<template>
  <div class="hello">
        <div class="calculator">
            <button @click="changeModeEvent" class="toggle-button">
              <p v-if="changeMode">Show Advanced Mode &nbsp; &nbsp; &#9864;</p>
              <p v-else>Show Basic Mode &nbsp; &nbsp; &#9862;</p>
            </button>
            <div class="results">
              <input class="input" v-model="current" />
            </div>
            <div class="mode" v-if="changeMode">
              <button class="button" @click="press">7</button>
              <button class="button" @click="press">8</button>
              <button class="button" @click="press">9</button>
              <button class="button" @click="press">*</button>
              <button class="button" @click="press">&#60;=</button>
              <button class="button" @click="press">C</button>
              <button class="button" @click="press">4</button>
              <button class="button" @click="press($event)">5</button>
              <button class="button" @click="press">6</button>
              <button class="button" @click="press">/</button>
              <button class="button" @click="press">(</button>
              <button class="button" @click="press">)</button>
              <button class="button" @click="press">1</button>
              <button class="button" @click="press">2</button>
              <button class="button" @click="press">3</button>
              <button class="button" @click="press">-</button>
              <button class="button" @click="press">x ²</button>
              <button class="button" @click="press">±</button>
              <button class="button" @click="press">0</button>
              <button class="button" @click="press">.</button>
              <button class="button" @click="press">%</button>
              <button class="button" @click="press">+</button>
              <button class="button equal-sign" @click="press">=</button>
            </div>
            <div class="mode" v-else>
              <button class="button" @click="press">sin</button>
              <button class="button" @click="press">cos</button>
              <button class="button" @click="press">tan</button>
              <button class="button" @click="press">x^</button>
              <button class="button" @click="press">&#60;=</button>
              <button class="button" @click="press">C</button>
              <button class="button" @click="press">log</button>
              <button class="button" @click="press">ln</button>
              <button class="button" @click="press">e</button>
              <button class="button" @click="press">∘</button>
              <button class="button" @click="press">rad</button>
              <button class="button" @click="press">√</button>
              <button class="button" @click="press">7</button>
              <button class="button" @click="press">8   </button>
              <button class="button" @click="press">9</button>
              <button class="button" @click="press">/</button>
              <button class="button" @click="press">x ²</button>
              <button class="button" @click="press">x !</button>
              <button class="button" @click="press">4</button>
              <button class="button" @click="press">5</button>
              <button class="button" @click="press">6</button>
              <button class="button" @click="press">*</button>
              <button class="button" @click="press">(</button>
              <button class="button" @click="press">)</button>
              <button class="button" @click="press">1</button>
              <button class="button" @click="press">2</button>
              <button class="button" @click="press">3</button>
              <button class="button" @click="press">-</button>
              <button class="button" @click="press">%</button>
              <button class="button" @click="press">±</button>
              <button class="button" @click="press">0</button>
              <button class="button" @click="press">.</button>
              <button class="button" @click="press">&#x003C0;</button>
              <button class="button" @click="press">+</button>
              <button class="button equal-sign" @click="press">=</button>
             </div>
          </div>
  </div>
</template>

<script>
export default {
  name: 'HelloWorld',
  data () {
    return {
      current: '',
      changeMode: true
    }
  },
  methods: {
    press: function press(event) {
      var me = this;
      var key = event.target.textContent;

      if (key != '=' && key != 'C' && key != '*' && key != '/' && key != '√' && key != "x ²" && key != "%" && key != "<=" && key != "±" && key != "sin" && key != "cos" && key != "tan" && key != "log" && key != "ln" && key != "x^" && key != "x !" && key != "π" && key != "e" && key != "rad" && key != "∘") {
        me.current += key;
      } else if (key === '=') {

        if (me.current.indexOf('^') > -1) {
          var base = me.current.slice(0, me.current.indexOf('^'));
          var exponent = me.current.slice(me.current.indexOf('^') + 1);
          me.current = eval('Math.pow(' + base + ',' + exponent + ')');
        } else {
          me.current = eval(me.current);
        }
      } else if (key === 'C') {

        me.current = '';
      } else if (key === '*') {

        me.current += '*';
      } else if (key === '/') {

        me.current += '/';
      } else if (key === '+') {

        me.current += '+';
      } else if (key === '-') {

        me.current += '-';
      } else if (key === '±') {

        if (me.current.charAt(0) === '-') {
          me.current = me.current.slice(1);
        } else {
          me.current = '-' + me.current;
        }
      } else if (key === '<=') {

        me.current = me.current.substring(0, me.current.length - 1);
      } else if (key === '%') {

        me.current = me.current / 100;
      } else if (key === 'π') {

        me.current = me.current * Math.PI;
      } else if (key === 'x ²') {

        me.current = eval(me.current * me.current);
      } else if (key === '√') {

        me.current = Math.sqrt(me.current);
      } else if (key === 'sin') {

        me.current = Math.sin(me.current);
      } else if (key === 'cos') {

        me.current = Math.cos(me.current);
      } else if (key === 'tan') {

        me.current = Math.tan(me.current);
      } else if (key === 'log') {

        me.current = Math.log10(me.current);
      } else if (key === 'ln') {

        me.current = Math.log(me.current);
      } else if (key === 'x^') {

        me.current += '^';
      } else if (key === 'x !') {

        var number = 1;
        if (me.current === 0) {
          me.current = '1';
        } else if (me.current < 0) {
          me.current = NaN;
        } else {
          var _number = 1;
          for (var i = me.current; i > 0; i--) {
            _number *= i;
          }
          me.current = _number;
        }
      } else if (key === 'e') {

        me.current = Math.exp(me.current);
      } else if (key === 'rad') {

        me.current = me.current * (Math.PI / 180);
      } else if (key === '∘') {

        me.current = me.current * (180 / Math.PI);
      }
    },
    changeModeEvent: function changeModeEvent() {
      var me = this;
      me.changeMode = !me.changeMode;
    }
  }
}
</script>
<style>

.hello {
//background: linear-gradient(to right, #85D8CE, #085078);
  font-family: 'Avenir', Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-align: center;
  color: #2c3e50;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-item: center;
}

.calculator {
  width: 440px;
  padding: 20px;
  border-radius: 5px;
  margin: 20px auto;
  font-size: 16px;
  background-color: #333333;
}

.input {
  width: 420px;
  height: 50px;
  border-radius: 0px;
  border: 1px solid black;
  background-color: #333333;
  color: #d9d9d9;
  padding: 0 5px 0 5px;
  margin: 0 0px 10px 0px;
  font-size: 30px;
}

.input:focus,
.input:active {
  border-color: #03a9f4;
  box-shadow: 0 0 4px #03A9F4;
  outline: none 0;
}

.button {
  margin: 3px;
  width: 63px;
  border: 1px solid #0d0d0d;
  height: 30px;
  border-radius: 4px;
  color: #d9d9d9;
  background-color: #1a1a1a;
  cursor: pointer;
  outline: none;
}

.mode {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-evenly;
}

.equal-sign {
  background-color: green;
  width: 133px;
}

.toggle-button {
  border: none;
  background-color: #333333;
  cursor: pointer;
  outline: none;
  font-size: 1rem;
  color: #fff;
  text-shadow: -1px -1px 0 rgba(0, 0, 0, 0.35);
}

p {
  margin-top: 0;
}

button::-moz-focus-inner {
  border-color: transparent;
}

</style>