/***** BEGIN LICENSE BLOCK *****
 * Version: EPL 2.0/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Eclipse Public
 * 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.eclipse.org/legal/epl-v20.html
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * Copyright (C) 2001 Alan Moore <alan_moore@gmx.net>
 * Copyright (C) 2001-2004 Jan Arne Petersen <jpetersen@uni-bonn.de>
 * Copyright (C) 2002 Benoit Cerrina <b.cerrina@wanadoo.fr>
 * Copyright (C) 2002-2004 Anders Bengtsson <ndrsbngtssn@yahoo.se>
 * Copyright (C) 2002-2006 Thomas E Enebo <enebo@acm.org>
 * Copyright (C) 2004 Joey Gibson <joey@joeygibson.com>
 * Copyright (C) 2004-2005 Charles O Nutter <headius@headius.com>
 * Copyright (C) 2004 Stefan Matthias Aust <sma@3plus4.de>
 * Copyright (C) 2005 David Corbin <dcorbin@users.sf.net>
 * Copyright (C) 2006 Michael Studman <codehaus@michaelstudman.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
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 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
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 ***** END LICENSE BLOCK *****/

package org.jruby;

import org.jruby.anno.JRubyClass;
import org.jruby.anno.JRubyMethod;
import org.jruby.exceptions.Exception;
import org.jruby.exceptions.JumpException.FlowControlException;
import org.jruby.exceptions.RaiseException;
import org.jruby.java.proxies.ConcreteJavaProxy;
import org.jruby.runtime.*;
import org.jruby.runtime.backtrace.BacktraceData;
import org.jruby.runtime.backtrace.RubyStackTraceElement;
import org.jruby.runtime.backtrace.TraceType;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.runtime.builtin.Variable;
import org.jruby.runtime.component.VariableEntry;
import org.jruby.runtime.marshal.MarshalStream;
import org.jruby.runtime.marshal.UnmarshalStream;

import java.io.IOException;
import java.io.PrintStream;
import java.util.List;

import static org.jruby.runtime.Visibility.PRIVATE;
import static org.jruby.util.RubyStringBuilder.str;

/**
 *
 * @author  jpetersen
 */
@JRubyClass(name="Exception")
public class RubyException extends RubyObject {

    private static class Backtrace {
        private BacktraceData backtraceData;
        private IRubyObject backtraceObject;
        private IRubyObject backtraceLocations;

        public void copy(Backtrace clone) {
            this.backtraceData = clone.backtraceData;
            this.backtraceObject = clone.backtraceObject;
            this.backtraceLocations = clone.backtraceLocations;
        }

        /**
         * Generate a new backtrace (or returns nil if no backtrace data exists).
         * @param runtime
         * @return the generated Ruby backtrace
         */
        public IRubyObject generateBacktrace(Ruby runtime) {
            final BacktraceData backtraceData = this.backtraceData;
            if (backtraceData == null || backtraceData == BacktraceData.EMPTY) return runtime.getNil();
            return TraceType.generateMRIBacktrace(runtime, backtraceData.getBacktrace(runtime));
        }

        /**
         * Generate an array of backtrace location objects for this backtrace.
         *
         * @param context the current thread context
         * @return the array of backtrace locations
         */
        public IRubyObject generateBacktraceLocations(ThreadContext context) {
            final BacktraceData backtraceData = this.backtraceData;
            if (backtraceData == null) return context.nil;

            final Ruby runtime = context.runtime;
            return RubyThread.Location.newLocationArray(runtime, backtraceData.getBacktrace(runtime));
        }
    }

    public static final int TRACE_HEAD = 8;
    public static final int TRACE_TAIL = 4;
    public static final int TRACE_MAX = RubyException.TRACE_HEAD + RubyException.TRACE_TAIL + 6;

    private final Backtrace backtrace = new Backtrace();

    IRubyObject message;
    private IRubyObject cause = null;
    private RaiseException throwable;

    protected RubyException(Ruby runtime, RubyClass rubyClass) {
        super(runtime, rubyClass);
    }

    public RubyException(Ruby runtime, RubyClass rubyClass, String message) {
        super(runtime, rubyClass);

        this.setMessage(message == null ? runtime.getNil() : runtime.newString(message));
    }

