package val

import (
	"fmt"
	"net/mail"
	"regexp"
)

var (
	isValidUsername = regexp.MustCompile(`^[a-zA-Z0-9_]+$`).MatchString
	isValidFullName = regexp.MustCompile(`^[a-zA-Z\s]+$`).MatchString
)

func ValidateString(val string, minLength int, maxLength int) error {
	n := len(val)
	if n < minLength || n > maxLength {
		return fmt.Errorf("string length must be between %d and %d characters", minLength, maxLength)
	}
	return nil
}

func ValidateUsername(val string) error {
	err := ValidateString(val, 3, 100)
	if err != nil {
		return fmt.Errorf("invalid username: %v", err)
	}

	if !isValidUsername(val) {
		return fmt.Errorf("username can only contain lowercase alphanumeric characters and underscores")
	}
	return nil
}

func ValidateFullName(val string) error {
	err := ValidateString(val, 3, 100)
	if err != nil {
		return fmt.Errorf("invalid full name: %v", err)
	}

	if !isValidFullName(val) {
		return fmt.Errorf("full name can only contain alphabetic characters and spaces")
	}
	return nil
}

func ValidatePassword(val string) error {
	return ValidateString(val, 6, 100)
}

func ValidateEmail(val string) error {
	err := ValidateString(val, 3, 200)
	if err != nil {
		return fmt.Errorf("invalid username: %v", err)
	}

	if _, err := mail.ParseAddress(val); err != nil {
		return fmt.Errorf("is not a valid email address")
	}

	return nil
}

func ValidateEmailID(val int64) error {
	if val <= 0 {
		return fmt.Errorf("email ID must be a positive integer")
	}
	return nil
}

func ValidateVerificationCode(val string) error {
	return ValidateString(val, 32, 128)
}