added captcha types as required

src/main/java/lc/FontFunCaptcha.java

@@ -0,0 +1,48 @@
+package lc;
+
+import javax.imageio.ImageIO;
+import java.awt.*;
+import java.awt.image.BufferedImage;
+import java.io.ByteArrayOutputStream;
+import java.util.Random;
+
+public class FontFunCaptcha implements ChallengeProvider{
+
+    public String getId() {
+        return "FontFunCaptcha";
+    }
+
+    private byte[] fontFun(String captchaText){
+        String[] fonts = {"Captcha Code","Mom'sTypewriter","Annifont","SF Intoxicated Blues",
+                "BeachType","Batmos","Barbecue","Bad Seed","Aswell","Alien Marksman"};
+        String[] colors = {"#f68787","#f8a978","#f1eb9a","#a4f6a5"};
+        BufferedImage img = new BufferedImage(350, 100, BufferedImage.TYPE_INT_RGB);
+        Graphics2D graphics2D = img.createGraphics();
+        Random rand = new Random();
+        for(int i=0; i< captchaText.length(); i++) {
+            Font font = new Font(fonts[rand.nextInt(10)], Font.ROMAN_BASELINE, 48);
+            graphics2D.setFont(font);
+            FontMetrics fontMetrics = graphics2D.getFontMetrics();
+            HelperFunctions.setRenderingHints(graphics2D);
+            graphics2D.setColor(Color.decode(colors[rand.nextInt(4)]));
+            graphics2D.drawString(String.valueOf(captchaText.toLowerCase().charAt(i)), (i * 48), fontMetrics.getAscent());
+        }
+        graphics2D.dispose();
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        try {
+            ImageIO.write(img,"png",baos);
+        }catch (Exception e){
+            e.printStackTrace();
+        }
+        return baos.toByteArray();
+    }
+
+    public Challenge returnChallenge() {
+        String secret = HelperFunctions.randomString(7);
+        return new Challenge(fontFun(secret),"png",secret);
+    }
+
+    public boolean checkAnswer(String secret, String answer){
+        return secret.equals(answer);
+    }
+}

src/main/java/lc/GifCaptcha.java

@@ -0,0 +1,55 @@
+package lc;
+
+import java.awt.Font;
+import java.awt.Graphics2D;
+import java.awt.Color;
+import java.awt.image.BufferedImage;
+import java.io.IOException;
+import javax.imageio.stream.ImageOutputStream;
+import javax.imageio.stream.MemoryCacheImageOutputStream;
+import java.io.ByteArrayOutputStream;
+
+public class GifCaptcha implements ChallengeProvider{
+
+    private BufferedImage charToImg(String text){
+        BufferedImage img = new BufferedImage(250, 100, BufferedImage.TYPE_INT_RGB);
+        Font font = new Font("Bradley Hand", Font.ROMAN_BASELINE, 48);
+        Graphics2D graphics2D = img.createGraphics();
+        graphics2D.setFont(font);
+        graphics2D.setColor(new Color((int)(Math.random() * 0x1000000)));
+        graphics2D.drawString( text , 45, 45);
+        graphics2D.dispose();
+        return img;
+    }
+
+    public byte[] gifCaptcha(String text){
+        try {
+            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
+            ImageOutputStream output = new MemoryCacheImageOutputStream(byteArrayOutputStream);
+            GifSequenceWriter writer = new GifSequenceWriter( output, 1,1000, true );
+            for(int i=0; i< text.length(); i++){
+                BufferedImage nextImage = charToImg(String.valueOf(text.charAt(i)));
+                writer.writeToSequence(nextImage);
+            }
+            writer.close();
+            output.close();
+            return byteArrayOutputStream.toByteArray();
+        } catch (IOException e){
+            e.printStackTrace();
+        }
+        return null;
+    }
+
+    public Challenge returnChallenge() {
+        String secret = HelperFunctions.randomString(6);
+        return new Challenge(gifCaptcha(secret),"gif",secret);
+    }
+
+    public boolean checkAnswer(String secret, String answer) {
+        return secret.equals(answer);
+    }
+
+    public String getId() {
+        return "GifCaptcha";
+    }
+}

src/main/java/lc/HelperFunctions.java

@@ -0,0 +1,23 @@
+package lc;
+
+import java.awt.*;
+
+public class HelperFunctions {
+
+    public static void setRenderingHints(Graphics2D g2d){
+        g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
+                RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+        g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS,
+                RenderingHints.VALUE_FRACTIONALMETRICS_ON);
+    }
+
+    public static String randomString(int n){
+        String characters = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";
+        StringBuilder stringBuilder = new StringBuilder();
+        for(int i=0; i<n; i++){
+            int index = (int)(characters.length() * Math.random());
+            stringBuilder.append(characters.charAt(index));
+        }
+        return stringBuilder.toString();
+    }
+}

src/main/java/lc/ShadowTextCaptcha.java

@@ -0,0 +1,60 @@
+package lc;
+
+import javax.imageio.ImageIO;
+import java.awt.Graphics2D;
+import java.awt.Color;
+import java.awt.Font;
+import java.awt.font.TextLayout;
+import java.awt.image.BufferedImage;
+import java.awt.image.ConvolveOp;
+import java.awt.image.Kernel;
+import java.io.ByteArrayOutputStream;
+
+public class ShadowTextCaptcha implements ChallengeProvider{
+
+    public String getId() {
+        return "ShadowText";
+    }
+
+    public boolean checkAnswer(String secret, String answer) {
+        return secret.equals(answer);
+    }
+
+    public byte[] shadowText(String text){
+        BufferedImage img = new BufferedImage(350, 100, BufferedImage.TYPE_INT_RGB);
+        Font font = new Font("Arial",Font.ROMAN_BASELINE ,48);
+        Graphics2D graphics2D = img.createGraphics();
+        TextLayout textLayout = new TextLayout(text, font, graphics2D.getFontRenderContext());
+        HelperFunctions.setRenderingHints(graphics2D);
+        graphics2D.setPaint(Color.WHITE);
+        graphics2D.fillRect(0, 0, 350, 100);
+        graphics2D.setPaint(Color.BLACK);
+        textLayout.draw(graphics2D, 15, 50);
+        graphics2D.dispose();
+        float[] kernel = {
+                1f / 9f, 1f / 9f, 1f / 9f,
+                1f / 9f, 1f / 9f, 1f / 9f,
+                1f / 9f, 1f / 9f, 1f / 9f
+        };
+        ConvolveOp op =  new ConvolveOp(new Kernel(3, 3, kernel),
+                ConvolveOp.EDGE_NO_OP, null);
+        BufferedImage img2 = op.filter(img, null);
+        Graphics2D g2d = img2.createGraphics();
+        HelperFunctions.setRenderingHints(g2d);
+        g2d.setPaint(Color.WHITE);
+        textLayout.draw(g2d, 13, 50);
+        g2d.dispose();
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        try {
+            ImageIO.write(img2,"png",baos);
+        }catch(Exception e){
+            e.printStackTrace();
+        }
+        return baos.toByteArray();
+    }
+
+    public Challenge returnChallenge() {
+        String secret = HelperFunctions.randomString(6);
+        return new Challenge(shadowText(secret),"png",secret);
+    }
+}