    @JRubyMethod(name = "exception", optional = 1, rest = true, meta = true)
    public static IRubyObject exception(ThreadContext context, IRubyObject recv, IRubyObject[] args, Block block) {
        return ((RubyClass) recv).newInstance(context, args, block);
    }

    @JRubyMethod(name = "===", meta = true)
    public static IRubyObject op_eqq(ThreadContext context, IRubyObject recv, IRubyObject other) {
        Ruby runtime = context.runtime;
        // special case non-FlowControlException Java exceptions so they'll be caught by rescue Exception
        if (other instanceof ConcreteJavaProxy &&
                (recv == runtime.getException() || recv == runtime.getStandardError())) {

            Object object = ((ConcreteJavaProxy)other).getObject();
            if (object instanceof Throwable && !(object instanceof FlowControlException)) {
                if (recv == runtime.getException() || object instanceof java.lang.Exception) {
                    return context.tru;
                }
            }
        }
        // fall back on default logic
        return ((RubyClass)recv).op_eqq(context, other);
    }

    protected RaiseException constructThrowable(String message) {
        return new Exception(message, this);
    }

    public static RubyClass createExceptionClass(Ruby runtime) {
        RubyClass exceptionClass = runtime.defineClass("Exception", runtime.getObject(), EXCEPTION_ALLOCATOR);

        exceptionClass.setClassIndex(ClassIndex.EXCEPTION);
        exceptionClass.setReifiedClass(RubyException.class);

        exceptionClass.setMarshal(EXCEPTION_MARSHAL);
        exceptionClass.defineAnnotatedMethods(RubyException.class);

        return exceptionClass;
    }

    public static ObjectAllocator EXCEPTION_ALLOCATOR = (runtime, klass) -> new RubyException(runtime, klass);

    private static final ObjectMarshal<RubyException> EXCEPTION_MARSHAL = new ObjectMarshal<RubyException>() {
        @Override
        public void marshalTo(Ruby runtime, RubyException exc, RubyClass type,
                              MarshalStream marshalStream) throws IOException {
            marshalStream.registerLinkTarget(exc);
            List<Variable<Object>> attrs = exc.getVariableList();
            attrs.add(new VariableEntry<>("mesg", exc.getMessage()));
            attrs.add(new VariableEntry<>("bt", exc.getBacktrace()));
            marshalStream.dumpVariables(attrs);
        }

        @Override
        public RubyException unmarshalFrom(Ruby runtime, RubyClass type,
                                           UnmarshalStream unmarshalStream) throws IOException {
            RubyException exc = (RubyException) type.allocate();

            unmarshalStream.registerLinkTarget(exc);
            // FIXME: Can't just pull these off the wire directly? Or maybe we should
            // just use real vars all the time for these?
            unmarshalStream.defaultVariablesUnmarshal(exc);

            exc.setMessage((IRubyObject) exc.removeInternalVariable("mesg"));
            exc.set_backtrace((IRubyObject) exc.removeInternalVariable("bt"));

            return exc;
        }
    };

    public static RubyException newException(Ruby runtime, RubyClass exceptionClass, String msg) {
        if (msg == null) {
            msg = "No message available";
        }

        return (RubyException) exceptionClass.newInstance(runtime.getCurrentContext(), RubyString.newString(runtime, msg), Block.NULL_BLOCK);
    }

    public static RubyException newException(ThreadContext context, RubyClass exceptionClass, RubyString message) {
        return (RubyException) exceptionClass.newInstance(context, message, Block.NULL_BLOCK);
    }

    @Deprecated
    public static IRubyObject newException(ThreadContext context, RubyClass exceptionClass, IRubyObject message) {
        return newException(context, exceptionClass, message.convertToString());
    }

    @JRubyMethod
    public IRubyObject full_message(ThreadContext context) {
        return full_message(context, null);
    }

    @JRubyMethod
    public IRubyObject full_message(ThreadContext context, IRubyObject opts) {
        return RubyString.newString(context.runtime, TraceType.printFullMessage(context, this, opts));
    }

