const fs = require('fs');
const _ = require('lodash');

const nextId = table => {
  let id = 1;

  let currentData = JSON.parse(fs.readFileSync('data.json'), 'utf8');

  if (!currentData[table]) {
    return id;
  }

  return currentData[table][currentData[table].length - 1].id + 1;
};

const newPost = (author, title, body) => {
  let post = {
    author,
    title,
    body,
    date: new Date().toLocaleString(),
    votes: 1,
    id: nextId('posts')
  };

  let currentData = JSON.parse(fs.readFileSync('data.json', 'utf8'));

  if (!currentData.posts) {
    currentData.posts = [];
  }

  currentData.posts.push(post);

  fs.writeFileSync('data.json', JSON.stringify(currentData));

  return post;
};

const newComment = (author, post, comment) => {
  let ncomment = {
    author,
    post,
    comment,
    date: new Date().toLocaleString(),
    id: nextId('comments')
  };

  let currentData = JSON.parse(fs.readFileSync('data.json', 'utf8'));

  if (!currentData.comments) {
    currentData.comments = [];
  }

  currentData.comments.push(ncomment);

  fs.writeFileSync('data.json', JSON.stringify(currentData));

  return ncomment;
};

const newUser = (name, email, password) => {
  let user = {
    name,
    email,
    password,
    registration: new Date().toLocaleString(),
    id: nextId('users')
  };

  let currentData = JSON.parse(fs.readFileSync('data.json', 'utf8'));

  if (!currentData.users) {
    currentData.users = [];
  }

  currentData.users.push(user);

  fs.writeFileSync('data.json', JSON.stringify(currentData));

  return user;
};

const checkUser = (name, password) => {
  let currentData = JSON.parse(fs.readFileSync('data.json', 'utf8'));
  let users = currentData.users || [];

  return users.find(u => u.name === name && u.password === password);
};

const vote = (post, amount) => {
  let currentData = JSON.parse(fs.readFileSync('data.json', 'utf8'));
  let posts = currentData.posts;

  let found = posts.findIndex(p => p.id === post);

  if (found < 0) return;

  currentData.posts[found].votes += amount;

  fs.writeFileSync('data.json', JSON.stringify(currentData));
}

const upvotePost = post => {
  vote(post, +1);
};

const downvotePost = post => {
  vote(post, -1);
};

const getPosts = () => {
  return JSON.parse(fs.readFileSync('data.json', 'utf8')).posts || [];
}

const getUsers = () => {
  return JSON.parse(fs.readFileSync('data.json', 'utf8')).users || [];
}

const getComments = () => {
  return JSON.parse(fs.readFileSync('data.json', 'utf8')).comments || [];
}

const express = require('express');
const app = express();
const cors = require('cors');
const bodyParser = require('body-parser');

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
app.use(cors());
app.set('json spaces', 40);

app.get('/posts', function (req, res) {
  res.send(getPosts());
});

app.get('/users', function (req, res) {
  res.send(getUsers());
});

app.get('/comments', function (req, res) {
  res.send(getComments());
});

app.post('/addpost', function (req, res) {
  let post = newPost(req.body.author.id, req.body.title, req.body.body);

  res.send(post);
});

app.post('/adduser', function (req, res) {
  let user = newUser(req.body.username, req.body.email, req.body.password);

  res.send(user);
});

app.post('/addcomment', function (req, res) {
  let comment = newComment(req.body.user, req.body.post, req.body.body);

  res.send(comment);
});

app.post('/upvote', function (req, res) {
  let current = upvotePost(req.body.post);

  res.send(current);
});

app.post('/downvote', function (req, res) {
  let current = downvotePost(req.body.post);

  res.send(current);
});

app.post('/login', function (req, res) {
  let user = checkUser(req.body.username, req.body.password);

  res.send(user);
});

app.listen(3000, () => {
  console.log('server listening at localhost:3000');
});