/*
 * 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.facebook.presto.sql.gen;

import com.facebook.presto.byteCode.ClassDefinition;
import com.facebook.presto.byteCode.ClassInfoLoader;
import com.facebook.presto.byteCode.DumpByteCodeVisitor;
import com.facebook.presto.byteCode.DynamicClassLoader;
import com.facebook.presto.byteCode.ParameterizedType;
import com.facebook.presto.byteCode.SmartClassWriter;
import com.google.common.collect.ImmutableList;
import com.google.common.io.Files;
import io.airlift.log.Logger;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.util.CheckClassAdapter;
import org.objectweb.asm.util.TraceClassVisitor;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.lang.invoke.MethodHandle;
import java.nio.charset.StandardCharsets;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;

public final class CompilerUtils
{
    private static final Logger log = Logger.get(CompilerUtils.class);

    private static final boolean DUMP_BYTE_CODE_TREE = false;
    private static final boolean DUMP_BYTE_CODE_RAW = false;
    private static final boolean RUN_ASM_VERIFIER = false; // verifier doesn't work right now
    private static final AtomicReference<String> DUMP_CLASS_FILES_TO = new AtomicReference<>();
    private static final AtomicLong CLASS_ID = new AtomicLong();

    private CompilerUtils()
    {
    }

    public static ParameterizedType makeClassName(String baseName)
    {
        return ParameterizedType.typeFromJavaClassName("com.facebook.presto.$gen." + baseName + "_" + CLASS_ID.incrementAndGet());
    }

    public static <T> Class<? extends T> defineClass(ClassDefinition classDefinition, Class<T> superType, DynamicClassLoader classLoader)
    {
        Class<?> clazz = defineClasses(ImmutableList.of(classDefinition), classLoader).values().iterator().next();
        return clazz.asSubclass(superType);
    }

    public static <T> Class<? extends T> defineClass(ClassDefinition classDefinition, Class<T> superType,  Map<Long, MethodHandle> callSiteBindings, ClassLoader parentClassLoader)
    {
        Class<?> clazz = defineClass(classDefinition, superType, new DynamicClassLoader(parentClassLoader, callSiteBindings));
        return clazz.asSubclass(superType);
    }

    private static Map<String, Class<?>> defineClasses(List<ClassDefinition> classDefinitions, DynamicClassLoader classLoader)
    {
        ClassInfoLoader classInfoLoader = ClassInfoLoader.createClassInfoLoader(classDefinitions, classLoader);

        if (DUMP_BYTE_CODE_TREE) {
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            DumpByteCodeVisitor dumpByteCode = new DumpByteCodeVisitor(new PrintStream(out));
            for (ClassDefinition classDefinition : classDefinitions) {
                dumpByteCode.visitClass(classDefinition);
            }
            System.out.println(new String(out.toByteArray(), StandardCharsets.UTF_8));
        }

        Map<String, byte[]> byteCodes = new LinkedHashMap<>();
        for (ClassDefinition classDefinition : classDefinitions) {
            ClassWriter cw = new SmartClassWriter(classInfoLoader);
            classDefinition.visit(cw);
            byte[] byteCode = cw.toByteArray();
            if (RUN_ASM_VERIFIER) {
                ClassReader reader = new ClassReader(byteCode);
                CheckClassAdapter.verify(reader, classLoader, true, new PrintWriter(System.out));
            }
            byteCodes.put(classDefinition.getType().getJavaClassName(), byteCode);
        }

        String dumpClassPath = DUMP_CLASS_FILES_TO.get();
        if (dumpClassPath != null) {
            for (Map.Entry<String, byte[]> entry : byteCodes.entrySet()) {
                File file = new File(dumpClassPath, ParameterizedType.typeFromJavaClassName(entry.getKey()).getClassName() + ".class");
                try {
                    log.debug("ClassFile: " + file.getAbsolutePath());
                    Files.createParentDirs(file);
                    Files.write(entry.getValue(), file);
                }
                catch (IOException e) {
                    log.error(e, "Failed to write generated class file to: %s" + file.getAbsolutePath());
                }
            }
        }
        if (DUMP_BYTE_CODE_RAW) {
            for (byte[] byteCode : byteCodes.values()) {
                ClassReader classReader = new ClassReader(byteCode);
                classReader.accept(new TraceClassVisitor(new PrintWriter(System.err)), ClassReader.SKIP_FRAMES);
            }
        }
        return classLoader.defineClasses(byteCodes);
    }
}

@@ -1004,16 +1004,61 @@
 .Files;%0A
+import com.google.common.reflect.Reflection;%0A
 import i
@@ -5355,30 +5355,55 @@
   %7D%0A        
-return
+Map%3CString, Class%3C?%3E%3E classes =
  classLoader
@@ -5429,16 +5429,263 @@
 Codes);%0A
+        try %7B%0A            for (Class%3C?%3E clazz : classes.values()) %7B%0A                Reflection.initialize(clazz);%0A            %7D%0A        %7D%0A        catch (VerifyError e) %7B%0A            throw new RuntimeException(e);%0A        %7D%0A        return classes;%0A
     %7D%0A%7D%0A

Initialize generated classes during class loading