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Java wrapper for the popular chat & VOIP service: Discord https://discord.com

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/*
 * Copyright 2015 Austin Keener, Michael Ritter, Florian Spieß, and the JDA contributors
 *
 * 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 net.dv8tion.jda.api.utils;

import net.dv8tion.jda.api.exceptions.HttpException;
import net.dv8tion.jda.api.requests.RestConfig;
import net.dv8tion.jda.internal.requests.FunctionalCallback;
import net.dv8tion.jda.internal.utils.Checks;
import net.dv8tion.jda.internal.utils.FutureUtil;
import net.dv8tion.jda.internal.utils.IOUtil;
import okhttp3.Call;
import okhttp3.HttpUrl;
import okhttp3.OkHttpClient;
import okhttp3.Request;

import javax.annotation.Nonnull;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.UncheckedIOException;
import java.nio.file.*;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.function.Function;

/**
 * A utility class to download files.
 */
public class FileProxy
{
    private static volatile OkHttpClient defaultHttpClient;

    private final String url;
    private OkHttpClient customHttpClient;

    /**
     * Constructs a new {@link FileProxy} for the provided URL.
     *
     * @param url
     *        The URL to download from
     *
     * @throws IllegalArgumentException
     *         If the provided URL is null
     */
    public FileProxy(@Nonnull String url)
    {
        Checks.notNull(url, "URL");
        this.url = url;
    }

    /**
     * Sets the default OkHttpClient used by {@link FileProxy} and {@link ImageProxy}.
     * 
This can still be overridden on a per-instance basis with {@link #withClient(OkHttpClient)}. * * @param httpClient * The default {@link OkHttpClient} to use while making HTTP requests * * @throws IllegalArgumentException * If the provided {@link OkHttpClient} is null */ public static void setDefaultHttpClient(@Nonnull OkHttpClient httpClient) { Checks.notNull(httpClient, "Default OkHttpClient"); FileProxy.defaultHttpClient = httpClient; } /** * Returns the URL that has been passed to this proxy. *
This URL is always from Discord. * * @return The URL of the file. */ @Nonnull public String getUrl() { return url; } /** * Sets the custom OkHttpClient used by this instance, regardless of if {@link #setDefaultHttpClient(OkHttpClient)} has been used or not. * * @param customHttpClient * The custom {@link OkHttpClient} to use while making HTTP requests * * @throws IllegalArgumentException * If the provided {@link OkHttpClient} is null * * @return This proxy for chaining convenience. */ @Nonnull public FileProxy withClient(@Nonnull OkHttpClient customHttpClient) { Checks.notNull(customHttpClient, "Custom HTTP client"); this.customHttpClient = customHttpClient; return this; } // INTERNAL DOWNLOAD METHODS protected OkHttpClient getHttpClient() { // Return custom HTTP client if set if (customHttpClient != null) return customHttpClient; // Otherwise, see if a default one has been assigned // If there is no client then create a default one if (defaultHttpClient == null) { synchronized (this) { if (defaultHttpClient == null) defaultHttpClient = new OkHttpClient(); } } return defaultHttpClient; } protected Request getRequest(String url) { return new Request.Builder() .url(url) .addHeader("user-agent", RestConfig.USER_AGENT) .addHeader("accept-encoding", "gzip, deflate") .build(); } protected CompletableFuture download(String url) { // We need to apply a pattern of CompletableFuture as shown here https://discord.com/channels/125227483518861312/942488867167146005/942492134446088203 // This CompletableFuture is going to be passed to the user / other proxy methods and must not be overridden with other "completion stages" (see CF#exceptionally return type) // This is done in order to make cancelling these downloads actually cancel all the tasks that depends on the previous ones. // If we did not do this, CF#cancel would have only cancelled the *last* CompletableFuture, so the download would still have occurred for example // So since we return a completely different future, we need to use #complete / #completeExceptionally manually, // i.e. When the underlying CompletableFuture (the actual download task) has completed in any state final DownloadTask downloadTask = downloadInternal(url); return FutureUtil.thenApplyCancellable(downloadTask.getFuture(), Function.identity(), downloadTask::cancelCall); } private DownloadTask downloadInternal(String url) { final CompletableFuture future = new CompletableFuture<>(); final Request req = getRequest(url); final OkHttpClient httpClient = getHttpClient(); final Call newCall = httpClient.newCall(req); newCall.enqueue(FunctionalCallback .onFailure((call, e) -> future.completeExceptionally(new UncheckedIOException(e))) .onSuccess((call, response) -> { if (response.isSuccessful()) { InputStream body = IOUtil.getBody(response); if (!future.complete(body)) IOUtil.silentClose(response); } else { future.completeExceptionally(new HttpException(response.code() + ": " + response.message())); IOUtil.silentClose(response); } }).build()); return new DownloadTask(newCall, future); } protected CompletableFuture downloadToPath(String url) { final HttpUrl parsedUrl = HttpUrl.parse(url); Checks.check(parsedUrl != null, "URL '%s' is invalid", url); final List segments = parsedUrl.pathSegments(); final String fileName = segments.get(segments.size() - 1); //Download to a file named the same as the last segment of the URL return downloadToPath(Paths.get(fileName)); } protected CompletableFuture downloadToPath(String url, Path path) { //Turn this into an absolute path so we can check the parent folder final Path absolute = path.toAbsolutePath(); //Check if the parent path, the folder, exists final Path parent = absolute.getParent(); Checks.check(parent != null && Files.exists(parent), "Parent folder of the file '%s' does not exist.", absolute); if (Files.exists(absolute)) { Checks.check(Files.isRegularFile(absolute), "Path '%s' is not a regular file.", absolute); Checks.check(Files.isWritable(absolute), "File at '%s' is not writable.", absolute); } final DownloadTask downloadTask = downloadInternal(url); return FutureUtil.thenApplyCancellable(downloadTask.getFuture(), stream -> { try { //Temporary file follows this pattern: filename + random_number + ".part" // The random number is generated until a filename becomes valid, until no file with the same name exists in the tmp directory final Path tmpPath = Files.createTempFile(absolute.getFileName().toString(), ".part"); //A user might use a file's presence as an indicator of something being successfully downloaded, //This might prevent a file from being partial, say, if the user shuts down its bot while it's downloading something //Meanwhile, the time window to "corrupt" a file is very small when moving it //This is why we copy the file into a temporary file and then move it. Files.copy(stream, tmpPath, StandardCopyOption.REPLACE_EXISTING); Files.move(tmpPath, absolute, StandardCopyOption.REPLACE_EXISTING); return absolute; } catch (IOException e) { throw new UncheckedIOException(e); } finally { IOUtil.silentClose(stream); } }, downloadTask::cancelCall); } //API DOWNLOAD METHOD /** * Retrieves the {@link InputStream} of this file * * @return {@link CompletableFuture} which holds an {@link InputStream}, the {@link InputStream} must be closed manually */ @Nonnull public CompletableFuture download() { return download(url); } /** * Downloads the data of this file, and stores it in a file with the same name as the queried file name (this would be the last segment of the URL). * *

