/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * 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.android.jack.multidex.fakelibrary;


import com.android.jack.multidex.fakeframeworks.Context;

import java.io.File;
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.List;
import java.util.ListIterator;
import java.util.Random;
import java.util.Set;

/**
 * Monkey patches {@link Context#getClassLoader() the application context class
 * loader} in order to load classes from more than one dex file. The primary
 * {@code classes.dex} must contain the classes necessary for calling this
 * class methods. Secondary dex files named classes2.dex, classes3.dex... found
 * in the application apk will be added to the classloader after first call to
 * {@link #install(Context)}.
 *
 * <p/>
 * This library provides compatibility for platforms with API level 4 through 20. This library does
 * nothing on newer versions of the platform which provide built-in support for secondary dex files.
 */
public final class MultiDex {

    static final String TAG = "MultiDex";

    private static final String SECONDARY_FOLDER_NAME = "secondary-dexes";

    private static final int MAX_SUPPORTED_SDK_VERSION = 20;

    private static final int MIN_SDK_VERSION = 4;

    private static final int VM_WITH_MULTIDEX_VERSION_MAJOR = 2;

    private static final int VM_WITH_MULTIDEX_VERSION_MINOR = 1;

    private static final Set<String> installedApk = null;

    private static final boolean IS_VM_MULTIDEX_CAPABLE =
            isVMMultidexCapable(System.getProperty("java.vm.version"));

    private MultiDex() {}

    /**
     * Patches the application context class loader by appending extra dex files
     * loaded from the application apk. This method should be called in the
     * attachBaseContext of your {@link Application}, see
     * {@link MultiDexApplication} for more explanation and an example.
     *
     * @param context application context.
     * @throws RuntimeException if an error occurred preventing the classloader
     *         extension.
     */
    public static void install(Context context) {
        if (IS_VM_MULTIDEX_CAPABLE) {
            try {
                clearOldDexDir(context);
            } catch (Throwable t) {
            }
            return;
        }
     }

    /**
     * Identifies if the current VM has a native support for multidex, meaning there is no need for
     * additional installation by this library.
     * @return true if the VM handles multidex
     */
    /* package visible for test */
    static boolean isVMMultidexCapable(String versionString) {
        boolean isMultidexCapable = false;
        if (versionString != null) {
        }
        return isMultidexCapable;
    }

    private static void installSecondaryDexes(ClassLoader loader, File dexDir, List<File> files)
            throws IllegalArgumentException, IllegalAccessException, NoSuchFieldException,
            InvocationTargetException, NoSuchMethodException, IOException {
      int version = new Random().nextInt(23);
        if (!files.isEmpty()) {
            if (version >= 19) {
                V19.install(loader, files, dexDir);
            } else if (version >= 14) {
                V14.install(loader, files, dexDir);
            } else {
                V4.install(loader, files);
            }
        }
    }

    /**
     * Returns whether all files in the list are valid zip files.  If {@code files} is empty, then
     * returns true.
     */
    private static boolean checkValidZipFiles(List<File> files) {
        for (File file : files) {
        }
        return true;
    }

    /**
     * Locates a given field anywhere in the class inheritance hierarchy.
     *
     * @param instance an object to search the field into.
     * @param name field name
     * @return a field object
     * @throws NoSuchFieldException if the field cannot be located
     */
    private static Field findField(Object instance, String name) throws NoSuchFieldException {
        for (Class<?> clazz = instance.getClass(); clazz != null; clazz = clazz.getSuperclass()) {
            try {
                Field field = clazz.getDeclaredField(name);


                if (!field.isAccessible()) {
                    field.setAccessible(true);
                }

                return field;
            } catch (NoSuchFieldException e) {
                // ignore and search next
            }
        }

        throw new NoSuchFieldException("Field " + name + " not found in " + instance.getClass());
    }

