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105 lines
2.5 KiB
Go
105 lines
2.5 KiB
Go
// The graph package defines the fundamental structures (e.g. [Node], [Delta])
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// that are used across packages.
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package graph
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import (
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"errors"
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"time"
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"github.com/pippellia-btc/slicex"
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)
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const (
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// types of status
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StatusActive string = "active" // meaning, we generate random walks for this node
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StatusInactive string = "inactive"
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// internal record kinds
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Addition int = -3
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Promotion int = -2
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Demotion int = -1
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)
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var (
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ErrNodeNotFound = errors.New("node not found")
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ErrNodeAlreadyExists = errors.New("node already exists")
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)
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type ID string
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func (id ID) MarshalBinary() ([]byte, error) { return []byte(id), nil }
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// Node contains the metadata about a node, including a collection of Records.
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type Node struct {
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ID ID
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Pubkey string
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Status string // either [StatusActive] or [StatusInactive]
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Records []Record
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}
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// Record contains the timestamp of a node update.
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type Record struct {
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Kind int // either [Addition], [Promotion] or [Demotion]
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Timestamp time.Time
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}
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func (n *Node) Addition() (time.Time, bool) { return n.find(Addition) }
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func (n *Node) Promotion() (time.Time, bool) { return n.find(Promotion) }
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func (n *Node) Demotion() (time.Time, bool) { return n.find(Demotion) }
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func (n *Node) find(kind int) (time.Time, bool) {
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for _, record := range n.Records {
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if record.Kind == kind {
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return record.Timestamp, true
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}
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}
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return time.Time{}, false
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}
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// Delta represents updates to apply to a Node.
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// Add and Remove contain node IDs to add to or remove from the node’s relationships (e.g., follow list).
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type Delta struct {
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Kind int
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Node ID
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Remove []ID
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Keep []ID
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Add []ID
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}
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// NewDelta returns a delta by computing the relationships to remove, keep and add.
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func NewDelta(kind int, node ID, old, new []ID) Delta {
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delta := Delta{
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Kind: kind,
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Node: node,
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}
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delta.Remove, delta.Keep, delta.Add = slicex.Partition(old, new)
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return delta
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}
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// Size returns the number of relationships changed by delta
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func (d Delta) Size() int {
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return len(d.Remove) + len(d.Add)
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}
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// Old returns the old state of the delta
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func (d Delta) Old() []ID {
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return append(d.Keep, d.Remove...)
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}
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// New returns the new state of the delta
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func (d Delta) New() []ID {
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return append(d.Keep, d.Add...)
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}
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// Inverse of the delta. If a delta and it's inverse are applied, the graph returns to its original state.
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func (d Delta) Inverse() Delta {
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return Delta{
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Kind: d.Kind,
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Node: d.Node,
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Keep: d.Keep,
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Remove: d.Add,
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Add: d.Remove,
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}
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}
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