/*
 * Copyright (c) 2015 LingoChamp Inc.
 *
 * 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.liulishuo.filedownloader.util;

import android.annotation.SuppressLint;
import android.content.Context;

import com.liulishuo.filedownloader.IThreadPoolMonitor;
import com.liulishuo.filedownloader.connection.FileDownloadConnection;
import com.liulishuo.filedownloader.database.SqliteDatabaseImpl;
import com.liulishuo.filedownloader.exception.PathConflictException;
import com.liulishuo.filedownloader.message.MessageSnapshotFlow;
import com.liulishuo.filedownloader.message.MessageSnapshotTaker;
import com.liulishuo.filedownloader.model.FileDownloadModel;
import com.liulishuo.filedownloader.database.FileDownloadDatabase;
import com.liulishuo.filedownloader.stream.FileDownloadOutputStream;
import com.liulishuo.filedownloader.stream.FileDownloadRandomAccessFile;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;

/**
 * The helper for cache the {@code APP_CONTEXT} and {@code OK_HTTP_CLIENT} for the main process and
 * the filedownloader process.
 */
public class FileDownloadHelper {

    @SuppressLint("StaticFieldLeak")
    private static Context APP_CONTEXT;

    public static void holdContext(final Context context) {
        APP_CONTEXT = context;
    }

    public static Context getAppContext() {
        return APP_CONTEXT;
    }

    @SuppressWarnings("UnusedParameters")
    public interface IdGenerator {
        /**
         * Invoke this method when the data is restoring from the database.
         *
         * @param oldId           the old download id which is generated through the different.
         * @param url             the url path.
         * @param path            the download path.
         * @param pathAsDirectory {@code true}: if the {@code path} is absolute directory to store
         *                        the downloading file, and the {@code filename} will be found in
         *                        contentDisposition from the response as default, if can't find
         *                        contentDisposition,the {@code filename} will be generated by
         *                        {@link FileDownloadUtils#generateFileName(String)}  with
         *                        {@code url}.
         *                        </p>
         *                        {@code false}: if the {@code path} = (absolute directory/filename)
         * @return the new download id.
         */
        int transOldId(final int oldId, final String url, final String path,
                       final boolean pathAsDirectory);

        /**
         * Invoke this method when there is a new task from very beginning.
         * <p>
         * Important Ting: this method would be used on the FileDownloadService and the upper-layer,
         * so as default FileDownloadService is running on the `:filedownloader` process, and
         * upper-layer
         * is on the user process, in this case, if you want to cache something on this instance, it
         * would be two different caches on two processes.
         * <p>
         * Tips: if you want the FileDownloadService runs on the upper-layer process too, just
         * config {@code process.non-separate=true} on the filedownloader.properties, more detail
         * please move to {@link FileDownloadProperties}
         *
         * @param url             the download url.
         * @param path            the download path.
         * @param pathAsDirectory {@code true}: if the {@code path} is absolute directory to store
         *                        the downloading file, and the {@code filename} will be found in
         *                        contentDisposition from the response as default, if can't find
         *                        contentDisposition,the {@code filename} will be generated by
         *                        {@link FileDownloadUtils#generateFileName(String)}  with
         *                        {@code url}.
         *                        </p>
         *                        {@code false}: if the {@code path} = (absolute directory/filename)
         * @return the download task identify.
         */
        int generateId(final String url, final String path, final boolean pathAsDirectory);
    }

    @SuppressWarnings("UnusedParameters")
    public interface ConnectionCountAdapter {
        /**
         * Before invoke this method to determine how many connection will be used to downloading
         * this task,
         * there are several conditions must be confirmed:
         * <p>
         * 1. the connection is support multiple connection(SUPPORT"Partial Content(206)" AND NOT
         * Chunked)
         * 2. the current {@link FileDownloadOutputStream} support seek(The default
         * one({@link FileDownloadRandomAccessFile} is support)
         * 3. this is a new task NOT resume from breakpoint( If the task resume from breakpoint
         * the connection count would be using
         * the one you determined when the task
         * first created ).
         * <p/>
         * The best strategy is refer to how much speed of each connection for the ip:port not file
         * size.
         *
         * @param downloadId  the download id.
         * @param url         the task url.
         * @param path        the task path.
         * @param totalLength the total length of the file.
         * @return the count of connection you want for the task. the value must be large than 0.
         */
        int determineConnectionCount(int downloadId, String url, String path, long totalLength);
    }

    public interface DatabaseCustomMaker {
        /**
         * The database is used for storing the {@link FileDownloadModel}.
         * <p/>
         * The data stored in the database is only used for task resumes from the breakpoint.
         * <p>
         * The task of the data stored in the database must be a task that has not finished
         * downloading yet, and if the task has finished downloading, its data will be
         * {@link FileDownloadDatabase#remove(int)} from the database, since that data is no longer
         * available for resumption of its task pass.
         *
         * @return Nullable, Customize {@link FileDownloadDatabase} which will be used for storing
         * downloading model.
         * @see SqliteDatabaseImpl
         */
        FileDownloadDatabase customMake();
    }

