#!/usr/bin/python3

from flask import Flask, render_template, request, jsonify, redirect, url_for
import requests
import os
import json
import urllib.parse
import random
import simplejson
import psycopg2
from geopy.distance import distance

# select gid, code, name from scotland where st_contains(geom, ST_Transform(ST_SetSRID(ST_MakePoint(-4.177, 55.7644), 4326), 27700));

commons_cat_start = 'https://commons.wikimedia.org/wiki/Category:'
use_cache = False

headers = {
    'User-Agent': 'UK gecode/0.1 (edward@4angle.com)',
}

OVERPASS_URL = 'https://lz4.overpass-api.de'
wikidata_query_api_url = 'https://query.wikidata.org/bigdata/namespace/wdq/sparql'
wikidata_url = 'https://www.wikidata.org/w/api.php'
wd_entity = 'http://www.wikidata.org/entity/Q'
city_of_london_qid = 'Q23311'

samples = [
    (50.8326, -0.2689, 'Adur'),
    (52.4914, -0.69645, 'Corby'),
    (50.893, -4.265, 'Newton St Petrock'),
    (51.779, 0.128, 'Harlow'),
    (52.387, 0.294, 'Ely'),
    (50.9, -1.6, 'Minstead'),
    (52.43, -1.11, 'South Kilworth'),
    (53.117, -0.202, 'Tattershall Thorpe'),
    (53.351, -2.701, 'Halton'),
    (52.421, -0.651, 'Warkton'),
    (51.51, -1.547, 'Lambourn'),
    (52.62, -1.884, 'Shenstone'),
    (53.309, -1.539, 'Sheffield'),
    (53.322, 0.032, 'Haugham'),
    (51.05, -2.598, 'Babcary'),
    (51.158, -1.906, 'Berwick St James'),
    (51.867, -1.204, 'Weston-on-the-Green'),
    (51.034, -2.005, 'Ebbesbourne Wake'),
    (51.07, -0.718, 'Fernhurst'),
    (53.059, -0.144, 'Wildmore'),
    (51.473, 0.221, 'Dartford'),
    (51.059, 0.05, 'Danehill'),
    (52.253, -0.122, 'Papworth Everard'),
    (53.498, -0.415, 'West Lindsey'),
    (53.392, -0.022, 'Brackenborough with Little Grimsby'),
    (53.463, -0.027, 'Fulstow'),
    (52.766, 0.31, 'Terrington St Clement'),
    (53.1540, -1.8034, 'Hartington Town Quarter'),
    (51.8532, -0.8829, 'Fleet Marston'),
    (51.4785, -0.354, 'London Borough of Hounslow'),
    (51.9687, -0.0327, 'Buckland, Hertfordshire'),
    (51.0804, -2.3263, 'Zeals'),
    (55.7644, -4.1770, 'East Kilbride'),
    (51.4520, -2.6210, 'Bristol'),
]

class QueryError(Exception):
    def __init__(self, query, r):
        self.query = query
        self.r = r


app = Flask(__name__)
app.debug = True


def get_random_lat_lon():
    ''' Select random lat/lon within the UK '''
    south, east = 50.8520, 0.3536
    north, west = 53.7984, -2.7296

    mul = 10000
    lat = random.randrange(int(south * mul), int(north * mul)) / mul
    lon = random.randrange(int(west * mul), int(east * mul)) / mul

    return lat, lon


@app.route("/random")
def random_location():
    lat, lon = get_random_lat_lon()

    elements = get_osm_elements(lat, lon)
    result = do_lookup(elements, lat, lon)

    return render_template('random.html', lat=lat, lon=lon, result=result, elements=elements)


@app.route("/wikidata_tag")
def wikidata_tag():
    lat = float(request.args.get('lat'))
    lon = float(request.args.get('lon'))

    scotland_code = get_scotland_code(lat, lon)

    if scotland_code:
        rows = lookup_scottish_parish_in_wikidata(scotland_code)
        hit = commons_from_rows(rows)
        elements = []
        result = build_dict(hit, lat, lon)
    else:
        elements = get_osm_elements(lat, lon)
        result = do_lookup(elements, lat, lon)

    return render_template('wikidata_tag.html', lat=lat, lon=lon, result=result, elements=elements)


