1
package chord
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import (
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	"fmt"
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	"net/http"
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	"strconv"
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	"go.miragespace.co/specter/spec/chord"
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	"go.miragespace.co/specter/spec/protocol"
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	"github.com/dominikbraun/graph"
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	"github.com/dominikbraun/graph/draw"
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)
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func formatNode(n *protocol.Node) string {
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	return fmt.Sprintf("%s/%d", n.GetAddress(), n.GetId())
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}
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var vOptions = []func(*graph.VertexProperties){
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	graph.VertexAttribute("shape", "box"),
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}
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var rootVOptions = append(vOptions,
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	graph.VertexAttribute("style", "filled"),
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	graph.VertexAttribute("color", "yellow"),
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)
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var selfVOptions = append(vOptions,
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	graph.VertexAttribute("style", "filled"),
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	graph.VertexAttribute("color", "lightgrey"),
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)
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func ringGraphHandler(root *LocalNode) http.HandlerFunc {
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	return func(w http.ResponseWriter, r *http.Request) {
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		var err error
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		var next chord.VNode = root
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		nodes := make([]*protocol.Node, 0)
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		seen := make(map[uint64]bool)
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		lookup := make(map[string]*protocol.Node)
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		predecessor := root.getPredecessor()
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		if predecessor == nil {
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			http.Error(w, "predecessor is nil", 500)
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			return
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		}
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		for {
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			next, err = root.FindSuccessor(chord.ModuloSum(next.ID(), 1))
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			if err != nil {
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				http.Error(w, err.Error(), 500)
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				return
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			}
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			if next == nil {
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				http.Error(w, "successor is nil", 500)
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				return
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			}
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			if next.ID() == root.ID() {
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				nodes = append(nodes, root.Identity())
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				break
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			}
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			if seen[next.ID()] {
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				http.Error(w, "ring is unstable", 500)
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				return
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			}
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			nodes = append(nodes, next.Identity())
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			seen[next.ID()] = true
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		}
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		ring := graph.New(formatNode, graph.Directed())
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		for _, node := range nodes {
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			if node.GetId() == root.ID() {
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				ring.AddVertex(node, rootVOptions...)
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			} else if node.GetAddress() == root.Identity().GetAddress() {
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				ring.AddVertex(node, selfVOptions...)
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			} else {
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				ring.AddVertex(node, vOptions...)
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			}
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			lookup[strconv.FormatUint(node.GetId(), 10)] = node
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		}
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		ring.AddEdge(formatNode(root.Identity()), formatNode(predecessor.Identity()), graph.EdgeAttribute("color", "blue"))
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		for i := 0; i < len(nodes)-1; i++ {
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			ring.AddEdge(formatNode(nodes[i]), formatNode(nodes[i+1]), graph.EdgeAttribute("color", "red"))
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		}
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		ring.AddEdge(formatNode(nodes[len(nodes)-1]), formatNode(nodes[0]), graph.EdgeAttribute("color", "red"))
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		fingers := root.fingerTrace()
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		for r, id := range fingers {
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			s := formatNode(root.Identity())
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			d := formatNode(lookup[id])
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			err := ring.AddEdge(s, d, graph.EdgeAttribute("label", r))
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			if err == graph.ErrEdgeAlreadyExists {
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				ring.RemoveEdge(s, d)
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				ring.AddEdge(s, d, graph.EdgeAttribute("label", r), graph.EdgeAttribute("color", "red"))
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			}
98
		}
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		w.Header().Set("content-type", "text/plain")
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		draw.DOT(ring, w)
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	}
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}