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|
#----------------------------------------------------------------------
# Backend utilities for the Klimatanalys Norr project (download MRR layers)
# Copyright © 2024 Guilhem Moulin <info@guilhem.se>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
#----------------------------------------------------------------------
# Unfortunately SGU/Bergsstaten doesn't offer MRR layer files to
# download, cf.
#
# https://www.sgu.se/produkter-och-tjanster/geologiska-data/vara-data-per-amnesomrade/berggrundsgeologiska-data/mineralrattigheter/
#
# but it has an online webmap (WMS) at
#
# https://apps.sgu.se/kartvisare/kartvisare-mineralrattigheter.html
#
# so we add a dedicated module to probe and fetch features from it.
from os import O_RDONLY, O_WRONLY, O_RDWR, O_CREAT, O_CLOEXEC, O_TMPFILE
import os
from pathlib import Path
from time import time, sleep, monotonic as time_monotonic
import re
import logging
import requests
import itertools
import random
import json
from math import sqrt
from hashlib import sha256
from lxml import etree
from osgeo import gdal, ogr
gdal.UseExceptions()
import common
LAST_UPDATED = 'Last updated'
class WMS:
def __init__(self, headers={}, session=requests, url=None, version='1.1.1'):
self.req_count = 0
self.headers = headers
self.session = session
self.url = url
self.version = version
def __del__(self):
self.print_req_count()
def print_req_count(self, elapsed=None):
if self.req_count is None or self.url is None:
return
elif elapsed is None:
logging.info('%d WMS requests sent to %s', self.req_count, self.url)
else:
logging.info('%d WMS requests (%.2f\u202Freq/s) sent to %s', self.req_count,
self.req_count/elapsed, self.url)
# Send a request to the WMS server
def req(self, request, content_type=None, params={}, max_tries=10, timeout=10):
params2 = {
'SERVICE': 'WMS',
'VERSION': self.version,
'REQUEST': request,
} | params
for i in itertools.count(1):
try:
r = self.session.get(self.url,
headers = self.headers,
params = params2,
timeout = timeout,
)
except (requests.Timeout, requests.ConnectionError) as e:
if i < max_tries:
logging.error('Timeout')
continue
raise e
self.req_count += 1
if i < max_tries and r.status_code in [requests.codes.bad_gateway, requests.codes.gateway_timeout]:
logging.error(r.status_code)
sleep(30)
continue
r.raise_for_status()
if content_type is not None:
content_type2 = r.headers.get('Content-Type')
content_type2 = content_type2.split(';')[0] if content_type2 is not None else None
if content_type2 is None or content_type2 != content_type:
raise Exception(f'Content-Type mismatch: expected {content_type}, got {content_type2}')
return r
# Return metadata for the given feature
def getFeatureInfo(self, x, y, layer, res=.25):
content_type = 'application/json'
width = height = 101 # value from https://apps.sgu.se/kartvisare/kartvisare-mineralrattigheter.html
half_width = res * width/2
half_height = res * height/2
x1 = x - half_width
x2 = x + half_width
y1 = y - half_height
y2 = y + half_height
bbox = [x1, y1, x2, y2]
max_count = 300
r = self.req('GetFeatureInfo', content_type=content_type, params={
'LAYERS': layer,
'FORMAT': 'image/png',
'TRANSPARENT': 'true',
'TILED': 'false',
'WIDTH': width,
'HEIGHT': height,
'QUERY_LAYERS': layer,
'INFO_FORMAT': content_type,
'FEATURE_COUNT': max_count,
'X': 50,
'Y': 50,
'BBOX': ','.join(map(str, bbox)),
'SRS': common.config['SRS'],
})
data = r.json()
if data.get('type', '') != 'FeatureCollection':
raise Exception(f'Did not return a feature collection')
if data.get('features', None) is None:
raise Exception(f'Missing features list')
if len(data.get('features')) >= max_count:
logging.warning('Returned max number of features (%d), possibly missing some!', max_count)
