//! Various utilities for working with files

use log;
use errors::{Result, ChainErr};

use std::path::{Path, PathBuf};
use std::fs;
use std::io::Read;
use toml;

/// Move file or directory `src` to `dst` recursively,
/// overwriting previous contents of `dst`. If corresponding
/// old file has the same content as the new file, timestamps
/// of the old file are preserved.
pub fn move_files(src: &PathBuf, dst: &PathBuf) -> Result<()> {
  let err = || format!("failed: move_files({:?}, {:?})", src, dst);
  if src.as_path().is_dir() {
    if !dst.as_path().is_dir() {
      log::llog(log::DebugMoveFiles,
                || format!("New dir created: {}", dst.display()));
      create_dir(dst).chain_err(&err)?;
    }

    for item in read_dir(dst).chain_err(&err)? {
      let item = item.chain_err(&err)?;
      if !src.with_added(item.file_name()).as_path().exists() {
        let path = item.path();
        if path.as_path().is_dir() {
          log::llog(log::DebugMoveFiles,
                    || format!("Old dir removed: {}", path.display()));
          remove_dir_all(&path).chain_err(&err)?;
        } else {
          log::llog(log::DebugMoveFiles,
                    || format!("Old file removed: {}", path.display()));
          remove_file(&path).chain_err(&err)?;
        }
      }
    }

    for item in read_dir(src).chain_err(&err)? {
      let item = item.chain_err(&err)?;
      let from = item.path().to_path_buf();
      let to = dst.with_added(item.file_name());
      move_files(&from, &to).chain_err(&err)?;
    }
    remove_dir_all(src).chain_err(&err)?;
  } else {
    move_one_file(src, dst).chain_err(&err)?;
  }
  Ok(())
}

/// Copy file or directory `src` to `dst` recursively
pub fn copy_recursively(src: &PathBuf, dst: &PathBuf) -> Result<()> {
  let err = || format!("failed: copy_recursively({:?}, {:?})", src, dst);
  if src.as_path().is_dir() {
    create_dir(&dst).chain_err(&err)?;
    for item in read_dir(src).chain_err(&err)? {
      let item = item.chain_err(&err)?;
      let from = item.path().to_path_buf();
      let to = dst.with_added(item.file_name());
      copy_recursively(&from, &to).chain_err(&err)?;
    }
  } else {
    copy_file(src, dst).chain_err(&err)?;
  }
  Ok(())
}

/// Move file `old_path` to `new_path`. If contents of files are the same,
/// timestamps of the old file are preserved.
fn move_one_file(old_path: &PathBuf, new_path: &PathBuf) -> Result<()> {
  let err = || format!("failed: move_one_file({:?}, {:?})", old_path, new_path);
  let is_changed = if new_path.as_path().is_file() {
    let string1 = file_to_string(old_path).chain_err(&err)?;
    let string2 = file_to_string(new_path).chain_err(&err)?;
    string1 != string2
  } else {
    true
  };

  if is_changed {
    if new_path.as_path().exists() {
      remove_file(&new_path).chain_err(&err)?;
    }
    rename_file(&old_path, &new_path).chain_err(&err)?;
    log::llog(log::DebugMoveFiles,
              || format!("File changed: {}", new_path.display()));
  } else {
    remove_file(&old_path).chain_err(&err)?;
    log::llog(log::DebugMoveFiles,
              || format!("File not changed: {}", new_path.display()));
  }
  Ok(())
}

/// Adds `with_added` function for paths.
pub trait PathBufWithAdded {
  /// Appends `path` to `self` and returns it as new `PathBuf`,
  /// leaving `self` unchanged.
  fn with_added<P: AsRef<Path>>(&self, path: P) -> PathBuf;
}

impl<T: AsRef<Path>> PathBufWithAdded for T {
  fn with_added<P: AsRef<Path>>(&self, path: P) -> PathBuf {
    let mut p = self.as_ref().to_path_buf();
    p.push(path);
    p
  }
}

/// A wrapper over `std::fs::File` containing ths file's  path.
pub struct FileWrapper {
  file: fs::File,
  path: PathBuf,
}

/// A wrapper over `std::fs::File::open` with better error reporting.
pub fn open_file<P: AsRef<Path>>(path: P) -> Result<FileWrapper> {
  Ok(FileWrapper {
       file: fs::File::open(path.as_ref())
         .chain_err(|| format!("Failed to open file for reading: {:?}", path.as_ref()))?,
       path: path.as_ref().to_path_buf(),
     })
}

/// Returns content of the file `path` as a string.
pub fn file_to_string<P: AsRef<Path>>(path: P) -> Result<String> {
  let mut f = open_file(path)?;
  f.read_all()
}

