Initial commit (mvp)

.gitignore

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+node_modules

package.json

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+{
+  "name": "d20ql",
+  "version": "1.0.0",
+  "main": "index.js",
+  "author": "juusaw",
+  "license": "MIT",
+  "dependencies": {
+    "apollo-server": "^2.4.0",
+    "graphql": "^14.1.1",
+    "ts-node": "^8.0.2",
+    "typescript": "^3.3.3"
+  },
+  "scripts": {
+    "start": "ts-node src/index.ts"
+  }
+}

src/index.ts

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+import { ApolloServer } from 'apollo-server'
+import { GraphQLSchema, GraphQLObjectType, GraphQLString, GraphQLInt, GraphQLNonNull, GraphQLFloat } from 'graphql'
+
+type Dice = [number, number, number]
+
+function parseDice(dice: string): Dice {
+  const [multiplier, sides, constant] = dice
+    .match(/(\d*)d(\d+)([\+|-]\d+)?/)
+    .slice(1)
+    .map(str => parseInt(str, 10))
+  return [
+    multiplier || 1,
+    sides,
+    constant || 0
+  ]
+}
+
+function countResult(multiplier: number, sides: number, constant: number) {
+  return multiplier * Math.floor(Math.random() * sides + 1) + constant
+}
+
+function calculateMean(multiplier: number, sides: number, constant: number) {
+  return multiplier * (sides + 1) / 2 + constant
+}
+
+const RollResultType = new GraphQLObjectType({
+  name: 'Roll',
+  fields: {
+    result: { type: GraphQLInt, resolve: (parent: {dice: Dice}) => countResult(...parent.dice) },
+    statistics: { type: GraphQLFloat, resolve: (parent: {dice: Dice}) => calculateMean(...parent.dice) }
+  }
+})
+
+const schema = new GraphQLSchema({
+  query: new GraphQLObjectType({
+    name: 'Query',
+    fields: {
+      roll: {
+        type: RollResultType,
+        description: 'Roll a dice. Example argument: 2d12+5',
+        args: {
+          dice: {
+            name: 'dice',
+            type: new GraphQLNonNull(GraphQLString) 
+          }
+        },
+        resolve: (_, args) => ({dice: parseDice(args.dice)})
+      }
+    }
+  })
+})
+
+const server = new ApolloServer({ schema })
+
+server.listen().then(({ url }) => {
+  console.log(`🚀 Server ready at ${url}`);
+})