From 06311cbb4a74da85a44f707d77a8d1eaf690bda6 Mon Sep 17 00:00:00 2001
From: Abhimanyu Singh <superhit0@gmail.com>
Date: Sun, 1 Jul 2018 14:53:33 +0530
Subject: [PATCH] Fix cursor Issue#205

---
 src/components/IntlTelInputApp.js | 45 +++++++++++++++++++++++++++++--
 src/components/TelInput.js        | 18 ++++++++++++-
 2 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/src/components/IntlTelInputApp.js b/src/components/IntlTelInputApp.js
index ad0e893f3..7a212e221 100644
--- a/src/components/IntlTelInputApp.js
+++ b/src/components/IntlTelInputApp.js
@@ -13,6 +13,35 @@ const mobileUserAgentRegexp =
   /Android.+Mobile|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i;
 
 class IntlTelInputApp extends Component {
+
+  // Get the position of Cursor
+  static getCursorPosition(prevBeforeCursor, prev, next) {
+    if (prev === next) {
+      return prevBeforeCursor.length;
+    }
+    let cursorShift = 0;
+
+    if (prev.length > next.length) {
+      for (let i = 0, j = 0; i < prevBeforeCursor.length && j < next.length; i += 1) {
+        if (prevBeforeCursor[i] !== next[j]) {
+          cursorShift -= 1;
+        } else {
+          j += 1;
+        }
+      }
+    } else {
+      for (let i = 0, j = 0; i < prevBeforeCursor.length && j < next.length; j += 1) {
+        if (prevBeforeCursor[i] !== next[j]) {
+          cursorShift += 1;
+        } else {
+          i += 1;
+        }
+      }
+    }
+
+    return prevBeforeCursor.length + cursorShift;
+  }
+
   constructor(props) {
     super(props);
 
@@ -61,6 +90,7 @@ class IntlTelInputApp extends Component {
       title: '',
       countryCode: 'us',
       dialCode: '',
+      cursorPosition: (props.value || props.defaultValue).length,
     };
 
     this.selectedCountryData = {};
@@ -1055,14 +1085,24 @@ class IntlTelInputApp extends Component {
   // Either notify phoneNumber changed if component is controlled
   // or udpate the state and notify change if component is uncontrolled
   handleInputChange(e) {
+    let cursorPosition = e.target.selectionStart;
+    const previousValue = e.target.value;
+    const previousStringBeforeCursor = previousValue === '' ? previousValue : previousValue.substring(0, cursorPosition);
     const value = this.props.format ? this.formatNumber(e.target.value) : e.target.value;
 
+    cursorPosition = this.constructor.getCursorPosition(previousStringBeforeCursor, previousValue, value);
+
     if (this.props.value !== undefined) {
-      this.updateFlagFromNumber(value);
-      this.notifyPhoneNumberChange(value);
+      this.setState({
+        cursorPosition,
+      }, () => {
+        this.updateFlagFromNumber(value);
+        this.notifyPhoneNumberChange(value);
+      });
     } else {
       this.setState({
         value,
+        cursorPosition,
       }, () => {
         this.updateFlagFromNumber(value);
         this.notifyPhoneNumberChange(value);
@@ -1170,6 +1210,7 @@ class IntlTelInputApp extends Component {
           autoFocus={ this.props.autoFocus }
           autoComplete={ this.props.autoComplete }
           inputProps={ this.props.telInputProps }
+          cursorPosition={ this.state.cursorPosition }
         />
       </div>
     );
diff --git a/src/components/TelInput.js b/src/components/TelInput.js
index 152cc9185..bfbfab783 100644
--- a/src/components/TelInput.js
+++ b/src/components/TelInput.js
@@ -2,11 +2,26 @@ import React, { Component } from 'react';
 import PropTypes from 'prop-types';
 
 class TelInput extends Component {
+  constructor(props) {
+    super(props);
+
+    this.refHandler = this.refHandler.bind(this);
+  }
+
+  componentDidUpdate() {
+    this.tel.setSelectionRange(this.props.cursorPosition, this.props.cursorPosition);
+  }
+
+  refHandler(element) {
+    this.tel = element;
+    this.props.refCallback(element);
+  }
+
   render() {
     return (
       <input
         { ...this.props.inputProps }
-        ref={ this.props.refCallback }
+        ref={ this.refHandler }
         type="tel"
         autoComplete={ this.props.autoComplete }
         className={ this.props.className }
@@ -38,6 +53,7 @@ TelInput.propTypes = {
   autoComplete: PropTypes.string,
   inputProps: PropTypes.object, // eslint-disable-line react/forbid-prop-types
   refCallback: PropTypes.func.isRequired,
+  cursorPosition: PropTypes.number,
 };
 
 export default TelInput;