/*
 * Copyright (C) 2015 The Project Lombok Authors.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package lombok.core.debug;

import java.io.FileOutputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.Date;
import java.util.Random;
import java.util.concurrent.atomic.AtomicBoolean;

import lombok.core.Version;

We make a number of assumptions in lombok code, and if these assumptions fail, we try to fall back to a 'least bad' scenario. However, we would prefer to
just know about these cases, without confronting our users with error messages. The 'fix' is to log such assertion failures to this logger, which promptly
ignores them, _unless_ you specifically enable logging them to a file. If you'd like to help out or want to assist in debugging, turn this on.
/**
 * We make a number of assumptions in lombok code, and if these assumptions fail, we try to fall back to a 'least bad' scenario. However, we would prefer to
 * just know about these cases, without confronting our users with error messages. The 'fix' is to log such assertion failures to this logger, which promptly
 * ignores them, _unless_ you specifically enable logging them to a file. If you'd like to help out or want to assist in debugging, turn this on.
 */
public class AssertionLogger {
	private static final String LOG_PATH;
	
	static {
		String log = System.getProperty("lombok.assertion.log", null);
		if (log != null) {
			LOG_PATH = log.isEmpty() ? null : log;
		} else {
			try {
				log = System.getenv("LOMBOK_ASSERTION_LOG");
			} catch (Exception e) {
				log = null;
			}
			LOG_PATH = (log == null || log.isEmpty()) ? null : log;
		}
	}
	
	private static final AtomicBoolean loggedIntro = new AtomicBoolean(false);
	private static final String PROCESS_ID = generateProcessId();
	
	private static final String ID_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
	
	private static String generateProcessId() {
		char[] ID = new char[4];
		Random r = new Random();
		for (int i = 0; i < ID.length; i++) ID[i] = ID_CHARS.charAt(r.nextInt(ID_CHARS.length()));
		return new String(ID);
	}
	
	private static synchronized void logToFile(String msg) {
		if (msg == null) return;
		
		try {
			OutputStream out = new FileOutputStream(LOG_PATH, true);
			out.write(msg.getBytes("UTF-8"));
			out.close();
		} catch (Exception e) {
			throw new RuntimeException("assertion logging can't write to log file", e);
		}
	}
	
	private static void logIntro() {
		if (loggedIntro.getAndSet(true)) return;
		
		String version;
		try {
			version = Version.getFullVersion();
		} catch (Exception e) {
			version = Version.getVersion();
		}
		
		logToFile(String.format("{%s} [%s -- START %s]\n", PROCESS_ID, new Date(), version));
	}
	
	public static <T extends Throwable> T assertLog(String message, T throwable) {
		if (LOG_PATH == null) return throwable;
		
		logIntro();
		
		if (message == null) message = "(No message)";
		String stackMsg = "";
		if (throwable != null) {
			StringWriter sw = new StringWriter();
			PrintWriter pw = new PrintWriter(sw);
			throwable.printStackTrace(pw);
			pw.close();
			stackMsg = "\n  " + sw.toString().replace("\r", "").replace("\n", "\n  ").trim();
		}
		logToFile(String.format("{%s} [%ty%<tm%<tdT%<tH%<tM%<tS.%<tL] %s%s\n", PROCESS_ID, new Date(), message, stackMsg));
		return throwable;
	}
	
	public static void assertLog(String message) {
		if (LOG_PATH == null) return;
		assertLog(message, null);
	}
}