/*
 * Copyright 2014 NAVER Corp.
 * Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.navercorp.pinpoint.profiler.instrument.interceptor;

import java.lang.reflect.Method;

import com.navercorp.pinpoint.bootstrap.instrument.InstrumentClass;
import com.navercorp.pinpoint.bootstrap.instrument.InstrumentMethod;
import com.navercorp.pinpoint.profiler.metadata.ApiMetaDataService;

/**
 * @author Jongho Moon
 *
 */
public class InvokeBeforeCodeGenerator extends InvokeCodeGenerator {
    private final int interceptorId;
    private final InstrumentClass targetClass;
    
    public InvokeBeforeCodeGenerator(int interceptorId, InterceptorDefinition interceptorDefinition, InstrumentClass targetClass, InstrumentMethod targetMethod, ApiMetaDataService apiMetaDataService) {
        super(interceptorId, interceptorDefinition, targetMethod, apiMetaDataService);
        
        this.interceptorId = interceptorId;
        this.targetClass = targetClass;
    }

    public String generate() {
        final CodeBuilder builder = new CodeBuilder();
        
        builder.begin();

        // try {
        //     _$PINPOINT$_holder13 = InterceptorRegistry.findInterceptor(13);
        //     (($INTERCEPTOR_TYPE)_$PINPOINT$_holder13.getInterceptor.before($ARGUMENTS);
        // } catch (Throwable t) {
        //     InterceptorInvokerHelper.handleException(t);
        // }
        
        builder.append("try { ");
        builder.format("%1$s = %2$s.getInterceptor(%3$d); ", getInterceptorVar(), getInterceptorRegistryClassName(), interceptorId);

        final Method beforeMethod = interceptorDefinition.getBeforeMethod();
        if (beforeMethod != null) {
            builder.format("((%1$s)%2$s).before(", getInterceptorType(), getInterceptorVar());
            appendArguments(builder);
            builder.format(");");
        }
        
        builder.format("} catch (java.lang.Throwable _$PINPOINT_EXCEPTION$_) { %1$s.handleException(_$PINPOINT_EXCEPTION$_); }", getInterceptorInvokerHelperClassName());
        
        builder.end();
        
        return builder.toString();
    }

    private void appendArguments(CodeBuilder builder) {
        final InterceptorType type = interceptorDefinition.getInterceptorType();
        switch (type) {
        case ARRAY_ARGS:
            appendSimpleBeforeArguments(builder);
            break;
        case STATIC:
            appendStaticBeforeArguments(builder);
            break;
        case API_ID_AWARE:
            appendApiIdAwareBeforeArguments(builder);
            break;
        case BASIC:
            appendCustomBeforeArguments(builder);
            break;
        }
    }

    private void appendSimpleBeforeArguments(CodeBuilder builder) {
        builder.format("%1$s, %2$s", getTarget(), getArguments());
    }
    
    private void appendStaticBeforeArguments(CodeBuilder builder) {
        builder.format("%1$s, \"%2$s\", \"%3$s\", \"%4$s\", %5$s", getTarget(), targetClass.getName(), targetMethod.getName(), getParameterTypes(), getArguments());
    }

    private void appendApiIdAwareBeforeArguments(CodeBuilder builder) {
        builder.format("%1$s, %2$d, %3$s", getTarget(), getApiId(), getArguments());
    }

    private void appendCustomBeforeArguments(CodeBuilder builder) {
        final Method interceptorMethod = interceptorDefinition.getBeforeMethod();
        final Class<?>[] paramTypes = interceptorMethod.getParameterTypes();
        
        if (paramTypes.length == 0) {
            return;
        }
        
        builder.append(getTarget());
        
        int i = 0;
        int argNum = targetMethod.getParameterTypes().length;
        int interceptorArgNum = paramTypes.length - 1;
        int matchNum = Math.min(argNum, interceptorArgNum);
        
        for (; i < matchNum; i++) {
            builder.append(", ($w)$" + (i + 1));
        }
        
        for (; i < interceptorArgNum; i++) {
            builder.append(", null");
        }
    }
}