Add contracts for parser functions

PR-URL: metarhia#12

lib/parser.js

@@ -1,41 +1,86 @@
 'use strict';
 
+const PROTOCOL_VERSION = 1;
 const HANDSHAKE_LENGTH = 36;
 const PARCEL_LENGTH = 16;
 const CHUNK_LENGTH = 12;
 
-const parcel = (buffer) => {
+const readParcel = (buffer) => {
   // Read parcel from buffer
   // Return parcel object
   const rest = Buffer.from(buffer, 1, PARCEL_LENGTH);
   return rest;
 };
 
-const chunk = (buffer) => {
+const parcel = (
+  // Encode parcel structure to Buffer
+  // id, // parcelId: 4b
+  // type, // parcelType: 4b
+  // compression, // 1b: no = 0, gzip = 1
+  // encoding, // 1b: binary = 0, jstp = 1, json = 2, bson = 3, v8 = 4
+  // length // 8b
+) => {
+  const parcel = Buffer.alloc(PARCEL_LENGTH);
+  parcel.writeInt8(0, 0);
+  // Write parcel fields to buffer
+  return parcel;
+};
+
+const readChunk = (buffer) => {
   // Read chunkk from buffer
   // Return chunk object
   const rest = Buffer.from(buffer, 1, CHUNK_LENGTH);
   return rest;
 };
 
-const handshake = (buffer) => {
+const chunk = (
+  // Encode chunk structure to Buffer
+  // id, // parcelId: 4b
+  // flags, // 1b: more = 1, stop = 2, pause = 4, resume = 8
+  // length, // 2b
+  // payload // Buffer
+) => {
+  const chunk = Buffer.alloc(CHUNK_LENGTH);
+  chunk.writeInt8(1, 0);
+  // Write chunk fields to buffer
+  return chunk;
+};
+
+const readHandshake = (buffer) => {
   // Read handshake from buffer
   // Return handshake object
   const rest = Buffer.from(buffer, 0, HANDSHAKE_LENGTH);
   return rest;
 };
 
+const handshake = (
+  // Encode handshake structure to Buffer
+  // status // 1b: 0 = new, 1 = restore
+  // reserved // 1b
+  // token // 32b (optional)
+) => {
+  const handshake = Buffer.alloc(HANDSHAKE_LENGTH);
+  handshake.writeInt16LE(PROTOCOL_VERSION, 0);
+  // Write handshake to buffer
+  return handshake;
+};
+
 const structTypes = [
-  /* 0 */ parcel,
-  /* 1 */ chunk
+  /* 0 */ readParcel,
+  /* 1 */ readChunk
 ];
 
-const structure = (buffer) => {
+const readStruct = (buffer) => {
   // Read structure from buffer
   // Return parcel or chunk object
   const structType = buffer.readInt8(0, true);
   const parser = structTypes[structType];
   if (parser) return parser(buffer);
 };
 
-module.exports = { structure, handshake, chunk, parcel };
+module.exports = {
+  handshake, readHandshake,
+  chunk, readChunk,
+  parcel, readParcel,
+  readStruct
+};