Add wrap manager for tracking gift wraps

packages/relay/src/wrapManager.ts

@@ -0,0 +1,122 @@
+import {Emitter, remove, omit} from "@welshman/lib"
+import {HashedEvent, SignedEvent} from "@welshman/util"
+import {Tracker} from "./tracker.js"
+import {LocalRelay} from "./relay.js"
+
+export type WrapItem = Omit<HashedEvent, "content"> & {
+  rumorId: string
+  recipient: string
+}
+
+export type WrapReference = string[]
+
+export type WrapManagerOptions = {
+  relay: LocalRelay
+  tracker: Tracker
+}
+
+export class WrapManager extends Emitter {
+  _wrapIndex = new Map<string, WrapItem>()
+  _rumorIndex = new Map<string, WrapReference>()
+  _recipientIndex = new Map<string, WrapReference>()
+
+  constructor(readonly options: WrapManagerOptions) {
+    super()
+  }
+
+  getRumor = (id: string) => {
+    const wrapItem = this._wrapIndex.get(id)
+
+    if (wrapItem) {
+      return this.options.relay.repository.getEvent(wrapItem.rumorId)
+    }
+  }
+
+  // Adding/importing
+
+  load = (wrapItems: WrapItem[]) => {
+    this._wrapIndex.clear()
+    this._rumorIndex.clear()
+    this._recipientIndex.clear()
+
+    for (const wrapItem of wrapItems) {
+      this._add(wrapItem)
+    }
+
+    this.emit("load")
+  }
+
+  add = ({recipient, rumor, wrap}: {recipient: string; rumor: HashedEvent; wrap: SignedEvent}) => {
+    const wrapItem = {
+      ...omit(["content"], wrap),
+      rumorId: rumor.id,
+      recipient,
+    }
+
+    this._add(wrapItem)
+
+    // Send via our relay so that listeners get notified
+    this.options.relay.send("EVENT", rumor)
+
+    // Mark the rumor as having come from the wrap's urls
+    this.options.tracker.copy(wrap.id, rumor.id)
+
+    this.emit("add", wrapItem)
+  }
+
+  // Removing
+
+  remove = (id: string) => {
+    const wrapItem = this._wrapIndex.get(id)
+
+    if (wrapItem) {
+      this._remove(wrapItem)
+      this.options.relay.repository.removeEvent(wrapItem.rumorId)
+      this.emit("remove", wrapItem)
+    }
+  }
+
+  removeByRumorId = (rumorId: string) => {
+    for (const id of this._rumorIndex.get(rumorId) || []) {
+      this.remove(id)
+    }
+  }
+
+  // Utils
+
+  _add = (wrapItem: WrapItem) => {
+    this._wrapIndex.set(wrapItem.id, wrapItem)
+    this._addReference(this._rumorIndex, wrapItem.rumorId, wrapItem.id)
+    this._addReference(this._recipientIndex, wrapItem.recipient, wrapItem.id)
+  }
+
+  _addReference = (index: Map<string, WrapReference>, key: string, wrapId: string) => {
+    const reference = index.get(key)
+
+    if (reference) {
+      reference.push(wrapId)
+    } else {
+      index.set(key, [wrapId])
+    }
+  }
+
+  _remove = (wrapItem: WrapItem) => {
+    this._wrapIndex.delete(wrapItem.id)
+    this._removeReference(this._rumorIndex, wrapItem.rumorId, wrapItem.id)
+    this._removeReference(this._recipientIndex, wrapItem.recipient, wrapItem.id)
+  }
+
+  _removeReference = (index: Map<string, WrapReference>, key: string, wrapId: string) => {
+    const reference = index.get(key)
+
+    if (reference) {
+      const wraps = remove(wrapId, reference)
+
+      if (wraps.length > 0) {
+        index.set(key, wraps)
+      } else {
+        index.delete(key)
+      }
+    }
+  }
+}