package model

import "io"

type RR = io.Writer

// 轨道
type Link interface {
	RtssModel
	PipeElement
}

// 轨道连接点
type LinkNode interface {
	Turnout() Turnout
	PipeElement
}

var _ Link = (*LinkImpl)(nil)
var _ LinkNode = (*LinkNodeImpl)(nil)

type LinkImpl struct {
	uid        string
	paLinkNode *PipeLink
	pbLinkNode *PipeLink
}

type LinkNodeImpl struct {
	turnout    Turnout
	paPipeLink *PipeLink
	pbPipeLink *PipeLink
	pcPipeLink *PipeLink
}

func NewLink(nodea LinkNode, nodeb LinkNode) Link {
	uid := buildLinkUid(nodea, nodeb)
	return &LinkImpl{
		uid: uid,
	}
}

func NewLinkNode(turnout Turnout) LinkNode {
	return &LinkNodeImpl{
		turnout: turnout,
	}
}

func (l *LinkImpl) Uid() string {
	return l.uid
}

func (l *LinkImpl) Ports() []PipePort {
	return twoPorts
}

func (l *LinkImpl) GetLinkedElement(port PipePort) *PipeLink {
	if port == PipePortA {
		return l.paLinkNode
	} else if port == PipePortB {
		return l.pbLinkNode
	}
	return nil
}

func (n *LinkNodeImpl) Turnout() Turnout {
	return n.turnout
}

func (n *LinkNodeImpl) Ports() []PipePort {
	return threePorts
}

func (n *LinkNodeImpl) GetLinkedElement(port PipePort) *PipeLink {
	if port == PipePortA {
		return n.paPipeLink
	} else if port == PipePortB {
		return n.pbPipeLink
	} else if port == PipePortC {
		return n.pcPipeLink
	}
	return nil
}

func buildLinkUid(nodea LinkNode, nodeb LinkNode) string {
	if nodea == nil && nodeb == nil {
		panic("构造link Uid错误: nodea和nodeb不能同时为空")
	}
	if nodea == nil {
		return "->" + nodeb.Turnout().Uid()
	}
	if nodeb == nil {
		return nodea.Turnout().Uid() + "->"
	}
	return nodea.Turnout().Uid() + "-" + nodeb.Turnout().Uid()
}