/***** 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) 2001-2004 Jan Arne Petersen <jpetersen@uni-bonn.de>
 * Copyright (C) 2002 Benoit Cerrina <b.cerrina@wanadoo.fr>
 * Copyright (C) 2004 Anders Bengtsson <ndrsbngtssn@yahoo.se>
 * Copyright (C) 2004 Stefan Matthias Aust <sma@3plus4.de>
 * Copyright (C) 2005 Charles O Nutter <headius@headius.com>
 * Copyright (C) 2006 Miguel Covarrubias <mlcovarrubias@gmail.com>
 * Copyright (C) 2006 Thomas E Enebo <enebo@acm.org>
 *
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package org.jruby;

import org.jruby.anno.JRubyMethod;
import org.jruby.anno.JRubyModule;
import org.jruby.runtime.CallSite;
import org.jruby.runtime.JavaSites.ComparableSites;
import org.jruby.runtime.ThreadContext;
import org.jruby.runtime.builtin.IRubyObject;

import static org.jruby.runtime.Helpers.invokedynamic;

/** Implementation of the Comparable module.
 *
 */
@JRubyModule(name="Comparable")
public class RubyComparable {
    public static RubyModule createComparable(Ruby runtime) {
        RubyModule comparableModule = runtime.defineModule("Comparable");
        runtime.setComparable(comparableModule);

        comparableModule.defineAnnotatedMethods(RubyComparable.class);

        return comparableModule;
    }

    /*  ================
     *  Utility Methods
     *  ================
     */

    /** rb_cmpint
     *
     */
    public static int cmpint(ThreadContext context, CallSite op_gt, CallSite op_lt, IRubyObject val, IRubyObject a, IRubyObject b) {
        if (val == context.nil) cmperr(a, b);
        if (val instanceof RubyFixnum) {
            final int asInt = RubyNumeric.fix2int((RubyFixnum) val);

            if (asInt > 0) {
                return 1;
            }

            if (asInt < 0) {
                return -1;
            }

            return 0;
        }
        if (val instanceof RubyBignum) return ((RubyBignum) val).signum() == -1 ? -1 : 1;

        RubyFixnum zero = RubyFixnum.zero(context.runtime);

        if (op_gt.call(context, val, val, zero).isTrue()) return 1;
        if (op_lt.call(context, val, val, zero).isTrue()) return -1;

        return 0;
    }

    public static int cmpint(ThreadContext context, IRubyObject val, IRubyObject a, IRubyObject b) {
        ComparableSites sites = sites(context);
        return cmpint(context, sites.op_gt, sites.op_lt, val, a, b);
    }

    public static int cmpAndCmpint(ThreadContext context, IRubyObject a, IRubyObject b) {
        IRubyObject cmpResult = sites(context).op_cmp.call(context, a, a, b);
        return cmpint(context, cmpResult, a, b);
    }

    public static int cmpAndCmpint(ThreadContext context, CallSite op_cmp, CallSite op_gt, CallSite op_lt, IRubyObject a, IRubyObject b) {
        IRubyObject cmpResult = op_cmp.call(context, a, a, b);
        return cmpint(context, op_gt, op_lt, cmpResult, a, b);
    }

    /** rb_cmperr
     *
     */
    public static IRubyObject cmperr(IRubyObject recv, IRubyObject other) {
        IRubyObject target;
        if (other.isImmediate() || !(other.isNil() || other.isTrue() || other == recv.getRuntime().getFalse())) {
            target = other.inspect();
        } else {
            target = other.getType();
        }

        throw recv.getRuntime().newArgumentError("comparison of " + recv.getType() + " with " + target + " failed");
    }

    /** rb_invcmp
     *
     */
    public static IRubyObject invcmp(final ThreadContext context, final IRubyObject recv, final IRubyObject other) {
        return invcmp(context, DEFAULT_INVCMP, recv, other);
    }

    private static final ThreadContext.RecursiveFunctionEx DEFAULT_INVCMP = new ThreadContext.RecursiveFunctionEx<IRubyObject>() {
        @Override
        public IRubyObject call(ThreadContext context, IRubyObject recv, IRubyObject other, boolean recur) {
            if (recur || !sites(context).respond_to_op_cmp.respondsTo(context, other, other)) return context.nil;
            return sites(context).op_cmp.call(context, other, other, recv);
        }
    };

    /** rb_invcmp
     *
     */
    public static IRubyObject invcmp(final ThreadContext context, ThreadContext.RecursiveFunctionEx func, IRubyObject recv, IRubyObject other) {
        IRubyObject result = context.safeRecurse(func, recv, other, "<=>", true);

        if (result.isNil()) return result;
        return RubyFixnum.newFixnum(context.runtime, -cmpint(context, result, recv, other));
    }

