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images.py
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images.py
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#!/usr/bin/env python
"""
Greynir: Natural language processing for Icelandic
Image retrieval module
Copyright (C) 2022 Miðeind ehf.
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 http://www.gnu.org/licenses/.
This module contains a function that retrieves the URL of an image corresponding to
a (person) name. It uses a Google API on top of the Google Custom Search feature.
Retrieved image information is cached in the database.
"""
from typing import List, Dict, NamedTuple, Optional, Sequence, Union
import sys
import json
import logging
import urllib.request
import urllib.parse
from urllib.error import HTTPError
from io import BytesIO
from datetime import datetime, timedelta
from contextlib import closing
import requests
from db import Session, SessionContext
from db.models import Link, BlacklistedLink
from settings import Settings
from utility import read_api_key
# HTTP request timeout
QUERY_TIMEOUT = 4.0
def _server_query(url: str, q: Dict[str, Union[int, str]]) -> Optional[bytes]:
"""Query a server via HTTP GET with a URL-encoded query string obtained q"""
doc = None
if len(q):
url += "?" + urllib.parse.urlencode(q)
try:
with closing(urllib.request.urlopen(url, timeout=QUERY_TIMEOUT)) as response:
if response:
# Decode the HTML Content-type header to obtain the
# document type and the charset (content encoding), if specified
encoding = "ISO-8859-1"
# TODO: Why is this parsing done manually instead of using the stdlib?
ctype = response.getheader("Content-type", "")
if ";" in ctype:
s = ctype.split(";")
ctype = s[0]
enc = s[1].strip()
s = enc.split("=")
if s[0] == "charset" and len(s) == 2:
encoding = s[1]
if ctype == "application/json":
doc = response.read() # doc is a bytes object
if doc:
doc = doc.decode(encoding)
except HTTPError as ex:
logging.warning("server_query exception: {0}".format(ex))
return doc
# Google Custom Search Engine identifier
_CX = "001858240983628375092:9aogptqla5e"
# The content type we're using in the links table
_CTYPE = "image-search-"
# Time (in days) before cached items expire
_CACHE_EXPIRATION_DAYS = 30
# Number of image URLs to fetch and store
_NUM_IMG_URLS = 6
# The returned image descriptor tuple
Img = NamedTuple(
"Img",
[
("src", str),
("width", int),
("height", int),
("link", str),
("origin", str),
("name", str),
],
)
def get_image_url(
name: str,
*,
hints: Sequence[str] = [],
size: str = "large",
thumb: bool = False,
enclosing_session: Optional[Session] = None,
cache_only: bool = False,
) -> Optional[Img]:
"""Use Google Custom Search API to obtain an image corresponding to a (person) name"""
jdoc = None
ctype = _CTYPE + size
with SessionContext(commit=True, session=enclosing_session) as session:
link = (
session.query(Link.content, Link.timestamp)
.filter(Link.ctype == ctype)
.filter(Link.key == name)
.one_or_none()
)
if link is not None:
# Found in cache. If the result is old, purge it
period = timedelta(days=_CACHE_EXPIRATION_DAYS)
expired = datetime.utcnow() - link.timestamp > period
if expired and not cache_only:
_purge_single(name, ctype=ctype, enclosing_session=session)
else:
jdoc = link.content
if not jdoc and cache_only:
return None
if not jdoc:
# Not found in cache: prepare to ask Google
key = read_api_key("GoogleServerKey")
if not key:
# No API key: can't ask for an image
logging.warning("No API key for image lookup")
return None
# Assemble the query parameters
search_str = '"{0}" {1}'.format(name, " ".join(hints)).strip()
q: Dict[str, Union[str, int]] = dict(
q=search_str,
num=_NUM_IMG_URLS,
start=1,
imgSize=size,
# imgType = "face", # Only images with faces
lr="lang_is", # Higher priority for Icelandic language pages
gl="is", # Higher priority for .is results
searchType="image",
cx=_CX,
key=key,
)
if Settings.DEBUG:
print(
"Sending Google image search request for '{0}'".format(search_str)
)
jdoc = _server_query("https://www.googleapis.com/customsearch/v1", q)
if Settings.DEBUG:
print("Back from Google image search for '{0}'".format(search_str))
if jdoc:
# Store in the cache
lnk = Link(
ctype=ctype, key=name, content=jdoc, timestamp=datetime.utcnow()
)
session.add(lnk)
if not jdoc:
return None
answer = json.loads(jdoc)
if (
answer
and "items" in answer
and answer["items"]
and "link" in answer["items"][0]
):
blacklist = _blacklisted_urls_for_key(name, enclosing_session=session)
for item in answer["items"]:
