/*
 * Copyright 2018 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 androidx.webkit.internal;

import android.os.Build;
import android.webkit.WebView;

import androidx.annotation.NonNull;

import org.chromium.support_lib_boundary.WebViewProviderFactoryBoundaryInterface;
import org.chromium.support_lib_boundary.util.BoundaryInterfaceReflectionUtil;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * Utility class for calling into the WebView APK.
 */
public class WebViewGlueCommunicator {
    private static final String GLUE_FACTORY_PROVIDER_FETCHER_CLASS =
            "org.chromium.support_lib_glue.SupportLibReflectionUtil";
    private static final String GLUE_FACTORY_PROVIDER_FETCHER_METHOD =
            "createWebViewProviderFactory";

    /**
     * Fetch the one global support library WebViewProviderFactory from the WebView glue layer.
     */
    @NonNull
    public static WebViewProviderFactory getFactory() {
        return LAZY_FACTORY_HOLDER.INSTANCE;
    }

    @NonNull
    public static WebkitToCompatConverter getCompatConverter() {
        return LAZY_COMPAT_CONVERTER_HOLDER.INSTANCE;
    }

    private static class LAZY_FACTORY_HOLDER {
        static final WebViewProviderFactory INSTANCE =
                        WebViewGlueCommunicator.createGlueProviderFactory();
    }

    private static class LAZY_COMPAT_CONVERTER_HOLDER {
        static final WebkitToCompatConverter INSTANCE = new WebkitToCompatConverter(
                WebViewGlueCommunicator.getFactory().getWebkitToCompatConverter());
    }

    private static InvocationHandler fetchGlueProviderFactoryImpl() throws IllegalAccessException,
            InvocationTargetException, ClassNotFoundException, NoSuchMethodException {
        Class<?> glueFactoryProviderFetcherClass = Class.forName(
                GLUE_FACTORY_PROVIDER_FETCHER_CLASS, false, getWebViewClassLoader());
        Method createProviderFactoryMethod = glueFactoryProviderFetcherClass.getDeclaredMethod(
                GLUE_FACTORY_PROVIDER_FETCHER_METHOD);
        return (InvocationHandler) createProviderFactoryMethod.invoke(null);
    }

    @SuppressWarnings("WeakerAccess") /* synthetic access */
    @NonNull
    static WebViewProviderFactory createGlueProviderFactory() {
        // We do not support pre-L devices since their WebView APKs cannot be updated.
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
            return new IncompatibleApkWebViewProviderFactory();
        }
        InvocationHandler invocationHandler;
        try {
            invocationHandler = fetchGlueProviderFactoryImpl();
            // The only way we should fail to fetch the provider-factory is if the class we are
            // calling into doesn't exist - any other kind of failure is unexpected and should cause
            // a run-time exception.
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        } catch (InvocationTargetException e) {
            throw new RuntimeException(e);
        } catch (ClassNotFoundException e) {
            // If WebView APK support library glue entry point doesn't exist then return a Provider
            // factory that declares that there are no features available.
            return new IncompatibleApkWebViewProviderFactory();
        } catch (NoSuchMethodException e) {
            throw new RuntimeException(e);
        }
        return new WebViewProviderFactoryAdapter(BoundaryInterfaceReflectionUtil.castToSuppLibClass(
                WebViewProviderFactoryBoundaryInterface.class, invocationHandler));
    }

    /**
     * Load the WebView code from the WebView APK and return the classloader containing that code.
     */
    @NonNull
    public static ClassLoader getWebViewClassLoader() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
            return ApiHelperForP.getWebViewClassLoader();
        } else {
            return getWebViewProviderFactory().getClass().getClassLoader();
        }
    }

    @SuppressWarnings({"JavaReflectionMemberAccess", "PrivateApi"})
    private static Object getWebViewProviderFactory() {
        try {
            Method getFactoryMethod = WebView.class.getDeclaredMethod("getFactory");
            getFactoryMethod.setAccessible(true);
            return getFactoryMethod.invoke(null);
        } catch (NoSuchMethodException e) {
            throw new RuntimeException(e);
        } catch (InvocationTargetException e) {
            throw new RuntimeException(e);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }
    }

    private WebViewGlueCommunicator() {
    }
}