@app.route("/detail")
def detail_page():
    try:
        lat, lon = [float(request.args.get(param)) for param in ('lat', 'lon')]
    except TypeError:
        return redirect(url_for('index'))
    reply = lat_lon_to_wikidata(lat, lon)
    return render_template('random.html', lat=lat, lon=lon, **reply)


def bounding_box_area(element):
    bbox = element['bounds']

    x = distance((bbox['maxlat'], bbox['minlon']), (bbox['maxlat'], bbox['maxlon']))
    y = distance((bbox['minlat'], bbox['maxlon']), (bbox['maxlat'], bbox['minlon']))

    return x.km * y.km


def wd_to_qid(wd):
    # expecting {'type': 'url', 'value': 'https://www.wikidata.org/wiki/Q30'}
    if wd['type'] == 'uri':
        return wd_uri_to_qid(wd['value'])


def wd_uri_to_qid(value):
    assert value.startswith(wd_entity)
    return value[len(wd_entity) - 1:]


def build_dict(hit, lat, lon):
    coords = {'lat': lat, 'lon': lon}
    if hit is None:
        return dict(commons_cat=None, missing=True, coords=coords)
    commons_cat = hit['commons_cat']
    url = commons_cat_start + urllib.parse.quote(commons_cat.replace(' ', '_'))
    return dict(commons_cat={'title': commons_cat, 'url': url},
                coords=coords,
                admin_level=hit.get('admin_level'),
                wikidata=hit['wikidata'])


def do_lookup(elements, lat, lon):
    try:
        hit = osm_lookup(elements, lat, lon)
    except QueryError as e:
        return {
            'query': e.query,
            'error': e.r.text,
            'query_url': 'https://query.wikidata.org/#' + e.query,
        }

    return build_dict(hit, lat, lon)


def get_scotland_code(lat, lon):
    conn = psycopg2.connect(dbname='geocode', user='geocode', password='ooK3ohgh', host='localhost')
    cur = conn.cursor()

    point = f'ST_Transform(ST_SetSRID(ST_MakePoint({lon}, {lat}), 4326), 27700)'
    cur.execute(f'select code, name from scotland where st_contains(geom, {point});')
    row = cur.fetchone()

    # expand search, disabled for now 2020-04-20
    if not row:
        cur.execute(f'select code, name from scotland where ST_DWithin(geom, {point}, 100);')
        row = cur.fetchone()

    conn.close()
    if row:
        return row[0]


def wdqs_geosearch_query(lat, lon):
    if isinstance(lat, float):
        lat = f'{lat:f}'
    if isinstance(lon, float):
        lon = f'{lon:f}'

    query_template = '''

SELECT DISTINCT ?item ?distance ?itemLabel ?isa ?isaLabel ?commonsCat ?commonsSiteLink WHERE {
  {
    SELECT DISTINCT ?item ?location ?distance ?isa WHERE {
      ?item wdt:P31/wdt:P279* wd:Q486972.
      ?item wdt:P31 ?isa .
      SERVICE wikibase:around {
        ?item wdt:P625 ?location.
        bd:serviceParam wikibase:center "Point(LON LAT)"^^geo:wktLiteral;
          wikibase:radius 5;
          wikibase:distance ?distance.
      }
    }
  }
  MINUS { ?item wdt:P582 ?endTime . }
  OPTIONAL { ?item wdt:P373 ?commonsCat. }
  OPTIONAL { ?commonsSiteLink schema:about ?item;
             schema:isPartOf <https://commons.wikimedia.org/>. }
  SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
} ORDER BY (?distance)'''

    query = query_template.replace('LAT', lat).replace('LON', lon)
    reply = wdqs(query)
    return reply['results']['bindings']


def wdqs_geosearch(lat, lon):
    default_max_dist = 1
    rows = wdqs_geosearch_query(lat, lon)
    max_dist = {
        'Q188509': 1,   # suburb
        'Q3957': 2,     # town
        'Q532': 1,      # village
        'Q5084': 1,     # hamlet
        'Q515': 2,      # city
        'Q1549591': 3,  # big city
    }
    for row in rows:
        isa = wd_uri_to_qid(row['isa']['value'])

