Refactor multipart form handling for more reusability

plugins/tiddlywiki/multiwikiserver/modules/routes/helpers/multipart-forms.js

@@ -0,0 +1,104 @@
+/*\
+title: $:/plugins/tiddlywiki/multiwikiserver/routes/helpers/multipart-forms.js
+type: application/javascript
+module-type: library
+
+A function that handles an incoming multipart/form-data stream, streaming the data to temporary files
+in the store/inbox folder. Once the data is received, it imports any tiddlers and invokes a callback.
+
+\*/
+
+(function() {
+
+/*
+Process an incoming new multipart/form-data stream. Options include:
+
+store - tiddler store
+state - provided by server.js
+response - provided by server.js
+bagname - name of bag to write to
+callback - invoked as callback(err,results). Results is an array of titles of imported tiddlers
+*/
+exports.processIncomingStream = function(options) {
+	const self = this;
+	const path = require("path"),
+		fs = require("fs");
+	// Process the incoming data
+	const inboxName = $tw.utils.stringifyDate(new Date());
+	const inboxPath = path.resolve(options.store.attachmentStore.storePath,"inbox",inboxName);
+	$tw.utils.createDirectory(inboxPath);
+	let fileStream = null; // Current file being written
+	let hash = null; // Accumulating hash of current part
+	let length = 0; // Accumulating length of current part
+	const parts = []; // Array of {name:, headers:, value:, hash:} and/or {name:, filename:, headers:, inboxFilename:, hash:} 
+	options.state.streamMultipartData({
+		cbPartStart: function(headers,name,filename) {
+			console.log(`Received file ${name} and ${filename} with ${JSON.stringify(headers)}`)
+			const part = {
+				name: name,
+				filename: filename,
+				headers: headers
+			};
+			if(filename) {
+				const inboxFilename = (parts.length).toString();
+				part.inboxFilename = path.resolve(inboxPath,inboxFilename);
+				fileStream = fs.createWriteStream(part.inboxFilename);
+			} else {
+				part.value = "";
+			}
+			hash = new $tw.sjcl.hash.sha256();
+			length = 0;
+			parts.push(part)
+		},
+		cbPartChunk: function(chunk) {
+			if(fileStream) {
+				fileStream.write(chunk);
+			} else {
+				parts[parts.length - 1].value += chunk;
+			}
+			length = length + chunk.length;
+			hash.update(chunk);
+			console.log(`Got a chunk of length ${chunk.length}, length is now ${length}`);
+		},
+		cbPartEnd: function() {
+			if(fileStream) {
+				fileStream.end();
+			}
+			fileStream = null;
+			parts[parts.length - 1].hash = $tw.sjcl.codec.hex.fromBits(hash.finalize()).slice(0,64).toString();
+			hash = null;
+		},
+		cbFinished: function(err) {
+			if(err) {
+				return options.callback(err);
+			} else {
+				console.log(`Multipart form data processed as ${JSON.stringify(parts,null,4)}`);
+				const partFile = parts.find(part => part.name === "file-to-upload" && !!part.filename);
+				if(!partFile) {
+					return state.sendResponse(400, {"Content-Type": "text/plain"},"Missing file to upload");
+				}
+				const type = partFile.headers["content-type"];
+				const tiddlerFields = {
+					title: partFile.filename,
+					type: type
+				};
+				for(const part of parts) {
+					const tiddlerFieldPrefix = "tiddler-field-";
+					if(part.name.startsWith(tiddlerFieldPrefix)) {
+						tiddlerFields[part.name.slice(tiddlerFieldPrefix.length)] = part.value.trim();
+					}
+				}
+				console.log(`Creating tiddler with ${JSON.stringify(tiddlerFields)} and ${partFile.filename}`)
+				options.store.saveBagTiddlerWithAttachment(tiddlerFields,options.bagname,{
+					filepath: partFile.inboxFilename,
+					type: type,
+					hash: partFile.hash
+				});
+				$tw.utils.deleteDirectory(inboxPath);
+				options.callback(null,[tiddlerFields.title]);
+			}
+		}
+	});
+};
+
+})();