stub a ja-JP translation and add routing (#43)

src/main.py

@@ -1,4 +1,4 @@
-from flask import Flask, render_template
+from flask import Flask, render_template, abort
 from flask_talisman import Talisman
 from csp import csp
 
@@ -7,10 +7,18 @@
          content_security_policy=csp,
          content_security_policy_nonce_in=['script-src'])
 
+SUPPORTED_LANGS = ('en', 'ja')
 
 @app.route('/')
 def index():
-    return render_template('en-US/index.html')
+    return render_template('en/index.html')
+
+@app.route('/<lang>/')
+def index_i18n(lang):
+    if lang not in SUPPORTED_LANGS:
+        abort(404)
+
+    return render_template('%s/index.html' % lang)
 
 
 @app.errorhandler(500)

src/templates/en-US/index.html → src/templates/en/index.html

@@ -1,4 +1,4 @@
-{% extends "en-US/base.html" %}
+{% extends "en/base.html" %}
 
 {% block title %}
 The Web Almanac by HTTP Archive

src/templates/ja/base.html

@@ -0,0 +1,3 @@
+{% extends "base.html" %}
+
+{% block lang %}ja-JP{% endblock %}

src/templates/ja/index.html

@@ -0,0 +1,32 @@
+{% extends "ja/base.html" %}
+
+{% block title %}
+The Web Almanac by HTTP Archive
+{% endblock %}
+
+{# TODO(MSakamaki): Translate to Japanese. #}
+{% block main %}
+<section>
+  <div>
+    <img src="../static/images/ha.png" alt="HTTP Archive">
+
+    <h1>
+      Introducing the <b>Web Almanac</b>, coming November 2019.
+    </h1>
+
+    <p>
+      The Web Almanac is HTTP Archive's annual "state of the web" report.
+      Our mission is to combine the powerful analytics of HTTP Archive with the
+      expertise of the web community. The Almanac is made up of four primary
+      sections: page content, user experience, content delivery, and
+      content distribution. Each section is comprised of chapters that explore
+      the state of specific areas like JavaScript usage, accessibility,
+      content management systems, and compression.
+    </p>
+
+    <a href="https://github.com/HTTPArchive/almanac.httparchive.org">
+      Learn more
+    </a>
+  </div>
+</section>
+{% endblock %}