From e9655f1055bd9b767b177e3a2e666906b3e72708 Mon Sep 17 00:00:00 2001
From: Kayne Ruse <kayneruse@gmail.com>
Date: Mon, 16 Mar 2020 06:31:29 +1100
Subject: [PATCH] Got it working!

---
 server/handler.js        | 10 ++++-
 server/server.js         |  8 ++--
 server/simpleQL/index.js | 88 +++++++++++++++++++++++++++++++++++++---
 3 files changed, 95 insertions(+), 11 deletions(-)

diff --git a/server/handler.js b/server/handler.js
index 0468582..f44dc77 100644
--- a/server/handler.js
+++ b/server/handler.js
@@ -45,7 +45,15 @@ const handler = {
 
 		//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);
+			const author = authors.find(a => a.books.filter(b => b.title == parent.context.title).length > 0);
+
+			//ensure only the named scalars are returned (hack)
+			const ret = {};
+			if (scalars.filter(s => s.name == 'name').length > 0) {
+				ret.name = author.name;
+			}
+
+			return [ret]; //must return an array
 		}
 
 		//return all authors
diff --git a/server/server.js b/server/server.js
index 22b5f46..0b5e5fe 100644
--- a/server/server.js
+++ b/server/server.js
@@ -12,12 +12,12 @@ const simpleQL = require('./simpleQL');
 const simple = simpleQL(schema, handler);
 
 //open the end
-app.post('/simpleql', (req, res) => {
-    const [code, result] = simple(req.body);
-    res.status(code).send(result);
+app.post('/simpleql', async (req, res) => {
+	const [code, result] = await simple(req.body);
+	res.status(code).send(result);
 });
 
 //startup
 app.listen(process.env.WEB_PORT || 3100, err => {
-    console.log(`listening to *:${process.env.WEB_PORT || 3100}`);
+	console.log(`listening to *:${process.env.WEB_PORT || 3100}`);
 });
\ No newline at end of file
diff --git a/server/simpleQL/index.js b/server/simpleQL/index.js
index ed7f68b..4bca894 100644
--- a/server/simpleQL/index.js
+++ b/server/simpleQL/index.js
@@ -5,7 +5,7 @@ const main = (schema, handler) => {
 	console.log(typeGraph);
 
 	//the receiving function - this will be called multiple times
-	return reqBody => {
+	return async reqBody => {
 		//parse the query
 		const tokens = reqBody.split(/(\s+)/).filter(s => s.trim().length > 0);
 		let pos = 0;
@@ -22,11 +22,10 @@ const main = (schema, handler) => {
 
 				//no leading keyword - regular query
 				default:
-					parseQuery(handler, tokens, pos, typeGraph);
+					const result = await parseQuery(handler, tokens, pos, typeGraph[tokens[pos]], typeGraph);
 
-					return [200, ''];
+					return [200, result];
 
-					//TODO
 					break;
 			}
 		}
@@ -135,8 +134,73 @@ const parseCompoundType = (tokens, pos) => {
 	return compound;
 };
 
-const parseQuery = (handler, tokens, pos, typeGraph) => {
-	//TODO
+const parseQuery = async (handler, tokens, pos, typeGraph, superTypeGraph, parent = null) => {
+	//returns an object result from handler
+
+	//get the "parent object" contents for sub-objects
+	const queryName = superTypeGraph[tokens[pos]] ? null : tokens[pos]; //if you're a type, name = null
+	const queryType = superTypeGraph[tokens[pos]] ? tokens[pos] : superTypeGraph[parent.typeName][tokens[pos]].typeName; //use this type or derive the type from the parent
+
+	//move on
+	pos++;
+
+	//the opening brace
+	if (tokens[pos++] != '{') {
+		throw 'Expected \'{\' in query, found ' + tokens[pos - 1];
+	}
+
+	//the scalars to pass to the handler
+	const scalarFields = [];
+	const deferredCalls = []; //functions (promises) that will be called at the end of this function
+
+	while(tokens[pos] != '}') { //while not at the end of this block
+		//not the end of the query
+		if (!tokens[pos]) {
+			throw 'Expected field in query, got end';
+		}
+
+		//prevent using keywords
+		if (['create', 'update', 'delete', 'set', 'match'].includes(tokens[pos])) {
+			throw 'Unexpected keyword ' + tokens[pos];
+		}
+
+		//type is a scalar, and can be queried
+		if (superTypeGraph[typeGraph[tokens[pos]].typeName].scalar) {
+			//push the scalar object to the queryFields
+			scalarFields.push({ typeName: typeGraph[tokens[pos]].typeName, name: tokens[pos] });
+
+			pos++;
+		} else {
+			const pos2 = pos; //cache the value to keep it from changing
+
+			//recurse
+			deferredCalls.push(async (result) => [tokens[pos2], await parseQuery(
+				handler,
+				tokens,
+				pos2,
+				superTypeGraph[typeGraph[tokens[pos2]].typeName],
+				superTypeGraph,
+				{ typeName: queryType, scalars: scalarFields, context: result }
+			)]);
+
+			pos = eatBlock(tokens, pos);
+		}
+	}
+
+	//eat the end bracket
+	pos++;
+
+	let results = handler[queryType](parent, scalarFields);
+
+	results = await Promise.all(results.map(async res => {
+		const tuples = await Promise.all(deferredCalls.map(async call => await call(res)));
+
+		tuples.forEach(tuple => res[tuple[0]] = tuple[1]);
+
+		return res;
+	}));
+
+	return results;
 };
 
 //utils
@@ -146,5 +210,17 @@ const checkAlphaNumeric = (str) => {
 	}
 };
 
+const eatBlock = (tokens, pos) => {
+	while (tokens[pos] && tokens[pos] != '}') {
+		if (tokens[pos] == '{') {
+			pos = eatBlock(tokens, pos+1);
+		} else {
+			pos++;
+		}
+	}
+
+	return pos;
+};
+
 //return
 module.exports = main;
\ No newline at end of file