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.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.nio.charset.StandardCharsets;
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 main(String[] args) {
		//fileCopyNoBuffer();
		//fileCopyWithBufferAndArray();
		//readFromStandardInput();
		System.out.println(System.getProperty("user.dir"));
	}
}