use std::error::Error;
use std::fmt;
use std::fs::File as FsFile;

use std::io::{Read, Write};

use std::path::Path;

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

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

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

impl<C: AsRef<str>, D: AsRef<Path>> Symbol for File<C, D> {
  fn target_reached(&self) -> Result<bool, Box<dyn Error>> {
    if !self.path.as_ref().exists() {
      return Ok(false);
    }
    let file = FsFile::open(self.path.as_ref())?;
    // Check if content is the same
    let mut file_content = file.bytes();
    let mut target_content = self.content.as_ref().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 = FsFile::create(self.path.as_ref())?;
    file.write_all(self.content.as_ref().as_bytes())?;
    Ok(())
  }

  fn get_prerequisites(&self) -> Vec<Resource> {
    if let Some(parent) = self.path.as_ref().parent() {
      vec![Resource::new("dir", parent.to_str().unwrap())]
    } else {
      vec![]
    }
  }

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