PatternMatcher.java

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class PatternMatcher {

    // PII Patterns
    private static final Pattern EMAIL_PATTERN = Pattern.compile("[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,6}");
    private static final Pattern PHONE_PATTERN = Pattern
            .compile("\\b\\d{10}\\b|\\b\\d{3}[-.\\s]\\d{3}[-.\\s]\\d{4}\\b");
    private static final Pattern CREDIT_CARD_PATTERN = Pattern.compile("\\b(?:\\d{4}[-\\s]?){3}\\d{4}\\b");

    // Malicious Patterns (Simple keywords for demonstration)
    private static final Pattern MALICIOUS_KEYWORD_PATTERN = Pattern
            .compile("(?i)(password\\s*=|eval\\(|exec\\(|rm\\s+-rf|malware|virus|hack)");

    public List<String> scanFile(File file) {
        List<String> findings = new ArrayList<>();

        if (!file.canRead()) {
            findings.add("Error: Cannot read file.");
            return findings;
        }

        try (BufferedReader reader = new BufferedReader(new FileReader(file))) {
            String line;
            int lineNumber = 0;
            while ((line = reader.readLine()) != null) {
                lineNumber++;
                checkPattern(line, lineNumber, EMAIL_PATTERN, "Potential Email", findings);
                checkPattern(line, lineNumber, PHONE_PATTERN, "Potential Phone Number", findings);
                checkPattern(line, lineNumber, CREDIT_CARD_PATTERN, "Potential Credit Card", findings);
                checkPattern(line, lineNumber, MALICIOUS_KEYWORD_PATTERN, "Suspicious Keyword", findings);
            }
        } catch (IOException e) {
            findings.add("Error reading file: " + e.getMessage());
        }

        return findings;
    }

    private void checkPattern(String line, int lineNumber, Pattern pattern, String type, List<String> findings) {
        Matcher matcher = pattern.matcher(line);
        if (matcher.find()) {
            findings.add(String.format("[Line %d] %s found: %s", lineNumber, type, matcher.group()));
        }
    }
}