From baf0898dfda49d2222ba5a29d8918a0ff5bb37bb Mon Sep 17 00:00:00 2001
From: Guilhem Moulin <guilhem@fripost.org>
Date: Tue, 11 Jun 2024 04:19:47 +0200
Subject: webmap-import: Add geometry conversion support.

---
 webmap-import | 33 +++++++++++++++++++++++++--------
 1 file changed, 25 insertions(+), 8 deletions(-)

diff --git a/webmap-import b/webmap-import
index 3242b3a..adfc0cf 100755
--- a/webmap-import
+++ b/webmap-import
@@ -960,13 +960,15 @@ def importSource2(lyr_dst, path, args={}, basedir=None, extent=None):
 
     defn_dst = lyr_dst.GetLayerDefn()
     eGType_dst = defn_dst.GetGeomType()
+    eGType_dst_HasZ = ogr.GT_HasZ(eGType_dst)
+    eGType_dst_HasM = ogr.GT_HasM(eGType_dst)
+    dGeomIsUnknown = ogr.GT_Flatten(eGType_dst) == ogr.wkbUnknown
 
     n = 0
-    #mismatch = 0
+    mismatch = {}
     feature = lyr.GetNextFeature()
     while feature is not None:
         feature2 = ogr.Feature(defn_dst)
-        # TODO MakeValid, force geometry, dimension
         feature2.SetFromWithMap(feature, False, fieldMap)
 
         geom = feature2.GetGeometryRef()
@@ -974,22 +976,37 @@ def importSource2(lyr_dst, path, args={}, basedir=None, extent=None):
             raise Exception('Could not apply coordinate transformation')
 
         eGType = geom.GetGeometryType()
-        if eGType != eGType_dst:
-            if eGType == ogr.wkbPolygon and eGType_dst == ogr.wkbMultiPolygon:
-                geom = ogr.ForceToMultiPolygon(geom)
+        if eGType != eGType_dst and not dGeomIsUnknown:
+            # Promote to multi, cf. apps/ogr2ogr_lib.cpp:ConvertType()
+            eGType2 = eGType
+            if eGType == ogr.wkbTriangle or eGType == ogr.wkbTIN or eGType == ogr.wkbPolyhedralSurface:
+                eGType2 = ogr.wkbMultiPolygon
+            elif not ogr.GT_IsSubClassOf(eGType, ogr.wkbGeometryCollection):
+                eGType2 = ogr.GT_GetCollection(eGType)
+
+            eGType2 = ogr.GT_SetModifier(eGType2, eGType_dst_HasZ, eGType_dst_HasM)
+            if eGType2 == eGType_dst:
+                mismatch[eGType] = mismatch.get(eGType, 0) + 1
+                geom = ogr.ForceTo(geom, eGType_dst)
+                # TODO call MakeValid()?
             else:
-                raise Exception('Not implemented')
+                raise Exception(f'Conversion from {ogr.GeometryTypeToName(eGType)} '
+                    f'to {ogr.GeometryTypeToName(eGType_dst)} not implemented')
             feature2.SetGeometryDirectly(geom)
-            #mismatch += 1
 
         lyr_dst.CreateFeature(feature2)
         n += 1
         feature = lyr.GetNextFeature()
 
-    #print(mismatch)
     lyr = None
     logging.info('Imported %d features from source layer "%s"', n, layername)
 
+    if len(mismatch) > 0:
+        mismatches = [ ogr.GeometryTypeToName(t) + ' (×' + str(n) + ')'
+            for t,n in sorted(mismatch.items(), key=lambda x: x[1]) ]
+        logging.info('Forced conversion to %s: %s',
+            ogr.GeometryTypeToName(eGType_dst), ', '.join(mismatches))
+
 
 if __name__ == '__main__':
     logging.basicConfig(format='%(levelname)s: %(message)s', level=logging.INFO)
-- 
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