package forms

import (
	"fmt"
	"reflect"
	"strconv"
	"strings"
)

func nonzero(field string, value any, _ string) error {
	v := reflect.ValueOf(value)
	if v.Kind() == reflect.String && v.Len() == 0 {
		return fmt.Errorf("field '%s' must not be empty", field)
	}
	if v.Kind() == reflect.Slice && v.Len() == 0 {
		return fmt.Errorf("field '%s' must not be empty", field)
	}
	if v.Kind() >= reflect.Int && v.Kind() <= reflect.Float64 && v.IsZero() {
		return fmt.Errorf("field '%s' must be non-zero", field)
	}
	return nil
}

func minlen(field string, value any, param string) error {
	min, err := strconv.Atoi(param)
	if err != nil {
		return fmt.Errorf("invalid minlen param for field '%s'", field)
	}
	if str, ok := value.(string); ok && len(str) < min {
		return fmt.Errorf("field '%s' must be at least %d characters", field, min)
	}
	return nil
}

func email(field string, value any, _ string) error {
	str, ok := value.(string)
	if !ok || !strings.Contains(str, "@") {
		return fmt.Errorf("field '%s' must be a valid email address", field)
	}
	return nil
}