return data
# Refine a geometry at the given resolution.
# Return the iteration count at which the feature was found (or None if it was not found) along
# with a dictionary `fingerprint:feature` found along the way.
def refineGeometry(self, layername, fpr, feature, res=1, crs=None, max_tries=1024, features={}):
geojson = json.dumps(feature.get('geometry'))
geom = ogr.CreateGeometryFromJson(geojson)
if geom is None:
raise Exception(f'Invalid GeoJSON geometry')
triangulation = triangulate(geom.MakeValid())
i = 0
while fpr not in features and i < max_tries:
x, y = getRandomPoint(triangulation)
data = self.getFeatureInfo(x, y, layername, res=res)
crs2 = data.get('crs', None)
features2 = data['features']
if ((crs is None and crs2 is not None) or (crs is not None and crs2 is None)
or (crs is not None and crs2 is not None and crs != crs2)):
if len(features2) > 0:
# the server should never return different CRSs
raise Exception(f'{json.dumps(crs)} != {json.dumps(crs2)}')
for feature2 in features2:
fpr2, feature2 = mkFeature(feature2, layername)
features[fpr2] = feature2
i += 1
if fpr not in features:
return None, features
return i, features
# Refine geometries at the given resolution, modifying features in place
def refineGeometries(self, features, layername, res=1, crs=None, max_tries=1024, progress=None):
feature_count = len(features)
features2 = {}
pbar = None
stats = {}
try:
if progress is not None:
pbar = progress(total=feature_count, leave=False, unit='')
for fpr, feature in features.items():
i, _ = self.refineGeometry(layername, fpr, feature,
res=res, crs=crs, max_tries=max_tries, features=features2)
if i is None:
i = '-'
stats[i] = stats.get(i, 0) + 1
if pbar is not None:
pbar.update(1)
finally:
if pbar is not None:
pbar.close()
features.update(features2)
# show refinement stats
if stats.get(0, 0) + stats.get(1, 0) == feature_count:
details = 'all on first attempt'
else:
details = []
for ks, vs in sorted(stats.items(), key=lambda item: max_count+1 if item[0] == '-' else item[0]):
if ks == '-':
msg = f'{vs}× FAILED'
elif len(details) > 0:
msg = f'{vs}× {ks}'
elif ks == 1:
msg = f'{vs}× after 1 attempt'
else:
msg = f'{vs}× after {ks} attempts'
details.append(msg)
details = ', '.join(details)
w = 'geometry' if feature_count == 1 else 'geometries'
logging.info('Refined %d %s at resolution %s (%s)', feature_count, w, str(res), details)
# Guess whether the cached layer at path is up to date
def is_uptodate(self, layername, path, dir_fd=None,
oldsvg_fp=None, newsvg='',
max_age=864000):
try:
fd = os.open(path, O_RDONLY, dir_fd=dir_fd)
except (OSError, ValueError):
# couldn't open cached file
logging.debug('%s is stale: open() failed', path)
return False
try:
try:
st = os.fstat(fd)
svg_st = os.fstat(oldsvg_fp.fileno())
except (OSError, ValueError):
logging.debug('%s is stale: fstat() failed', path)
return False
if st.st_mtime < svg_st.st_mtime:
# writing SVG is racy so always assume that a younger SVG
# means a stale GeoJSON
logging.debug('%s is stale: SVG is younger (%f < %f)', path,
st.st_mtime, svg_st.st_mtime)
return False
try:
oldsvg = oldsvg_fp.read()
finally:
# seek back to the begining (we then truncate and write the SVG)
oldsvg_fp.seek(0)
if newsvg is None or oldsvg != newsvg:
logging.debug('%s is stale: SVG differs', path)
return False
if max_age is not None:
current_time = time()
mtime = max(st.st_ctime, st.st_mtime)
if max_age + mtime < current_time:
