sdis1819-t7g02

package service;

import java.io.File;

import java.io.IOException;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.security.MessageDigest;

import java.text.SimpleDateFormat;

import java.util.ArrayList;

import java.util.Arrays;

/**

 * The porpous of this class is to load a file and split it to chunks so it they can be shared

 *

 */

public class FileChunker implements java.io.Serializable {

        private String name;

        private String id;

        private ArrayList<Chunk> fileChunks = new ArrayList<Chunk>();

        private String fileDate;

        private Path fileLocation;

        private int replication_degree;

        public FileChunker(String path, int replication_degree) throws IOException {

                this.fileLocation = Paths.get(path);

                byte[] fileData = Files.readAllBytes(fileLocation);

                int fileDataLength = fileData.length;

                byte[] aux;

                int to = 0;

                Chunk auxChunk = null;

                name = fileLocation.getFileName().toString();

                fileDate = new SimpleDateFormat("yyyy/MM/dd").format(new File(fileLocation.toString()).lastModified());

                id = SHA256(name + fileDate);

                System.out.println(name + " has " + fileDataLength + " bytes.");

                for(int chunkID = 0, from = 0; from < fileDataLength; chunkID++, from += (to-from)) {

                        to = fileDataLength - from > Constants.MAX_CHUNK_SIZE ? from + Constants.MAX_CHUNK_SIZE : fileData.length;

                        try {

                                aux = Arrays.copyOfRange(fileData, from, to);

                                //System.out.println("Chunk no " + chunkID + " with " + aux.length + " created with bytes from " + from + " to " + to);

                                auxChunk = new Chunk(chunkID, aux, id, replication_degree);

                                auxChunk.setFilePathName(name);

                                fileChunks.add(auxChunk); // para podermos distinguir entre diferentes versões 

                        } catch(Exception e) {

                                System.out.println("Invalid chunk size, might be corrupted");

                        }

                }

        }

        public FileChunker(String path) throws IOException 

        {

                this.fileLocation = Paths.get(path);

                name = fileLocation.getFileName().toString();

                fileDate = new SimpleDateFormat("yyyy/MM/dd").format(new File(fileLocation.toString()).lastModified());

                id = SHA256(name + fileDate);

        }

        public ArrayList<Chunk> getChunks() {

                return fileChunks;

        }

        public String getFileID() {

                return id;

        }

        public String getFileName()

        {

                return this.name;

        }

        public int getFileSize() {

                int size = 0;

                for(Chunk c : fileChunks) {

                        size += c.getChunkSize();

                }

                return size;

        }

        public Path getPath()

        {

                return this.fileLocation;

        }

        public int getReplicationDegree()

        {

                return this.replication_degree;

        }

        private static String SHA256(String base) {

        try {

            MessageDigest digest = MessageDigest.getInstance("SHA-256");

            byte[] hash = digest.digest(base.getBytes("UTF-8"));

            StringBuffer hexString = new StringBuffer();

            for (byte aHash : hash) {

                String hex = Integer.toHexString(0xff & aHash);

                if (hex.length() == 1) {

                        hexString.append('0');

                }

                hexString.append(hex);

            }

            return hexString.toString();

        } catch (Exception ex) {

            throw new RuntimeException(ex);

        }

    }

}