JeffDeCola/my-go-examples

// my-go-examples error-example

package main

import (
    "errors"
    "fmt"
    "io"
    "os"
    "strconv"

    log "github.com/sirupsen/logrus"
)

// ErrIncorrectAnswer is an error that is returned when the answer is incorrect
var ErrIncorrectAnswer = errors.New("the answer is incorrect")

func askQuestion(r io.Reader) (string, error) {

    var userInput string

    fmt.Print("What is 2+2 (type stop to quit)? ")
    // THIS WILL BLOCK
    _, err := fmt.Fscan(r, &userInput)
    if err != nil {
        return "", fmt.Errorf("unable to get string from user: %w", err)
    }

    return userInput, nil

}

func checkAnswer(answer string) error {

    // CONVERT TO INT
    answerInt, err := strconv.Atoi(answer)
    if err != nil {
        return fmt.Errorf("unable to convert to integer: %w", err)
    }

    // CHECK NUMBER
    err = checkNumber(answerInt)
    if err != nil {
        return fmt.Errorf("error calling checkNumber: %w", err)
    }

    return err

}

func checkNumber(answer int) error {

    // IS ANSWER CORRECT?
    if answer != 4 {
        return fmt.Errorf("%d was provided: %w", answer, ErrIncorrectAnswer)
    }

    return nil

}

func main() {

    separator := "------------------------"

    // ASK USER A MATH QUESTION UNTIL THEY TYPE "stop"
    for {

        // ASK AND GET ANSWER
        userAnswer, err := askQuestion(os.Stdin)
        if err != nil {
            log.Fatalf("Error getting User Input: %s", err)
        }

        // STOP
        if userAnswer == "stop" {
            fmt.Println("Done")
            break
        }

        // CHECK USER ANSWER
        err = checkAnswer(userAnswer)
        if err != nil {
            switch {
            case errors.Is(err, strconv.ErrSyntax):
                fmt.Println("Not an integer")
            case errors.Is(err, ErrIncorrectAnswer):
                fmt.Println("INCORRECT!")
            }
            log.Errorf("Error with answer: %s\n%s\n", err, separator)
            continue
        }

        fmt.Printf("YOUR ANSWER %s IS CORRECT!\n%s\n", userAnswer, separator)

    }

}