text: import React from 'react';
  import { makeStyles } from '@material-ui/core/styles';
  import Stepper from '@material-ui/core/Stepper';
  import Step from '@material-ui/core/Step';
  import StepLabel from '@material-ui/core/StepLabel';
  import Button from '@material-ui/core/Button';
  import Typography from '@material-ui/core/Typography';
  
  const useStyles = makeStyles((theme) => ({
    root: {
      width: '100%',
    },
    button: {
      marginRight: theme.spacing(1),
    },
    instructions: {
      marginTop: theme.spacing(1),
      marginBottom: theme.spacing(1),
    },
  }));
  
  function getSteps() {
    return ['Select campaign settings', 'Create an ad group', 'Create an ad'];
  }
  
  function getStepContent(step) {
    switch (step) {
      case 0:
        return 'Select campaign settings...';
      case 1:
        return 'What is an ad group anyways?';
      case 2:
        return 'This is the bit I really care about!';
      default:
        return 'Unknown step';
    }
  }
  
  export default function HorizontalNonLinearStepperWithError() {
    const classes = useStyles();
    const [activeStep, setActiveStep] = React.useState(0);
    const [skipped, setSkipped] = React.useState(new Set());
    const steps = getSteps();
  
    const isStepOptional = (step) => {
      return step === 1;
    };
  
    const isStepFailed = (step) => {
      return step === 1;
    };
  
    const isStepSkipped = (step) => {
      return skipped.has(step);
    };
  
    const handleNext = () => {
      let newSkipped = skipped;
      if (isStepSkipped(activeStep)) {
        newSkipped = new Set(skipped.values());
        newSkipped.delete(activeStep);
      }
  
      setActiveStep((prevActiveStep) => prevActiveStep + 1);
      setSkipped(newSkipped);
    };
  
    const handleBack = () => {
      setActiveStep((prevActiveStep) => prevActiveStep - 1);
    };
  
    const handleSkip = () => {
      if (!isStepOptional(activeStep)) {
        // You probably want to guard against something like this,
        // it should never occur unless someone's actively trying to break something.
        throw new Error("You can't skip a step that isn't optional.");
      }
  
      setSkipped((prevSkipped) => {
        const newSkipped = new Set(prevSkipped.values());
        newSkipped.add(activeStep);
        return newSkipped;
      });
      setActiveStep((prevActiveStep) => prevActiveStep + 1);
    };
  
    const handleReset = () => {
      setActiveStep(0);
    };
  
    return (
      <div className={classes.root}>
        <Stepper activeStep={activeStep}>
          {steps.map((label, index) => {
            const stepProps = {};
            const labelProps = {};
            if (isStepOptional(index)) {
              labelProps.optional = (
                <Typography variant="caption" color="error">
                  Alert message
                </Typography>
              );
            }
            if (isStepFailed(index)) {
              labelProps.error = true;
            }
            if (isStepSkipped(index)) {
              stepProps.completed = false;
            }
            return (
              <Step key={label} {...stepProps}>
                <StepLabel {...labelProps}>{label}</StepLabel>
              </Step>
            );
          })}
        </Stepper>
        <div>
          {activeStep === steps.length ? (
            <div>
              <Typography className={classes.instructions}>
                All steps completed - you&apos;re finished
              </Typography>
              <Button onClick={handleReset} className={classes.button}>
                Reset
              </Button>
            </div>
          ) : (
            <div>
              <Typography className={classes.instructions}>{getStepContent(activeStep)}</Typography>
              <div>
                <Button disabled={activeStep === 0} onClick={handleBack} className={classes.button}>
                  Back
                </Button>
                {isStepOptional(activeStep) && (
                  <Button
                    variant="contained"
                    color="primary"
                    onClick={handleSkip}
                    className={classes.button}
                  >
                    Skip
                  </Button>
                )}
  
                <Button
                  variant="contained"
                  color="primary"
                  onClick={handleNext}
                  className={classes.button}
                >
                  {activeStep === steps.length - 1 ? 'Finish' : 'Next'}
                </Button>
              </div>
            </div>
          )}
        </div>
      </div>
    );
  }
  