/// A wrapper over `std::fs::File::create` with better error reporting.
pub fn create_file<P: AsRef<Path>>(path: P) -> Result<FileWrapper> {
  Ok(FileWrapper {
       file: fs::File::create(path.as_ref())
         .chain_err(|| format!("Failed to create file: {:?}", path.as_ref()))?,
       path: path.as_ref().to_path_buf(),
     })
}

/// A wrapper over `std::fs::OpenOptions::open` with better error reporting.
pub fn open_file_with_options<P: AsRef<Path>>(path: P,
                                              options: &fs::OpenOptions)
                                              -> Result<FileWrapper> {
  Ok(FileWrapper {
       file: options
         .open(path.as_ref())
         .chain_err(|| format!("Failed to open file: {:?}", path.as_ref()))?,
       path: path.as_ref().to_path_buf(),
     })
}

impl FileWrapper {
  /// Read content of the file to a string
  pub fn read_all(&mut self) -> Result<String> {
    let mut r = String::new();
    self
      .file
      .read_to_string(&mut r)
      .chain_err(|| format!("Failed to read from file: {:?}", self.path))?;
    Ok(r)
  }

  /// Write `text` to the file
  pub fn write<S: AsRef<str>>(&mut self, text: S) -> Result<()> {
    use std::io::Write;
    self
      .file
      .write_all(text.as_ref().as_bytes())
      .chain_err(|| format!("Failed to write to file: {:?}", self.path))
  }

  /// Returns underlying `std::fs::File`
  pub fn into_file(self) -> fs::File {
    self.file
  }
}

/// Deserialize value from JSON file `path`.
pub fn load_json<P: AsRef<Path>, T: ::serde::Deserialize>(path: P) -> Result<T> {
  let file = open_file(path.as_ref())?;
  ::serde_json::from_reader(file.into_file())
    .chain_err(|| format!("failed to parse file as JSON: {}", path.as_ref().display()))
}

/// Serialize `value` into JSON file `path`.
pub fn save_json<P: AsRef<Path>, T: ::serde::Serialize>(path: P, value: &T) -> Result<()> {
  let file = create_file(path.as_ref())?;
  ::serde_json::to_writer(&mut file.into_file(), value).chain_err(|| {
    format!("failed to serialize to JSON file: {}",
            path.as_ref().display())
  })
}

/// Deserialize value from binary file `path`.
pub fn load_bincode<P: AsRef<Path>, T: ::serde::Deserialize>(path: P) -> Result<T> {
  let mut file = open_file(path.as_ref())?.into_file();
  ::bincode::deserialize_from(&mut file, ::bincode::Infinite)
    .chain_err(|| format!("load_bincode failed: {}", path.as_ref().display()))
}

/// Serialize `value` into binary file `path`.
pub fn save_bincode<P: AsRef<Path>, T: ::serde::Serialize>(path: P, value: &T) -> Result<()> {
  let mut file = create_file(path.as_ref())?.into_file();
  ::bincode::serialize_into(&mut file, value, ::bincode::Infinite)
    .chain_err(|| format!("save_bincode failed: {}", path.as_ref().display()))
}

/// Load data from a TOML file
pub fn load_toml<P: AsRef<Path>>(path: P) -> Result<toml::Table> {
  let data = file_to_string(path.as_ref())?;
  let mut parser = toml::Parser::new(&data);
  parser
    .parse()
    .chain_err(|| format!("failed to parse TOML file: {}", path.as_ref().display()))
}

/// Save `data` to a TOML file
pub fn save_toml<P: AsRef<Path>>(path: P, data: toml::Table) -> Result<()> {
  let mut file = create_file(path.as_ref())?;
  file
    .write(toml::Value::Table(data).to_string())
    .chain_err(|| format!("failed to write to TOML file: {}", path.as_ref().display()))
}

/// A wrapper over `std::fs::create_dir` with better error reporting
pub fn create_dir<P: AsRef<Path>>(path: P) -> Result<()> {
  fs::create_dir(path.as_ref()).chain_err(|| format!("Failed to create dir: {:?}", path.as_ref()))
}

/// A wrapper over `std::fs::create_dir_all` with better error reporting
pub fn create_dir_all<P: AsRef<Path>>(path: P) -> Result<()> {
  fs::create_dir_all(path.as_ref()).chain_err(|| {
    format!("Failed to create dirs (with parent components): {:?}",
            path.as_ref())
  })
}