Implementation note: * The file is first downloaded into a temporary file, the file is then moved to its real destination when the download is complete. * * @return {@link CompletableFuture} which holds a {@link Path} which corresponds to the location the file has been downloaded. */ @Nonnull public CompletableFuture downloadToPath() { return downloadToPath(url); } /** * Downloads the data of this file into the specified file. * *

Implementation note: * The file is first downloaded into a temporary file, the file is then moved to its real destination when the download is complete. * * @param file * The file in which to download the data * * @throws IllegalArgumentException * If any of the follow checks are true *

    *
  • The target file is null
  • *
  • The parent folder of the target file does not exist
  • *
  • The target file exists and is not a {@link Files#isRegularFile(Path, LinkOption...) regular file}
  • *
  • The target file exists and is not {@link Files#isWritable(Path) writable}
  • *
* * @return {@link CompletableFuture} which holds a {@link File}, it is the same as the file passed in the parameters. */ @Nonnull public CompletableFuture downloadToFile(@Nonnull File file) { Checks.notNull(file, "File"); final CompletableFuture downloadToPathFuture = downloadToPath(url, file.toPath()); return FutureUtil.thenApplyCancellable(downloadToPathFuture, Path::toFile); } /** * Downloads the data of this file into the specified file. * *

Implementation note: * The file is first downloaded into a temporary file, the file is then moved to its real destination when the download is complete. *
The given path can also target filesystems such as a ZIP filesystem. * * @param path * The file in which to download the image * * @throws IllegalArgumentException * If any of the follow checks are true *

    *
  • The target path is null
  • *
  • The parent folder of the target path does not exist
  • *
  • The target path exists and is not a {@link Files#isRegularFile(Path, LinkOption...) regular file}
  • *
  • The target path exists and is not {@link Files#isWritable(Path) writable}
  • *
* * @return {@link CompletableFuture} which holds a {@link Path}, it is the same as the path passed in the parameters. */ @Nonnull public CompletableFuture downloadToPath(@Nonnull Path path) { Checks.notNull(path, "Path"); return downloadToPath(url, path); } protected static class DownloadTask { private final Call call; private final CompletableFuture future; public DownloadTask(Call call, CompletableFuture future) { this.call = call; this.future = future; } protected void cancelCall() { call.cancel(); } protected CompletableFuture getFuture() { return future; } } }




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