        if ('commonsCat' not in row and 'commonsSiteLink' not in row and isa not in max_dist):
            continue

        distance = float(row['distance']['value'])
        if distance > max_dist.get(isa, default_max_dist):
            continue

        if 'commonsCat' not in row and 'commonsSiteLink' not in row:
            break

        return row


def lat_lon_to_wikidata(lat, lon):
    scotland_code = get_scotland_code(lat, lon)

    if scotland_code:
        rows = lookup_scottish_parish_in_wikidata(scotland_code)
        hit = commons_from_rows(rows)
        elements = []
        result = build_dict(hit, lat, lon)

        return {'elements': elements, 'result': result}

    elements = get_osm_elements(lat, lon)
    result = do_lookup(elements, lat, lon)

    # special case because the City of London is admin_level=6 in OSM
    if result['wikidata'] == city_of_london_qid:
        return {'elements': elements, 'result': result}

    admin_level = result['admin_level']

    if not admin_level or admin_level >= 7:
        return {'elements': elements, 'result': result}

    row = wdqs_geosearch(lat, lon)
    if row:
        hit = commons_from_rows([row])
        elements = []
        result = build_dict(hit, lat, lon)

    return {'elements': elements, 'result': result}


@app.route("/")
def index():
    q = request.args.get('q')
    if q and q.strip():
        lat, lon = [v.strip() for v in q.split(',', 1)]
        return redirect(url_for('detail_page', lat=lat, lon=lon))

    lat = request.args.get('lat')
    lon = request.args.get('lon')
    if lat is None or lon is None:
        samples.sort(key=lambda row: row[2])
        return render_template('index.html', samples=samples)

    return jsonify(lat_lon_to_wikidata(lat, lon)['result'])


def wikidata_api_call(params):
    call_params = {
        'format': 'json',
        'formatversion': 2,
        **params,
    }

    r = requests.get(wikidata_url, params=call_params, headers=headers)
    return r

def get_entity(qid):
    json_data = wikidata_api_call({'action': 'wbgetentities', 'ids': qid}).json()

    try:
        entity = list(json_data['entities'].values())[0]
    except KeyError:
        return
    if 'missing' not in entity:
        return entity


def qid_to_commons_category(qid):
    entity = get_entity(qid)
    try:
        commons_cat = entity['claims']['P373'][0]['mainsnak']['datavalue']['value']
    except Exception:
        commons_cat = None

    return commons_cat


def wdqs(query):
    r = requests.post(wikidata_query_api_url,
                      data={'query': query, 'format': 'json'},
                      headers=headers)

    try:
        return r.json()
    except simplejson.errors.JSONDecodeError:
        raise QueryError(query, r)


def endpoint():
    return OVERPASS_URL + '/api/interpreter'


def run_query(oql, error_on_rate_limit=True):
    return requests.post(endpoint(),
                         data=oql.encode('utf-8'),
                         headers=headers)


def get_elements(oql):
    return run_query(oql).json()['elements']


def is_in_lat_lon(lat, lon):
    oql = f'''
[out:json][timeout:25];
is_in({lat},{lon})->.a;
(way(pivot.a); rel(pivot.a););
out bb tags qt;'''

    return run_query(oql)


def lookup_scottish_parish_in_wikidata(code):
    query = '''
SELECT ?item ?itemLabel ?commonsSiteLink ?commonsCat WHERE {
  ?item wdt:P528 "CODE" .
  ?item wdt:P31 wd:Q5124673 .
  OPTIONAL { ?commonsSiteLink schema:about ?item ;
             schema:isPartOf <https://commons.wikimedia.org/> }
  OPTIONAL { ?item wdt:P373 ?commonsCat }
  SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
}
'''.replace('CODE', code)
    reply = wdqs(query)
    return reply['results']['bindings']


def lookup_gss_in_wikidata(gss):
    query = '''
SELECT ?item ?itemLabel ?commonsSiteLink ?commonsCat WHERE {
  ?item wdt:P836 GSS .
  OPTIONAL { ?commonsSiteLink schema:about ?item ;
             schema:isPartOf <https://commons.wikimedia.org/> }
  OPTIONAL { ?item wdt:P373 ?commonsCat }
  SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
}
'''.replace('GSS', repr(gss))
    reply = wdqs(query)
    return reply['results']['bindings']