/// A wrapper over `std::fs::remove_dir` with better error reporting
pub fn remove_dir<P: AsRef<Path>>(path: P) -> Result<()> {
  fs::remove_dir(path.as_ref()).chain_err(|| format!("Failed to remove dir: {:?}", path.as_ref()))
}

/// A wrapper over `std::fs::remove_dir_all` with better error reporting
pub fn remove_dir_all<P: AsRef<Path>>(path: P) -> Result<()> {
  fs::remove_dir_all(path.as_ref()).chain_err(|| {
                                                format!("Failed to remove dir (recursively): {:?}",
                                                        path.as_ref())
                                              })
}

/// A wrapper over `std::fs::remove_file` with better error reporting
pub fn remove_file<P: AsRef<Path>>(path: P) -> Result<()> {
  fs::remove_file(path.as_ref()).chain_err(|| format!("Failed to remove file: {:?}", path.as_ref()))
}

/// A wrapper over `std::fs::rename` with better error reporting
pub fn rename_file<P: AsRef<Path>, P2: AsRef<Path>>(path1: P, path2: P2) -> Result<()> {
  fs::rename(path1.as_ref(), path2.as_ref()).chain_err(|| {
    format!("Failed to rename file from {:?} to {:?}",
            path1.as_ref(),
            path2.as_ref())
  })
}

/// A wrapper over `std::fs::copy` with better error reporting
pub fn copy_file<P: AsRef<Path>, P2: AsRef<Path>>(path1: P, path2: P2) -> Result<()> {
  fs::copy(path1.as_ref(), path2.as_ref())
    .map(|_| ())
    .chain_err(|| {
                 format!("Failed to copy file from {:?} to {:?}",
                         path1.as_ref(),
                         path2.as_ref())
               })
}

/// A wrapper over `std::fs::DirEntry` iterator with better error reporting
pub struct ReadDirWrapper {
  read_dir: fs::ReadDir,
  path: PathBuf,
}

/// A wrapper over `std::fs::read_dir` with better error reporting
pub fn read_dir<P: AsRef<Path>>(path: P) -> Result<ReadDirWrapper> {
  Ok(ReadDirWrapper {
       read_dir: fs::read_dir(path.as_ref())
         .chain_err(|| format!("Failed to read dir: {:?}", path.as_ref()))?,
       path: path.as_ref().to_path_buf(),
     })
}

impl Iterator for ReadDirWrapper {
  type Item = Result<fs::DirEntry>;
  fn next(&mut self) -> Option<Result<fs::DirEntry>> {
    self
      .read_dir
      .next()
      .map(|value| value.chain_err(|| format!("Failed to read dir (in item): {:?}", self.path)))
  }
}

/// Canonicalize `path`. Similar to `std::fs::canonicalize`, but
/// `\\?\` prefix is removed. Windows implementation of `std::fs::canonicalize`
/// adds this prefix, but many tools don't process it correctly, including
/// CMake and compilers.
pub fn canonicalize<P: AsRef<Path>>(path: P) -> Result<PathBuf> {
  let r = fs::canonicalize(path.as_ref())
    .chain_err(|| format!("failed to canonicalize {}", path.as_ref().display()))?;
  {
    let str = path_to_str(&r)?;
    if str.starts_with(r"\\?\") {
      return Ok(PathBuf::from(&str[4..]));
    }
  }
  Ok(r)
}

/// A wrapper over `Path::to_str` with better error reporting
pub fn path_to_str(path: &Path) -> Result<&str> {
  path
    .to_str()
    .chain_err(|| format!("Path is not valid unicode: {}", path.display()))
}

use std::ffi::{OsStr, OsString};

/// A wrapper over `OsStr::to_str` with better error reporting
pub fn os_str_to_str(os_str: &OsStr) -> Result<&str> {
  os_str
    .to_str()
    .chain_err(|| format!("String is not valid unicode: {}", os_str.to_string_lossy()))
}

/// A wrapper over `OsString::into_string` with better error reporting
pub fn os_string_into_string(s: OsString) -> Result<String> {
  s.into_string()
    .map_err(|s| format!("String is not valid unicode: {}", s.to_string_lossy()).into())
}

/// Returns current absolute path of `relative_path`.
/// `relative_path` is relative to the repository root.
pub fn repo_crate_local_path(relative_path: &str) -> Result<PathBuf> {
  let path = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
  let parent = path
    .parent()
    .chain_err(|| "failed to get parent directory")?;
  let parent2 = parent
    .parent()
    .chain_err(|| "failed to get parent directory")?;
  let result = parent2.with_added(relative_path);
  if !result.exists() {
    return Err(format!("detected path does not exist: {}", result.display()).into());
  }
  Ok(result)
}