import { GraphQLServer } from "graphql-yoga";
import uuidv4 from "uuid/v4";

// Demo user data
const users = [
  { id: "1", name: "Andrew", email: "andrew@example.com", age: 27 },
  { id: "2", name: "Sarah", email: "sarah@example.com" },
  { id: "3", name: "Mike", email: "mike@example.com" }
];

const posts = [
  {
    id: "10",
    author: "1",
    title: "GraphQL 101",
    body: "This is how to use GraphQL...",
    published: true
  },
  {
    id: "11",
    author: "1",
    title: "GraphQL 201",
    body: "This is an advanced GraphQL post...",
    published: false
  },
  {
    id: "12",
    author: "2",
    title: "Programming Music",
    body: "",
    published: false
  }
];

const comments = [
  {
    id: "102",
    author: "3",
    post: "10",
    text: "This worked well for me. Thanks!"
  },
  { id: "103", author: "1", post: "10", text: "Gladd you enjoted it." },
  { id: "104", author: "2", post: "11", text: "This did not work." },
  { id: "105", author: "2", post: "11", text: "Nevermind, I got it to work." }
];

// Type definitions
const typeDefs = `
    type Query {
        users(query: String): [User!]!
        posts(query: String): [Post!]!
        comments: [Comment!]!
        me: User!
        post(id: ID!): Post!
    }

    type Mutation {
        createUser(name: String!, email: String!, age: Int): User!
    }

    type User {
        id: ID!
        name: String!
        email: String!
        age: Int
        posts: [Post!]!
        comments: [Comment!]!
    }

    type Post {
        id: ID!
        author: User!
        title: String!
        body: String!
        published: Boolean!
        comments: [Comment!]!
    }

    type Comment {
        id: ID!
        text: String!
        author: User!
        post: Post!
    }
`;

// Resolvers
// If one of the fields is not a scalar type, setup custom resolvers to teach GQL how to get the data
const resolvers = {
  Query: {
    users(parent, { query }, ctx, info) {
      if (!query) {
        return users;
      }

      return users.filter(user =>
        user.name.toLowerCase().includes(query.toLowerCase())
      );
    },
    posts(parent, { query }, ctx, info) {
      if (!query) {
        return posts;
      }

      return posts.filter(post => {
        const isTitleMatch = post.title
          .toLowerCase()
          .includes(query.toLowerCase());
        const isBodyMatch = post.body
          .toLowerCase()
          .includes(query.toLowerCase());

        return isTitleMatch || isBodyMatch;
      });
    },
    comments(parent, args, ctx, info) {
      return comments;
    },
    me() {
      return {
        id: "123098",
        name: "Mike",
        email: "mike@example.com"
      };
    },
    post() {
      return {
        id: "092",
        title: "GraphQL 101",
        body: "",
        published: false
      };
    }
  },
  Mutation: {
    createUser(parent, args, ctx, info) {
      const emailTaken = users.some(user => user.email === args.email);

      if (emailTaken) {
        throw new Error("Email taken.");
      }

      const user = {
        // id: uuidv4(),
        name: args.name,
        email: args.email,
        age: args.age
      };

      users.push(user);

      return user;
    }
  },
  Post: {
    author({ author }, args, ctx, info) {
      return users.find(user => user.id === author);
    },
    comments(parent, args, ctx, info) {
      return comments.filter(comment => comment.post === parent.id);
    }
  },
  User: {
    posts(parent, args, ctx, info) {
      return posts.filter(post => post.author === parent.id);
    },
    comments(parent, args, ctx, info) {
      return comments.filter(comment => comment.author === parent.id);
    }
  },
  Comment: {
    author(parent, args, ctx, info) {
      return users.find(user => user.id === parent.author);
    },
    post(parent, args, ctx, info) {
      return posts.find(post => post.id === parent.post);
    }
  }
};

const server = new GraphQLServer({
  typeDefs,
  resolvers
});

// Port 4000
server.start(() => {
  console.log("The server is up!");
});