Support streaming in final commit call

[coyotte508]

Needs first better browser support, & http2 support on hf.co's side

Some code snippets:

	// https://github.com/whatwg/fetch/issues/1438#issuecomment-1228635501
	function supportRequestStream(): boolean {
		if (!ENABLE_REQUEST_STREAM) {
			return false;
		}
		// This works because the browser adds a Content-Type header of text/plain;charset=UTF-8 to the request
		// if the body is text.
		// The browser only treats the body as text if it doesn't support request streams,
		// otherwise it won't add a Content-Type header at all.
		return (
			ReadableStream &&
			!new Request("", {
				body: new ReadableStream(),
				method: "POST",
				// @ts-expect-error chrome suppport, see https://github.com/whatwg/fetch/issues/1438#issuecomment-1228635501
				duplex: "half",
			}).headers.has("Content-Type")
		);
	}

	// https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream#async_iterator_to_stream
	function iteratorToStream(iterator: AsyncIterator<string>) {
		return new ReadableStream<string>({
			async pull(controller) {
				const { value, done } = await iterator.next();

				if (done) {
					controller.close();
				} else {
					controller.enqueue(value);
				}
			},
		});
	}

	async function* commitPayload(lfsFiles: UploadFile[], nonLfsFiles: UploadFile[]): AsyncGenerator<string> {
		const initialChangeCount = changeCount;

		const line: CommitJsonLine = {
			key: "header",
			value: {
				summary:
					summary ||
					(selectedFiles.length === 1 ? `Upload ${selectedFiles[0].name}` : `Upload ${selectedFiles.length} files`),
				description,
				parentCommit: latestCommit,
			},
		};

		yield JSON.stringify(line);

		if (changeCount !== initialChangeCount) {
			throw new Error("upload aborted");
		}

		for (const file of lfsFiles) {
			const line: CommitJsonLine = {
				key: "lfsFile",
				value: {
					oid: file.upload.sha256!,
					size: file.size,
					algo: "sha256",
					path: path ? `${path}/${file.fullPath}` : file.fullPath,
				},
			};
			yield "\n" + JSON.stringify(line);

			if (changeCount !== initialChangeCount) {
				throw new Error("upload aborted");
			}
		}

		const isReadStream = supportRequestStream();

		for (const file of nonLfsFiles) {
			const fileIndex = selectedFiles.indexOf(file);

			const line: CommitJsonLine = {
				key: "file",
				value: {
					path: path ? `${path}/${file.fullPath}` : file.fullPath,
					encoding: "base64",
					content: await blobToBase64(file),
				},
			};
			if (changeCount !== initialChangeCount) {
				throw new Error("upload aborted");
			}
			const payload = "\n" + JSON.stringify(line);

			file.upload.progressRatio = 0;
			file.upload.state = "uploading";
			selectedFiles[fileIndex] = selectedFiles[fileIndex];

			// In case of an actual working read stream, we update the progress bar for the file as we release
			// the data
			if (isReadStream) {
				const chunks = chunk(payload, 20_000);
				for (let i = 0; i < chunks.length; i++) {
					yield chunks[i];
					file.upload.progressRatio = (i + 1) / chunks.length;
					selectedFiles[fileIndex] = selectedFiles[fileIndex];

					if (changeCount !== initialChangeCount) {
						throw new Error("upload aborted");
					}
				}
			} else {
				yield payload;
			}

			file.upload.state = "completed";
		}
	}

	async function uploadWithProgressFetch(
		source: AsyncIterator<string>,
		url: string,
		opts: {
			headers?: Record<string, string>;
			index?: number;
			method: "PUT" | "POST";
		}
	) {
		return fetch(url, {
			method: opts.method,
			body: iteratorToStream(source).pipeThrough(new TextEncoderStream()),
			headers: opts.headers,
			// @ts-expect-error chrome suppport, see https://github.com/whatwg/fetch/issues/1438#issuecomment-1228635501
			duplex: "half",
		});
	}