package com.semanticsquare.io;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FilenameFilter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.Scanner;

public class IODemo {
	static String inFileStr = "walden.jpg";
	static String outFileStr = "walden-out.jpg";
	
	public static void fileCopyNoBuffer() {
		System.out.println("\nInside fileCopyNoBuffer ...");
		
		long startTime, elapsedTime; // for speed benchmarking

		// Print file length
		File fileIn = new File(inFileStr);
		System.out.println("File size is " + fileIn.length() + " bytes");

		try (FileInputStream in = new FileInputStream(inFileStr);
				FileOutputStream out = new FileOutputStream(outFileStr)) {
			startTime = System.nanoTime();
			int byteRead;
			// Read a raw byte, returns an int of 0 to 255.
			while ((byteRead = in.read()) != -1) {
				// Write the least-significant byte of int, drop the upper 3
				// bytes
				out.write(byteRead);
			}
			elapsedTime = System.nanoTime() - startTime;
			System.out.println("Elapsed Time is " + (elapsedTime / 1000000.0) + " msec");
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	// Most common way to read byte streams from a file
	public static void fileCopyWithBufferAndArray() {
		System.out.println("\nInside fileCopyWithBufferAndArray ...");
		
		long startTime, elapsedTime; // for speed benchmarking
		startTime = System.nanoTime();
		try (BufferedInputStream in = new BufferedInputStream(new FileInputStream(inFileStr));
				BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(outFileStr))) {

			byte[] byteBuf = new byte[4000];
			int numBytesRead;
			while ((numBytesRead = in.read(byteBuf)) != -1) {
				out.write(byteBuf, 0, numBytesRead);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
		elapsedTime = System.nanoTime() - startTime;
		System.out.println("fileCopyWithBufferAndArray: " + (elapsedTime / 1000000.0) + " msec");
	}
	
	private static void readFromStandardInput() {
		System.out.println("\nInside readFromStandardInput ...");
		String data;
		/*
		System.out.print("Enter \"start\" to continue (Using BufferedReader): ");		
				
		try (BufferedReader in = new BufferedReader(new InputStreamReader(System.in, "UTF-8"))){
			while ((data = in.readLine()) != null && !data.equals("start")) {
				System.out.print("\nDid not enter \"start\". Try again: ");				
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
		System.out.println("Correct!!");
		*/
		
		
		System.out.print("\nEnter \"start\" to continue (Using java.util.Scanner): ");		
		Scanner scanner = new Scanner(System.in);
		
		while(!(data = scanner.nextLine()).equals("start")) {
			System.out.print("\nDid not enter \"start\". Try again: ");	
	    }	
		System.out.println("Correct!!");
		
		
		System.out.println("Now, enter the start code: ");
		int code = scanner.nextInt(); // other methods: nextLong, nextDouble, etc
		System.out.println("Thanks. You entered code: " + code);
		
		
		/**
		 * Scanner ~ a text scanner for parsing primitives & string
		 *         ~ breaks its input into tokens using a delimited pattern (default: whitespace)
		 *         ~ when System.in is used, internally constructor uses 
		 *            an InputStreamReader to read from it
		 *         ~ hasXXX & nextXXX can be used together
		 *         ~ InputMismatchException is thrown
		 *         ~ From Java 5 onwards
		 */
		
		Scanner s1 = new Scanner("Hello, How are you?");
		while(s1.hasNext()) {
			System.out.println(s1.next());
		}	
	}
	
	public static void fileMethodsDemo() {
		System.out.println("\nInside fileMethodsDemo ...");
		
		File f = new File("C:\\jid\\demo\\src\\..\\walden.jpg"); // "movies\\movies.txt" also works
		//File f = new File("walden.jpg");
		
		System.out.println("getAbsolutePath(): " + f.getAbsolutePath());
		try {
			System.out.println("getCanonicalPath(): " + f.getCanonicalPath());
			System.out.println("createNewFile(): " + f.createNewFile());
		} catch (IOException e) {}		
		System.out.println("separator: " + f.separator);
		System.out.println("separatorChar: " + f.separatorChar);
		System.out.println("getParent(): " + f.getParent());
		System.out.println("lastModified(): " + f.lastModified());
		System.out.println("exists(): " + f.exists());
		System.out.println("isFile(): " + f.isFile());
		System.out.println("isDirectory(): " + f.isDirectory());
		System.out.println("length(): " + f.length());
		
		System.out.println("My working or user directory: " + System.getProperty("user.dir"));
		System.out.println("new File(\"testdir\").mkdir(): " + new File("testdir").mkdir());
		System.out.println("new File(\"testdir\\test\").mkdir(): " + new File("testdir\\test").mkdir());
		System.out.println("new File(\"testdir\").delete(): " + new File("testdir").delete());
		System.out.println("new File(\"testdir\\test1\\test2\").mkdir(): " + new File("testdir\\test1\\test2").mkdir());
		System.out.println("new File(\"testdir\\test1\\test2\").mkdirs(): " + new File("testdir\\test1\\test2").mkdirs());
		
		try {
			File f2 = new File("temp.txt");
			System.out.println("f2.createNewFile(): " + f2.createNewFile());
			System.out.println("f2.renameTo(...): " + f2.renameTo(new File("testdir\\temp1.txt"))); // move!!
		} catch (IOException e) {}
		
	}
	
	public static void dirFilter(boolean applyFilter) {
	    System.out.println("\nInside dirFilter ...");
	    
	    File path = new File(".");
		String[] list;
		
		if(!applyFilter)
		    list = path.list();
		else
		    list = path.list(new DirFilter());
		
		//Arrays.sort(list, String.CASE_INSENSITIVE_ORDER);
		for(String dirItem : list)
		    System.out.println(dirItem);
	}

	public static void main(String[] args) {
		//fileCopyNoBuffer();
		//fileCopyWithBufferAndArray();
		//readFromStandardInput();
		fileMethodsDemo();
		dirFilter(true);
	}
}

class DirFilter implements FilenameFilter {
	// Holds filtering criteria
	public boolean accept(File file, String name) {
		return name.endsWith(".jpg") || name.endsWith(".JPG");
	}
}