/*
 * Copyright (C) 2024 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.server.net.ct;

import android.app.DownloadManager;
import android.app.DownloadManager.Query;
import android.app.DownloadManager.Request;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;

import androidx.annotation.VisibleForTesting;

import com.google.auto.value.AutoValue;

/** Class to handle downloads for Certificate Transparency. */
public class DownloadHelper {

    private final DownloadManager mDownloadManager;

    @VisibleForTesting
    DownloadHelper(DownloadManager downloadManager) {
        mDownloadManager = downloadManager;
    }

    DownloadHelper(Context context) {
        this(context.getSystemService(DownloadManager.class));
    }

    /**
     * Sends a request to start the download of a provided url.
     *
     * @param url the url to download
     * @return a downloadId if the request was created successfully, -1 otherwise.
     */
    public long startDownload(String url) {
        return mDownloadManager.enqueue(
                new Request(Uri.parse(url))
                        .setAllowedOverRoaming(false)
                        .setNotificationVisibility(DownloadManager.Request.VISIBILITY_HIDDEN)
                        .setRequiresCharging(true));
    }

    /**
     * Returns the status of the provided download id.
     *
     * @param downloadId the download.
     * @return {@link DownloadStatus} of the download.
     */
    public DownloadStatus getDownloadStatus(long downloadId) {
        DownloadStatus.Builder builder = DownloadStatus.builder().setDownloadId(downloadId);
        try (Cursor cursor = mDownloadManager.query(new Query().setFilterById(downloadId))) {
            if (cursor != null && cursor.moveToFirst()) {
                builder.setStatus(
                        cursor.getInt(cursor.getColumnIndexOrThrow(DownloadManager.COLUMN_STATUS)));
                builder.setReason(
                        cursor.getInt(cursor.getColumnIndex(DownloadManager.COLUMN_REASON)));
            }
        }
        return builder.build();
    }

    /**
     * Returns the URI of the specified download, or null if the download did not complete
     * successfully.
     *
     * @param downloadId the download.
     * @return the {@link Uri} if the download completed successfully, null otherwise.
     */
    public Uri getUri(long downloadId) {
        if (downloadId == -1) {
            return null;
        }
        return mDownloadManager.getUriForDownloadedFile(downloadId);
    }

    /** A wrapper around the status and reason Ids returned by the {@link DownloadManager}. */
    @AutoValue
    public abstract static class DownloadStatus {

        abstract long downloadId();

        abstract int status();

        abstract int reason();

        boolean isSuccessful() {
            return status() == DownloadManager.STATUS_SUCCESSFUL;
        }

        boolean isStorageError() {
            int status = status();
            int reason = reason();
            return status == DownloadManager.STATUS_FAILED
                    && (reason == DownloadManager.ERROR_DEVICE_NOT_FOUND
                            || reason == DownloadManager.ERROR_FILE_ERROR
                            || reason == DownloadManager.ERROR_FILE_ALREADY_EXISTS
                            || reason == DownloadManager.ERROR_INSUFFICIENT_SPACE);
        }

        boolean isHttpError() {
            int status = status();
            int reason = reason();
            return status == DownloadManager.STATUS_FAILED
                    && (reason == DownloadManager.ERROR_HTTP_DATA_ERROR
                            || reason == DownloadManager.ERROR_TOO_MANY_REDIRECTS
                            || reason == DownloadManager.ERROR_UNHANDLED_HTTP_CODE
                            // If an HTTP error occurred, reason will hold the HTTP status code.
                            || (400 <= reason && reason < 600));
        }

        @AutoValue.Builder
        abstract static class Builder {
            abstract Builder setDownloadId(long downloadId);

            abstract Builder setStatus(int status);

            abstract Builder setReason(int reason);

            abstract DownloadStatus build();
        }

        static Builder builder() {
            return new AutoValue_DownloadHelper_DownloadStatus.Builder()
                    .setDownloadId(-1)
                    .setStatus(-1)
                    .setReason(-1);
        }
    }
}