k = item["link"] if not thumb else item["image"]["thumbnailLink"]
if k and item["link"] not in blacklist:
image = item["image"]
h = image["height"] if not thumb else image["thumbnailHeight"]
w = image["width"] if not thumb else image["thumbnailWidth"]
return Img(k, w, h, image["contextLink"], item["displayLink"], name)
# No answer that makes sense
return None
def blacklist_image_url(name: str, url: str) -> Optional[Img]:
"""Blacklist image URL for a given key"""
with SessionContext(commit=True) as session:
# Verify that URL exists in DB
if not _get_cached_entry(name, url, enclosing_session=session):
return None
# Check if already blacklisted
if url in _blacklisted_urls_for_key(name, enclosing_session=session):
return None
# Add to blacklist
b = BlacklistedLink(
key=name, url=url, link_type="image", timestamp=datetime.utcnow()
)
session.add(b)
return get_image_url(name, enclosing_session=session)
def update_broken_image_url(name: str, url: str) -> Optional[Img]:
"""Refetch image URL for name if broken"""
with SessionContext() as session:
# Verify that URL exists in DB
r = _get_cached_entry(name, url, enclosing_session=session)
if r:
# Verify that URL is indeed broken
if not check_image_url(url):
# Blacklist the URL, purge results from cache and refetch
blacklist_image_url(name, url)
_purge_single(name, ctype=r.ctype, enclosing_session=session)
return get_image_url(name)
return None
def check_image_url(url: str) -> bool:
"""Check if image exists at URL by sending HEAD request"""
req = urllib.request.Request(url, method="HEAD")
try:
response = urllib.request.urlopen(req, timeout=2.0)
return response.status == 200
except Exception:
pass
return False
def _blacklisted_urls_for_key(
key: str, enclosing_session: Optional[Session] = None
) -> List[str]:
"""Fetch blacklisted urls for a given key"""
with SessionContext(commit=True, session=enclosing_session) as session:
q = (
session.query(BlacklistedLink.url)
.filter(BlacklistedLink.link_type == "image")
.filter(BlacklistedLink.key == key)
.all()
)
return [r for (r,) in q]
return [] # Satisfy Pylance
def _get_cached_entry(name: str, url: str, enclosing_session: Optional[Session] = None):
"""Fetch cached entry by key and url"""
with SessionContext(commit=True, session=enclosing_session) as session:
# TODO: content column should be converted to jsonb
# from varchar to query faster & more intelligently
return (
session.query(Link)
.filter(Link.key == name)
.filter(Link.content.like("%" + url + "%"))
.one_or_none()
)
def _purge_single(
key: str,
ctype: Optional[str] = None,
enclosing_session: Optional[Session] = None,
) -> None:
"""Remove cache entry"""
with SessionContext(commit=True, session=enclosing_session) as session:
filters = [Link.key == key]
if ctype:
filters.append(Link.ctype == ctype)
session.query(Link).filter(*filters).delete()
def _purge():
"""Remove all cache entries"""
if input("Purge all cached data? (y/n): ").lower().startswith("y"):
with SessionContext(commit=True) as session:
session.query(Link).delete()
STATICMAP_URL = (
"https://maps.googleapis.com/maps/api/staticmap?"
"zoom={0}&style=feature:poi%7Cvisibility:off"
"&size={1}x{2}&language=is&scale=2&maptype=roadmap"
"&key={3}&markers={4},{5}"
)
def get_staticmap_image(
latitude: float,
longitude: float,
zoom: int = 6,
width: int = 180,
height: int = 180,
) -> Optional[BytesIO]:
"""Request image from Google Static Maps API, return image data as bytes"""
key = read_api_key("GoogleServerKey")
if not key:
return None
url = STATICMAP_URL.format(zoom, width, height, key, latitude, longitude)
try:
r = requests.get(url, stream=True, timeout=10)
except Exception as e:
logging.warning(str(e))
return None
if r.status_code == 200:
r.raw.decode_content = True
return BytesIO(r.raw.data)
logging.warning("Status {0} when requesting static map image".format(r.status_code))
return None
def _test():
"""Test image lookup"""
print("Testing...")
print("Bjarni Benediktsson")
img = get_image_url("Bjarni Benediktsson")
print("{0}".format(img))
print("Vilhjálmur Þorsteinsson")
img = get_image_url("Vilhjálmur Þorsteinsson")
print("{0}".format(img))
print("Blængur Klængsson Eyfjörð")
img = get_image_url("Blængur Klængsson Eyfjörð")
print("{0}".format(img)) # Should be None
if __name__ == "__main__":
cmap = {"test": _test, "purge": _purge}
cmd = sys.argv[1] if len(sys.argv) > 1 else "test"
if cmd in cmap.keys():
cmap[cmd]()
elif cmd:
# Any other arg is a name to fetch an image for
img = get_image_url(cmd)
print("{0}".format(img))