DEV: add password validation helper class (#31541)

Partial backport of
b8a4b11cbb.

This adds the `password-validation-helper.js` class so that anything
else depending on `stable` is able to use this class.

app/assets/javascripts/discourse/app/lib/password-validation-helper.js

@@ -0,0 +1,104 @@
+import { tracked } from "@glimmer/tracking";
+import { dependentKeyCompat } from "@ember/object/compat";
+import { isEmpty } from "@ember/utils";
+import { TrackedArray, TrackedMap } from "@ember-compat/tracked-built-ins";
+import { i18n } from "discourse-i18n";
+
+function failedResult(attrs) {
+  return {
+    failed: true,
+    ok: false,
+    element: document.querySelector("#new-account-password"),
+    ...attrs,
+  };
+}
+
+function validResult(attrs) {
+  return { ok: true, ...attrs };
+}
+
+export default class PasswordValidationHelper {
+  @tracked rejectedPasswords = new TrackedArray();
+  @tracked rejectedPasswordsMessages = new TrackedMap();
+
+  constructor(owner) {
+    this.owner = owner;
+  }
+
+  get passwordInstructions() {
+    return i18n("user.password.instructions", {
+      count: this.passwordMinLength,
+    });
+  }
+
+  get passwordMinLength() {
+    return this.owner.admin || this.owner.isDeveloper
+      ? this.owner.siteSettings.min_admin_password_length
+      : this.owner.siteSettings.min_password_length;
+  }
+
+  @dependentKeyCompat
+  get passwordValidation() {
+    if (!this.owner.passwordRequired) {
+      return validResult();
+    }
+
+    if (this.rejectedPasswords.includes(this.owner.accountPassword)) {
+      return failedResult({
+        reason:
+          this.rejectedPasswordsMessages.get(this.owner.accountPassword) ||
+          i18n("user.password.common"),
+      });
+    }
+
+    // If blank, fail without a reason
+    if (isEmpty(this.owner.accountPassword)) {
+      return failedResult({
+        message: i18n("user.password.required"),
+        reason: this.owner.forceValidationReason
+          ? i18n("user.password.required")
+          : null,
+      });
+    }
+
+    // If too short
+    if (this.owner.accountPassword.length < this.passwordMinLength) {
+      return failedResult({
+        reason: i18n("user.password.too_short", {
+          count: this.passwordMinLength,
+        }),
+      });
+    }
+
+    if (
+      !isEmpty(this.owner.accountUsername) &&
+      this.owner.accountPassword === this.owner.accountUsername
+    ) {
+      return failedResult({
+        reason: i18n("user.password.same_as_username"),
+      });
+    }
+
+    if (
+      !isEmpty(this.owner.accountName) &&
+      this.owner.accountPassword === this.owner.accountName
+    ) {
+      return failedResult({
+        reason: i18n("user.password.same_as_name"),
+      });
+    }
+
+    if (
+      !isEmpty(this.owner.accountEmail) &&
+      this.owner.accountPassword === this.owner.accountEmail
+    ) {
+      return failedResult({
+        reason: i18n("user.password.same_as_email"),
+      });
+    }
+
+    return validResult({
+      reason: i18n("user.password.ok"),
+    });
+  }
+}