package mgossip

import (
	"math"

	"git.wecise.com/wecise/odbserver/mring/matrix"
	"git.wecise.com/wecise/odbserver/mring/mgossip"
)

type Router interface {
	Init() error
	Start() error
}

type mRouter struct {
	cnode matrix.ClusterNode
	mtopo mgossip.Topology
}

func NewMRouter(cnode matrix.ClusterNode) Router {
	mtopo := mgossip.MTopology(cnode)
	mr := &mRouter{
		cnode: cnode,
		mtopo: mtopo}
	// mtopo.OnTopoChange(func(connectedPeers map[matrix.PeerID]matrix.PeerIDs, update *mgossip.TopoInfo) {
	// peers := matrix.MPeerIDSet(cnode.Peers())
	// if !mpeers.Equal(peers) {
	// 	mpeers = peers
	// 	logger.Info(cnode.Name(), cnode.ID(), ":\n", mpeers.List())
	// }
	// })
	return mr
}

func (mr *mRouter) Init() (err error) {
	// 拓扑管理初始化，开启本地网络监听端口，
	if err = mr.mtopo.Init(); err != nil {
		return
	}

	return
}

func (mr *mRouter) Start() (err error) {
	// 拓扑管理初始化，开启本地网络监听端口，
	if err = mr.mtopo.Start(); err != nil {
		return
	}

	return
}

func (mr *mRouter) topoGraph(ti *mgossip.TopoInfo) {
	if ti == nil {
		return
	}
	fw := newFloydWarshall(len(ti.Nodes))
	for pid, ni := range ti.Nodes {
		bi := ni.BaseInfo
		if bi == nil {
			continue // 正常情况下不会为空
		}
		for rid, pi := range ni.Peers {
			// TODO 统计分析得出连接权重
			if len(pi.Connections) > 0 {
				fw.addEdge(pid, rid, 1)
				fw.addEdge(rid, pid, 1)
			}
		}
	}
	return
}

type graph struct {
	to int
	wt float64
}

type FloydWarshall struct {
	mindex map[matrix.PeerID]int
	rindex []matrix.PeerID
	mgraph [][]graph
	mpath  [][][]matrix.PeerID
	mdist  [][]float64
}

func newFloydWarshall(nodescount int) *FloydWarshall {
	return &FloydWarshall{
		mindex: map[matrix.PeerID]int{},
		rindex: make([]matrix.PeerID, nodescount+1),
		mgraph: make([][]graph, nodescount+1),
	}
}

func (fw *FloydWarshall) index(pid matrix.PeerID) int {
	fi, has := fw.mindex[pid]
	if !has {
		fi = len(fw.mindex) + 1
		fw.mindex[pid] = fi
	}
	if len(fw.rindex) < fi+1 {
		fw.rindex = append(fw.rindex, pid)
	} else {
		fw.rindex[fi] = pid
	}
	return fi
}

func (fw *FloydWarshall) addEdge(from, to matrix.PeerID, weight float64) {
	fi := fw.index(from)
	ti := fw.index(to)
	if len(fw.mgraph) < fi+1 {
		fw.mgraph = append(fw.mgraph, []graph{})
	}
	fw.mgraph[fi] = append(fw.mgraph[fi], graph{ti, weight})
}

func (fw *FloydWarshall) calculate() {
	fw.mpath = make([][][]matrix.PeerID, len(fw.mgraph))
	fw.mdist = make([][]float64, len(fw.mgraph))
	for i := range fw.mdist {
		pi := make([][]matrix.PeerID, len(fw.mgraph))
		di := make([]float64, len(fw.mgraph))
		for j := range di {
			di[j] = math.Inf(1)
			pi[j] = []matrix.PeerID{}
		}
		di[i] = 0
		fw.mdist[i] = di
		fw.mpath[i] = pi
	}
	for u, graphs := range fw.mgraph {
		for _, v := range graphs {
			fw.mdist[u][v.to] = v.wt
			fw.mpath[u][v.to] = []matrix.PeerID{fw.rindex[u], fw.rindex[v.to]}
		}
	}
	for k, dk := range fw.mdist {
		pk := fw.mpath[k]
		for i, di := range fw.mdist {
			pi := fw.mpath[i]
			for j, dij := range di {
				if d := di[k] + dk[j]; dij > d {
					di[j] = d
					pi[j] = append(pi[k], pk[j][1:]...)
				}
			}
		}
	}
}

func (fw *FloydWarshall) getPath(from, to matrix.PeerID) (dist float64, path matrix.PeerIDs) {
	fi := fw.index(from)
	ti := fw.index(to)
	if fi >= len(fw.mpath) || fi >= len(fw.mdist) {
		return 0, nil
	}
	if ti >= len(fw.mpath[fi]) || ti >= len(fw.mdist[fi]) {
		return 0, nil
	}
	return fw.mdist[fi][ti], fw.mpath[fi][ti]
}