Add clean message flashing, error handling.

app.py

@@ -3,7 +3,7 @@
 
 from pathlib import Path
 
-from flask import Flask, g, redirect, request, url_for
+from flask import Flask, flash, g, redirect, request, url_for
 from flask_mako import MakoTemplates, render_template
 
 import calefaction
@@ -11,8 +11,10 @@ from calefaction.auth import AuthManager
 from calefaction.config import Config
 from calefaction.database import Database
 from calefaction.eve import EVE
-from calefaction.exceptions import AccessDeniedError, EVEAPIError
-from calefaction.util import catch_errors, set_up_asset_versioning
+from calefaction.messages import Messages
+from calefaction.util import (
+    try_func, make_error_catcher, make_route_restricter,
+    set_up_asset_versioning)
 
 app = Flask(__name__)
 
@@ -21,6 +23,9 @@ config = Config(basepath / "config")
 Database.path = str(basepath / "data" / "db.sqlite3")
 eve = EVE(config)
 auth = AuthManager(config, eve)
+catch_exceptions = make_error_catcher(app, "error.mako")
+route_restricted = make_route_restricter(
+    auth, lambda: redirect(url_for("index"), 303))
 
 MakoTemplates(app)
 set_up_asset_versioning(app)
@@ -37,32 +42,44 @@ app.before_request(Database.pre_hook)
 app.teardown_appcontext(Database.post_hook)
 
 @app.route("/")
-@catch_errors(app)
+@catch_exceptions
 def index():
-    ...  # handle flashed error messages in _base.mako
-    if auth.is_authenticated():  # ... need to check for exceptions
+    success, _ = try_func(auth.is_authenticated)
+    if success:
         return render_template("home.mako")
     return render_template("landing.mako")
 
 @app.route("/login", methods=["GET", "POST"])
-@catch_errors(app)
+@catch_exceptions
 def login():
     code = request.args.get("code")
     state = request.args.get("state")
-    try:
-        auth.handle_login(code, state)
-    except EVEAPIError:
-        ...  # flash error message
-    except AccessDeniedError:
-        ...  # flash error message
-    if getattr(g, "_session_expired"):
-        ...  # flash error message
+
+    success, caught = try_func(lambda: auth.handle_login(code, state))
+    if success:
+        flash(Messages.LOGGED_IN, "success")
+    elif getattr(g, "_session_expired", False):
+        flash(Messages.SESSION_EXPIRED, "error")
+    elif not caught:
+        flash(Messages.LOGIN_FAILED, "error")
     return redirect(url_for("index"), 303)
 
-# @app.route("/logout") ...
+@app.route("/logout", methods=["GET", "POST"])
+@catch_exceptions
+def logout():
+    if request.method == "GET":
+        return render_template("logout.mako")
+
+    auth.handle_logout()
+    flash(Messages.LOGGED_OUT, "success")
+    return redirect(url_for("index"), 303)
 
-# @auth.route_restricted ...
-# check for same exceptions as login() and use same flashes
+@app.route("/test")
+@catch_exceptions
+@route_restricted
+def test():
+    ...
+    return "Success! You are authenticated!"
 
 if __name__ == "__main__":
     app.run(debug=True, port=8080)

calefaction/auth.py

@@ -238,3 +238,11 @@ class AuthManager:
         g.db.attach_session(sid, char_id)
         g.db.touch_session(sid)
         return True
+
+    def handle_logout(self):
+        """Log out the user if they are logged in.
+
+        Invalidates their session and clears the session cookie.
+        """
+        self._invalidate_session()
+        session.clear()

calefaction/messages.py

@@ -0,0 +1,17 @@
+# -*- coding: utf-8  -*-
+
+__all__ = ["Messages"]
+
+class Messages:
+    """Namespace for user interface message strings."""
+    # success
+    LOGGED_IN = "Logged in."
+    LOGGED_OUT = "Logged out."
+
+    # error
+    LOG_IN_FIRST = "You need to log in to access that page."
+    ACCESS_DENIED = "Your character is not permitted to access this site."
+    SESSION_EXPIRED = "Session expired. You need to log in again."
+    LOGIN_FAILED = "Login failed."
+    EVE_API_ERROR = ("There was an error communicating with EVE's servers. "
+                     "Please wait a while and try again.")

calefaction/util.py

@@ -5,12 +5,33 @@ from hashlib import md5
 from os import path
 from traceback import format_exc
 