    @JRubyMethod(optional = 2, visibility = PRIVATE)
    public IRubyObject initialize(IRubyObject[] args, Block block) {
        if ( args.length == 1 ) setMessage(args[0]);
        // cause filled in at RubyKernel#raise ... Exception.new does not fill-in cause!
        return this;
    }

    @JRubyMethod
    public IRubyObject backtrace() {
        return getBacktrace();
    }

    @JRubyMethod(required = 1)
    public IRubyObject set_backtrace(IRubyObject obj) {
        setBacktrace(obj);
        return backtrace();
    }

    public void setBacktrace(IRubyObject obj) {
        if (obj.isNil() || isArrayOfStrings(obj)) {
            backtrace.backtraceObject = obj;
        } else if (obj instanceof RubyString) {
            backtrace.backtraceObject = RubyArray.newArray(getRuntime(), obj);
        } else {
            throw getRuntime().newTypeError("backtrace must be Array of String");
        }
    }

    @JRubyMethod(omit = true)
    public IRubyObject backtrace_locations(ThreadContext context) {
        IRubyObject backtraceLocations = backtrace.backtraceLocations;
        if (backtraceLocations != null) return backtraceLocations;
        return backtrace.backtraceLocations = backtrace.generateBacktraceLocations(context);
    }

    @JRubyMethod(optional = 1)
    public RubyException exception(IRubyObject[] args) {
        switch (args.length) {
            case 0 :
                return this;
            case 1 :
                if (args[0] == this) return this;
                RubyException ret = (RubyException) rbClone();
                ret.initialize(args, Block.NULL_BLOCK); // This looks wrong, but it's the way MRI does it.
                return ret;
            default :
                throw getRuntime().newArgumentError("Wrong argument count");
        }
    }

    @JRubyMethod(name = "to_s")
    public IRubyObject to_s(ThreadContext context) {
        final IRubyObject msg = getMessage();
        if ( ! msg.isNil() ) return msg.asString();
        return context.runtime.newString(getMetaClass().getRealClass().getName());
    }

    @Deprecated
    public IRubyObject to_s19(ThreadContext context) { return to_s(context); }

    @JRubyMethod(name = "message")
    public IRubyObject message(ThreadContext context) {
        return callMethod(context, "to_s");
    }

    /** inspects an object and return a kind of debug information
     *
     *@return A RubyString containing the debug information.
     */
    @JRubyMethod(name = "inspect")
    public RubyString inspect(ThreadContext context) {
        // rb_class_name skips intermediate classes (JRUBY-6786)
        RubyString rubyClass = getMetaClass().getRealClass().rubyName();
        RubyString exception = RubyString.objAsString(context, this);

        if (exception.isEmpty()) return rubyClass;

        return RubyString.newString(context.runtime, str(context.runtime, "#<", rubyClass, ": ", exception, ">"));
    }

    @Override
    @JRubyMethod(name = "==")
    public RubyBoolean op_equal(ThreadContext context, IRubyObject other) {
        if (this == other) return context.tru;

        boolean equal = context.runtime.getException().isInstance(other) &&
                getMetaClass().getRealClass() == other.getMetaClass().getRealClass() &&
                callMethod(context, "message").equals(other.callMethod(context, "message")) &&
                callMethod(context, "backtrace").equals(other.callMethod(context, "backtrace"));
        return RubyBoolean.newBoolean(context, equal);
    }

    @JRubyMethod(name = "cause")
    public IRubyObject cause(ThreadContext context) {
        return cause == null ? context.nil : cause;
    }

    /**
     * Coerce this Ruby exception to the requested Java type, if possible.
     *
     * If the requested type is a supertype of RaiseException, the attached throwable will be returned.
     *
     * Otherwise, it will fall back on RubyBasicObject toJava logic.
     *
     * @param target the target type to which this object should be converted
     * @return the converted result
     */
    @Override
    public <T> T toJava(Class<T> target) {
        if (target != Object.class && target.isAssignableFrom(RaiseException.class)) {
            return target.cast(toThrowable());
        }
        return super.toJava(target);
    }