def lookup_wikidata_by_name(name, lat, lon):
    query = '''
SELECT DISTINCT ?item ?itemLabel ?commonsSiteLink ?commonsCat WHERE {
  ?item rdfs:label LABEL@en .
  FILTER NOT EXISTS { ?item wdt:P31 wd:Q17362920 } .# ignore Wikimedia duplicated page
  OPTIONAL { ?commonsSiteLink schema:about ?item ;
             schema:isPartOf <https://commons.wikimedia.org/> }
  OPTIONAL { ?item wdt:P373 ?commonsCat }
  ?item wdt:P625 ?coords .

  FILTER(geof:distance(?coords, "Point(LON LAT)"^^geo:wktLiteral) < 10)
  FILTER(?commonsCat || ?commonsSiteLink)

  SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
}
'''.replace('LABEL', repr(name)).replace('LAT', str(lat)).replace('LON', str(lon))

    reply = wdqs(query)
    return reply['results']['bindings']


def unescape_title(t):
    return urllib.parse.unquote(t.replace('_', ' '))


def commons_from_rows(rows):
    for row in rows:
        if 'commonsCat' in row:
            qid = wd_to_qid(row['item'])
            return {'wikidata': qid,
                    'commons_cat': row['commonsCat']['value']}
        if 'commonsSiteLink' in row:
            site_link = row['commonsSiteLink']['value']
            qid = wd_to_qid(row['item'])
            cat = unescape_title(site_link[len(commons_cat_start):])
            return {'wikidata': qid, 'commons_cat': cat}


def get_commons_cat_from_gss(gss):
    print('GSS:', gss)
    rows = lookup_gss_in_wikidata(gss)
    return commons_from_rows(rows)


def get_osm_elements(lat, lon):
    filename = f'cache/{lat}_{lon}.json'

    if use_cache and os.path.exists(filename):
        elements = json.load(open(filename))['elements']
    else:
        r = is_in_lat_lon(lat, lon)
        if use_cache:
            open(filename, 'wb').write(r.content)
        elements = r.json()['elements']

    return elements


def osm_lookup(elements, lat, lon):
    is_in = []
    elements.sort(key=lambda e: bounding_box_area(e))

    if False:
        for e in sorted(elements, key=lambda e: e['area']):
            try:
                admin_level = int(e['tags']['admin_level'])
            except (ValueError, KeyError):
                admin_level = None

            if admin_level is None:
                if e['id'] == 6038068:  # Great Britain
                    continue
                if 'place' in e['tags'] or e['tags'].get('type') == 'boundary':
                    is_in.append((99, e['tags']))
                continue

            is_in.append((admin_level, e['tags']))

    # for _, tags in sorted(is_in, key=lambda i: i[0], reverse=True):
    for e in elements:
        if 'tags' not in e:
            continue
        tags = e['tags']
        admin_level_tag = tags.get('admin_level')
        admin_level = int(admin_level_tag) if admin_level_tag and admin_level_tag.isdigit() else None
        if not admin_level and tags.get('boundary') != 'political':
            continue
        if 'wikidata' in tags:
            qid = tags['wikidata']
            commons = qid_to_commons_category(qid)
            if commons:
                return {
                    'wikidata': qid,
                    'commons_cat': commons,
                    'admin_level': admin_level,
                }
        gss = tags.get('ref:gss')
        if gss:
            ret = get_commons_cat_from_gss(gss)
            if ret:
                ret['admin_level'] = admin_level
                return ret

        name = tags.get('name')
        if not name:
            continue
        if name.endswith(' CP'):
            name = name[:-3]
        rows = lookup_wikidata_by_name(name, lat, lon)

        if len(rows) == 1:
            ret = commons_from_rows(rows)
            if ret:
                ret['admin_level'] = admin_level
                return ret

    has_wikidata_tag = [e['tags'] for e in elements if 'wikidata' in e['tags']]
    if len(has_wikidata_tag) != 1:
        return

    qid = has_wikidata_tag[0]['wikidata']
    return {
        'wikidata': qid,
        'commons_cat': qid_to_commons_category(qid),
        'admin_level': admin_level,
    }


if __name__ == '__main__':
    app.run(host='0.0.0.0')