CipherApp/templates/CaesarEncrypt.html

<div class="form-group">
    <form method="POST" action="{{ url_for('CaesarCipherED') }}">
        <label for="plaintext_input">
            Enter Plaintext Here:
        </label>
        <input type="text" id="plaintext_input" name="plaintext_input"
               placeholder="Enter your text here" class="form-control">
        <div class="form-group">
            <label for="key-input">Shift Value:</label>
            <div class="input-group">
    <span class="input-group-prepend">
      <button class="btn btn-outline-secondary" type="button" onclick="decrementKey()">-</button>
    </span>
                <input type="text" id="key-input" name="key" class="form-control" min="1" max="1000000000000000"
                       value="3" oninput="updateSliderValue()">
                <span class="input-group-append">
      <button class="btn btn-outline-secondary" type="button" onclick="incrementKey()">+</button>
    </span>
            </div>
        </div>
        <div>
            <label for="key-slider">
                Enter shift value:
            </label>
            <input type="range" id="key-slider" name="key" min="1" max="1000000000000000"
                   value="3"
                   class="form-control" oninput="updateKeyInput()">
        </div>
        <div class="custom-file">
            <input type="file" id="file-input" onchange="updateLabel()">
            <label for="file-input" id="file-label">Choose file</label>
            <button id="remove-file-btn" onclick="removeFile()" style="display: none;">Remove</button>
        </div>
        <div class="container">
            <div class="row justify-content-center">
                <div class="col-lg-8">
                    <div class="form-group alert alert-success">
                        <label for="ciphertext">Cipher Text:</label>
                        <input type="text" id="ciphertext" name="ciphertext" placeholder="Cipher Text"
                               class="form-control" readonly>
                        <span onclick="copyToClipboardCaesarEncrypt()" class="btn btn-outline-secondary">Copy to Clipboard</span>
                    </div>
                </div>
            </div>
        </div>
        <div class="container">
            <div class="row justify-content-center">
                <div class="col-lg-8">
                    <div class="form-group">
                        <label for="cleartext">Clear Text:</label>
                        <input type="text" id="cleartext" name="cleartext" placeholder="Clear Text"
                               class="form-control" readonly>
                    </div>
                </div>
            </div>
        </div>
    </form>
</div>

<script>
    function update() {
        let plaintext = document.getElementById('plaintext_input').value;
        let key = document.getElementById('key-slider').value;
        let pad_file = document.getElementById('file-input').files[0];

        let formData = new FormData();
        formData.append('plaintext_input', plaintext);
        formData.append('key', key);
        formData.append('pad_file', pad_file);

        let xhrEncrypt = new XMLHttpRequest();
        xhrEncrypt.open('POST', '{{ url_for("CaesarCipherED") }}');
        xhrEncrypt.onload = function () {
            let ciphertext = JSON.parse(xhrEncrypt.responseText)['ciphertext'];
            let cleartext = JSON.parse(xhrEncrypt.responseText)['cleartext'];
            document.getElementById('ciphertext').value = ciphertext;
            document.getElementById('cleartext').value = cleartext;
        };
        xhrEncrypt.send(formData);
    }

    function updateSliderValue() {
        document.getElementById('key-slider').value = document.getElementById('key-input').value;
        update();
    }

    function updateKeyInput() {
        document.getElementById('key-input').value = document.getElementById('key-slider').value;
        update();
    }

    function incrementKey() {
        let keyInput = document.getElementById('key-input');
        let currentValue = parseInt(keyInput.value);
        if (currentValue < parseInt(keyInput.max)) {
            keyInput.value = currentValue + 1;
            updateSliderValue();
        }
    }

    function decrementKey() {
        let keyInput = document.getElementById('key-input');
        let currentValue = parseInt(keyInput.value);
        if (currentValue > parseInt(keyInput.min)) {
            keyInput.value = currentValue - 1;
            updateSliderValue();
        }
    }

    function updateLabel() {
        let fileInput = document.getElementById('file-input');
        let fileLabel = document.getElementById('file-label');
        let removeBtn = document.getElementById('remove-file-btn');

        if (fileInput.value) {
            fileLabel.innerHTML = fileInput.value.match(/[\/\\]([\w\d\s\.\-\(\)]+)$/)[1];
            removeBtn.style.display = 'inline-block';
        } else {
            fileLabel.innerHTML = 'Choose file';
            removeBtn.style.display = 'none';
        }
    }

    function removeFile() {
        let fileInput = document.getElementById('file-input');
        let fileLabel = document.getElementById('file-label');
        let removeBtn = document.getElementById('remove-file-btn');

        fileInput.value = '';
        fileLabel.innerHTML = 'Choose file';
        removeBtn.style.display = 'none';
    }

    function copyToClipboardCaesarEncrypt() {
        const ciphertextInput = document.getElementById("ciphertext");
        ciphertextInput.select();
        document.execCommand("copy");
        alert("Copied to clipboard!");
    }

    document.getElementById('plaintext_input').addEventListener('input', update);
    document.getElementById('key-slider').addEventListener('input', updateKeyInput);
    document.getElementById('key-input').addEventListener('input', updateSliderValue);
</script>