From 1e21ccecea0b81f13cea220b69e387542a861551 Mon Sep 17 00:00:00 2001
From: Guilhem Moulin <guilhem@fripost.org>
Date: Mon, 10 Jun 2024 19:07:19 +0200
Subject: =?UTF-8?q?Add=20TZFlag=20support=20(for=20GDAl=20=E2=89=A53.8).?=
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(Commented out in config.yml for now since Bookworm has only v3.6.)
---
 config.yml    | 10 ++++++---
 webmap-import | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++---------
 2 files changed, 63 insertions(+), 12 deletions(-)

diff --git a/config.yml b/config.yml
index a28ec0b..89a32c7 100644
--- a/config.yml
+++ b/config.yml
@@ -135,7 +135,11 @@ layers:
 #          #  * UUID (UUID string representation, only valid for String).
 #          SubType: UUID
 #
-#          # Default timezone (optional), for Time and DateTime types
+#          # Feature field timezone (optional), for Time, Date and DateTime types.  One of:
+#          #  * None (unknown timezone);
+#          #  * Local (local time);
+#          #  * UTC (alias GMT); or
+#          #  * [+-]HH:MM or UTC[+-]HH:MM
 #          #TZFlag: local
 #
 #          # Formatting precision for this field in characters (optional, this should
@@ -237,7 +241,7 @@ layers:
           #width: 36
         - name: skapad
           type: DateTime
-          #TZFlag: TODO
+          #tz: local
         - name: lanskod
           type: Integer
           subtype: Int16
@@ -270,7 +274,7 @@ layers:
           #width: 36
         - name: skapad
           type: DateTime
-          #TZFlag: TODO
+          #tz: local
         - name: kommunkod
           type: Integer
           subtype: Int16
diff --git a/webmap-import b/webmap-import
index 5515dd0..2939ca1 100755
--- a/webmap-import
+++ b/webmap-import
@@ -22,6 +22,7 @@ import os
 import logging
 import argparse
 import tempfile
+import re
 from fnmatch import fnmatchcase
 from pathlib import Path
 
@@ -282,6 +283,52 @@ def parseSubFieldType(name):
     else:
         raise Exception(f'Unknown field subtype "{name}"')
 
+# Parse timezone (XXX for GDAL ≥3.8 only)
+TZ_RE = re.compile(r'(?:UTC\b)?([\+\-]?)([0-9][0-9]):?([0-9][0-9])', flags=re.IGNORECASE)
+def parseTimeZone(tz):
+    if tz is None:
+        raise Exception('parseTimeZone(None)')
+    tz2 = tz.lower()
+    if tz2 == 'none':
+        return ogr.TZFLAG_UNKNOWN
+    elif tz2 == 'local':
+        return ogr.TZFLAG_LOCALTIME
+    elif tz2 == 'utc' or tz2 == 'gmt':
+        return ogr.TZFLAG_UTC
+
+    m = TZ_RE.fullmatch(tz)
+    if m is None:
+        raise Exception(f'Invalid timezone "{tz}"')
+    tzSign = m.group(1)
+    tzHour = int(m.group(2))
+    tzMinute = int(m.group(3))
+    if tzHour > 14 or tzMinute >= 60 or tzMinute % 15 != 0:
+        raise Exception(f'Invalid timezone "{tz}"')
+    tzFlag = tzHour*4 + int(tzMinute/15)
+    if tzSign == '-':
+        tzFlag = 100 - tzFlag
+    else:
+        tzFlag += 100
+    return tzFlag
+
+# Pretty-print timezone flag, cf.
+# ogr/ogrutils.cpp:OGRGetISO8601DateTime()
+def formatTZFlag(tzFlag):
+    if tzFlag is None:
+        raise Exception('printTimeZone(None)')
+    if tzFlag == ogr.TZFLAG_UNKNOWN:
+        return 'none'
+    elif tzFlag == ogr.TZFLAG_LOCALTIME:
+        return 'local'
+    elif tzFlag == ogr.TZFLAG_UTC:
+        return 'UTC'
+
+    tzOffset = abs(tzFlag - 100) * 15;
+    tzHour = int(tzOffset / 60);
+    tzMinute = int(tzOffset % 60);
+    tzSign = '+' if tzFlag > 100 else '-'
+    return f'{tzSign}{tzHour:02}{tzMinute:02}'
+
 # Validate layer creation options and schema.  The schema is modified in
 # place with the parsed result.
 # (We need the driver of the output dataset to determine capability on
@@ -339,9 +386,8 @@ def validateSchema(layers, drvo=None, lco_defaults=None):
                         fld_def2['Type'] = parseFieldType(v)
                     elif k2 == 'subtype':
                         fld_def2['SubType'] = parseSubFieldType(v)
-                    elif k2 == 'tzflag':
-                        pass # TODO
-                        #fld_def2['TZFlag'] = v
+                    elif k2 == 'tz':
+                        fld_def2['TZFlag'] = parseTimeZone(v)
                     elif k2 == 'width' and v is not None and isinstance(v, int):
                         fld_def2['Width'] = v
                     elif k2 == 'precision' and v is not None and isinstance(v, int):
@@ -471,10 +517,10 @@ def validateOutputLayer(lyr, srs=None, options=None):
 
             if 'TZFlag' in fld:
                 v1 = defn.GetTZFlag()
-                v2, n2 = fld['TZFlag']
+                v2 = fld['TZFlag']
                 if v1 != v2:
-                    logging.warning('Field "%s" has TZFlag=%d, expected %d (%s)',
-                        fldName, v1, v2, n2)
+                    logging.warning('Field "%s" has TZFlag=%d (%s), expected %d (%s)',
+                        fldName, v1, formatTZFlag(v1), v2, formatTZFlag(v2))
                     ok = False
 
             if 'Precision' in fld:
@@ -589,8 +635,9 @@ def createOutputLayer(ds, layername, srs=None, options=None):
             defn.SetSubType(v)
 
         if 'TZFlag' in fld:
-            v, n = fld['TZFlag']
-            logging.debug('Set TZFlag=%d (%s) on output field "%s"', v, n, fldName)
+            v = fld['TZFlag']
+            logging.debug('Set TZFlag=%d (%s) on output field "%s"',
+                v, formatTZFlag(v), fldName)
             defn.SetTZFlag(v)
 
         if 'Precision' in fld:
@@ -674,7 +721,7 @@ def clearLayer(ds, lyr):
             return
     layername_esc = escapeIdentifier(lyr.GetName())
 
-    # GDAL <3.9 doesn't have lyr.GetDataset() so we pass the DS along with the layer
+    # XXX GDAL <3.9 doesn't have lyr.GetDataset() so we pass the DS along with the layer
     drv = ds.GetDriver()
     if drv.ShortName == 'PostgreSQL':
         # https://www.postgresql.org/docs/15/sql-truncate.html
-- 
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