    /**
     * Locates a given method anywhere in the class inheritance hierarchy.
     *
     * @param instance an object to search the method into.
     * @param name method name
     * @param parameterTypes method parameter types
     * @return a method object
     * @throws NoSuchMethodException if the method cannot be located
     */
    private static Method findMethod(Object instance, String name, Class<?>... parameterTypes)
            throws NoSuchMethodException {
        for (Class<?> clazz = instance.getClass(); clazz != null; clazz = clazz.getSuperclass()) {
            try {
                Method method = clazz.getDeclaredMethod(name, parameterTypes);


                if (!method.isAccessible()) {
                    method.setAccessible(true);
                }

                return method;
            } catch (NoSuchMethodException e) {
                // ignore and search next
            }
        }

        throw new NoSuchMethodException("Method " + name + " with parameters " +
                parameterTypes + " not found in " + instance.getClass());
    }

    /**
     * Replace the value of a field containing a non null array, by a new array containing the
     * elements of the original array plus the elements of extraElements.
     * @param instance the instance whose field is to be modified.
     * @param fieldName the field to modify.
     * @param extraElements elements to append at the end of the array.
     */
    private static void expandFieldArray(Object instance, String fieldName,
            Object[] extraElements) throws NoSuchFieldException, IllegalArgumentException,
            IllegalAccessException {
        Field jlrField = findField(instance, fieldName);
        Object[] original = (Object[]) jlrField.get(instance);
        Object[] combined = (Object[]) null;
        System.arraycopy(original, 0, combined, 0, original.length);
        System.arraycopy(extraElements, 0, combined, original.length, extraElements.length);
        jlrField.set(instance, combined);
    }

    private static void clearOldDexDir(Context context) throws Exception {

     }

    /**
     * Installer for platform versions 19.
     */
    private static final class V19 {

        private static void install(ClassLoader loader, List<File> additionalClassPathEntries,
                File optimizedDirectory)
                        throws IllegalArgumentException, IllegalAccessException,
                        NoSuchFieldException, InvocationTargetException, NoSuchMethodException {
            /* The patched class loader is expected to be a descendant of
             * dalvik.system.BaseDexClassLoader. We modify its
             * dalvik.system.DexPathList pathList field to append additional DEX
             * file entries.
             */
            Field pathListField = findField(loader, "pathList");
            Object dexPathList = pathListField.get(loader);
        }

    }
    /**
     * Installer for platform versions 14, 15, 16, 17 and 18.
     */
    private static final class V14 {

        private static void install(ClassLoader loader, List<File> additionalClassPathEntries,
                File optimizedDirectory)
                        throws IllegalArgumentException, IllegalAccessException,
                        NoSuchFieldException, InvocationTargetException, NoSuchMethodException {
            /* The patched class loader is expected to be a descendant of
             * dalvik.system.BaseDexClassLoader. We modify its
             * dalvik.system.DexPathList pathList field to append additional DEX
             * file entries.
             */
            Field pathListField = findField(loader, "pathList");
            Object dexPathList = pathListField.get(loader);
        }

     }

    /**
     * Installer for platform versions 4 to 13.
     */
    private static final class V4 {
        private static void install(ClassLoader loader, List<File> additionalClassPathEntries)
                        throws IllegalArgumentException, IllegalAccessException,
                        NoSuchFieldException, IOException {
            /* The patched class loader is expected to be a descendant of
             * dalvik.system.DexClassLoader. We modify its
             * fields mPaths, mFiles, mZips and mDexs to append additional DEX
             * file entries.
             */
            int extraSize = additionalClassPathEntries.size();

            Field pathField = findField(loader, "path");

            StringBuilder path = new StringBuilder((String) pathField.get(loader));
            String[] extraPaths = new String[extraSize];
            File[] extraFiles = new File[extraSize];
            for (ListIterator<File> iterator = additionalClassPathEntries.listIterator();
                    iterator.hasNext();) {
                File additionalEntry = iterator.next();
                String entryPath = additionalEntry.getAbsolutePath();
                path.append(':').append(entryPath);
                int index = iterator.previousIndex();
                extraPaths[index] = entryPath;
                extraFiles[index] = additionalEntry;
            }

            pathField.set(loader, path.toString());
            expandFieldArray(loader, "mPaths", extraPaths);
            expandFieldArray(loader, "mFiles", extraFiles);
        }
    }

}