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package org.jruby.ext.jruby;

import java.util.Map;
import org.jruby.Ruby;
import org.jruby.RubyClass;
import org.jruby.RubyObject;
import org.jruby.RubyProc;
import org.jruby.anno.JRubyMethod;
import org.jruby.runtime.Block;
import org.jruby.runtime.ExecutionContext;
import org.jruby.runtime.ThreadContext;
import org.jruby.runtime.builtin.IRubyObject;

public abstract class JRubyExecutionContextLocal extends RubyObject {
    private IRubyObject default_value;
    private RubyProc default_proc;

    public JRubyExecutionContextLocal(Ruby runtime, RubyClass type) {
        super(runtime, type);
        default_value = runtime.getNil();
        default_proc = null;
    }

    @JRubyMethod(name = "initialize", required = 0, optional = 1)
    public IRubyObject rubyInitialize(ThreadContext context, IRubyObject[] args, Block block) {
        if (block.isGiven()) {
            if (args.length != 0) {
                throw context.runtime.newArgumentError("wrong number of arguments");
            }
            default_proc = block.getProcObject();
            if (default_proc == null) {
                default_proc = RubyProc.newProc(context.runtime, block, block.type);
            }
        } else {
            if (args.length == 1) {
                default_value = args[0];
            } else if (args.length != 0) {
                throw context.runtime.newArgumentError("wrong number of arguments");
            }
        }
        return context.runtime.getNil();
    }

    @JRubyMethod(name = "default", required = 0)
    public IRubyObject getDefault(ThreadContext context) {
        return default_value;
    }

    @JRubyMethod(name = "default_proc", required = 0)
    public IRubyObject getDefaultProc(ThreadContext context) {
        if (default_proc != null) {
            return default_proc;
        } else {
            return context.runtime.getNil();
        }
    }
    private static final IRubyObject[] EMPTY_ARGS = new IRubyObject[]{};

    @JRubyMethod(name = "value", required = 0)
    public IRubyObject getValue(ThreadContext context) {
        final IRubyObject value;
        final Map<Object, IRubyObject> contextVariables;
        contextVariables = getContextVariables(context);
        value = contextVariables.get(this);
        if (value != null) {
            return value;
        } else if (default_proc != null) {
            // pre-set for the sake of terminating recursive calls
            contextVariables.put(this, context.runtime.getNil());
            final IRubyObject new_value;
            new_value = default_proc.call(context, EMPTY_ARGS, null, Block.NULL_BLOCK);
            contextVariables.put(this, new_value);
            return new_value;
        } else {
            return default_value;
        }
    }

    @JRubyMethod(name = "value=", required = 1)
    public IRubyObject setValue(ThreadContext context, IRubyObject value) {
        getContextVariables(context).put(this, value);
        return value;
    }

    protected final Map<Object, IRubyObject> getContextVariables(ThreadContext context) {
        return getExecutionContext(context).getContextVariables();
    }

    protected abstract ExecutionContext getExecutionContext(ThreadContext context);
    
}
