/*
 * Copyright (C) 2015 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.compatibility.common.deviceinfo;

import android.content.pm.ApplicationInfo;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PermissionInfo;
import com.android.compatibility.common.util.DeviceInfoStore;

import java.io.IOException;
import java.util.*;

/**
 * PackageDeviceInfo collector.
 */
public class PackageDeviceInfo extends DeviceInfo {

    private static final String PACKAGE = "package";

    private static final String NAME = "name";
    private static final String VERSION_NAME = "version_name";
    private static final String SYSTEM_PRIV = "system_priv";
    private static final String PRIV_APP_DIR = "/system/priv-app";
    private static final String MIN_SDK = "min_sdk";
    private static final String TARGET_SDK = "target_sdk";

    private static final String REQUESTED_PERMISSIONS = "requested_permissions";
    private static final String PERMISSION_NAME = "name";
    private static final String PERMISSION_FLAGS = "flags";
    private static final String PERMISSION_GROUP = "permission_group";
    private static final String PERMISSION_PROTECTION = "protection_level";
    private static final String PERMISSION_PROTECTION_FLAGS = "protection_level_flags";

    private static final String HAS_SYSTEM_UID = "has_system_uid";

    private static final String SHARES_INSTALL_PERMISSION = "shares_install_packages_permission";
    private static final String INSTALL_PACKAGES_PERMISSION = "android.permission.INSTALL_PACKAGES";

    @Override
    protected void collectDeviceInfo(DeviceInfoStore store) throws Exception {
        final PackageManager pm = getContext().getPackageManager();
        final ApplicationInfo system = pm.getApplicationInfo("android", 0);

        final List<PackageInfo> allPackages = pm.getInstalledPackages(PackageManager.GET_PERMISSIONS);

        store.startArray(PACKAGE);
        for (PackageInfo pkg : allPackages) {
            store.startGroup();

            store.addResult(NAME, pkg.packageName);
            store.addResult(VERSION_NAME, pkg.versionName);

            store.startArray(REQUESTED_PERMISSIONS);
            if (pkg.requestedPermissions != null && pkg.requestedPermissions.length > 0) {
                for (String permission : pkg.requestedPermissions) {
                    try {
                        final PermissionInfo pi = pm.getPermissionInfo(permission, 0);

                        store.startGroup();
                        store.addResult(PERMISSION_NAME, permission);
                        store.addResult(PERMISSION_FLAGS, pi.flags);
                        store.addResult(PERMISSION_GROUP, pi.group);
                        store.addResult(PERMISSION_PROTECTION, pi.getProtection());
                        store.addResult(PERMISSION_PROTECTION_FLAGS, pi.getProtectionFlags());
                        store.endGroup();
                    } catch (PackageManager.NameNotFoundException e) {
                        // ignore unrecognized permission and continue
                    }
                }
            }
            store.endArray();

            final ApplicationInfo appInfo = pkg.applicationInfo;
            if (appInfo != null) {
                String dir = appInfo.sourceDir;
                store.addResult(SYSTEM_PRIV, dir != null && dir.startsWith(PRIV_APP_DIR));

                store.addResult(MIN_SDK, appInfo.minSdkVersion);
                store.addResult(TARGET_SDK, appInfo.targetSdkVersion);

                store.addResult(HAS_SYSTEM_UID, appInfo.uid == system.uid);

                final boolean canInstall = sharesUidWithPackageHolding(pm, appInfo.uid, INSTALL_PACKAGES_PERMISSION);
                store.addResult(SHARES_INSTALL_PERMISSION, canInstall);
            }

            store.endGroup();
        }
        store.endArray(); // "package"
    }
    private static boolean sharesUidWithPackageHolding(PackageManager pm, int uid, String permission) {
        final String[] sharesUidWith = pm.getPackagesForUid(uid);

        if (sharesUidWith == null) {
            return false;
        }

        // Approx 20 permissions per package for rough estimate of sizing
        final List<String> sharedPermissions = new ArrayList<>(sharesUidWith.length * 20);
        for (String pkg :sharesUidWith){
            try {
                final PackageInfo info = pm.getPackageInfo(pkg, PackageManager.GET_PERMISSIONS);

                if (info.requestedPermissions == null) {
                    continue;
                }

                for (String p : info.requestedPermissions) {
                    if (p != null) {
                        sharedPermissions.add(p);
                    }
                }
            } catch (PackageManager.NameNotFoundException e) {
                // ignore, continue
            }
        }

        return sharedPermissions.contains(permission);
    }
}