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) 2010, 2011 Wayne Meissner
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
of those above. If you wish to allow use of your version of this file only
under the terms of either the GPL or the LGPL, and not to allow others to
use your version of this file under the terms of the EPL, indicate your
decision by deleting the provisions above and replace them with the notice
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
the terms of any one of the EPL, the GPL or the LGPL.
END LICENSE BLOCK /***** 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) 2010, 2011 Wayne Meissner
 *
 * 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
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the EPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * 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
 * the terms of any one of the EPL, the GPL or the LGPL.
 ***** END LICENSE BLOCK *****/

package org.jruby.ext.ffi;

import java.util.IdentityHashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.jruby.anno.JRubyClass;
import org.jruby.anno.JRubyMethod;
import org.jruby.Ruby;
import org.jruby.RubyArray;
import org.jruby.RubyClass;
import org.jruby.RubyFixnum;
import org.jruby.RubyHash;
import org.jruby.RubyInteger;
import org.jruby.RubyModule;
import org.jruby.RubyObject;
import org.jruby.RubySymbol;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.runtime.ObjectAllocator;
import org.jruby.runtime.ThreadContext;
import org.jruby.runtime.Visibility;

Represents a C enum
/**
 * Represents a C enum
 */
@JRubyClass(name="FFI::Enum", parent="Object")
public final class Enum extends RubyObject {
    private IRubyObject nativeType;
    private final RubyHash kv_map;
    private volatile IRubyObject tag;

    private volatile Map<RubySymbol, RubyInteger> symbolToValue = new IdentityHashMap<RubySymbol, RubyInteger>();
    private volatile ConcurrentHashMap<Long, RubySymbol> valueToSymbol = new ConcurrentHashMap<Long, RubySymbol>();

    public static RubyClass createEnumClass(Ruby runtime, RubyModule ffiModule) {
        RubyClass enumClass = ffiModule.defineClassUnder("Enum", runtime.getObject(),
                Allocator.INSTANCE);
        enumClass.defineAnnotatedMethods(Enum.class);
        enumClass.defineAnnotatedConstants(Enum.class);
        enumClass.includeModule(ffiModule.getConstant("DataConverter"));
        
        return enumClass;
    }

    private static final class Allocator implements ObjectAllocator {
        private static final ObjectAllocator INSTANCE = new Allocator();

        public final IRubyObject allocate(Ruby runtime, RubyClass klass) {
            return new Enum(runtime, klass);
        }
    }

    private Enum(Ruby runtime, RubyClass klass) {
        super(runtime, klass);
        kv_map = RubyHash.newHash(runtime);
        tag = runtime.getNil();
    }

    @JRubyMethod(name = "initialize", visibility = Visibility.PRIVATE)
    public final IRubyObject initialize(ThreadContext context, IRubyObject arg) {
        return initialize(context, null, null, arg);
    }

    @JRubyMethod(name = "initialize", visibility = Visibility.PRIVATE)
    public final IRubyObject initialize(ThreadContext context, IRubyObject arg0, IRubyObject arg1) {
        if (arg0 instanceof org.jruby.ext.ffi.Type)
            return initialize(context, arg0, arg1, null);

        if (arg1.isNil())
            return initialize(context, null, arg0, null);

        // Handles bad args and tag, values case.
        return initialize(context, null, arg0, arg1);
    }

    @JRubyMethod(name = "initialize", visibility = Visibility.PRIVATE)
    public final IRubyObject initialize(ThreadContext context, IRubyObject type, IRubyObject values, IRubyObject tag) {
        int offset = 0;
        if (type instanceof org.jruby.ext.ffi.Type) {
            nativeType = type;
        } else {
            if (!(type == null || type.isNil()))
                throw context.runtime.newTypeError(type, context.runtime.getModule("FFI").getClass("Type"));

            nativeType = context.runtime.getModule("FFI").getClass("Type").getConstant("INT");
        }

        if (!(tag == null || tag.isNil() || tag instanceof RubySymbol))
            throw context.runtime.newTypeError(tag, context.runtime.getSymbol());

        this.tag = tag;

        if (!(values instanceof RubyArray)) {
            throw context.runtime.newTypeError(values, context.runtime.getArray());
        }

