package Files;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

// examples of reading and writing text files with multiple lines
public class TextFileExample {

    // writing and a multi line text file from a list
    public static void textLines(List<String> lines) {
        try {
            // create object that knows how to write to a file
            // use buffers for efficiency
            // throws IOException      
            PrintWriter fileout = new PrintWriter(new BufferedWriter(new FileWriter(new File("filename.txt"))));
            // actually writing text to file
            for (String line : lines) {
                fileout.println(line);
            }
            // done with file
            fileout.close();
            
        } catch (FileNotFoundException ex) { // subclass of IOException
            System.out.println("could not find file to read");
        } catch (IOException ex) {
            System.out.println("could not access files to write");
        }        
    }
    // make a stream and write some text to file
    public static void fileWrite() {
        // dealing with files is dangerous
        try {
            // create stream that knows how to write to the file
            // PrintWriter has println
            // BufferedWriter uses a buffer to make output more efficient
            // FileWriter does actual writing
            PrintWriter firstWriter
                    = new PrintWriter(
                            new BufferedWriter(
                                    new FileWriter(new File("out.txt"))));
            
            
            // we can write as many lines to the file as we need to
            // print, println, printf all work
            firstWriter.println("text goes in the file");
            firstWriter.println("more text");
            
            
            // done, so release the file
            firstWriter.close();
        } catch (FileNotFoundException ex) {
            System.out.println("could not create / replace existing file");
        } catch (IOException ex) {
            System.out.println("could not access file to write");
        }
    }

    // write to file, appending
    public static void fileWriteAppend() {
        try {
            // PrintWriter has println
            // BufferedWriter uses a buffer to make output more efficient
            // FileWriter does actual writing, allows append with this constructor
            boolean append = true; // do I want to append (true) or replace (false)
            PrintWriter smartWriter
                    = new PrintWriter(
                            new BufferedWriter(
                                    new FileWriter(new File("out.txt"), append)));

            smartWriter.println("look, even More text");
            
            
            smartWriter.close();
        } catch (FileNotFoundException ex) {
            System.out.println("could not find file");
        } catch (IOException ex) {
            System.out.println("could not access file to write");
        }
    }

    
    
    // read multiple lines from a file, just print them out
    public static void fileRead() {
      
        try {
            // scanner has various next methods
            // BufferedWriter uses a buffer to make output more efficient
            // FileWriter does actual reading
            Scanner scan
                    = new Scanner(
                            new BufferedReader(
                                    new FileReader(new File("out.txt"))));

            // check if there is still an unread line in the file
            while (scan.hasNext()) {
                // read the current line -- lines of file are already strings
                String line = scan.nextLine();

                // all we're doing with this line from the file is printing it
                // probably could do more interesting things with it...
                System.out.println(line);
            }
            
            scan.close();
        } catch (IOException ex) {
            System.out.println("could not access file to read");
        }
        
    }
    
    // sometimes we want to hold onto the contents of a file
    // return all the lines from the file in a list
    public static List<String> fileGetContents() {
        // to hold lines of file as we read them in
        List<String> linesOfFile = new ArrayList<>();

        try {
            // scanner has various next methods
            // BufferedWriter uses a buffer to make output more efficient
            // FileWriter does actual reading
            Scanner scan
                    = new Scanner(
                            new BufferedReader(
                                    new FileReader(new File("out.txt"))));

            // check if there is still an unread line in the file
            while (scan.hasNext()) {
            
                // read the current line -- lines of file are already strings
                String line = scan.nextLine();
                // put it in the arraylist
                linesOfFile.add(line);
            }
            
            
            scan.close();
        } catch (IOException ex) {
            System.out.println("could not access file to read");
        }
        
        return linesOfFile;
    }
    
    
       

    public static void main(String[] args) {
        fileWrite();
        fileWriteAppend();
        fileRead();
        
        List<String> fileIn = fileGetContents();
        
        System.out.println();
        System.out.println("File Contents:");
        int ln = 1;
        for (String line : fileIn) {
            System.out.println(ln + " " + line);
            ln++;
        }
    }
}