package deltanet

// A connection between exactly two nodes in a graph.
type Edge struct {
	A, B Node
}

// Returns all nodes the edge is connected to.
func (e Edge) GetConnections() []Node { return []Node{e.A, e.B} }

// Determines if a node is connected via this edge.
func (e Edge) IsConnected(n Node) bool { return e.A == n || e.B == n }

// Swaps an edges connected with one node, for another.
func (e *Edge) Swap(from Node, to Node) {
	if e.A == from {
		e.A = to
	}
	if e.B == from {
		e.B = to
	}
}

// Returns true if the edge is connected to each node via their pricniple ports.
func (e Edge) IsPrincipleEdge() bool {
	return e.A.GetMainPort() == e && e.B.GetMainPort() == e
}

type Node interface {
	// Returns the principle port that the node is attached to.
	GetMainPort() Edge

	// Returns all auxiliary ports that the node has. These ports are guaranteed
	// to be ordered clockwise, as they would appear graphically.
	GetAuxPorts() []Edge

	// Returns the label of the node. May be blank.
	GetLabel() string
}

type EraserNode struct {
	Main Edge
}

func (n EraserNode) GetLabel() string    { return "Ⓧ" }
func (n EraserNode) GetMainPort() Edge   { return n.Main }
func (n EraserNode) GetAuxPorts() []Edge { return []Edge{} }

type ReplicatorNode struct {
	Main   Edge
	Level  uint
	Aux    []Edge
	Deltas []int
}

func (n ReplicatorNode) GetLabel() string    { return "" }
func (n ReplicatorNode) GetMainPort() Edge   { return n.Main }
func (n ReplicatorNode) GetAuxPorts() []Edge { return n.Aux }

// Returns the level of the replicator node.
func (n ReplicatorNode) GetLevel() uint { return n.Level }

type FanNode struct {
	Label       string
	Main        Edge
	Left, Right Edge
}

func (n FanNode) GetLabel() string    { return n.Label }
func (n FanNode) GetMainPort() Edge   { return n.Main }
func (n FanNode) GetAuxPorts() []Edge { return []Edge{n.Left, n.Right} }

type TerminalNode struct {
	Label string
	Main  Edge
}

func (n TerminalNode) GetLabel() string    { return n.Label }
func (n TerminalNode) GetMainPort() Edge   { return n.Main }
func (n TerminalNode) GetAuxPorts() []Edge { return []Edge{} }