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use std::fs;
use std::path::Path;
use std::fs::File;

use std::io::prelude::*;
use std::io::Read;
use std::io::SeekFrom;

use reader::Reader;
use buffer::Buffer;

#[derive(Debug)]
pub struct FileReader {
  pub filename: String,
  pub position: u64,
  pub file: File,
  pub buffer: Buffer
}

pub fn exists(filename: &String) -> bool {
  Path::new(&filename).exists()
}

impl Reader for FileReader {
  fn open(filename: &String) -> FileReader {
    match File::open(filename) {
      Err(msg) => panic!(msg.to_string()),
      Ok(file) =>
        FileReader {
          filename: filename.to_string(),
          position: 0,
          file: file,
          buffer: Buffer {
            size: None,
            position: 0,
            buffer: vec![]
          }
        },
    }
  }

  fn get_position(&mut self) -> Result<u64, String> {
    Ok(self.position)
  }

  fn get_cache_size(&self) -> Option<usize> {
    self.buffer.size
  }

  fn set_cache_size(&mut self, cache_size: Option<usize>) {
    self.buffer.size = cache_size;
  }

  fn get_size(&mut self) -> Result<u64, String> {
    let metadata = try!(fs::metadata(self.filename.clone()).map_err(|e| e.to_string()));
    Ok(metadata.len())
  }

  fn read(&mut self, size: usize) -> Result<Vec<u8>, String> {
    let mut data = vec![0; size];
    let loaded_size = try!(self.file.read(&mut data).map_err(|e| e.to_string()));

    match loaded_size == size {
      true => {
        self.position = self.position + size as u64;
        Ok(data)
      },
      false => Ok(Vec::new()),
    }
  }

  fn seek(&mut self, seek: SeekFrom) -> Result<u64, String> {
    let position = try!(self.file.seek(seek).map_err(|e| e.to_string()));
    self.position = position;
    Ok(position)
  }
}