# always consider files older than max_age as stale
logging.debug('%s is stale: too old (%f + %f < %f)', path,
max_age, mtime, current_time)
return False
with os.fdopen(fd, mode='rb', closefd=False) as fp:
try:
# load cached geojson
data = json.load(fp)
except json.JSONDecodeError:
logging.warning('%s is stale: not a valid JSON file', path)
return False
finally:
os.close(fd)
# more checks on the GeoJSON content
if (not isinstance(data, dict) or 'type' not in data or data['type'] != 'FeatureCollection'
or 'features' not in data or not isinstance(data['features'], list)):
logging.warning('%s: not a valid GeoJSON file', path)
return False
crs = data.get('crs', None)
data = data['features']
if len(data) == 0:
# always assume empty cached files are stale
logging.debug('%s is stale: has no features', path)
return False
data = random.choice(data) # random features
if (not isinstance(data, dict) or 'type' not in data or data['type'] != 'Feature'
or 'geometry' not in data or not isinstance(data['geometry'], dict)):
logging.warning('%s: not a valid GeoJSON file', path)
return False
last_updated = data['properties'].get(LAST_UPDATED, None)
if last_updated is None or last_updated == '':
logging.debug('%s is stale: %s has no "%s" value', path,
json.dumps(data), LAST_UPDATED)
return False
# check whether the randomly chosen feature is still there and that
# its "Last updated" value has not changed
# (this check comes last as it is potentially expensive)
fpr, data = mkFeature(data, layername)
found, features = self.refineGeometry(layername, fpr, data, res=.25, crs=crs, max_tries=10)
if not found:
logging.debug('%s is stale: could not find feature %s', path, json.dumps(data))
return False
last_updated2 = features[fpr]['properties'].get(LAST_UPDATED, None)
if last_updated2 is None or last_updated != last_updated2:
logging.debug('%s is stale: "%s" values differ (%s != %s)',
path, LAST_UPDATED, last_updated, last_updated2)
return False
# assume the cached file is up to date
logging.debug('is_uptodate(%s, %s, …) == True', layername, path)
return True
def getFeatures(self, layername, path_strings, gt, progress=None):
crs = None
max_probe_count = 3
probes = []
for d in path_strings:
d0 = d
m = POINT0_RE.match(d)
if m is None:
raise Exception(f"Can't parse <path>'s \"d\" attribute value: \"{d0}\"")
d = d.removeprefix(m.group())
x = float(m.group(1))
y = float(m.group(2))
path = [ [x, y] ]
# get first part of the path (until the pen is moved)
while True:
m = POINT_RE.match(d)
if m is None:
break
d = d.removeprefix(m.group())
x = float(m.group(1))
y = float(m.group(2))
if path[-1] != [x, y]:
path.append([x, y])
if d.startswith('Z') and len(path) > 0:
if path[0] != path[-1]:
path.append(path[0])
d = d.removeprefix("Z")
logging.debug('d="%s" -> path=%s, rest="%s"', d0, path, d)
# convert to an outer ring
ring0 = ogr.Geometry(ogr.wkbLinearRing)
for px, py in path:
x, y = gdal.ApplyGeoTransform(gt, px, py)
ring0.AddPoint_2D(x, y)
poly0 = ogr.Geometry(ogr.wkbPolygon)
poly0.AddGeometry(ring0)
# randomly probe once per 10km² (1000ha), but not more than max_probe_count
probe_count = poly0.GetArea() / 1e7
if probe_count < 1:
probe_count = 1
elif probe_count > max_probe_count:
probe_count = max_probe_count
else:
probe_count = round(probe_count)
probes.append( (poly0.MakeValid(), probe_count) )
if len(probes) == 0:
self.req_count = None # don't print request count
return {}, crs
features = {}
probe_count_sum = sum([n for _, n in probes])
pbar = None
try:
