From 5476d476a8fe37072f27caccac4468263a4b52c7 Mon Sep 17 00:00:00 2001
From: William Hua <william@attente.ca>
Date: Wed, 18 Oct 2023 14:35:50 -0400
Subject: [PATCH] signhub: InteractiveSigner

---
 packages/signhub/src/signers/interactive.ts | 109 ++++++++++++++++++++
 1 file changed, 109 insertions(+)
 create mode 100644 packages/signhub/src/signers/interactive.ts

diff --git a/packages/signhub/src/signers/interactive.ts b/packages/signhub/src/signers/interactive.ts
new file mode 100644
index 000000000..3900692cf
--- /dev/null
+++ b/packages/signhub/src/signers/interactive.ts
@@ -0,0 +1,109 @@
+import { BytesLike } from 'ethers'
+import { Status, isSignerStatusPending } from '../orchestrator'
+import { SapientSigner } from './signer'
+
+export class InteractiveSigner implements SapientSigner {
+  private readonly requests: Map<string, Request> = new Map()
+
+  constructor(
+    private readonly signer: SapientSigner,
+    private readonly dependencies: string[]
+  ) {}
+
+  async prompt(id: string) {
+    const request = this.requests.get(id)
+
+    if (request === undefined) {
+      return
+    }
+
+    this.signer.requestSignature(id, request.message, request.metadata, {
+      onSignature(signature) {
+        request.callbacks.onSignature(signature)
+        request.resolve()
+      },
+      onRejection(_error) {},
+      onStatus(_situation) {}
+    })
+  }
+
+  getAddress(): Promise<string> {
+    return this.signer.getAddress()
+  }
+
+  requestSignature(
+    id: string,
+    message: BytesLike,
+    metadata: object,
+    callbacks: {
+      onSignature: (signature: BytesLike) => void
+      onRejection: (error: string) => void
+      onStatus: (situation: string) => void
+    }
+  ): Promise<boolean> {
+    return new Promise(resolve => {
+      const request = {
+        message,
+        metadata,
+        callbacks,
+        autoPrompts: 0,
+        resolve: () => resolve(true)
+      }
+
+      this.requests.set(id, request)
+
+      // prompt immediately if we're not waiting for other signers
+      if (this.dependencies.length === 0) {
+        request.autoPrompts++
+        this.prompt(id)
+      }
+    })
+  }
+
+  notifyStatusChange(id: string, status: Status, metadata: object): void {
+    const request = this.requests.get(id)
+
+    if (request === undefined) {
+      return
+    }
+
+    request.metadata = metadata
+
+    if (status.ended) {
+      this.requests.delete(id)
+      return
+    }
+
+    if (request.autoPrompts > 0) {
+      return
+    }
+
+    const isPending = (dependency: string) => {
+      const signerStatus = status.signers[dependency]
+      return signerStatus !== undefined && isSignerStatusPending(signerStatus)
+    }
+
+    if (this.dependencies.some(isPending)) {
+      return
+    }
+
+    request.autoPrompts++
+    this.prompt(id)
+  }
+
+  suffix(): BytesLike {
+    return this.signer.suffix()
+  }
+}
+
+type Request = {
+  message: BytesLike
+  metadata: object
+  callbacks: {
+    onSignature: (signature: BytesLike) => void
+    onRejection: (error: string) => void
+    onStatus: (situation: string) => void
+  }
+  autoPrompts: number
+  resolve: () => void
+}