
//!   improved error messages. Contains methods and trait implements for both readable _and_
//!   writeable files.
//!
//! ### Differing Method Signatures
//!
//! The type signatures of the `File*` types regarding `read`, `write` and other methods is
//! slightly different than `std::fs::File` -- they all take `&mut` instead of `&`. This is to
//! avoid a [common possible footgun](https://github.com/rust-lang/rust/issues/47708).
//!
//! To demonstrate, imagine the following scenario:
//!
//! - You pass your open `&File` to a method, which puts it in a thread. This thread constantly
//!   calls `seek(SeekFrom::Start(10))`
//! - You periodically read from a file expecting new data, but are always getting the same data.
//!
//! Yes, this is actually allowed by the rust compiler since `seek` is implemented for
//! [`&File`](https://doc.rust-lang.org/std/fs/struct.File.html#impl-Seek-1). Technically this is
//! still _memory safe_ since the operating system will handle any contention, however many would
//! argue that it isn't _expected_ that an immutable reference passed to another
//! function can affect the seek position of a file.
//!
//!
//! # Examples
//! Recreating `Cargo.init` in `example/`
//!
//! ```rust
//! # extern crate path_abs;
//! # extern crate tempdir;
//! use std::path::Path;
//! use std::collections::HashSet;
//! use path_abs::{
//!     PathAbs,   // absolute path
//!     PathDir,   // absolute path to a directory
//!     PathFile,  // absolute path to a file
//!     PathType,  // enum of Dir or File
//!     FileRead,  // Open read-only file handler
//!     FileWrite, // Open write-only file handler
//!     FileEdit,  // Open read/write file handler
//! };
//!
//! # fn try_main() -> ::std::io::Result<()> {
//! let example = Path::new("example");
//! # let tmp = tempdir::TempDir::new("ex")?;
//! # let example = &tmp.path().join(example);
//!
//! // Create your paths
//! let project = PathDir::create_all(example)?;
//! let src = PathDir::create(project.join("src"))?;
//! let lib = PathFile::create(src.join("lib.rs"))?;
//! let cargo = PathFile::create(project.join("Cargo.toml"))?;
//!
//! // Write the templates
//! lib.write_str(r#"
//! #[cfg(test)]
//! mod tests {
//!     #[test]
//!     fn it_works() {
//!         assert_eq!(2 + 2, 4);
//!     }
//! }"#)?;
//!
//! cargo.write_str(r#"
//! [package]
//! name = "example"
//! version = "0.1.0"
//! authors = ["Garrett Berg <vitiral@gmail.com>"]
//!
//! [dependencies]
//! "#)?;
//!
//! // Put our result into a HashMap so we can assert it
//! let mut result = HashSet::new();
//! for p in project.list()? {
//!     result.insert(p?);
//! }
//!
//! // Create our expected value
//! let mut expected = HashSet::new();
//! expected.insert(PathType::Dir(src));
//! expected.insert(PathType::File(cargo));
//!
//! assert_eq!(expected, result);
//!
//! // ----------------------------------
//! // Creating types from existing paths
//!
//! // Creating a generic path
//! let lib_path = example.join("src").join("lib.rs");
//! let abs = PathAbs::new(&lib_path)?;
//!
//! // Or a path with a known type
//! let file = PathType::new(&lib_path)
//!     ?
//!     .unwrap_file();
//!
//! // Or use `PathAbs::into_file`
//! let file2 = abs.clone().into_file()?;
//!
//! assert!(abs.is_file());
//! assert!(file.is_file());
//! assert!(file2.is_file());
//!
//! // ----------------------------------
//! // Opening a File
//!
//! // open read-only using the PathFile method
//! let read = file.read()?;
//!
//! // Or use the type directly: open for appending
//! let write = FileWrite::append(&file)?;
//!
//! // Open for read/write editing.
//! let edit = file.edit()?;
//! # Ok(()) } fn main() { try_main().unwrap() }
//! ```

#[cfg(feature = "serialize")]
extern crate serde;
#[macro_use]
#[cfg(feature = "serialize")]
extern crate serde_derive;
extern crate std_prelude;
#[cfg(feature = "serialize")]
extern crate stfu8;

