Better mimetype handling, index list all routes

app.py

@@ -1,35 +1,69 @@
 import os
 
-from flask import Flask, request, Response
+from flask import Flask, request, Response, render_template, jsonify
 
 app = Flask(__name__)
 
 
 @app.route("/")
 def index():
-    return f"TODO"
+    """List all available routes"""
+    routes = {}
+    for rule in app.url_map.iter_rules():
+        if rule.endpoint != "static":
+            routes[rule.rule] = app.view_functions[rule.endpoint].__doc__
 
+    if request.accept_mimetypes.accept_json:
+        return jsonify(routes)
 
-@app.route("/headers")
-def headers():
-    content = "\n".join(
-        [
-            "{key}={value}".format(key=key, value=value)
-            for key, value in request.headers.items()
-        ]
+    if request.accept_mimetypes.accept_html:
+        return render_template("index.j2", routes=routes)
+
+    return Response(
+        "\n".join(
+            [
+                "{path:32s}: {doc}".format(path=path, doc=doc)
+                for path, doc in routes.items()
+            ]
+        ),
+        content_type="text/plain",
     )
-    return Response(content, content_type="text/plain")
 
 
 @app.route("/environment")
 def environment():
-    content = "\n".join(
-        [
-            "{key}={value}".format(key=key, value=value)
-            for key, value in os.environ.items()
-        ]
+    """Return defined environment"""
+
+    if request.accept_mimetypes.accept_json:
+        return jsonify(os.environ.copy())
+
+    return Response(
+        "\n".join(
+            [
+                "{key}={value}".format(key=key, value=value)
+                for key, value in os.environ.items()
+            ]
+        ),
+        content_type="text/plain",
+    )
+
+
+@app.route("/headers")
+def headers():
+    """Return request headers"""
+
+    if request.accept_mimetypes.accept_json:
+        return jsonify(dict(request.headers))
+
+    return Response(
+        "\n".join(
+            [
+                "{key}={value}".format(key=key, value=value)
+                for key, value in request.headers
+            ]
+        ),
+        content_type="text/plain",
     )
-    return Response(content, content_type="text/plain")
 
 
 if __name__ == "__main__":

templates/index.j2

@@ -0,0 +1,3 @@
+{% for path, help in routes.items() %}
+<a href="{{ path }}"> {{ help }}
+{% endfor %}