import React from 'react';
import { Formik } from 'formik';

const BasicExample = () => (
  <div>
    <h1>My Form</h1>
    <Formik
      initialValues={{ name: 'jared' }}
      onSubmit={(values, actions) => {
        setTimeout(() => {
          alert(JSON.stringify(values, null, 2));
          actions.setSubmitting(false);
        }, 1000);
      }}
    >
      {props => (
        <form onSubmit={props.handleSubmit}>
          <input
            type="text"
            onChange={props.handleChange}
            onBlur={props.handleBlur}
            value={props.values.name}
            name="name"
          />
          {props.errors.name && <div id="feedback">{props.errors.name}</div>}
          <button type="submit">Submit</button>
        </form>
      )}
    </Formik>
  </div>
);

<button onClick={handleReset}>...</button>

<Formik component={ContactForm} />;

const ContactForm = ({
  handleSubmit,
  handleChange,
  handleBlur,
  values,
  errors,
}) => (
  <form onSubmit={handleSubmit}>
    <input
      type="text"
      onChange={handleChange}
      onBlur={handleBlur}
      value={values.name}
      name="name"
    />
    {errors.name && <div>{errors.name}</div>}
    <button type="submit">Submit</button>
  </form>
);

<Formik children={props => <ContactForm {...props} />} />

// or...

<Formik>
  {({ handleSubmit, handleChange, handleBlur, values, errors }) => (
    <form onSubmit={handleSubmit}>
      <input
        type="text"
        onChange={handleChange}
        onBlur={handleBlur}
        value={values.name}
        name="name"
      />
      {errors.name &&
        <div>
          {errors.name}
        </div>}
      <button type="submit">Submit</button>
    </form>
  )}
</Formik>

// Synchronous validation
const validate = values => {
  const errors = {};

  if (!values.email) {
    errors.email = 'Required';
  } else if (!/^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i.test(values.email)) {
    errors.email = 'Invalid email address';
  }

  //...

  return errors;
};

// Async Validation
const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));

const validate = values => {
  return sleep(2000).then(() => {
    const errors = {};
    if (['admin', 'null', 'god'].includes(values.username)) {
      errors.username = 'Nice try';
    }
    // ...
    return errors;
  });
};