/*
 * Copyright (C) 2022 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.rkpdapp.interfaces;

import android.annotation.TestApi;
import android.hardware.security.keymint.IRemotelyProvisionedComponent;
import android.os.ServiceManager;
import android.util.Log;

import java.util.Arrays;
import java.util.Map;
import java.util.Objects;

/**
 * Provides convenience methods for interfacing with ServiceManager class and its static functions.
 */
public class ServiceManagerInterface {
    private static final String TAG = "RkpdSvcManagerInterface";
    private static SystemInterface[] sInstances;
    private static Map<String, IRemotelyProvisionedComponent> sBinders;

    private ServiceManagerInterface() {
    }

    private static SystemInterface tryCreateSystemInterface(IRemotelyProvisionedComponent binder,
            String serviceName) {
        try {
            return new SystemInterface(binder, serviceName);
        } catch (UnsupportedOperationException e) {
            Log.i(TAG, serviceName + " is unsupported.");
            return null;
        }
    }

    private static IRemotelyProvisionedComponent getBinder(String serviceName) {
        IRemotelyProvisionedComponent binder = IRemotelyProvisionedComponent.Stub.asInterface(
                ServiceManager.waitForDeclaredService(serviceName));
        if (binder == null) {
            throw new IllegalArgumentException("Cannot find any implementation for " + serviceName);
        }
        return binder;
    }

    /**
     * Gets all the instances on this device for IRemotelyProvisionedComponent as an array. The
     * returned values each contain a binder for interacting with the instance.
     *
     * For testing purposes, the instances may be overridden by either setInstances or setBinders.
     */
    public static SystemInterface[] getAllInstances() {
        if (sBinders != null) {
            return sBinders.entrySet().stream()
                    .map(x -> tryCreateSystemInterface(x.getValue(), x.getKey()))
                    .filter(Objects::nonNull)
                    .toArray(SystemInterface[]::new);
        }
        if (sInstances != null) {
            return sInstances;
        }

        String irpcInterface = IRemotelyProvisionedComponent.DESCRIPTOR;
        return Arrays.stream(ServiceManager.getDeclaredInstances(irpcInterface))
                .map(x -> {
                    String serviceName = irpcInterface + "/" + x;
                    return tryCreateSystemInterface(getBinder(serviceName), serviceName);
                })
                .filter(Objects::nonNull)
                .toArray(SystemInterface[]::new);
    }

    /**
     * Get a specific system interface instance for a given IRemotelyProvisionedComponent.
     * If the given serviceName does not map to a known IRemotelyProvisionedComponent, this
     * method throws IllegalArgumentException.
     * If the given serviceName is not supported, this method throws UnsupportedOperationException.
     *
     * For testing purposes, the instances may be overridden by either setInstances or setBinders.
     */
    public static SystemInterface getInstance(String serviceName) {
        if (sBinders != null) {
            if (sBinders.containsKey(serviceName)) {
                return new SystemInterface(sBinders.get(serviceName), serviceName);
            }
            throw new IllegalArgumentException("Cannot find any binder for " + serviceName);
        }
        if (sInstances != null) {
            for (SystemInterface i : sInstances) {
                if (i.getServiceName().equals(serviceName)) {
                    return i;
                }
            }
            throw new IllegalArgumentException("Cannot find any implementation for " + serviceName);
        }

        return new SystemInterface(getBinder(serviceName), serviceName);
    }

    @TestApi
    public static void setInstances(SystemInterface[] instances) {
        sInstances = instances;
    }

    @TestApi
    public static void setBinders(Map<String, IRemotelyProvisionedComponent> binders) {
        sBinders = binders;
    }
}