#!/usr/bin/python3
###############################################################################
# $Id: assemblepoly.py d7e898f6034a9c6c0f83cfbff921434dfc2082be 2018-04-18 23:07:52 +1000 Ben Elliston $
#
# 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.
###############################################################################

from osgeo import ogr

# -
# 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 tile_ref not in lines_hash:
        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 = link_list.find(':')
        items = link_list[colon + 1:-1].split(',')
        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()