if progress is not None:
pbar = progress(total=probe_count_sum, leave=False, unit='')
for geom, probe_count in probes:
triangulation = triangulate(geom)
# always try the centroid first (later fallback to a random
# point if the centroid is not in geom)
x, y = nearCentroidWithin(geom)
# crude probing and add feature(s) found along the way
for i in range(probe_count):
if i > 0 or x is None or y is None:
x, y = getRandomPoint(triangulation)
data = self.getFeatureInfo(x, y, layername, res=1024)
crs2 = data.get('crs', None)
data = data['features']
if crs2 is not None:
if crs is None:
crs = crs2
elif crs != crs2 and len(data) > 0:
# the server should never return different CRSs
raise Exception(f'{json.dumps(crs)} != {json.dumps(crs2)}')
for feature in data:
fpr, feature = mkFeature(feature, layername)
features[fpr] = feature
data = None
if pbar is not None:
pbar.update(1)
geom = None
finally:
del probes[:]
if pbar is not None:
pbar.close()
logging.info('Found %d unique feature(s) after crude probing', len(features))
return features, crs
# Triangulate the input geometry
def triangulate(geom):
geomType = geom.GetGeometryType()
if geomType == ogr.wkbPolygon or geomType == ogr.wkbMultiPolygon or geomType == ogr.wkbGeometryCollection:
if geom.Area() < 1e-9:
# degenerate polygon
return geom.Boundary()
elif geomType == ogr.wkbLineString or geomType == ogr.wkbMultiLineString:
return geom
elif geomType == ogr.wkbPoint or geomType == ogr.wkbMultiPoint:
return geom
else:
raise Exception(f'Invalid geometry type: {geom}')
triangulation = geom.DelaunayTriangulation(dfTolerance=0., bOnlyEdges=False)
triangulation2 = ogr.Geometry(ogr.wkbGeometryCollection)
for i in range(triangulation.GetGeometryCount()):
triangle = triangulation.GetGeometryRef(i)
if geom.Contains(triangle):
triangulation2.AddGeometry(triangle)
if triangulation2.IsEmpty():
# can happen in some degenerate cases
return triangulation
else:
return triangulation2
# Return the centroid (modulo rounding) if is within the input geometry,
# and None, None otherwise
def nearCentroidWithin(geom, decimals=2):
centroid = geom.Centroid()
if centroid.GetGeometryType() != ogr.wkbPoint:
raise Exception(f'{centroid} is not a point')
x, y = centroid.GetPoint_2D(0)
if decimals is not None:
x = round(x, decimals)
y = round(y, decimals)
pt = ogr.Geometry(ogr.wkbPoint)
pt.AddPoint_2D(x, y)
if pt.Within(geom):
return x, y
else:
return None, None
# Get a random point within the given geometry
# The geometry needs to be triangulated first for speed, see
# see https://dev.to/bogdanalexandru/generating-random-points-within-a-polygon-in-unity-nce
def getRandomPoint(triangulation, decimals=2, max_tries=1024):
# special cases if source is a degenerate polygon
geomType = triangulation.GetGeometryType()
if geomType == ogr.wkbMultiPoint:
if triangulation.GetGeometryCount() == 0:
raise Exception(f'Empty {triangulation}')
i = random.randrange(0, triangulation.GetGeometryCount())
pt = triangulation.GetGeometryRef(i)
return pt.GetX(), pt.GetY()
elif geomType == ogr.wkbLineString:
i = random.uniform(0, triangulation.Length())
pt = triangulation.Value(i)
return pt.GetX(), pt.GetY()
elif geomType == ogr.wkbMultiLineString:
lengths = []
for i in range(triangulation.GetGeometryCount()):
line = triangulation.GetGeometryRef(i)
lengths.append(line.Length())
k = random.choices(range(triangulation.GetGeometryCount()), weights=lengths, k=1)[0]
line = triangulation.GetGeometryRef(k)