    public interface OutputStreamCreator {
        /**
         * The output stream creator is used for creating {@link FileDownloadOutputStream} which is
         * used to write the input stream to the file for downloading.
         * <p>
         * <strong>Note:</strong> please create a output stream which append the content to the
         * exist file, which means that bytes would be written to the end of the file rather than
         * the beginning.
         *
         * @param file the file will used for storing the downloading content.
         * @return The output stream used to write downloading byte array to the {@code file}.
         * @throws FileNotFoundException if the file exists but is a directory
         *                               rather than a regular file, does not exist but cannot
         *                               be created, or cannot be opened for any other reason
         * @see FileDownloadRandomAccessFile.Creator
         */
        FileDownloadOutputStream create(File file) throws IOException;

        /**
         * @return {@code true} if the {@link FileDownloadOutputStream} is created through
         * {@link #create(File)} support {@link FileDownloadOutputStream#seek(long)} function.
         * If the {@link FileDownloadOutputStream} is created through {@link #create(File)} doesn't
         * support {@link FileDownloadOutputStream#seek(long)}, please return {@code false}, in
         * order to let the internal mechanism can predict this situation, and handle it smoothly.
         */
        boolean supportSeek();
    }

    public interface ConnectionCreator {
        /**
         * The connection creator is used for creating {@link FileDownloadConnection} component
         * which is used to use some protocol to connect to the remote server.
         *
         * @param url the uniform resource locator, which direct the aim resource we need to connect
         * @return The connection creator.
         * @throws IOException if an I/O exception occurs.
         */
        FileDownloadConnection create(String url) throws IOException;
    }

    /**
     * @param id              the {@code id} used for filter out which task would be notified the
     *                        'completed' message if need.
     * @param path            if the file with {@code path} is exist it means the relate task would
     *                        be completed.
     * @param forceReDownload whether the task is force to re-download ignore whether the file has
     *                        been exist or not.
     * @param flowDirectly    {@code true} if flow the message if need directly without throw to the
     *                        message-queue.
     * @return whether the task with {@code id} has been downloaded.
     */
    public static boolean inspectAndInflowDownloaded(int id, String path, boolean forceReDownload,
                                                     boolean flowDirectly) {
        if (forceReDownload) {
            return false;
        }

        if (path != null) {
            final File file = new File(path);
            if (file.exists()) {
                MessageSnapshotFlow.getImpl().inflow(MessageSnapshotTaker.
                        catchCanReusedOldFile(id, file, flowDirectly));
                return true;
            }
        }

        return false;
    }

    /**
     * @param id           the {@code id} used for filter out which task would be notified the
     *                     'warn' message if need.
     * @param model        the target model will be checked for judging whether it is downloading.
     * @param monitor      the monitor for download-thread.
     * @param flowDirectly {@code true} if flow the message if need directly without throw to the
     *                     message-queue.
     * @return whether the {@code model} is downloading.
     */
    public static boolean inspectAndInflowDownloading(int id, FileDownloadModel model,
                                                      IThreadPoolMonitor monitor,
                                                      boolean flowDirectly) {
        if (monitor.isDownloading(model)) {
            MessageSnapshotFlow.getImpl().
                    inflow(MessageSnapshotTaker.catchWarn(id, model.getSoFar(), model.getTotal(),
                            flowDirectly));
            return true;
        }

        return false;
    }

    /**
     * @param id             the {@code id} used for filter out which task would be notified the
     *                       'error' message if need.
     * @param sofar          the so far bytes of the current checking-task.
     * @param tempFilePath   the temp file path(file path used for downloading) for the current
     *                       checking-task.
     * @param targetFilePath the target file path for the current checking-task.
     * @param monitor        the monitor for download-thread.
     * @return whether the task with {@code id} is refused to start, because of there is an another
     * running task with the same {@code tempFilePath}.
     */
    public static boolean inspectAndInflowConflictPath(int id, long sofar,
                                                       String tempFilePath, String targetFilePath,
                                                       IThreadPoolMonitor monitor) {
        if (targetFilePath != null && tempFilePath != null) {
            final int anotherSameTempPathTaskId =
                    monitor.findRunningTaskIdBySameTempPath(tempFilePath, id);
            if (anotherSameTempPathTaskId != 0) {
                MessageSnapshotFlow.getImpl().
                        inflow(MessageSnapshotTaker.catchException(id, sofar,
                                new PathConflictException(anotherSameTempPathTaskId, tempFilePath,
                                        targetFilePath)));
                return true;
            }
        }

        return false;
    }
}