Logger.java

package org.drip.analytics.support;

/*
 * -*- mode: java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 */

/*!
 * Copyright (C) 2020 Lakshmi Krishnamurthy
 * Copyright (C) 2019 Lakshmi Krishnamurthy
 * Copyright (C) 2018 Lakshmi Krishnamurthy
 * Copyright (C) 2017 Lakshmi Krishnamurthy
 * Copyright (C) 2016 Lakshmi Krishnamurthy
 * Copyright (C) 2015 Lakshmi Krishnamurthy
 * Copyright (C) 2014 Lakshmi Krishnamurthy
 * Copyright (C) 2013 Lakshmi Krishnamurthy
 * Copyright (C) 2012 Lakshmi Krishnamurthy
 * Copyright (C) 2011 Lakshmi Krishnamurthy
 * 
 *  This file is part of DROP, an open-source library targeting analytics/risk, transaction cost analytics,
 *      asset liability management analytics, capital, exposure, and margin analytics, valuation adjustment
 *      analytics, and portfolio construction analytics within and across fixed income, credit, commodity,
 *      equity, FX, and structured products. It also includes auxiliary libraries for algorithm support,
 *      numerical analysis, numerical optimization, spline builder, model validation, statistical learning,
 *      and computational support.
 *  
 *      https://lakshmidrip.github.io/DROP/
 *  
 *  DROP is composed of three modules:
 *  
 *  - DROP Product Core - https://lakshmidrip.github.io/DROP-Product-Core/
 *  - DROP Portfolio Core - https://lakshmidrip.github.io/DROP-Portfolio-Core/
 *  - DROP Computational Core - https://lakshmidrip.github.io/DROP-Computational-Core/
 * 
 *  DROP Product Core implements libraries for the following:
 *  - Fixed Income Analytics
 *  - Loan Analytics
 *  - Transaction Cost Analytics
 * 
 *  DROP Portfolio Core implements libraries for the following:
 *  - Asset Allocation Analytics
 *  - Asset Liability Management Analytics
 *  - Capital Estimation Analytics
 *  - Exposure Analytics
 *  - Margin Analytics
 *  - XVA Analytics
 * 
 *  DROP Computational Core implements libraries for the following:
 *  - Algorithm Support
 *  - Computation Support
 *  - Function Analysis
 *  - Model Validation
 *  - Numerical Analysis
 *  - Numerical Optimizer
 *  - Spline Builder
 *  - Statistical Learning
 * 
 *  Documentation for DROP is Spread Over:
 * 
 *  - Main                     => https://lakshmidrip.github.io/DROP/
 *  - Wiki                     => https://github.com/lakshmiDRIP/DROP/wiki
 *  - GitHub                   => https://github.com/lakshmiDRIP/DROP
 *  - Repo Layout Taxonomy     => https://github.com/lakshmiDRIP/DROP/blob/master/Taxonomy.md
 *  - Javadoc                  => https://lakshmidrip.github.io/DROP/Javadoc/index.html
 *  - Technical Specifications => https://github.com/lakshmiDRIP/DROP/tree/master/Docs/Internal
 *  - Release Versions         => https://lakshmidrip.github.io/DROP/version.html
 *  - Community Credits        => https://lakshmidrip.github.io/DROP/credits.html
 *  - Issues Catalog           => https://github.com/lakshmiDRIP/DROP/issues
 *  - JUnit                    => https://lakshmidrip.github.io/DROP/junit/index.html
 *  - Jacoco                   => https://lakshmidrip.github.io/DROP/jacoco/index.html
 * 
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *      you may not use this file except in compliance with the License.
 *   
 *  You may obtain a copy of the License at
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 *  Unless required by applicable law or agreed to in writing, software
 *      distributed under the License is distributed on an "AS IS" BASIS,
 *      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  
 *  See the License for the specific language governing permissions and
 *      limitations under the License.
 */

/**
 * <i>Logger</i> implements level-set logging, backed by either the screen or a file. Logging always includes
 * time stamps, and happens according to the level requested.
 *
 *  <br><br>
 *  <ul>
 *      <li><b>Module </b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/ProductCore.md">Product Core Module</a></li>
 *      <li><b>Library</b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/FixedIncomeAnalyticsLibrary.md">Fixed Income Analytics</a></li>
 *      <li><b>Project</b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/src/main/java/org/drip/analytics/README.md">Date, Cash Flow, and Cash Flow Period Measure Generation Utilities</a></li>
 *      <li><b>Package</b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/src/main/java/org/drip/analytics/support/README.md">Assorted Support and Helper Utilities</a></li>
 *  </ul>
 * 
 * @author Lakshmi Krishnamurthy
 */

public class Logger {

    /**
     * Logger level ERROR
     */

    public static final int ERROR = 0;

    /**
     * Logger level WARNING
     */

    public static final int WARNING = 1;

    /**
     * Logger level INFO
     */

    public static final int INFO = 2;

    /**
     * Logger level DEBUG
     */

    public static final int DEBUG = 4;

    private static boolean s_bInit = false;
    private static java.io.BufferedWriter _writeLog = null;

    private static final java.lang.String ImprintPreSub (
        final int iLevel,
        final java.lang.String strMsg)
    {
        if (null == strMsg || strMsg.isEmpty()) return "";

        java.lang.StringBuilder sb = new java.lang.StringBuilder();

        sb.append ("[").append ((new java.util.Date()).toString()).append ("|Level:").append (iLevel).append
            ("|").append (strMsg).append ("]\n");

        return sb.toString();
    }

    /**
     * Initialize the logger from a configuration file
     * 
     * @param strConfigFile Configuration file containing the logger file location
     * 
     * @return boolean indicating whether initialization succeeded
     */

    public static boolean Init (
        final java.lang.String strConfigFile)
    {
        if (null == strConfigFile || strConfigFile.isEmpty()) return true;

        if (s_bInit) return true;

        try {
            _writeLog = new java.io.BufferedWriter (new java.io.FileWriter
                (org.drip.param.config.ConfigLoader.LoggerLocation (strConfigFile)));

            return s_bInit = true;
        } catch (java.lang.Exception e) {
            e.printStackTrace();
        }

        return s_bInit = false;
    }

    /**
     * Log a specific message to the level
     * 
     * @param iLevel the level of message (ERROR/WARNING/INFO/DEBUG)
     * @param bHardLog whether the logging is to file/DB (true) or to screen (false)
     * @param strMsg Message to be logged
     * 
     * @return boolean indicating whether logging operation succeeded
     */

    public static boolean Log (
        final int iLevel,
        final boolean bHardLog,
        final java.lang.String strMsg)
    {
        if (!s_bInit || null == strMsg || strMsg.isEmpty()) return false;

        if (bHardLog) {
            try {
                _writeLog.write (ImprintPreSub (iLevel, strMsg));

                return true;
            } catch (java.lang.Exception e) {
                e.printStackTrace();
            }

            return false;
        }

        System.out.println (ImprintPreSub (iLevel, strMsg));

        return true;
    }
}