lowryel/my_golang_prep

Golang Studies

• Creating Go modules

• Modules in Golang are basically functions or objects that are referenced or imported in another function
• e.g. import "fmt" - fmt is an inbuilt module which contain all the print statements such as Print, Printf, Println, Sprintf, etc.

Let's create a module to Greet a User

• Greeting module:

• Create a folder called greetings and another hello
• In the greetings folder, run go mod init demo/greetings
• Create greetings.go file and add some code

    package greetings
    import ("fmt")

    func Hello (name string) string {
        message := fmt.Println("Hello %v" name)
        return message
    } 

• Now in the hello folder, run go mod init ex/hello
• Create a hello.go file and add the following code

    package main
    import (
        "fmt"
        "ex/greetings" //module we created earlier
        // You can give it any name that resonate with you
    )
    func main() {
        message := greetings.Hello("Eugene")
        fmt.Println(message)
    }

• In the same hello folder, in the terminal, run go mod edit -replace ex/greetings=../greetingsto replace ex/greetings with greetings
• Then run go mod tidy to synchronize the ex/hello module and add those dependencies that haven't been tracked
• Then run go run . in same hello folder to execute the program

Command to install go

[ ! -d "/usr/local/go" ] && cd /tmp && wget https://go.dev/dl/go1.17.4.linux-amd64.tar.gz && tar -C /usr/local/ -xzf go1.17.4.linux-amd64.tar.gz && cd /usr/local/ && echo "export PATH=\$PATH:/usr/local/go/bin:\$HOME/go/bin" >> ~/.bashrc && echo "export GOROOT=/usr/local/go" >> ~/.bashrc && echo "export PATH=\$PATH:/usr/local/go/bin:\$HOME/go/bin" >> /home/*/.bashrc && echo "export GOROOT=/usr/local/go" >> /home/*/.bashrc && source ~/.bashrc && source /home/*/.bashrc

Twilio SMS service

`go package validation

import (
    "fmt"
    "locus-api/pkg/logger"
    "os"
    "regexp"

    // "strconv"

    "github.com/twilio/twilio-go"
    openapi "github.com/twilio/twilio-go/rest/verify/v2"
    "golang.org/x/exp/rand"
)

// IsValidPIN validates a phone number
func IsValidPIN(pin string) bool {
    // Define a regular expression to match phone numbers.
    regex := `^\d{4}$`

    // Compile the regular expression.
    re := regexp.MustCompile(regex)

    // Test if the phone number matches the regular expression.
    return re.MatchString(pin)
}


var TWILIO_ACCOUNT_SID string = os.Getenv("TWILIO_ACCOUNT_SID")
var TWILIO_AUTH_TOKEN string = os.Getenv("TWILIO_AUTH_TOKEN")
var TWILIO_SERVICES_ID string = os.Getenv("TWILIO_SERVICES_ID")
var client *twilio.RestClient = twilio.NewRestClientWithParams(twilio.ClientParams{
    Username: TWILIO_ACCOUNT_SID,
    Password: TWILIO_AUTH_TOKEN,
})

// send OTP to user for phone verification
func SendOtp(to string) string {
params := &openapi.CreateVerificationParams{}
params.SetTo(to)
params.SetChannel("sms")
//    params.SetCustomCode()


resp, err := client.VerifyV2.CreateVerification(TWILIO_SERVICES_ID, params)

if err != nil {
    fmt.Println(err.Error())
} else {
    fmt.Printf("Sent verification '%s'\n", *resp.Sid)
}
return *resp.Sid
}

var letterRunes = []rune("0123456789")

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

// verify OTP with phone
func CheckOtp(to string) string {
code := RandStringRunes(4)
//    fmt.Println("Please check your phone and enter the code:")
//    fmt.Scanln(&code)
        logger.DevLog(code)
//    params := &openapi.CreateVerificationCheckParams{}
//    params.SetTo(to)
//    params.SetCode(code)
        logger.DevLog(to)
//    resp, err := client.VerifyV2.CreateVerificationCheck(TWILIO_SERVICES_ID, params)

//    if err != nil {
//        fmt.Println(err.Error())
//    } else if *resp.Status == "approved" {
//        fmt.Println("Correct!")
//    } else {
//        logger.DevLog("Incorrect pin!")
//        panic("Invalid pin")
//    }
    return string(code)
}

`