From 60a1585a37bfee43e3d6c7cac002eeee85768c5f Mon Sep 17 00:00:00 2001
From: Daniel Schadt <kingdread@gmx.de>
Date: Thu, 30 Mar 2023 21:19:46 +0200
Subject: check if data version matches at startup

This might be helpful to see some errors early.
---
 fietsboek/__init__.py         | 30 +++++++++++++++++++++++++++-
 fietsboek/updater/__init__.py | 46 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/fietsboek/__init__.py b/fietsboek/__init__.py
index 41e8a04..ee7d8b7 100644
--- a/fietsboek/__init__.py
+++ b/fietsboek/__init__.py
@@ -14,6 +14,7 @@ Content
 -------
 """
 import importlib.metadata
+import logging
 from pathlib import Path
 from typing import Callable, Optional
 
@@ -33,9 +34,12 @@ from . import transformers
 from .data import DataManager
 from .pages import Pages
 from .security import SecurityPolicy
+from .updater import Updater, UpdateState
 
 __VERSION__ = importlib.metadata.version("fietsboek")
 
+LOGGER = logging.getLogger(__name__)
+
 
 def locale_negotiator(request: Request) -> Optional[str]:
     """Negotiates the right locale to use.
@@ -88,12 +92,36 @@ def maintenance_mode(
     return tween
 
 
-def main(_global_config, **settings):
+def check_update_state(config_uri: str):
+    """Checks the update state of the data, and logs a warning if there is a
+    mismatch.
+
+    :param config_uri: Path to the configuration file.
+    """
+    updater = Updater(config_uri)
+    updater.load()
+    state = updater.state()
+
+    if state == UpdateState.OUTDATED:
+        LOGGER.warning(
+            "The data seems to be outdated - make sure to run the fietsupdate migrations!"
+        )
+    elif state == UpdateState.TOO_NEW:
+        LOGGER.warning("The data seems to be too new, make sure to update the code accordingly!")
+    elif state == UpdateState.UNKNOWN:
+        LOGGER.warning("Could not determine version state of the data - check `fietsupdate status`")
+
+
+def main(global_config, **settings):
     """This function returns a Pyramid WSGI application."""
     # Avoid a circular import by not importing at the top level
     # pylint: disable=import-outside-toplevel,cyclic-import
     from .views.tileproxy import TileRequester
 
+    # In tests this isn't passed, so guard against it
+    if "__file__" in global_config:
+        check_update_state(global_config["__file__"])
+
     parsed_config = mod_config.parse(settings)
     settings["jinja2.newstyle"] = True
 
diff --git a/fietsboek/updater/__init__.py b/fietsboek/updater/__init__.py
index fa7f5c6..5faa805 100644
--- a/fietsboek/updater/__init__.py
+++ b/fietsboek/updater/__init__.py
@@ -1,5 +1,6 @@
 """Updating (data migration) logic for fietsboek."""
 import datetime
+import enum
 import importlib.resources
 import importlib.util
 import logging
@@ -50,6 +51,26 @@ class Down(UpdateScript):
 """
 
 
+class UpdateState(enum.Enum):
+    """State of the applied updates.
+
+    This represents a "summary" of the output that ``fietsupdate status``
+    produces.
+    """
+
+    OKAY = enum.auto()
+    """Everything is good, the data is up to date."""
+
+    OUTDATED = enum.auto()
+    """The data is outdated, the update process should be run."""
+
+    TOO_NEW = enum.auto()
+    """The data contains revisions that are not known to Fietsboek yet."""
+
+    UNKNOWN = enum.auto()
+    """The data version could not be determined."""
+
+
 class Updater:
     """A class that implements the updating logic.
 
@@ -284,6 +305,31 @@ class Updater:
             return revision_id in self._transitive_versions()
         return revision_id in self._reverse_versions() | set(self.current_versions())
 
+    def state(self) -> UpdateState:
+        """Checks the update state of the instance.
+
+        This returns a condensed version of what ``fietsupdate status``
+        outputs.
+
+        :return: The update state of the data.
+        """
+        state = UpdateState.OKAY
+        current = self.current_versions()
+        heads = self.heads()
+        if current:
+            for i in current:
+                if not self.exists(i):
+                    state = UpdateState.TOO_NEW
+        else:
+            return UpdateState.UNKNOWN
+        updates = set(heads) - set(current)
+        if updates:
+            if state != UpdateState.OKAY:
+                # We are both too new and too old, so something is pretty wrong
+                return UpdateState.UNKNOWN
+            return UpdateState.OUTDATED
+        return state
+
 
 class UpdateScript:
     """Represents an update script."""
-- 
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