i = random.uniform(0, line.Length())
pt = line.Value(i)
return pt.GetX(), pt.GetY()
elif geomType != ogr.wkbGeometryCollection:
raise Exception(f'Not a GeometryCollection {triangulation}')
areas = []
for i in range(triangulation.GetGeometryCount()):
triangle = triangulation.GetGeometryRef(i)
areas.append(triangle.GetArea())
for i in range(max_tries):
# pick a random triangle (weighted by area)
k = random.choices(range(triangulation.GetGeometryCount()), weights=areas, k=1)[0]
triangle = triangulation.GetGeometryRef(k)
ring = triangle.GetGeometryRef(0)
if triangle.GetGeometryType() != ogr.wkbPolygon or triangle.GetGeometryCount() != 1 or ring.GetPointCount() != 4:
raise Exception('Not a triangle')
x0, y0 = ring.GetPoint_2D(0)
x1, y1 = ring.GetPoint_2D(1)
x2, y2 = ring.GetPoint_2D(2)
# pick a random point inside that triangle
r1 = random.uniform(0, 1)
r2 = random.uniform(0, 1)
sqrt_r1 = sqrt(r1)
sqrt_r2 = sqrt(r2)
x = (1 - sqrt_r1) * x0 + sqrt_r1 * (1 - r2) * x1 + sqrt_r1 * r2 * x2
y = (1 - sqrt_r1) * y0 + sqrt_r1 * (1 - r2) * y1 + sqrt_r1 * r2 * y2
if decimals is not None:
x = round(x, decimals)
y = round(y, decimals)
pt = ogr.Geometry(ogr.wkbPoint)
pt.AddPoint_2D(x, y)
if pt.Within(triangulation):
return x, y
# might need to retry due to rounding
raise Exception(f"Couldn't find point within geometry pt={pt} triangle={triangle} k={k} triangulation={triangulation}")
# Return a feature along with its "signature"
def mkFeature(feature, layername):
properties = feature.get('properties', None)
if properties is None:
raise Exception(f'Feature lacks "properties" attributes')
fid = feature.pop('id', None)
if fid is not None and layername is not None and not fid.startswith(layername.removeprefix('MRR:')):
raise Exception(f'Unexpected ID {fid} for layer {layername}')
properties2 = properties.copy()
properties2.pop(LAST_UPDATED, None) # always ignore "Last updated" values
properties2 = json.dumps(properties2, ensure_ascii=False, sort_keys=True, separators=(',', ':'))
fpr = sha256(properties2.encode('utf-8') + b'\x00' + layername.encode('utf-8'))
return fpr.hexdigest(), {
# RFC 7946 sec. 3.2
'type': 'Feature',
'geometry': feature.get('geometry'),
'properties': properties,
}
FLOAT_RE = r'(?:[0-9]+(?:\.[0-9]*)?|\.[0-9]+)'
PATH_RE = re.compile(r'^M\s*' +
FLOAT_RE + r'\s+' + FLOAT_RE + r'\s+' +
r'(?:L\s*' + FLOAT_RE + r'\s+' + FLOAT_RE + r'\s+)+' +
r'(?:[ZM]|$)')
POINT0_RE = re.compile(r'^M\s*(' + FLOAT_RE + r')\s+(' + FLOAT_RE + r')\s+')
POINT_RE = re.compile(r'^L\s*(' + FLOAT_RE + r')\s+(' + FLOAT_RE + r')(?:\s+|$)')
def download(dest, dl, dir_fd=None, headers={}, session=requests, progress=None):
dest_path = Path(dest)
if dest_path.suffix.lower() != '.geojson':
# mostly to check that nothing ends in .svg
raise Exception(f'{dest} must end with .geojson')
dest_tmp = str(dest_path.with_stem(f'.{dest_path.stem}.new'))
try:
# delete any leftover
os.unlink(dest_tmp, dir_fd=dir_fd)
except FileNotFoundError:
pass
layername = dl['layername']
logging.info(f'Processing layer %s…', layername)
headers.pop('If-Modified-Since', None) # never send If-Modified-Since headers
start = time_monotonic()
wms = WMS(
url='https://maps3.sgu.se/geoserver/wms',
version='1.1.1',
headers=headers,
session=session,
)
# download the SVG from the WMS server and try to parse it to list
# all features; an alternative would be to download a PNG and probe
# every single non-transparent pixel, but it's very slow (and not
# kind to the WMS server) due to the sheer amount of such pixels
bbox = common.config['extent']
