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const express = require('express');
const app = express();

// Serves Express Yourself website
app.use(express.static('public'));

const { getElementById, getIndexById, updateElement,
        seedElements, createElement } = require('./utils');

const expressions = [];
seedElements(expressions, 'expressions');
const animals = [];
seedElements(animals, 'animals');

const PORT = process.env.PORT || 4001;
// Use static server to serve the Express Yourself Website
app.use(express.static('public'));

app.get('/expressions', (req, res, next) => {
  res.send(expressions);
});

app.get('/expressions/:id', (req, res, next) => {
  const foundExpression = getElementById(req.params.id, expressions);
  if (foundExpression) {
    res.send(foundExpression);
  } else {
    res.status(404).send();
  }
});

app.put('/expressions/:id', (req, res, next) => {
  const expressionIndex = getIndexById(req.params.id, expressions);
  if (expressionIndex !== -1) {
    updateElement(req.params.id, req.query, expressions);
    res.send(expressions[expressionIndex]);
  } else {
    res.status(404).send();
  }
});

app.post('/expressions', (req, res, next) => {
  const receivedExpression = createElement('expressions', req.query);
  if (receivedExpression) {
    expressions.push(receivedExpression);
    res.status(201).send(receivedExpression);
  } else {
    res.status(400).send();
  }
});

**************
app.delete('/expressions/:id', (req, res, next) => {
  const elementIndex = getIndexById(req.params.id, expressions)
  if(elementIndex === -1) {
    res.status(404).send()
  } else {
    expressions.splice(elementIndex, 1)
    res.status(204).send()
  }
})  
****************
  
app.delete('/expressions/:id', (req, res, next) => {
  const expressionIndex = getIndexById(req.params.id, expressions);
  if (expressionIndex !== -1) {
    expressions.splice(expressionIndex, 1);
    res.status(204).send();
  } else {
    res.status(404).send();
  }
});

app.listen(PORT, () => {
  console.log(`Listening on port ${PORT}`); 
});

let expressionIdCounter = 0;
let animalIdCounter = 0;

const getElementById = (id, elementList) => {
  return elementList.find((element) => {
    return element.id === Number(id);
  });
};

const getIndexById = (id, elementList) => {
  return elementList.findIndex((element) => {
    return element.id === Number(id);
  });
};

const createElement = (elementType, queryArguments) => {
  if (queryArguments.hasOwnProperty('emoji') &&
      queryArguments.hasOwnProperty('name')) {
    let currentId;
    if (elementType === 'expressions') {
      expressionIdCounter += 1;
      currentId = expressionIdCounter;
    } else {
      animalIdCounter += 1;
      currentId = animalIdCounter;
    }
    return {
      'id':    currentId,
      'emoji': queryArguments.emoji,
      'name':  queryArguments.name,
    };
  } else {
    return false;
  }
};

const updateElement = (id, queryArguments, elementList) => {
  const elementIndex = getIndexById(id, elementList);
  if (elementIndex === -1) {
    throw new Error('updateElement must be called with a valid id parameter');
  }
  if (queryArguments.id) {
    queryArguments.id = Number(queryArguments.id);
  }
  Object.assign(elementList[elementIndex], queryArguments);
  return elementList[elementIndex];
};

const seedElements = (arr, type) => {
  if (type === 'expressions') {
    arr.push(createElement('expressions', {'emoji': '😀', 'name': 'happy'}));
    arr.push(createElement('expressions', {'emoji': '😎', 'name': 'shades'}));
    arr.push(createElement('expressions', {'emoji': '😴', 'name': 'sleepy'}));
  } else if (type === 'animals') {
    arr.push(createElement('animals', {'emoji': '🐶', 'name': 'Pupper'}));
    arr.push(createElement('animals', {'emoji': '🐍', 'name': 'Snek'}));
    arr.push(createElement('animals', {'emoji': '🐱', 'name': 'Maru'}));
  } else {
    throw new Error(`seed type must be either 'expression' or 'animal'`);
  }
};

module.exports = {
  createElement: createElement,
  getIndexById: getIndexById,
  getElementById: getElementById,
  updateElement: updateElement,
  seedElements: seedElements,
};