utils.go

package main

import (
	"bufio"
	"fmt"
	"math/rand"
	"os"
	"regexp"
	"strings"
)

var envVariableFormat = regexp.MustCompile(`[a-zA-Z_]+[a-zA-Z0-9_]+`)

// Checks and return params in expected format, exclude all params with incorrect format
func checkParams(params map[string]string) map[string]string {
	if params != nil {
		result := make(map[string]string)
		for k, v := range params {
			if envVariableFormat.MatchString(k) {
				result[strings.ToUpper(k)] = v
			}
		}
		return result
	}
	return nil
}

// Saves params into file in expected format
func saveParams(path string, params map[string]string) error {
	if len(params) > 0 {
		file, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
		if err != nil {
			return err
		}
		defer file.Close()

		for k, v := range params {
			if _, err := file.WriteString(fmt.Sprintf("%s=%s\n", k, strings.ReplaceAll(strings.ReplaceAll(v, "\r", "\\r"), "\n", "\\n"))); err != nil {
				return err
			}
		}
	}
	return nil
}

// Loads params from file into map, if not found, leave method without drama
func loadParams(path string) map[string]string {
	file, err := os.Open(path)
	if err != nil {
		return nil
	}
	defer file.Close()

	result := make(map[string]string)
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		splitIndex := strings.Index(line, "=")
		if splitIndex >= 0 {
			result[line[:splitIndex]] = strings.ReplaceAll(strings.ReplaceAll(line[splitIndex+1:], "\\\r", "\r"), "\\\n", "\n")
		}
	}
	return result
}

// Generates random token of defined length
func randomToken(n int) string {
	var letterRunes = []rune("0123456789abcdefghijklmnopqrstuvwxyz")

	b := make([]rune, n)
	for i := range b {
		b[i] = letterRunes[rand.Intn(len(letterRunes))]
	}
	return string(b)
}