res = 256
image_format = 'image/svg+xml'
r = wms.req('GetMap', content_type=image_format, params={
'LAYERS': layername,
'FORMAT': image_format,
'TRANSPARENT': 'true',
'TILED': 'false',
'WIDTH': f'{(bbox[2]-bbox[0])/res:.0f}',
'HEIGHT': f'{(bbox[3]-bbox[1])/res:.0f}',
'BBOX': ','.join(map(str, bbox)),
'SRS': common.config['SRS'],
})
svg_path = str(dest_path.with_suffix('.svg'))
svg_fd = os.open(svg_path, O_RDWR|O_CREAT|O_CLOEXEC, mode=0o644, dir_fd=dir_fd)
try:
with os.fdopen(svg_fd, mode='wb+', closefd=False) as fp:
if wms.is_uptodate(layername, dest, dir_fd=dir_fd,
oldsvg_fp=fp, newsvg=r.content):
logging.info('%s appears to be up to date, skipping', dest)
wms.req_count = None # don't print request count
return
# not atomic, but not a big deal (only used for comparison and mismatch
# causes the layer to be downloaded again); it's not possible to write
# the .geojson and the .svg in the same transaction anyway
fp.truncate()
fp.write(r.content)
finally:
os.close(svg_fd)
# https://gdal.org/tutorials/geotransforms_tut.html
gt = [bbox[0], res, 0, bbox[3], 0, -res]
ns = 'http://www.w3.org/2000/svg'
tree = etree.XML(r.content)
# parse SVG paths (approximation):
# https://developer.mozilla.org/en-US/docs/Web/SVG/Tutorial/Paths#line_commands
path_strings = set()
for elem in tree.iterfind(f'.//{{{ns}}}path'):
if elem.getparent().tag == f'{{{ns}}}clipPath':
continue
d = elem.attrib.get('d')
if d is None:
logging.error('<path> element has no "d" attribute')
continue
m = PATH_RE.match(d)
if m is None:
logging.error("Can't parse <path>'s \"d\" attribute value: \"%s\"", d)
continue
path_strings.add(d)
logging.info('Found %d unique SVG path(s)', len(path_strings))
features, crs = wms.getFeatures(layername, path_strings, gt, progress=progress)
# refine geometries
if len(features) > 0:
#resolutions = [128, 16, 2, .25]
resolutions = [16, .25]
for res in resolutions:
wms.refineGeometries(features, layername, crs=crs, res=res, progress=progress)
logging.info('Found %d unique feature(s) after refinement', len(features))
features = {
'type': 'FeatureCollection',
'name': layername,
'crs': crs,
'features': list(features.values()),
}
# write the destination GeoJSON file
fd = os.open(os.path.dirname(dest), O_WRONLY|O_CLOEXEC|O_TMPFILE, mode=0o644, dir_fd=dir_fd)
try:
with os.fdopen(fd, mode='w', closefd=False) as fp:
json.dump(features, fp, ensure_ascii=False, separators=(',', ':'))
st = os.fstat(fd)
size = st.st_size
feature_count = len(features['features'])
# XXX unfortunately there is no way for linkat() to clobber the destination,
# so we use a temporary file; it's racy, but thanks to O_TMPFILE better
# (shorter race) than if we were dumping chunks in a named file descriptor
os.link(f'/proc/self/fd/{fd}', dest_tmp, dst_dir_fd=dir_fd, follow_symlinks=True)
finally:
os.close(fd)
try:
# atomic rename (ensures output is never partially written)
os.rename(dest_tmp, dest, src_dir_fd=dir_fd, dst_dir_fd=dir_fd)
except (OSError, ValueError) as e:
try:
os.unlink(dest_tmp, dir_fd=dir_fd)
finally:
raise e
elapsed = time_monotonic() - start
wms.print_req_count(elapsed=elapsed)
wms.req_count = None
logging.info('%s: Fetched %d features (%s) in %s (%.2f\u202Ffeat/s, %s/s)', dest,
feature_count, common.format_bytes(size),
common.format_time(elapsed),
feature_count/elapsed,
common.format_bytes(int(size/elapsed)))
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