Implement received Webmention handling

Add the Flask application setup, database models and migrations,
authentication, and configuration for development and testing.

Implement asynchronous Webmention verification with Huey, including HTML
and plain-text source validation, retries, status tracking, and size
limits.

Add status, login, and paginated received-Webmention views together with
comprehensive tests for forms, views, and receiver tasks.

4 files changed, 185 insertions, 0 deletions

diff --git a/webmentions_ssg/templates/base.html b/webmentions_ssg/templates/base.html
new file mode 100644
index 0000000..237a437
--- /dev/null
+++ b/webmentions_ssg/templates/base.html
@@ -0,0 +1,44 @@
+{% from "bootstrap5/utils.html" import render_messages %}
+<!DOCTYPE html>
+<html lang="en" data-bs-theme="dark">
+  <head>
+    {% block head %}
+      <!-- Required meta tags -->
+      <meta charset="utf-8">
+      <meta name="viewport"
+            content="width=device-width, initial-scale=1, shrink-to-fit=no">
+      {% block styles %}
+        <!-- Bootstrap CSS -->
+        {{ bootstrap.load_css() }}
+      {% endblock %}
+      <title>{{ title }}</title>
+    {% endblock %}
+  </head>
+  <body>
+    <header>
+      <nav class="navbar bg-primary py-1">
+        <div class="container-fluid px3">
+          <a class="navbar-brand fs-6 mb-0" href="{{ url_for("root.index") }}">Webmentions</a>
+          {% if current_user.is_authenticated %}
+            <div class="navbar-nav flex-row gap-3">
+              <a class="nav-link{% if request.endpoint == 'root.received' %} active{% endif %}"
+                 href="{{ url_for("root.received") }}">Received</a>
+              <span class="nav-link disabled">Sent</span>
+              <a class="nav-link" href="{{ url_for("root.logout") }}">Logout</a>
+            </div>
+          {% endif %}
+        </div>
+      </div>
+    </nav>
+  </header>
+  <div class="mt-4">{{ render_messages(container=True) }}</div>
+  <div class="container py-4">
+    {% block content %}
+    {% endblock %}
+  </div>
+  {% block scripts %}
+    <!-- Optional JavaScript -->
+    {{ bootstrap.load_js() }}
+  {% endblock %}
+</body>
+</html>
diff --git a/webmentions_ssg/templates/login.html b/webmentions_ssg/templates/login.html
new file mode 100644
index 0000000..e7d858c
--- /dev/null
+++ b/webmentions_ssg/templates/login.html
@@ -0,0 +1,8 @@
+{% extends "base.html" %}
+{% set title = "Login" %}
+{% from "bootstrap5/form.html" import render_form %}
+{% block content %}
+  <div class="row justify-content-center">
+    <div class="col-12 col-sm-8 col-md-6 col-lg-4">{{ render_form(form) }}</div>
+  </div>
+{% endblock %}
diff --git a/webmentions_ssg/templates/received.html b/webmentions_ssg/templates/received.html
new file mode 100644
index 0000000..ea74557
--- /dev/null
+++ b/webmentions_ssg/templates/received.html
@@ -0,0 +1,69 @@
+{% extends "base.html" %}
+{% from "bootstrap5/pagination.html" import render_pagination %}
+{% block content %}
+  <div class="d-flex justify-content-between align-items-center mb-3">
+    <h1 class="h3 mb-0">Received Webmentions</h1>
+    <span class="text-body-secondary">{{ webmentions.total }} total</span>
+  </div>
+  {% if webmentions.items %}
+    <div class="table-responsive">
+      <table class="table table-bordered table-striped table-hover align-middle">
+        <thead>
+          <tr>
+            <th scope="col">Status</th>
+            <th scope="col">Source</th>
+            <th scope="col">Target</th>
+            <th scope="col">Received</th>
+            <th scope="col">Updated</th>
+            <th scope="col">Reason</th>
+          </tr>
+        </thead>
+        <tbody>
+          {% for webmention in webmentions %}
+            {% if webmention.status == "verified" %}
+              {% set row_class = "table-success" %}
+              {% set display_status = "Verified" %}
+            {% elif webmention.status in ("received", "verifying") %}
+              {% set row_class = "table-warning" %}
+              {% set display_status = "Pending" %}
+            {% else %}
+              {% set row_class = "table-danger" %}
+              {% set display_status = "Declined" %}
+            {% endif %}
+            <tr class="{{ row_class }}">
+              <td>
+                <strong>{{ display_status }}</strong>
