package validate_test

import (
	"errors"
	"fmt"
	"strings"

	"code.aneur.in/go/validate"
)

// A validator is any func(T) error. Compose the built-ins with your own
// closures using All (stop at the first failure) or Collect (report all).
func Example() {
	username := validate.All(
		validate.MinLength(3),
		validate.MaxLength(16),
		validate.Chars("abcdefghijklmnopqrstuvwxyz0123456789_"),
		func(s string) error {
			if strings.HasPrefix(s, "_") {
				return errors.New("must not start with an underscore")
			}
			return nil
		},
	)

	fmt.Println(username("ok_name"))
	fmt.Println(username("_nope"))
	fmt.Println(username("Nope"))
	// Output:
	// <nil>
	// must not start with an underscore
	// contains disallowed characters
}

// Collect runs every validator and joins the failures; errors.Is still
// matches each one.
func Example_collectAll() {
	password := validate.Collect(
		validate.MinLength(8),
		validate.Chars("abcdefghijklmnopqrstuvwxyz"),
	)

	err := password("Ab1")
	fmt.Println(err)
	fmt.Println(errors.Is(err, validate.ErrMustBeLonger))
	fmt.Println(errors.Is(err, validate.ErrDisallowedChars))
	// Output:
	// must contain at least 8 characters
	// contains disallowed characters
	// true
	// true
}

// Errors are plain sentinels, so errors.Is works with no library-specific
// machinery. Err matches any error from this package.
func Example_errorsIs() {
	err := validate.Email("not-an-email")

	fmt.Println(err)
	fmt.Println(errors.Is(err, validate.ErrInvalidEmail))
	fmt.Println(errors.Is(err, validate.Err))
	// Output:
	// invalid email address
	// true
	// true
}