#[macro_use]
#[cfg(test)]
extern crate pretty_assertions;
#[cfg(test)]
extern crate regex;
#[cfg(test)]
extern crate serde_json;
#[cfg(test)]
extern crate tempdir;

use std::io;
use std::error;
use std::fmt;
use std_prelude::*;

mod abs;
mod arc;
mod dir;
mod edit;
mod file;
pub mod open;
#[cfg(feature = "serialize")]
mod ser;
mod ty;
mod write;
mod read;

pub use abs::PathAbs;
pub use arc::{current_dir, PathArc};
pub use dir::{ListDir, PathDir};
pub use file::PathFile;
pub use ty::PathType;

pub use edit::FileEdit;
pub use write::FileWrite;
pub use read::FileRead;

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

/// An error produced by performing an filesystem operation on a `Path`.
///
/// This error type is a light wrapper around [`std::io::Error`]. In particular, it adds the
/// following information:
///
/// - The action being performed when the error occured
/// - The path associated with the IO error.
///
/// To maintain good ergonomics, this type has a `impl From<Error> for std::io::Error` defined so
/// that you may use an [`io::Result`] with methods in this crate if you don't care about accessing
/// the underlying error data in a structured form (the pretty format will be preserved however).
///
/// [`std::io::Error`]: https://doc.rust-lang.org/stable/std/io/struct.Error.html
/// [`io::Result`]: https://doc.rust-lang.org/stable/std/io/type.Result.html
///
/// # Examples
/// ```rust
/// use path_abs::Error as PathError;
/// use path_abs::PathFile;
///
/// /// main function, note that you can use `io::Error`
/// fn try_main() -> Result<(), ::std::io::Error> {
///     let lib = PathFile::new("src/lib.rs")?;
///     Ok(())
/// }
///
/// ```
pub struct Error {
    io_err: io::Error,
    action: String,
    path: PathArc,
}

impl Error {
    /// Create a new error when the path and action are known.
    pub fn new(io_err: io::Error, action: &str, path: PathArc) -> Error {
        Error {
            io_err: io_err,
            action: action.into(),
            path: path,
        }
    }
}

impl fmt::Debug for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "Error<{}>", self)
    }
}

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(
            f,
            "{} when {} {}",
            self.io_err,
            self.action,
            self.path.display()
        )
    }
}

impl Error {
    /// Returns the path associated with this error.
    pub fn path(&self) -> &Path {
        self.path.as_ref()
    }

    /// Returns the `std::io::Error` associated with this errors.
    pub fn io_error(&self) -> &io::Error {
        &self.io_err
    }

    /// Returns the action being performed when this error occured.
    pub fn action(&self) -> &str {
        &self.action
    }
}

impl error::Error for Error {
    fn description(&self) -> &str {
        self.io_err.description()
    }

    fn cause(&self) -> Option<&error::Error> {
        Some(&self.io_err)
    }
}

impl From<Error> for io::Error {
    fn from(err: Error) -> io::Error {
        io::Error::new(err.io_err.kind(), err)
    }
}

#[cfg(test)]
mod tests {
    use std::path::Path;

    use tempdir::TempDir;
    use regex::{self, Regex};

    use super::*;

    macro_rules! assert_match {
        ($re: expr, $err: expr) => {{
            let re = Regex::new(&$re).unwrap();
            let err = $err.to_string();
            assert!(
                re.is_match(&err),
                "\nGot Err         : {:?}\nMatching against: {:?}",
                err.to_string(),
                $re
            );
        }};
    }

    fn escape<P: AsRef<Path>>(path: P) -> String {
        regex::escape(&format!("{}", path.as_ref().display()))
    }

    #[test]
    /// Tests to make sure the error messages look like we expect.
    fn sanity_errors() {
        let tmp_dir = TempDir::new("example").expect("create temp dir");
        let tmp_abs = PathDir::new(tmp_dir.path()).expect("tmp_abs");

        {
            let foo = PathFile::create(tmp_abs.join("foo.txt")).expect("foo.txt");
            foo.clone().remove().unwrap();
            let pat = if cfg!(unix) {
                format!(
                    r"No such file or directory \(os error \d+\) when opening {}",
                    escape(&foo)
                )
            } else {
                format!(
                    r"The system cannot find the file specified. \(os error \d+\) when opening {}",
                    escape(&foo)
                )
            };
            assert_match!(pat, foo.edit().unwrap_err())
        }
    }
}