package formparser

import (
	"errors"
	"fmt"
	"time"
)

// String parses a string, returning an error if it's outside the range of min,max. It still
// sets the value so that it can be used for the view model. It would be bad if the user lost
// a really long page because of the length limit
func String(value string, target *string, min, max int) error {
	*target = value

	if len(value) < min || len(value) > max {
		return fmt.Errorf("not between %d and %d", min, max)
	}

	return nil
}

// Select sets the targer if the given form value is inside the list. It will skip if optional
// is set and the value is empty
func Select(value string, target *string, allowedValues []string, optional bool) error {
	if value == "" {
		if !optional {
			return errors.New("no option selected")
		}

		return nil
	}

	for _, allowedValue := range allowedValues {
		if value == allowedValue {
			*target = value
			return nil
		}
	}

	return errors.New("not a valid option")
}

// Date parses a date, returning an error if it's missing (and not optional) and if it
// cannot be parsed according to RFC3339
func Date(value string, target *time.Time, optional bool) error {
	if value == "" {
		if optional {
			*target = time.Time{}
			return nil
		}

		return errors.New("missing")
	}

	date, err := time.Parse(time.RFC3339, value)
	if err != nil {
		return errors.New("an invalid date")
	}

	*target = date
	return nil
}