/*
 * Copyright (C) 2011-2013 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.javac;

import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.lang.reflect.Field;
import java.util.LinkedList;
import java.util.Map;
import java.util.Queue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import javax.tools.DiagnosticListener;
import javax.tools.JavaFileObject;

import com.sun.tools.javac.util.Context;
import com.sun.tools.javac.util.JCDiagnostic;
import com.sun.tools.javac.util.ListBuffer;
import com.sun.tools.javac.util.Log;

import lombok.permit.Permit;

During resolution, the resolver will emit resolution errors, but without appropriate file names and line numbers. If these resolution errors stick around
then they will be generated AGAIN, this time with proper names and line numbers, at the end. Therefore, we want to suppress the logger.
/**
 * During resolution, the resolver will emit resolution errors, but without appropriate file names and line numbers. If these resolution errors stick around
 * then they will be generated AGAIN, this time with proper names and line numbers, at the end. Therefore, we want to suppress the logger.
 */
public final class CompilerMessageSuppressor {
	
	private final Log log;
	private static final WriterField errWriterField, warnWriterField, noticeWriterField;
	private static final Field dumpOnErrorField, promptOnErrorField, diagnosticListenerField;
	private static final Field deferDiagnosticsField, deferredDiagnosticsField, diagnosticHandlerField;
	private static final ConcurrentMap<Class<?>, Field> handlerDeferredFields = new ConcurrentHashMap<Class<?>, Field>();
	private static final Field NULL_FIELD;
	private Boolean dumpOnError, promptOnError;
	private DiagnosticListener<?> contextDiagnosticListener, logDiagnosticListener;
	private final Context context;
	
	private static final ThreadLocal<Queue<?>> queueCache = new ThreadLocal<Queue<?>>();
	
	enum Writers {
		ERROR("errWriter", "ERROR"),
		WARNING("warnWriter", "WARNING"),
		NOTICE("noticeWriter", "NOTICE");
		
		final String fieldName;
		final String keyName;
		
		Writers(String fieldName, String keyName) {
			this.fieldName = fieldName;
			this.keyName = keyName;
		}
	}
	
	static {
		errWriterField = createWriterField(Writers.ERROR);
		warnWriterField = createWriterField(Writers.WARNING);
		noticeWriterField = createWriterField(Writers.NOTICE);
		dumpOnErrorField = getDeclaredField(Log.class, "dumpOnError");
		promptOnErrorField = getDeclaredField(Log.class, "promptOnError");
		diagnosticListenerField = getDeclaredField(Log.class, "diagListener");
		deferDiagnosticsField = getDeclaredField(Log.class, "deferDiagnostics");
		deferredDiagnosticsField = getDeclaredField(Log.class, "deferredDiagnostics");
		
		// javac8
		diagnosticHandlerField = getDeclaredField(Log.class, "diagnosticHandler");
		
		NULL_FIELD = getDeclaredField(JavacResolution.class, "NULL_FIELD");
	}
	
	static Field getDeclaredField(Class<?> c, String fieldName) {
		try {
			return Permit.getField(c, fieldName);
		} catch (Throwable t) {
			return null;
		}
	}
	
	public CompilerMessageSuppressor(Context context) {
		this.log = Log.instance(context);
		this.context = context;
	}
	
	public void disableLoggers() {
		contextDiagnosticListener = context.get(DiagnosticListener.class);
		context.put(DiagnosticListener.class, (DiagnosticListener<?>) null);

		errWriterField.pauze(log);
		warnWriterField.pauze(log);
		noticeWriterField.pauze(log);
		
		if (deferDiagnosticsField != null) try {
			if (Boolean.TRUE.equals(deferDiagnosticsField.get(log))) {
				queueCache.set((Queue<?>) deferredDiagnosticsField.get(log));
				Queue<?> empty = new LinkedList<Object>();
				deferredDiagnosticsField.set(log, empty);
			}
		} catch (Exception e) {}
		
		if (diagnosticHandlerField != null) try {
			Object handler = diagnosticHandlerField.get(log);
			Field field = getDeferredField(handler);
			if (field != null) {
				queueCache.set((Queue<?>) field.get(handler));
				Queue<?> empty = new LinkedList<Object>();
				field.set(handler, empty);
			}
		} catch (Exception e) {}
		
		if (dumpOnErrorField != null) try {
			dumpOnError = (Boolean) dumpOnErrorField.get(log);
			dumpOnErrorField.set(log, false);
		} catch (Exception e) {
		}
		
		if (promptOnErrorField != null) try {
			promptOnError = (Boolean) promptOnErrorField.get(log);
			promptOnErrorField.set(log, false);
		} catch (Exception e) {
		}
		
		if (diagnosticListenerField != null) try {
			logDiagnosticListener = (DiagnosticListener<?>) diagnosticListenerField.get(log);
			diagnosticListenerField.set(log, null);
		} catch (Exception e) {
		}
	}
	
	private static Field getDeferredField(Object handler) {
		Class<? extends Object> key = handler.getClass();
		Field field = handlerDeferredFields.get(key);
		if (field != null) {
			return field == NULL_FIELD ? null : field;
		}
		Field value = getDeclaredField(key, "deferred");
		handlerDeferredFields.put(key, value == null ? NULL_FIELD : value);
		return getDeferredField(handler);
	}

	public void enableLoggers() {
		if (contextDiagnosticListener != null) {
			context.put(DiagnosticListener.class, contextDiagnosticListener);
			contextDiagnosticListener = null;
		}
		
