package com.hubspot.singularity.runner.base.shared;

import static java.nio.charset.StandardCharsets.UTF_8;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;

import org.slf4j.Logger;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.base.Optional;
import com.google.inject.Inject;
import com.hubspot.mesos.JavaUtils;

public class JsonObjectFileHelper {

  private final ObjectMapper objectMapper;

  @Inject
  public JsonObjectFileHelper(ObjectMapper objectMapper) {
    this.objectMapper = objectMapper;
  }

  public <T> Optional<T> read(Path file, Logger log, Class<T> clazz) throws IOException {
    final long start = System.currentTimeMillis();

    log.info("Reading {}", file);

    byte[] bytes = new byte[0];

    try {
      bytes = Files.readAllBytes(file);

      log.trace("Read {} bytes from {} in {}", bytes.length, file, JavaUtils.duration(start));

      if (bytes.length == 0) {
        return Optional.absent();
      }

      T object = objectMapper.readValue(bytes, clazz);
      return Optional.of(object);
    } catch (NoSuchFileException nsfe) {
      log.warn("File {} does not exist", file);
    } catch (IOException e) {
      log.warn("File {} is not a valid {} ({})", file, clazz.getSimpleName(), new String(bytes, UTF_8), e);
    }

    return Optional.absent();
  }

  public boolean writeObject(Object object, Path path, Logger log) {
    final long start = System.currentTimeMillis();

    try {
      final byte[] bytes = objectMapper.writeValueAsBytes(object);

      log.info("Writing {} bytes of {} to {}", bytes.length, object, path);

      Files.write(path, bytes, StandardOpenOption.WRITE, StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING);

      return true;
    } catch (Throwable t) {
      log.error("Failed writing {}", object, t);
      return false;
    } finally {
      log.trace("Finishing writing {} after {}", object, JavaUtils.duration(start));
    }
  }

}