<div class="container">
  <h2>Password Generator</h2>
  <div class="result-container">
    <input type="text" id="result">
    <button class="copy-result" id="copy">
      Copy
    </button>
  </div>
  <div class="settings">
    <div class="input-group">
      <label>Password length (4-20)</label>
      <input type="range" id="length" min='4' max='20' step="1" />
      <span id="length-result">10</span>
    </div>
    <div class="input-group">
      <label>Include numbers</label> 
      <input type="checkbox" id="numbers" checked />
    </div>
    <div class="input-group">
      <label>Include symbols</label> 
      <input type="checkbox" id="symbols" checked />
    </div>
  </div>
  <button class="generate-btn" id="generate">
    Generate
  </button>
</div>

:root {
  --teal: #06b6d4; 
  --blue: #3b82f6;
  --lightgray: #cbd5e1;
  --gradient: linear-gradient(to right,var(--teal), var(--blue))
}

body {
  background-image: var(--gradient);
  font-family: "Lexend", sans-serif;
  accent-color: var(--blue);
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: 390px;
  margin: 5rem auto;
  padding: 26px;
  border-radius: 20px;
  background: white;
  box-shadow: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

.result-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: relative;
}

#result {
  flex: 1;
  font-family: Monaco, mono;
  background: #f4f4f4;
}

.copy-result {
  background-image: var(--gradient);
  border: none;
  padding: 14px 18px;
  color: white;
  border-radius: 25px;
  margin-left: 16px;
  position: absolute;
  right: 12px;
  font-weight: 600;
  cursor: pointer;
  z-index: 50;
  font-size: .8rem;
}

.copy-result:hover {
  background: var(--blue);
}

input[type="text"] {
  padding: 20px 24px;
  border: 1px solid var(--lightgray);
  border-radius: 50px;
}

input[type="range"] {
  padding: 8px 10px;
  background: #f8f8f8;
  flex: 1;
  margin-left: 1rem;
  margin-right: 1rem;
}

input[type="text"]:focus,
input[type="number"]:focus {
  border: 1px solid var(--teal);
  outline: none;
}

input[type="checkbox"] {
  width: 16px;
  height: 16px;
}

.settings {
  margin-top: 3rem;
}

.input-group {
  margin-bottom: 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.generate-btn {
  background-image: var(--gradient);
  padding: 14px 24px;
  border: none;
  font-weight: 600;
  color: white;
  display: block;
  width: 100%;
  border-radius: 25px;
  cursor: pointer;
  font-size: 1.25rem;
}

.generate-btn:hover,
.copy-btn:hover {
  box-shadow: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);

  background: var(--blue);
}

.alert {
  position: fixed;
  top: 6px;
  right: 6px;
  padding: 10px;
  border-radius: 4px;
  background: rgba(0,0,0, .4);
  color: white;
  font-size: 20px;
}

const result = document.querySelector('#result');
const passLength = document.querySelector('#length');
const passLengthResult = document.querySelector('#length-result')
const includeNumbers = document.querySelector('#numbers');
const includeSymbols = document.querySelector('#symbols');
const generateBtn = document.querySelector('#generate');
const copyPass = document.querySelector('#copy');


// Set default password length 20 max on load
document.addEventListener('DOMContentLoaded', () => {
  passLength.value = 20  
  passLengthResult.innerText = 20
  
  let onLoadLength = passLength.value
  let onLoadNumbers = includeNumbers.checked
  let onLoadSymbols = includeSymbols.checked
  result.value = generatePassword(onLoadNumbers, onLoadSymbols, onLoadLength)
})

// Listen for password range change
passLength.addEventListener('change', (event) => {
  passLengthResult.innerText  = event.target.value                   
})

// Listen for copy button
copyPass.addEventListener('click', () => {
  copy(result.value)
})

generateBtn.addEventListener('click', () => {
  const length = passLength.value
  const numbers = includeNumbers.checked
  const symbols = includeSymbols.checked
  result.value = generatePassword(numbers, symbols, length)
})

function generatePassword(number, symbol, length) {
  let generatedPassword = '';
  let variationsCount = [number, symbol].length
  
  for(let i = 0; i < length; i += variationsCount) {
    if (number) {
      generatedPassword += getRandomNumber()
    } 
    if (symbol) {
      generatedPassword += getRandomSymbol()
    }
    generatedPassword += getRandomLower()
  }
  
  const finalPassword = generatedPassword.slice(0, length);
  
  return finalPassword;
}

function getRandomLower() {
  return String.fromCharCode(Math.floor(Math.random() * 26) + 97);
}

function getRandomNumber() {
  return String.fromCharCode(Math.floor(Math.random() * 10) + 48);
}

function getRandomSymbol() {
  const symbols = '!@#$%^&*(){}[]=<>/,.'
  return symbols[Math.floor(Math.random() * symbols.length)];
}

// Copy generated password in more secure way
function copy(text) {
  const input = document.createElement('input');
  input.setAttribute('value', text);
  document.body.appendChild(input);
  input.select();
  let copiedResult = document.execCommand('copy');
  document.body.removeChild(input);
  
  const alert = document.createElement("div")
  alert.classList.add("alert");
  alert.textContent = "Copied!"
  document.body.appendChild(alert)
  
  setTimeout(() => {
    document.querySelector('.alert').style.display = "none"
    document.body.removeChild(alert)
  }, 1000)
  return result;
}