/*
 * 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.packageinstaller.permission.ui;

import static android.content.pm.PackageManager.PERMISSION_DENIED;
import static android.content.pm.PackageManager.PERMISSION_GRANTED;
import static android.content.res.Configuration.UI_MODE_TYPE_MASK;
import static android.content.res.Configuration.UI_MODE_TYPE_TELEVISION;

import android.app.Activity;
import android.app.admin.DevicePolicyManager;
import android.content.Intent;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.pm.PermissionInfo;
import android.content.res.Resources;
import android.graphics.drawable.Icon;
import android.hardware.camera2.utils.ArrayUtils;
import android.os.Bundle;
import android.text.SpannableString;
import android.text.style.ForegroundColorSpan;
import android.util.ArrayMap;
import android.util.Log;
import android.view.Window;
import android.view.WindowManager;

import com.android.packageinstaller.R;
import com.android.packageinstaller.permission.model.AppPermissionGroup;
import com.android.packageinstaller.permission.model.AppPermissions;
import com.android.packageinstaller.permission.model.Permission;
import com.android.packageinstaller.permission.utils.SafetyNetLogger;

import java.util.ArrayList;
import java.util.List;

public class GrantPermissionsActivity extends Activity
        implements GrantPermissionsViewHandler.ResultListener {

    private static final String LOG_TAG = "GrantPermissionsActivity";

    private String[] mRequestedPermissions;
    private int[] mGrantResults;

    private ArrayMap<String, GroupState> mRequestGrantPermissionGroups = new ArrayMap<>();

    private GrantPermissionsViewHandler mViewHandler;
    private AppPermissions mAppPermissions;

    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setFinishOnTouchOutside(false);

        int uiMode = getResources().getConfiguration().uiMode & UI_MODE_TYPE_MASK;
        if (uiMode == UI_MODE_TYPE_TELEVISION) {
            mViewHandler = new GrantPermissionsTvViewHandler(this).setResultListener(this);
        } else {
            mViewHandler = new GrantPermissionsDefaultViewHandler(this).setResultListener(this);
        }

        mRequestedPermissions = getIntent().getStringArrayExtra(
                PackageManager.EXTRA_REQUEST_PERMISSIONS_NAMES);
        if (mRequestedPermissions == null) {
            mRequestedPermissions = new String[0];
        }

        final int requestedPermCount = mRequestedPermissions.length;
        mGrantResults = new int[requestedPermCount];

        if (requestedPermCount == 0) {
            setResultAndFinish();
            return;
        }

        PackageInfo callingPackageInfo = getCallingPackageInfo();

        DevicePolicyManager devicePolicyManager = getSystemService(DevicePolicyManager.class);
        final int permissionPolicy = devicePolicyManager.getPermissionPolicy(null);

        // If calling package is null we default to deny all.
        updateDefaultResults(callingPackageInfo, permissionPolicy);

        if (callingPackageInfo == null) {
            setResultAndFinish();
            return;
        }

        mAppPermissions = new AppPermissions(this, callingPackageInfo, mRequestedPermissions, false,
                new Runnable() {
                    @Override
                    public void run() {
                        setResultAndFinish();
                    }
                });

        for (AppPermissionGroup group : mAppPermissions.getPermissionGroups()) {
            // We allow the user to choose only non-fixed permissions. A permission
            // is fixed either by device policy or the user denying with prejudice.
            if (!group.areRuntimePermissionsGranted() &&
                    !(group.isUserFixed() || group.isPolicyFixed())) {

                switch (permissionPolicy) {
                    case DevicePolicyManager.PERMISSION_POLICY_AUTO_GRANT: {
                        group.grantRuntimePermissions(false);
                    } break;

                    case DevicePolicyManager.PERMISSION_POLICY_AUTO_DENY: {
                        group.revokeRuntimePermissions(false);
                    } break;

                    default: {
                        mRequestGrantPermissionGroups.put(group.getName(), new GroupState(group));
                    } break;
                }
            }
        }

        setContentView(mViewHandler.createView());

        Window window = getWindow();
        WindowManager.LayoutParams layoutParams = window.getAttributes();
        mViewHandler.updateWindowAttributes(layoutParams);
        window.setAttributes(layoutParams);

        if (!showNextPermissionGroupGrantRequest()) {
            setResultAndFinish();
        }
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        mViewHandler.saveInstanceState(outState);
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        mViewHandler.loadInstanceState(savedInstanceState);
    }

    private boolean showNextPermissionGroupGrantRequest() {
        final int groupCount = mRequestGrantPermissionGroups.size();

        for (int i = 0; i < groupCount; i++) {
            GroupState groupState = mRequestGrantPermissionGroups.valueAt(i);
            if (!groupState.mGroup.areRuntimePermissionsGranted()
                    && groupState.mState == GroupState.STATE_UNKNOWN) {
                CharSequence appLabel = mAppPermissions.getAppLabel();
                SpannableString message = new SpannableString(getString(
                        R.string.permission_warning_template, appLabel,
                        groupState.mGroup.getDescription()));
                // Color the app name.
                int appLabelStart = message.toString().indexOf(appLabel.toString(), 0);
                int appLabelLength = appLabel.length();
                int color = getColor(R.color.grant_permissions_app_color);
                message.setSpan(new ForegroundColorSpan(color), appLabelStart,
                        appLabelStart + appLabelLength, 0);