        RubyArray ary = (RubyArray) values;

        Map<RubySymbol, RubyInteger> s2v = new IdentityHashMap<RubySymbol, RubyInteger>();
        IRubyObject prevConstant = null;
        long nextValue = 0;

        for (int i = 0; i < ary.size(); i++) {
            IRubyObject v = ary.entry(i);

            if (v instanceof RubySymbol) {
                s2v.put((RubySymbol) v, RubyFixnum.newFixnum(context.runtime, nextValue));
                prevConstant = v;
                nextValue++;

            } else if (v instanceof RubyInteger) {
                if (prevConstant == null) {
                    throw context.runtime.newArgumentError("invalid enum sequence - no symbol for value "
                            + v);
                }
                s2v.put((RubySymbol) prevConstant, (RubyFixnum) v);
                nextValue = ((RubyInteger) v).getLongValue() + 1;

            } else {
                throw context.runtime.newTypeError(v, context.runtime.getSymbol());
            }
        }

        symbolToValue = new IdentityHashMap<RubySymbol, RubyInteger>(s2v);
        valueToSymbol = new ConcurrentHashMap<Long, RubySymbol>(symbolToValue.size());
        for (Map.Entry<RubySymbol, RubyInteger> e : symbolToValue.entrySet()) {
            kv_map.fastASet(e.getKey(), e.getValue());
            valueToSymbol.put(e.getValue().getLongValue(), e.getKey());
        }

        return this;
    }

    @JRubyMethod(name = { "[]", "find" })
    public final IRubyObject find(ThreadContext context, IRubyObject query) {
        if (query instanceof RubySymbol) {
            IRubyObject value = kv_map.fastARef(query);
            return value != null ? value : context.nil;

        } else if (query instanceof RubyInteger) {
            RubySymbol symbol = valueToSymbol.get((Long)((RubyInteger) query).getLongValue());
            return symbol != null ? symbol : context.nil;

        } else {
            return context.nil;
        }
    }

    @JRubyMethod(name = { "symbol_map", "to_h", "to_hash" })
    public final IRubyObject symbol_map(ThreadContext context) {
        return kv_map.dup(context);
    }

    @JRubyMethod(name = { "symbols" })
    public final IRubyObject symbols(ThreadContext context) {
        return kv_map.keys(context);
    }

    @JRubyMethod(name = { "tag" })
    public final IRubyObject tag(ThreadContext context) {
        return tag;
    }

    @JRubyMethod(name = "native_type")
    public final IRubyObject native_type(ThreadContext context) {
        return nativeType;
    }

    @JRubyMethod(name = "to_native")
    public final IRubyObject to_native(ThreadContext context, IRubyObject name, IRubyObject ctx) {
        RubyInteger value;

        if (name instanceof RubyFixnum) {
            return name;

        } else if (name instanceof RubySymbol && (value = symbolToValue.get(name)) != null) {
            return value;

        } else if (name instanceof RubyInteger) {
            return name;

        } else if (name.respondsTo("to_int")) {

            return name.convertToInteger();

        } else {
            throw name.getRuntime().newArgumentError("invalid enum value, " + name.inspect());
        }
    }

    @JRubyMethod(name = "from_native")
    public final IRubyObject from_native(ThreadContext context, IRubyObject value, IRubyObject ctx) {

        RubySymbol sym;

        if (value instanceof RubyInteger && (sym = valueToSymbol.get((Long)((RubyInteger) value).getLongValue())) != null) {
            return sym;
        }

        return value;
    }

    @JRubyMethod(name = "reference_required?")
    public IRubyObject reference_required_p(ThreadContext context) {
        return context.fals;
    }
}