package cabana

import "encoding/json"

// FormSchema is the locale-neutral form contract compiled once at boot.
// Display strings stay as source keys until a request localizes a copy.
type FormSchema struct {
	Name       string      `json:"name,omitempty"`
	ModelClass string      `json:"modelClass,omitempty"`
	Fields     []FormField `json:"fields"`
}

// FormField is one Winter field in source order. JSON keys keep Winter spelling.
type FormField struct {
	Name        string                `json:"name"`
	Type        string                `json:"type"`
	Label       string                `json:"label,omitempty"`
	Comment     string                `json:"comment,omitempty"`
	Span        string                `json:"span,omitempty"`
	Tab         string                `json:"tab,omitempty"`
	Size        string                `json:"size,omitempty"`
	Context     *fieldContext         `json:"context,omitempty"`
	NameFrom    string                `json:"nameFrom,omitempty"`
	EmptyOption string                `json:"emptyOption,omitempty"`
	Relation    string                `json:"relation,omitempty"`
	Required    bool                  `json:"required,omitempty"`
	Default     *jsonScalar           `json:"default,omitempty"`
	Attributes  map[string]jsonScalar `json:"attributes,omitempty"`
	Options     []FormOption          `json:"options,omitempty"`

	optionsMethod string
}

// FormOption is one dropdown choice. Value keeps the YAML scalar's JSON type.
type FormOption struct {
	Value jsonScalar `json:"value"`
	Label string     `json:"label"`
}

// jsonScalar is a JSON scalar that still emits false, 0, and empty string.
type jsonScalar struct {
	raw json.RawMessage
}

func (s jsonScalar) MarshalJSON() ([]byte, error) {
	if len(s.raw) == 0 {
		return []byte("null"), nil
	}
	return s.raw, nil
}

// fieldContext preserves a single Winter context string or a source-ordered list.
type fieldContext struct {
	single bool
	values []string
}

func (c fieldContext) MarshalJSON() ([]byte, error) {
	if c.single {
		text := ""
		if len(c.values) > 0 {
			text = c.values[0]
		}
		return json.Marshal(text)
	}
	values := c.values
	if values == nil {
		values = []string{}
	}
	return json.Marshal(values)
}