#!/usr/bin/env python
###############################################################################
# $Id: assemblepoly.py,v 1.1 2003/02/15 19:39:12 warmerda Exp $
#
# Project:  OGR Python samples
# Purpose:  Assemble polygon geometries from arcs fulled from an arc layer.
#           Script is incomplete but shows use of many OGR features from
#           Python.
# Author:   Frank Warmerdam, warmerdam@pobox.com
#
###############################################################################
# Copyright (c) 2003, Frank Warmerdam <warmerdam@pobox.com>
# 
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the "Software"),
# to deal in the Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.
###############################################################################
# 
#  $Log: assemblepoly.py,v $
#  Revision 1.1  2003/02/15 19:39:12  warmerda
#  New
#
#

import osr
import ogr
import string

#############################################################################-
# Open the datasource to operate on.

#ds = ogr.Open( '/u/data/ntf/bl2000/HALTON.NTF' )
ds = ogr.Open( 'PG:dbname=test', update = 1 )

layer_count = ds.GetLayerCount()

#############################################################################-
# Establish access to the line and polygon layers.  Eventually we shouldn't
# hardcode this.

line_layer = ds.GetLayer(0)
poly_layer = ds.GetLayer(1)

#############################################################################
# Read all features in the line layer, holding just the geometry in a hash
# for fast lookup by GEOM_ID.

lines_hash = {}

feat = line_layer.GetNextFeature()
geom_id_field = feat.GetFieldIndex( 'GEOM_ID' )
tile_ref_field = feat.GetFieldIndex( 'TILE_REF' )
while feat is not None:
    geom_id = feat.GetField( geom_id_field )
    tile_ref = feat.GetField( tile_ref_field )

    if not lines_hash.has_key( tile_ref ):
        lines_hash[tile_ref] = {}

    sub_hash = lines_hash[tile_ref]
    sub_hash[geom_id] = feat.GetGeometryRef().Clone()

    feat.Destroy()

    feat = line_layer.GetNextFeature()

print 'Got %d lines.' % len(lines_hash)


#############################################################################
# Read all polygon features. 

feat = poly_layer.GetNextFeature()
link_field = feat.GetFieldIndex( 'GEOM_ID_OF_LINK' )
tile_ref_field = feat.GetFieldIndex( 'TILE_REF' )

while feat is not None:
    tile_ref = feat.GetField( tile_ref_field )
    link_list = feat.GetField( link_field )

    # If the list is in string form we need to convert it.
    if type(link_list).__name__ == 'str':
        colon = string.find(link_list,':')
        items = string.split( link_list[colon+1:-1], ',' )
        link_list = []
        for item in items:
            try:
                link_list.append(int(item))
            except:
                print 'item failed to translate: ', item

    link_coll = ogr.Geometry( type = ogr.wkbGeometryCollection )
    for geom_id in link_list:
        geom = lines_hash[tile_ref][geom_id]
        link_coll.AddGeometry( geom )

    try:
        poly = ogr.BuildPolygonFromEdges( link_coll )
        print poly.ExportToWkt()
        feat.SetGeometryDirectly( poly )
    except:
        print 'BuildPolygonFromEdges failed.' 

# For now we don't actually write back the assembled polygons.
#    poly_layer.SetFeature( feat )
    feat.Destroy()

    feat = poly_layer.GetNextFeature()