    /*  ================
     *  Module Methods
     *  ================
     */

    /** cmp_equal (cmp_eq inlined here)
     *
     */
    @JRubyMethod(name = "==", required = 1)
    public static IRubyObject op_equal(ThreadContext context, IRubyObject recv, IRubyObject other) {
        return callCmpMethod(context, recv, other, context.fals);
    }

    @Deprecated
    public static IRubyObject op_equal19(ThreadContext context, IRubyObject recv, IRubyObject other) {
        return op_equal(context, recv, other);
    }

    private static IRubyObject callCmpMethod(final ThreadContext context, final IRubyObject recv, final IRubyObject other, IRubyObject returnValueOnError) {
        final Ruby runtime = context.runtime;

        if (recv == other) return context.tru;

        IRubyObject result = context.safeRecurse(CMP_RECURSIVE, other, recv, "<=>", true);

        // This is only to prevent throwing exceptions by cmperr - it has poor performance
        if ( result.isNil() ) return returnValueOnError;

        return RubyBoolean.newBoolean(runtime, cmpint(context, result, recv, other) == 0);
    }

    /** cmp_gt
     *
     */
    // <=> may return nil in many circumstances, e.g. 3 <=> NaN
    @JRubyMethod(name = ">", required = 1)
    public static RubyBoolean op_gt(ThreadContext context, IRubyObject recv, IRubyObject other) {
        IRubyObject result = sites(context).op_cmp.call(context, recv, recv, other);

        if (result.isNil()) cmperr(recv, other);

        return RubyBoolean.newBoolean(context.runtime, cmpint(context, result, recv, other) > 0);
    }

    /** cmp_ge
     *
     */
    @JRubyMethod(name = ">=", required = 1)
    public static RubyBoolean op_ge(ThreadContext context, IRubyObject recv, IRubyObject other) {
        IRubyObject result = sites(context).op_cmp.call(context, recv, recv, other);

        if (result.isNil()) cmperr(recv, other);

        return RubyBoolean.newBoolean(context.runtime, cmpint(context, result, recv, other) >= 0);
    }

    /** cmp_lt
     *
     */
    @JRubyMethod(name = "<", required = 1)
    public static RubyBoolean op_lt(ThreadContext context, IRubyObject recv, IRubyObject other) {
        IRubyObject result = sites(context).op_cmp.call(context, recv, recv, other);

        if (result.isNil()) cmperr(recv, other);

        return RubyBoolean.newBoolean(context.runtime, cmpint(context, result, recv, other) < 0);
    }

    public static RubyBoolean op_lt(ThreadContext context, CallSite cmp, IRubyObject recv, IRubyObject other) {
        IRubyObject result = cmp.call(context, recv, recv, other);

        if (result.isNil()) cmperr(recv, other);

        return RubyBoolean.newBoolean(context.runtime, cmpint(context, result, recv, other) < 0);
    }

    /** cmp_le
     *
     */
    @JRubyMethod(name = "<=", required = 1)
    public static RubyBoolean op_le(ThreadContext context, IRubyObject recv, IRubyObject other) {
        IRubyObject result = sites(context).op_cmp.call(context, recv, recv, other);

        if (result.isNil()) cmperr(recv, other);

        return RubyBoolean.newBoolean(context.runtime, cmpint(context, result, recv, other) <= 0);
    }

    /** cmp_between
     *
     */
    @JRubyMethod(name = "between?", required = 2)
    public static RubyBoolean between_p(ThreadContext context, IRubyObject recv, IRubyObject first, IRubyObject second) {
        return context.runtime.newBoolean(op_lt(context, recv, first).isFalse() && op_gt(context, recv, second).isFalse());
    }

    @JRubyMethod(name = "clamp")
    public static IRubyObject clamp(ThreadContext context, IRubyObject recv, IRubyObject min, IRubyObject max) {
        int c;

        ComparableSites sites = sites(context);
        CallSite op_gt = sites.op_gt;
        CallSite op_lt = sites.op_lt;
        CallSite op_cmp = sites.op_cmp;

        if (cmpAndCmpint(context, op_cmp, op_gt, op_lt, min, max) > 0) {
            throw context.runtime.newArgumentError("min argument must be smaller than max argument");
        }

        c = cmpAndCmpint(context, op_cmp, op_gt, op_lt, recv, min);
        if (c == 0) return recv;
        if (c < 0) return min;
        c = cmpAndCmpint(context, op_cmp, op_gt, op_lt, recv, max);
        if (c > 0) return max;
        return recv;
    }

    private static ComparableSites sites(ThreadContext context) {
        return context.sites.Comparable;
    }

    private static class CmpRecursive implements ThreadContext.RecursiveFunctionEx<IRubyObject> {
        @Override
        public IRubyObject call(ThreadContext context, IRubyObject other, IRubyObject self, boolean recur) {
            if (recur) return context.nil;
            return sites(context).op_cmp.call(context, self, self, other);
        }
    }

    private static final CmpRecursive CMP_RECURSIVE = new CmpRecursive();
}