-from flask import url_for
+from flask import flash, url_for
 from flask_mako import render_template, TemplateError
 
-__all__ = ["catch_errors", "set_up_asset_versioning"]
+from .exceptions import AccessDeniedError, EVEAPIError
+from .messages import Messages
 
-def catch_errors(app):
+__all__ = [
+    "try_func", "make_error_catcher", "make_route_restricter",
+    "set_up_asset_versioning"]
+
+def try_func(inner):
+    """Evaluate inner(), catching subclasses of CalefactionError.
+
+    If nothing was caught, return (inner(), False). Otherwise, flash an
+    appropriate error message and return (False, True).
+    """
+    try:
+        result = inner()
+        return (result, False)
+    except EVEAPIError:
+        flash(Messages.EVE_API_ERROR, "error")
+        return (False, True)
+    except AccessDeniedError:
+        flash(Messages.ACCESS_DENIED, "error")
+        return (False, True)
+
+def make_error_catcher(app, error_template):
     """Wrap a route to display and log any uncaught exceptions."""
     def callback(func):
         @wraps(func)
@@ -19,10 +40,24 @@ def catch_errors(app):
                 return func(*args, **kwargs)
             except TemplateError as exc:
                 app.logger.error("Caught exception:\n{0}".format(exc.text))
-                return render_template("error.mako", traceback=exc.text)
+                return render_template(error_template, traceback=exc.text)
             except Exception:
                 app.logger.exception("Caught exception:")
-                return render_template("error.mako", traceback=format_exc())
+                return render_template(error_template, traceback=format_exc())
+        return inner
+    return callback
+
+def make_route_restricter(auth, on_failure):
+    """Wrap a route to ensure the user is authenticated."""
+    def callback(func):
+        @wraps(func)
+        def inner(*args, **kwargs):
+            success, caught = try_func(auth.is_authenticated)
+            if success:
+                return func(*args, **kwargs)
+            if not caught:
+                flash(Messages.LOG_IN_FIRST, "error")
+            return on_failure()
         return inner
     return callback
 
@@ -40,8 +75,8 @@ def set_up_asset_versioning(app):
             if cache and cache[0] == mtime:
                 hashstr = cache[1]
             else:
-                with open(fpath, "rb") as f:
-                    hashstr = md5(f.read()).hexdigest()
+                with open(fpath, "rb") as fp:
+                    hashstr = md5(fp.read()).hexdigest()
                 app._hash_cache[fpath] = (mtime, hashstr)
             return url_for("static", filename=filename, v=hashstr)
         raise error

static/main.css

@@ -149,3 +149,23 @@ footer ul li:not(:last-child):after {
 #error pre {
     white-space: pre-wrap;
 }
+
+#flashes {
+    margin-top: 0.5em;
+}
+
+#flashes > div {
+    padding: 0.5em 0.75em;
+    border-left-width: 4px;
+    border-left-style: solid;
+}
+
+#flashes > .success {
+    border-color: #33AA22;
+    background-color: rgba(60, 255, 30, 0.2);
+}
+
+#flashes > .error {
+    border-color: #AA3322;
+    background-color: rgba(255, 60, 30, 0.2);
+}

templates/_base.mako

@@ -38,6 +38,16 @@
             <div id="container">
                 <div>
                     <main>
+                        <%block name="flashes">
+                            <% messages = get_flashed_messages(with_categories=True) %>
+                            % if messages:
+                                <div id="flashes">
+                                    % for category, message in messages:
+                                        <div class="${category | h}">${message | h}</div>
+                                    % endfor
+                                </div>
+                            % endif
+                        </%block>
                         ${next.body()}
                     </main>
                 </div>

templates/_default.mako

@@ -6,6 +6,6 @@
     </nav>
 </%block>
 <%block name="righthead">
-    PLAYER_NAME... [logout]
+    PLAYER_NAME... [logout]  <!-- use GET /logout here and JS switch it to a POST form -->
 </%block>
 ${next.body()}

templates/logout.mako

@@ -0,0 +1,9 @@
+<%inherit file="_base.mako"/>
+<%block name="title">
+    Log out &ndash; ${g.config.get("corp.name") | h}
+</%block>
+<h1>Log out</h1>  <!-- ... style -->
+<p>Use the button below to safely log out and clear your session.</p>
+<form method="post">
+    <input type="submit" value="Log out">
+</form>