From a5b77d4d03d9121004ace8028eaf026acafddc67 Mon Sep 17 00:00:00 2001
From: Kayne Ruse <kayneruse@gmail.com>
Date: Fri, 6 Mar 2020 17:40:02 +1100
Subject: [PATCH] Wrote some example client code

---
 server/handler.js        | 71 ++++++++++++++++++++++++++++++++++------
 server/simpleQL/index.js | 21 ++++++++----
 2 files changed, 76 insertions(+), 16 deletions(-)

diff --git a/server/handler.js b/server/handler.js
index 341f2c7..0468582 100644
--- a/server/handler.js
+++ b/server/handler.js
@@ -1,20 +1,71 @@
 const database = require('./database.js');
 
+/* DOCS: The handler module connects the database to simpleQL.
+ * this will be user-implemented, but for now uses a fake database provided in database.js
+ * The 'scalars' will be objects containing a name and the type for each scalar field requested by a query.
+ * This can be used in several ways...
+ *
+ * The handlers should only handle scalar fields - compound fields will be queried separately by simpleQL.
+*/
+
 //the handler routines
 const handler = {
-	Book: scalars => {
+	Book: (parent, scalars) => {
+		//takes an object which is the result of the parent query, if there is one { typeName: 'Author', scalars: [scalars], context: parentObject }
+		//takes an array of scalar types as objects: { typeName: 'String', name: 'title' }
+		//must return an array of objects containing the results
+
+		let books = database.books;
+
+		//if this is a sub-query, use the parent to narrow the search
+		if (parent && parent.typeName == 'Author') {
+			//filter based on parent object
+			books = books.filter(b => b.author.name == parent.context.name);
+		}
+
+		//return all books
+		const fields = scalars.map(s => s.name);
+		return books.map(b => {
+			const ret = {};
+
+			if (fields.includes('title')) {
+				ret.title = b.title;
+			}
+
+			if (fields.includes('published')) {
+				ret.published = b.published;
+			}
+
+			return ret;
+		});
+	},
+
+	Author: (parent, scalars) => {
+		let authors = database.authors;
+
+		//if this is a sub-query, use the parent to find the author
+		if (parent && parent.typeName == 'Book') {
+			return authors.find(a => a.books.filter(b => b.title == parent.context.title).length > 0);
+		}
+
+		//return all authors
+		const fields = scalars.map(s => s.name);
+		return authors.map(a => {
+			const ret = {};
+
+			if (fields.includes('name')) {
+				ret.name = a.name;
+			}
+
+			return ret;
+		});
+	},
+
+	create: (matches, sets) => {
 		//TODO
 	},
 
-	Author: scalars => {
-		//TODO
-	},
-
-	create: (sets, matches) => {
-		//TODO
-	},
-
-	update: (sets, matches) => {
+	update: (matches, sets) => {
 		//TODO
 	},
 
diff --git a/server/simpleQL/index.js b/server/simpleQL/index.js
index 075717c..ada206d 100644
--- a/server/simpleQL/index.js
+++ b/server/simpleQL/index.js
@@ -12,17 +12,17 @@ const main = (schema, handler) => {
 
 		try {
 			//check for keywords
-			switch(tokens[pos++]) {
+			switch(tokens[pos]) {
 				case 'create':
 				case 'update':
 				case 'delete':
-					throw 'keyword not implemented';
+					throw 'keyword not implemented: ' + tokens[pos];
 					//TODO
 					break;
 
 				//no leading keyword - regular query
 				default:
-					//TODO: parse the query
+					parseQuery(handler, tokens, pos, typeGraph);
 
 					return [200, ''];
 
@@ -110,14 +110,19 @@ const parseCompoundType = (tokens, pos) => {
 			type = type.slice(0, type.length - 2);
 		}
 
+		//no mangled types or names
+		checkAlphaNumeric(type);
+		checkAlphaNumeric(name);
+
 		//can't use keywords
 		if (['type', 'scalar'].includes(type) || ['type', 'scalar'].includes(name)) {
 			throw 'Unexpected keyword found as type field or type name';
 		}
 
-		//no mangled types or names
-		checkAlphaNumeric(type);
-		checkAlphaNumeric(name);
+		//check for duplicate fields
+		if (Object.keys(compound).includes(name)) {
+			throw 'Unexpected duplicate filed name';
+		}
 
 		//finally, push to the compound definition
 		compound[name] = {
@@ -130,6 +135,10 @@ const parseCompoundType = (tokens, pos) => {
 	return compound;
 };
 
+const parseQuery = (handler, tokens, pos, typeGraph) => {
+	//TODO
+};
+
 //utils
 const checkAlphaNumeric = (str) => {
 	if (!/^[a-z0-9]+$/i.test(str)) {