Get PR number from a GitHub URL

get_pr.go

// Derived from paste at https://pastebin.com/iwqG6zvH
// Lightly edited to make it run
// Original discussion: https://t.me/GolangTZ/475

// You can edit this code!
// Click here and start typing.
package main

import (
	"bufio"
	"fmt"
	"io"
	"log"
	"os"
	"regexp"
	"strconv"
	"strings"
)

// Example 1: https://github.com/microsoft/vscode/pull/12345
// Example 2: https://github.com/refined-github/refined-github/pull/123
var prRe = regexp.MustCompile(`https://github.com/[[:word:]-\.]+/[[:word:]-\.]+/pull/([\d]+)`)

func main() {
	prLink, err := ReadInput(os.Stdin, "PR: ")
	if err != nil {
		log.Fatal(err)
		os.Exit(1)
	}

	pr, err := GetPR(prLink)

	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(pr)
}

func GetPR(prLink string) (PR, error) {
	var (
		pr  PR = PR{}
		err error
	)

	if err != nil {
		return pr, err
	}

	res := prRe.FindStringSubmatch(prLink)
	if len(res) == 0 {
		return pr, fmt.Errorf("invalid PR link")
	}

	num, err := strconv.Atoi(res[1])
	if err != nil {
		return pr, err
	}
	pr.link = prLink
	pr.num = num
	return pr, err
}

func ReadInput(reader io.Reader, msg string) (string, error) {
	if msg != "" {
		fmt.Print(msg)
	}

	r := bufio.NewReader(reader)
	text, err := r.ReadString('\n')
	if err != nil {
		return "", err
	}
	return strings.TrimSpace(text), nil
}

type PR struct {
	link string
	num  int
}