[Maposmatic-dev] [PATCH] Make the computation of the city contours more robust

[David Decotigny]

This should fix most of the #27413 issues. The original code was not
robust enough to support strange city contours. This patch makes it
more tolerant with "unusual" envelopes (those we did not foresee in
the first place) and more verbose in case of problems.
---
 ocitysmap/street_index.py |   41 +++++++++++++++++++++++++++++++++++------
 1 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/ocitysmap/street_index.py b/ocitysmap/street_index.py
index f24fcd3..ef1bc83 100644
--- a/ocitysmap/street_index.py
+++ b/ocitysmap/street_index.py
@@ -334,7 +334,8 @@ class OCitySMap:
         
         return BoundingBox.parse_wkt(records[0][0])
 
-    _regexp_contour = re.compile('^POLYGON\(\((\S*) (\S*),\S* (\S*),(\S*) 
\S*,\S* \S*,\S* \S*\),\(([^)]*)\)\)$')
+    _regexp_contour = re.compile('^POLYGON\(\(([^)]*)\),\(([^)]*)\)\)$')
+    _regexp_coords  = re.compile('^(\S*)\s+(\S*)$')
 
     def get_city_contour(self, db, city):
 
@@ -350,21 +351,49 @@ class OCitySMap:
                                  and admin_level='8' and name='%s';""" % \
                            pgdb.escape_string(city.encode('utf-8')))
         sl = cursor.fetchall()
-        cell00 = sl[0][0].strip()
-        if not cell00: return None
+        try:
+            cell00 = sl[0][0].strip()
+        except (KeyError,AttributeError):
+            l.error("Invalid DB contour structure")
+            return None
+
+        # Got nothing usable
+        if not cell00:
+            return None
 
         # Parse the answer, in order to add a margin around the area
         prev_locale = locale.getlocale(locale.LC_ALL)
         locale.setlocale(locale.LC_ALL, "C")
         try:
             matches = self._regexp_contour.match(cell00)
-            ymin, xmin, xmax, ymax, inside = matches.groups()
-            xmin, ymin, ymax, xmax = map(float, (xmin, ymin, ymax, xmax))
-            xmin -= 1. ; xmax += 1. # Add one degree around the area
+            if not matches:
+                l.error("Area not conformant")
+                return None
+            scoords, inside = matches.groups()
+
+            # Determine bbox envelope
+            xmin, ymin, ymax, xmax = (None,)*4
+            lcoords = scoords.split(',')
+            if len(lcoords) != 5:
+                l.warning("Coords look atypical: %s", lcoords)
+            for scoord in lcoords:
+                matches = self._regexp_coords.match(scoord)
+                y,x = map(float,matches.groups())
+                if (xmax is None) or xmax < x: xmax = x
+                if (xmin is None) or xmin > x: xmin = x
+                if (ymax is None) or ymax < y: ymax = y
+                if (ymin is None) or ymin > y: ymin = y
+
+            # Add one degree around the area
+            xmin -= 1. ; xmax += 1.
             ymin -= 1. ; ymax += 1.
             return "POLYGON((%f %f, %f %f, %f %f, %f %f, %f %f),(%s))" \
                 % (ymin, xmin, ymin, xmax, ymax, xmax, ymax, xmin, ymin, xmin,
                    inside)
+        except:
+            # Regexp error: area is not a "simple" polygon
+            l.exception("Unexpected exception")
+            return None
         finally:
             locale.setlocale(locale.LC_ALL, prev_locale)
 
-- 
1.6.0.4