package registry

// A Converter is a directed graph of conversions between representations. Each
// node is a representation name, and each edge is a Conversion.
type Converter struct {
	data map[string][]Conversion
}

// NewConverter creates an empty Converter with no registered conversions.
func NewConverter() *Converter {
	return &Converter{data: map[string][]Conversion{}}
}

// Add registers a conversion, adding an edge from its source representation
// to its target representation.
func (g *Converter) Add(c Conversion) {
	conversionsFromIn, ok := g.data[c.InType()]
	if !ok {
		conversionsFromIn = []Conversion{}
	}

	conversionsFromIn = append(conversionsFromIn, c)
	g.data[c.InType()] = conversionsFromIn
}

// ConversionsFrom returns all conversions that have the given representation
// as their source type.
func (g *Converter) ConversionsFrom(t string) []Conversion {
	return g.data[t]
}