Store exchange key in well known location (#285)

* Store exchange key in well known location

* Fix test

* Remove console.log

* Make contents an empty object

* Update CHANGELOG

* Add hasPublicExchangeKey function

* Mention hasPublicExchangeKey in changelog

* Store as directory instead

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+
+### v0.28.0
+
+Added the `fs.addPublicExchangeKey()` function which adds the public exchange key of that domain/browser/device to your filesystem at `/public/.well-known/exchange/DID_KEY`. Along with the `fs.hasPublicExchangeKey()` to check if it's there.
+
+
+
 ### v0.27.0
 
 - Fixed `webnative.apps.index()`, and now returns a list of domains, along with their `insertedAt` and `modifiedAt` ISO8601 timestamps.

src/fs/filesystem.ts

@@ -14,6 +14,7 @@ import * as cidLog from "../common/cid-log.js"
 import * as dataRoot from "../data-root.js"
 import * as debug from "../common/debug.js"
 import * as crypto from "../crypto/index.js"
+import * as did from "../did/index.js"
 import * as pathing from "../path.js"
 import * as typeCheck from "./types/check.js"
 import * as ucan from "../ucan/index.js"
@@ -53,6 +54,16 @@ type MutationOptions = {
 }
 
 
+// CONSTANTS
+
+
+export const EXCHANGE_PATH: DirectoryPath = pathing.directory(
+  pathing.Branch.Public,
+  ".well-known",
+  "exchange"
+)
+
+
 // CLASS
 
 
@@ -121,7 +132,7 @@ export class FileSystem {
     if (!this.localOnly) {
       // Publish when coming back online
       globalThis.addEventListener("online", this._whenOnline)
-      
+
       // Show an alert when leaving the page while updating the data root
       globalThis.addEventListener("beforeunload", this._beforeLeaving)
     }
@@ -212,6 +223,7 @@ export class FileSystem {
     return this
   }
 
+
   // POSIX INTERFACE (FILES)
   // -----------------------
 
@@ -247,6 +259,7 @@ export class FileSystem {
     return this.add(path, content, options)
   }
 
+
   // POSIX INTERFACE (GENERAL)
   // -------------------------
 
@@ -330,6 +343,33 @@ export class FileSystem {
   }
 
 
+  // COMMON
+  // ------
+
+  /**
+   * Stores the public part of the exchange key in the DID format,
+   * in the `/public/.well-known/exchange/DID_GOES_HERE/` directory.
+   */
+  async addPublicExchangeKey(): Promise<void> {
+    const publicDid = await did.exchange()
+
+    await this.mkdir(
+      pathing.combine(EXCHANGE_PATH, pathing.directory(publicDid))
+    )
+  }
+
+  /**
+   * Checks if the public exchange key was added in the well-known location.
+   * See `addPublicExchangeKey()` for the exact details.
+   */
+  async hasPublicExchangeKey(): Promise<boolean> {
+    const publicDid = await did.exchange()
+
+    return this.exists(
+      pathing.combine(EXCHANGE_PATH, pathing.directory(publicDid))
+    )
+  }
+
 
   // INTERNAL
   // --------

tests/fs/exchange.node.test.ts

@@ -0,0 +1,22 @@
+import expect from "expect"
+
+import "../../src/setup/node.js"
+
+import { EXCHANGE_PATH } from "../../src/fs/filesystem.js"
+import { emptyFilesystem } from "../helpers/filesystem.js"
+
+import * as did from "../../src/did/index.js"
+import * as path from "../../src/path.js"
+
+
+describe("the filesystem", () => {
+
+  it("adds public exchange key to well-known location", async function() {
+    const fs = await emptyFilesystem()
+    await fs.addPublicExchangeKey()
+    const exists = await fs.hasPublicExchangeKey()
+
+    expect(exists).toEqual(true)
+  })
+
+})