+              </td>
+              <td class="text-break">
+                <a href="{{ webmention.source }}">{{ webmention.source }}</a>
+              </td>
+              <td class="text-break">
+                <a href="{{ webmention.target }}">{{ webmention.target }}</a>
+              </td>
+              <td class="text-nowrap">
+                <time datetime="{{ webmention.created_at.isoformat() }}">
+                  {{ webmention.created_at.strftime("%Y-%m-%d %H:%M:%S") }}
+                </time>
+              </td>
+              <td class="text-nowrap">
+                <time datetime="{{ webmention.updated_at.isoformat() }}">
+                  {{ webmention.updated_at.strftime("%Y-%m-%d %H:%M:%S") }}
+                </time>
+              </td>
+              <td>{{ webmention.failure_reason or "—" }}</td>
+            </tr>
+          {% endfor %}
+        </tbody>
+      </table>
+    </div>
+    {% if webmentions.pages > 1 %}
+      <div class="mt-3">
+        {{ render_pagination(webmentions,
+                align="center",
+                size="sm") }}
+      </div>
+    {% endif %}
+  {% else %}
+    <p class="text-body-secondary">No Webmentions have been received yet.</p>
+  {% endif %}
+{% endblock %}
diff --git a/webmentions_ssg/templates/status.html b/webmentions_ssg/templates/status.html
new file mode 100644
index 0000000..451f26f
--- /dev/null
+++ b/webmentions_ssg/templates/status.html
@@ -0,0 +1,64 @@
+{% extends "base.html" %}
+{% from "bootstrap5/utils.html" import render_icon %}
+{% block content %}
+  <main class="py-5">
+    <div class="text-center mb-5">
+      {% if webmention.status == "verified" %}
+        <div class="text-success mb-3">{{ render_icon("check-circle-fill", size="5rem", title="Verified") }}</div>
+        <h1 class="h3">Webmention verified</h1>
+      {% elif webmention.status in ("received", "verifying") %}
+        <div class="text-warning mb-3">{{ render_icon("hourglass-split", size="5rem", title="Verification pending") }}</div>
+        <h1 class="h3">Webmention verification pending</h1>
+      {% elif webmention.status == "deleted" %}
+        <div class="text-danger mb-3">{{ render_icon("x-circle-fill", size="5rem", title="Not verified") }}</div>
+        <h1 class="h3">Webmention not verified</h1>
+      {% elif webmention.status == "failed" %}
+        <div class="text-danger mb-3">{{ render_icon("x-circle-fill", size="5rem", title="Verification failed") }}</div>
+        <h1 class="h3">Webmention verification failed</h1>
+      {% else %}
+        <div class="text-secondary mb-3">{{ render_icon("question-circle-fill", size="5rem", title="Unknown status") }}</div>
+        <h1 class="h3">Unknown Webmention status</h1>
+      {% endif %}
+    </div>
+    <div class="card mx-auto" style="max-width: 48rem;">
+      <div class="card-body">
+        <dl class="row mb-0">
+          <dt class="col-sm-3">Status</dt>
+          <dd class="col-sm-9">
+            {{ webmention.status }}
+          </dd>
+          <dt class="col-sm-3">Source</dt>
+          <dd class="col-sm-9 text-break">
+            <a href="{{ webmention.source }}">{{ webmention.source }}</a>
+          </dd>
+          <dt class="col-sm-3">Target</dt>
+          <dd class="col-sm-9 text-break">
+            <a href="{{ webmention.target }}">{{ webmention.target }}</a>
+          </dd>
+          <dt class="col-sm-3">Received</dt>
+          <dd class="col-sm-9">
+            <time datetime="{{ webmention.created_at.isoformat() }}">
+              {{ webmention.created_at.strftime("%Y-%m-%d %H:%M:%S %Z") }}
+            </time>
+          </dd>
+          <dt class="col-sm-3">Last updated</dt>
+          <dd class="col-sm-9">
+            <time datetime="{{ webmention.updated_at.isoformat() }}">
+              {{ webmention.updated_at.strftime("%Y-%m-%d %H:%M:%S %Z") }}
+            </time>
+          </dd>
+          <dt class="col-sm-3">ID</dt>
+          <dd class="col-sm-9">
+            <code>{{ webmention.uuid }}</code>
+          </dd>
+          {% if webmention.failure_reason %}
+            <dt class="col-sm-3">Reason</dt>
+            <dd class="col-sm-9">
+              {{ webmention.failure_reason }}
+            </dd>
+          {% endif %}
+        </dl>
+      </div>
+    </div>
+  </main>
+{% endblock %}