import java.util.HashMap;

import java.util.Map;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

public class LogMapper {

/**

* Maps log fields from a log line using regex.

* @param logLine The log line to parse.

* @param fieldRegex A map where keys are field names and values are regex patterns.

* @return A map containing the extracted field values, or null if parsing fails.

*/

public static Map<String, String> mapLogFields(String logLine, Map<String, String> fieldRegex) {

Map<String, String> fields = new HashMap<>();

if (logLine == null || logLine.isEmpty() || fieldRegex == null || fieldRegex.isEmpty()) {

return null; // Handle null or empty input

}

for (Map.Entry<String, String> entry : fieldRegex.entrySet()) {

String fieldName = entry.getKey();

String regex = entry.getValue();

Pattern pattern = Pattern.compile(regex);

Matcher matcher = pattern.matcher(logLine);

if (matcher.find()) {

fields.put(fieldName, matcher.group());

} else {

// Field not found in the log line

fields.put(fieldName, null); // Or handle missing fields differently (e.g., throw an exception)

}

}

return fields;

}

public static void main(String[] args) {

// Example Usage

String logLine = "2023-10-27 10:00:00 [INFO] User: John Doe, ID: 12345 - Message: User logged in";

Map<String, String> fieldRegex = new HashMap<>();

fieldRegex.put("timestamp", "(\\d{4}-\\d{2}-\\d{2} \\d{2}:\\d{2}:\\d{2})");

fieldRegex.put("level", "\[(\\w+)\]");

fieldRegex.put("user", "User: (\\w+ \\w+)");

fieldRegex.put("id", "ID: \\d+");

fieldRegex.put("message", "Message: (.*)");

Map<String, String> mappedFields = mapLogFields(logLine, fieldRegex);

if (mappedFields != null) {

System.out.println(mappedFields);

} else {

System.out.println("Error: Invalid log line or field regex.");

}

}

}