package errors

import (
	"strings"

	"github.com/gin-gonic/gin"
	"github.com/go-playground/validator/v10"
)

var (
	ReadOnlyFieldMessage          = "is read-only"
	RequiredFieldMessage          = "is required"
	InvalidRFC1123HostnameMessage = "must be a valid RFC 1123 Hostname"
)

// NewErrorResponse returns a new gin API error response
func NewErrorResponse(errors ...*Error) gin.H {
	return gin.H{
		"errors": errors,
	}
}

// Error represents an individual error returned by the API
//
// swagger:model
type Error struct {
	// A description of the error
	//
	// required: true
	// example: X is a read-only field
	Detail string `json:"detail"`
}

// NewError returns a new error struct containing the provided detail
func NewError(detail string) *Error {
	return &Error{
		Detail: detail,
	}
}

// String returns the errors internal detail string
func (e *Error) String() string {
	return e.Detail
}

// FromFieldError sets the error detail from the provided field error
func (e *Error) FromFieldError(fe validator.FieldError) {
	e.Detail = NewFieldErrorDetail(fe)
}

// NewFieldErrorDetail returns an error detail message appropriate for the
// provided field error
func NewFieldErrorDetail(fe validator.FieldError) string {
	switch fe.Tag() {
	case "required":
		return NewRequiredFieldMessage(fe.Field())
	case "hostname_rfc1123":
		return NewInvalidRFC1123HostnameMessage(fe.Field())
	}
	return fe.Error()
}

// NewReadOnlyFieldMessage returns a new read-only field error detail string for
// the provided field
func NewReadOnlyFieldMessage(field string) string {
	return NewMessage(field, ReadOnlyFieldMessage)
}

// NewRequiredFieldMessage returns a new required field error detail string for
// the provided field
func NewRequiredFieldMessage(field string) string {
	return NewMessage(field, RequiredFieldMessage)
}

// NewValidRFC1123HostnameMessage returns a new invalid RFC1123 hostname field
// error detail string for the provided field
func NewInvalidRFC1123HostnameMessage(field string) string {
	return NewMessage(field, InvalidRFC1123HostnameMessage)
}

// NewMessage returns a new detail string combining the provided field and
// message
func NewMessage(field, message string) string {
	return strings.Join([]string{field, message}, " ")
}