use std::error::Error;
use std::fmt;
use std::fs::File as FsFile;
use std::io;
use std::io::{Read, Write};
use std::ops::Deref;
use std::path::Path;

use symbols::{Action, OwnedSymbolAction, Symbol, SymbolAction, SymbolRunner};
use resources::Resource;

pub struct File<C, D> where C: Deref<Target=str>, D: AsRef<Path> {
  path: D,
  content: C
}

impl<C, D> File<C, D> where C: Deref<Target=str>, D: AsRef<Path> {
  pub fn new(path: D, content: C) -> Self {
    File { path, content }
  }
}

impl<C, D> Symbol for File<C, D> where C: Deref<Target=str>, D: AsRef<Path> {
  fn target_reached(&self) -> Result<bool, Box<dyn Error>> {
    let file = FsFile::open(self.path.as_ref());
    // Check if file exists
    if let Err(e) = file {
      return if e.kind() == io::ErrorKind::NotFound {
        Ok(false)
      } else {
        Err(Box::new(e))
      };
    }
    // Check if content is the same
    let mut file_content = file.unwrap().bytes();
    let mut target_content = self.content.bytes();
    loop {
      match (file_content.next(), target_content.next()) {
        (None, None) => return Ok(true),
        (Some(Ok(a)), Some(b)) if a == b => {},
        (Some(Err(e)), _) => return Err(Box::new(e)),
        (_, _) => return Ok(false)
      }
    }
  }

  fn execute(&self) -> Result<(), Box<dyn Error>> {
    let mut file = try!(FsFile::create(self.path.as_ref()));
    try!(file.write_all(self.content.as_bytes()));
    Ok(())
  }

  fn get_prerequisites(&self) -> Vec<Resource> {
    vec![ Resource::new("dir", Path::new(self.path.as_ref()).parent().unwrap().to_string_lossy() ) ]
  }

  fn as_action<'a>(&'a self, runner: &'a dyn SymbolRunner) -> Box<dyn Action + 'a> {
    Box::new(SymbolAction::new(runner, self))
  }

  fn into_action<'a>(self: Box<Self>, runner: &'a dyn SymbolRunner) -> Box<dyn Action + 'a> where Self: 'a {
    Box::new(OwnedSymbolAction::new(runner, *self))
  }
}

impl<C, D> fmt::Display for File<C, D> where C: Deref<Target=str>, D: AsRef<Path> {
  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error>{
    write!(f, "File {}", self.path.as_ref().display())
  }
}