basic stuff for loading map data

src/c3nav/mapdata/__init__.py

@@ -1,5 +1,5 @@
-from .classes import MapDataManager
+from .classes import MapManager
 
 default_app_config = 'c3nav.mapdata.apps.MapdataConfig'
 
-objects = MapDataManager()
+mapmanager = MapManager()

src/c3nav/mapdata/apps.py

@@ -1,4 +1,19 @@
 from django.apps import AppConfig
+from django.conf import settings
+from django.core.checks import Warning, register
+
+from . import mapmanager
+
+
+@register()
+def has_map_data_check(app_configs, **kwargs):
+    if not settings.MAP_DIRS:
+        return [Warning(
+            'There are no map data directories configured.',
+            hint='Add mapdirs=/path/to/directory to your c3nav.cfg.',
+            id='mapdata.W001',
+        )]
+    return []
 
 
 class MapdataConfig(AppConfig):
@@ -6,4 +21,5 @@ class MapdataConfig(AppConfig):
     verbose_name = 'map data manager'
 
     def ready(self):
-        pass
+        for map_dir in settings.MAP_DIRS:
+            mapmanager.add_map_dir(map_dir)

src/c3nav/mapdata/classes.py

@@ -1,8 +1,49 @@
-class MapDataManager:
-    def __init__(self):
-        pass
+import json
+import os
+from collections import OrderedDict
 
 
-class MapDataSource:
+class MapInitError(Exception):
+    pass
+
+
+class MapManager:
     def __init__(self):
-        pass
+        self.main_pkg = None
+        self.pkgs = OrderedDict()
+
+    def add_map_dir(self, path):
+        pkg = MapDataPackage(path)
+        if pkg.name in self.pkgs:
+            raise MapInitError('Duplicate map package: '+pkg.name)
+
+        if pkg.extends is None:
+            if self.main_pkg is not None:
+                raise MapInitError('There can not be more than one root map package: tried to add '+pkg.name+', '
+                                   'but '+self.main_pkg.name+' was there first.')
+            self.main_pkg = pkg
+        else:
+            if pkg.extends not in self.pkgs:
+                raise MapInitError('map package'+pkg.name+' extends '+pkg.exends+', which was not imported '
+                                   'beforehand.')
+
+        self.pkgs[pkg.name] = pkg
+
+
+class MapDataPackage:
+    def __init__(self, path):
+        self.path = path
+
+        main_file = os.path.join(path, 'map.json')
+        try:
+            data = json.load(open(main_file))
+        except FileNotFoundError:
+            raise MapInitError(main_file+' not found')
+        except json.decoder.JSONDecodeError as e:
+            raise MapInitError('Could not decode '+main_file+': '+str(e))
+
+        self.name = data.get('name')
+        if self.name is None:
+            raise MapInitError('Map package '+path+' has no name in map.json.')
+
+        self.extends = data.get('extends')

src/c3nav/settings.py

@@ -17,7 +17,7 @@ BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 DATA_DIR = config.get('c3nav', 'datadir', fallback=os.environ.get('DATA_DIR', 'data'))
 LOG_DIR = os.path.join(DATA_DIR, 'logs')
 
-MAP_DIRS = config.get('c3nav', 'mapdir', fallback=None)
+MAP_DIRS = tuple(n for n in config.get('c3nav', 'mapdirs', fallback='').split(',') if n)
 
 if not os.path.exists(DATA_DIR):
     os.mkdir(DATA_DIR)