                // Set the new grant view
                // TODO: Use a real message for the action. We need group action APIs
                Resources resources;
                try {
                    resources = getPackageManager().getResourcesForApplication(
                            groupState.mGroup.getIconPkg());
                } catch (NameNotFoundException e) {
                    // Fallback to system.
                    resources = Resources.getSystem();
                }
                int icon = groupState.mGroup.getIconResId();

                mViewHandler.updateUi(groupState.mGroup.getName(), groupCount, i,
                        Icon.createWithResource(resources, icon), message,
                        groupState.mGroup.isUserSet());
                return  true;
            }
        }

        return false;
    }

    @Override
    public void onPermissionGrantResult(String name, boolean granted, boolean doNotAskAgain) {
        GroupState groupState = mRequestGrantPermissionGroups.get(name);
        if (groupState.mGroup != null) {
            if (granted) {
                groupState.mGroup.grantRuntimePermissions(doNotAskAgain);
                groupState.mState = GroupState.STATE_ALLOWED;
                updateGrantResults(groupState.mGroup);
            } else {
                groupState.mGroup.revokeRuntimePermissions(doNotAskAgain);
                groupState.mState = GroupState.STATE_DENIED;
            }
        }
        if (!showNextPermissionGroupGrantRequest()) {
            setResultAndFinish();
        }
    }

    private void updateGrantResults(AppPermissionGroup group) {
        for (Permission permission : group.getPermissions()) {
            if (permission.isGranted()) {
                final int index = ArrayUtils.getArrayIndex(
                        mRequestedPermissions, permission.getName());
                if (index >= 0) {
                    mGrantResults[index] = PackageManager.PERMISSION_GRANTED;
                }
            }
        }
    }

    private int computePermissionGrantState(PackageInfo callingPackageInfo,
            String permission, int permissionPolicy) {
        boolean permissionRequested = false;

        for (int i = 0; i < callingPackageInfo.requestedPermissions.length; i++) {
            if (permission.equals(callingPackageInfo.requestedPermissions[i])) {
                permissionRequested = true;
                if ((callingPackageInfo.requestedPermissionsFlags[i]
                        & PackageInfo.REQUESTED_PERMISSION_GRANTED) != 0) {
                    return PERMISSION_GRANTED;
                }
                break;
            }
        }

        if (!permissionRequested) {
            return PERMISSION_DENIED;
        }

        try {
            PermissionInfo pInfo = getPackageManager().getPermissionInfo(permission, 0);
            if ((pInfo.protectionLevel & PermissionInfo.PROTECTION_MASK_BASE)
                    != PermissionInfo.PROTECTION_DANGEROUS) {
                return PERMISSION_DENIED;
            }
        } catch (NameNotFoundException e) {
            return PERMISSION_DENIED;
        }

        switch (permissionPolicy) {
            case DevicePolicyManager.PERMISSION_POLICY_AUTO_GRANT: {
                return PERMISSION_GRANTED;
            }
            default: {
                return PERMISSION_DENIED;
            }
        }
    }

    private PackageInfo getCallingPackageInfo() {
        try {
            return getPackageManager().getPackageInfo(getCallingPackage(),
                    PackageManager.GET_PERMISSIONS);
        } catch (NameNotFoundException e) {
            Log.i(LOG_TAG, "No package: " + getCallingPackage(), e);
            return null;
        }
    }

    private void updateDefaultResults(PackageInfo callingPackageInfo, int permissionPolicy) {
        final int requestedPermCount = mRequestedPermissions.length;
        for (int i = 0; i < requestedPermCount; i++) {
            String permission = mRequestedPermissions[i];
            mGrantResults[i] = callingPackageInfo != null
                    ? computePermissionGrantState(callingPackageInfo, permission, permissionPolicy)
                    : PERMISSION_DENIED;
        }
    }

    private void setResultAndFinish() {
        logRequestedPermissionGroups();
        Intent result = new Intent(PackageManager.ACTION_REQUEST_PERMISSIONS);
        result.putExtra(PackageManager.EXTRA_REQUEST_PERMISSIONS_NAMES, mRequestedPermissions);
        result.putExtra(PackageManager.EXTRA_REQUEST_PERMISSIONS_RESULTS, mGrantResults);
        setResult(RESULT_OK, result);
        finish();
    }

    private void logRequestedPermissionGroups() {
        if (mRequestGrantPermissionGroups.isEmpty()) {
            return;
        }

        final int groupCount = mRequestGrantPermissionGroups.size();
        List<AppPermissionGroup> groups = new ArrayList<>(groupCount);
        for (int i = 0; i < groupCount; i++) {
            groups.add(mRequestGrantPermissionGroups.valueAt(i).mGroup);
        }

        SafetyNetLogger.logPermissionsRequested(mAppPermissions.getPackageInfo(), groups);
    }

    private static final class GroupState {
        static final int STATE_UNKNOWN = 0;
        static final int STATE_ALLOWED = 1;
        static final int STATE_DENIED = 2;

        final AppPermissionGroup mGroup;
        int mState = STATE_UNKNOWN;

        GroupState(AppPermissionGroup group) {
            mGroup = group;
        }
    }
}