    /**
     * Get a throwable suitable for throwing in Java.
     *
     * The throwable here will be constructed lazily by calling constructThrowable and then cached for future calls.
     *
     * All throwables returned by Ruby exception objects will descend from RaiseException and follow the Throwable
     * hierarchy below {@link Exception}
     * @return
     */
    public RaiseException toThrowable() {
        if (throwable == null) {
            return throwable = constructThrowable(getMessageAsJavaString());
        }
        return throwable;
    }

    public void setCause(IRubyObject cause) {
        this.cause = cause;
    }

    // NOTE: can not have IRubyObject as NativeException has getCause() returning Throwable
    public Object getCause() {
        return cause;
    }

    public RubyStackTraceElement[] getBacktraceElements() {
        if (backtrace.backtraceData == null) {
            return RubyStackTraceElement.EMPTY_ARRAY;
        }
        return backtrace.backtraceData.getBacktrace(getRuntime());
    }

    public void captureBacktrace(ThreadContext context) {
        backtrace.backtraceData = context.runtime.getInstanceConfig().getTraceType().getBacktrace(context);
    }

    public IRubyObject getBacktrace() {
        IRubyObject backtraceObject = backtrace.backtraceObject;
        if (backtraceObject != null) return backtraceObject;

        return backtrace.backtraceObject = backtrace.generateBacktrace(getRuntime());
    }

    /**
     * Retrieve the current backtrace object for a given exception.
     * @param exception
     * @return set (or already generated) backtrace, null otherwise
     * @note Internal API.
     */
    public static IRubyObject retrieveBacktrace(RubyException exception) {
        return exception.backtrace.backtraceObject;
    }

    @Override
    public void copySpecialInstanceVariables(IRubyObject clone) {
        RubyException exception = (RubyException)clone;
        exception.backtrace.copy(backtrace);
        exception.message = message;
    }

    /**
     * Print the Ruby exception's backtrace to the given PrintStream.
     *
     * @param errorStream the PrintStream to which backtrace should be printed
     */
    public void printBacktrace(PrintStream errorStream) {
        printBacktrace(errorStream, 0);
    }

    /**
     * Print the Ruby exception's backtrace to the given PrintStream. This
     * version accepts a number of lines to skip and is primarily used
     * internally for exception printing where the first line is treated specially.
     *
     * @param errorStream the PrintStream to which backtrace should be printed
     */
    public void printBacktrace(PrintStream errorStream, int skip) {
        IRubyObject trace = callMethod(getRuntime().getCurrentContext(), "backtrace");
        TraceType.printBacktraceToStream(trace, errorStream, skip);
    }

    private boolean isArrayOfStrings(IRubyObject backtrace) {
        if (!(backtrace instanceof RubyArray)) return false;

        final RubyArray rTrace = ((RubyArray) backtrace);

        for (int i = 0 ; i < rTrace.getLength() ; i++) {
            if (!(rTrace.eltInternal(i) instanceof RubyString)) return false;
        }

        return true;
    }

     /**
     * @return error message if provided or nil
     */
    public IRubyObject getMessage() {
        return message == null ? getRuntime().getNil() : message;
    }

    /**
     * Set the message for this NameError.
     * @param message the message
     */
    public void setMessage(IRubyObject message) {
        this.message = message;
    }

    public String getMessageAsJavaString() {
        final IRubyObject msg = getMessage();
        return msg.isNil() ? null : msg.toString();
    }

    // Note: we override this because we do not use traditional internal variables (concurrency complications)
    // for a few fields but MRI does.  Both marshal and oj (native extensions) expect to see these.
    @Override
    public List<Variable<Object>> getVariableList() {
        List<Variable<Object>> attrs = super.getVariableList();

        attrs.add(new VariableEntry<>("mesg", getMessage()));
        IRubyObject backtrace = getBacktrace();
        attrs.add(new VariableEntry<>("bt", backtrace));

        return attrs;
    }

    @Override
    public List<String> getVariableNameList() {
        List<String> names = super.getVariableNameList();

        names.add("mesg");
        names.add("bt");

        return names;
    }

    @Deprecated
    public void prepareIntegratedBacktrace(ThreadContext context, StackTraceElement[] javaTrace) {
        // if it's null, build a backtrace
        if (backtrace.backtraceData == null) {
            backtrace.backtraceData = context.runtime.getInstanceConfig().getTraceType().getIntegratedBacktrace(context, javaTrace);
        }
    }
}