		errWriterField.resume(log);
		warnWriterField.resume(log);
		noticeWriterField.resume(log);
		
		if (dumpOnError != null) try {
			dumpOnErrorField.set(log, dumpOnError);
			dumpOnError = null;
		} catch (Exception e) {}
		
		if (promptOnError != null) try {
			promptOnErrorField.set(log, promptOnError);
			promptOnError = null;
		} catch (Exception e) {}
		
		if (logDiagnosticListener != null) try {
			diagnosticListenerField.set(log, logDiagnosticListener);
			logDiagnosticListener = null;
		} catch (Exception e) {}
		
		if (diagnosticHandlerField != null && queueCache.get() != null) try {
			Object handler = diagnosticHandlerField.get(log);
			Field field = getDeferredField(handler);
			if (field != null) {
				field.set(handler, queueCache.get());
				queueCache.set(null);
			}
		} catch (Exception e) {}
		
		if (deferDiagnosticsField != null && queueCache.get() != null) try {
			deferredDiagnosticsField.set(log, queueCache.get());
			queueCache.set(null);
		} catch (Exception e) {}
	}
	
	public void removeAllBetween(JavaFileObject sourcefile, int startPos, int endPos) {
		DiagnosticListener<?> listener = context.get(DiagnosticListener.class);
		if (listener instanceof CapturingDiagnosticListener) {
			((CapturingDiagnosticListener) listener).suppress(startPos, endPos);
		}
		
		Field field = null;
		Object receiver = null;
		if (deferDiagnosticsField != null) try {
			if (Boolean.TRUE.equals(deferDiagnosticsField.get(log))) {
				field = deferredDiagnosticsField;
				receiver = log;
			}
		} catch (Exception e) {}
		
		if (diagnosticHandlerField != null) try {
			Object handler = diagnosticHandlerField.get(log);
			field = getDeferredField(handler);
			receiver = handler;
		} catch (Exception e) {}
		
		if (field == null || receiver == null) return;
		
		try {
			ListBuffer<?> deferredDiagnostics = (ListBuffer<?>) field.get(receiver);
			ListBuffer<Object> newDeferredDiagnostics = new ListBuffer<Object>();
			for (Object diag_ : deferredDiagnostics) {
				if (!(diag_ instanceof JCDiagnostic)) {
					newDeferredDiagnostics.add(diag_);
					continue;
				}
				JCDiagnostic diag = (JCDiagnostic) diag_;
				long here = diag.getStartPosition();
				if (here >= startPos && here < endPos && diag.getSource() == sourcefile) {
					// We eliminate it
				} else {
					newDeferredDiagnostics.add(diag);
				}
			}
			field.set(receiver, newDeferredDiagnostics);
		} catch (Exception e) {
			// We do not expect failure here; if failure does occur, the best course of action is to silently continue; the result will be that the error output of
			// javac will contain rather a lot of messages, but this is a lot better than just crashing during compilation!
		}
	}
	
	private static WriterField createWriterField(Writers w) {
		// jdk9
		try {
			Field writers = getDeclaredField(Log.class, "writer");
			if (writers != null) {
				Class<?> kindsClass = Class.forName("com.sun.tools.javac.util.Log$WriterKind");
				for (Object enumConstant : kindsClass.getEnumConstants()) {
					if (enumConstant.toString().equals(w.keyName)) {
						return new Java9WriterField(writers, enumConstant);
					}
				}
				return WriterField.NONE;
			}
		} catch (Exception e) {
		}
		
		// jdk8
		Field writerField = getDeclaredField(Log.class, w.fieldName);
		if (writerField != null) return new Java8WriterField(writerField);
		
		// other jdk
		return WriterField.NONE;
	}
	
	interface WriterField {
		final PrintWriter NO_WRITER = new PrintWriter(new OutputStream() {
			@Override public void write(int b) throws IOException {
				// Do nothing on purpose
			}
		});

		final WriterField NONE = new WriterField() {
			@Override public void pauze(Log log) {
				// do nothing
			}
			@Override public void resume(Log log) {
				// no nothing
			}
		};
		
		void pauze(Log log);
		void resume(Log log);
	}
	
	static class Java8WriterField implements WriterField {
		private final Field field;
		private PrintWriter writer;
		
		public Java8WriterField(Field field) {
			this.field = field;
		}

		@Override public void pauze(Log log) {
			try {
				writer = (PrintWriter) field.get(log);
				field.set(log, NO_WRITER);
			} catch (Exception e) {
			}
		}

		@Override public void resume(Log log) {
			if (writer != null) {
				try {
					field.set(log, writer);
				} catch (Exception e) {
				}
			}
			writer = null;
		}
	}
	
	
	static class Java9WriterField implements WriterField {
		private final Field field;
		private final Object key;
		private PrintWriter writer;
		
		public Java9WriterField(Field field, Object key) {
			this.field = field;
			this.key = key;
		}
		
		@Override public void pauze(Log log) {
			try {
				@SuppressWarnings("unchecked") Map<Object,PrintWriter> map = (Map<Object,PrintWriter>)field.get(log);
				writer = map.get(key);
				map.put(key, NO_WRITER);
			} catch (Exception e) {
			}
		}
		
		@Override public void resume(Log log) {
			if (writer != null) {
				try {
					@SuppressWarnings("unchecked") Map<Object,PrintWriter> map = (Map<Object,PrintWriter>)field.get(log);
					map.put(key, writer);
				} catch (Exception e) {
				}
			}
			writer = null;
		}
	}
}