Add login via nostr (web extension)

app/javascript/controllers/nostr_login_controller.js

@@ -0,0 +1,53 @@
+import { Controller } from "@hotwired/stimulus"
+
+// Connects to data-controller="nostr-login"
+export default class extends Controller {
+  static targets = [ "loginForm", "loginButton" ]
+  static values  = { site: String, sharedSecret: String }
+
+  connect() {
+    if (window.nostr) {
+      this.loginButtonTarget.disabled = false
+      this.loginFormTarget.classList.remove("hidden")
+    }
+  }
+
+  async login () {
+    this.loginButtonTarget.disabled = true
+
+    try {
+      // Auth based on NIP-42
+      const signedEvent = await window.nostr.signEvent({
+        created_at: Math.floor(Date.now() / 1000),
+        kind: 22242,
+        tags: [
+          ["site", this.siteValue],
+          ["challenge", this.sharedSecretValue]
+        ],
+        content: ""
+      })
+
+      const res = await fetch("/users/nostr_login", {
+        method: "POST", credentials: "include", headers: {
+          "Accept": "application/json", 'Content-Type': 'application/json',
+          "X-CSRF-Token": this.csrfToken
+        }, body: JSON.stringify({ signed_event: signedEvent })
+      })
+
+      if (res.status === 200) {
+        res.json().then(r => { window.location.href = r.redirect_url })
+      } else {
+        window.location.reload()
+      }
+    } catch (error) {
+      console.warn('Unable to authenticate:', error.message)
+    } finally {
+      this.loginButtonTarget.disabled = false
+    }
+  }
+
+  get csrfToken () {
+    const element = document.head.querySelector('meta[name="csrf-token"]')
+    return element.getAttribute("content")
+  }
+}