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Geocoding service for converting location names to coordinates.
Provides both online API and offline fallback geocoding capabilities.
"""
import asyncio
try:
import aiohttp
except Exception:
aiohttp = None
import logging
import sqlite3
from dataclasses import dataclass
from pathlib import Path
from app.services.infrastructure.circuit_breaker import (
CircuitBreakerConfig,
circuit_breaker,
)
logger = logging.getLogger(__name__)
@dataclass
class Location:
"""Represents a geographic location with coordinates."""
latitude: float
longitude: float
city: str
country: str
confidence: float = 1.0
class GeocodingService:
"""Service for geocoding location names to coordinates."""
def __init__(self, db_path: str = "./data/geocoding_cache.db"):
self.db_path = db_path
self.cache_db_path = Path(db_path)
self.cache_db_path.parent.mkdir(parents=True, exist_ok=True)
self._init_cache_db()
# Free geocoding API endpoints (no API key required)
self.geocoding_apis = [
"https://nominatim.openstreetmap.org/search",
"https://api.opencagedata.com/geocode/v1/json", # Limited free tier
]
# Fallback coordinates for major cities/countries
self.fallback_locations = self._load_fallback_locations()
def _init_cache_db(self):
"""Initialize the geocoding cache database."""
with sqlite3.connect(self.cache_db_path) as conn:
conn.execute(
"""
CREATE TABLE IF NOT EXISTS geocoding_cache (
location_key TEXT PRIMARY KEY,
latitude REAL,
longitude REAL,
city TEXT,
country TEXT,
confidence REAL,
cached_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
)
"""
)
conn.execute(
"""
CREATE INDEX IF NOT EXISTS idx_location_key
ON geocoding_cache(location_key)
"""
)
def _load_fallback_locations(self) -> dict[str, Location]:
"""Load fallback location data for common cities/countries."""
return {
# Major cities
"new york, united states": Location(
40.7128, -74.0060, "New York", "United States"
),
"london, united kingdom": Location(
51.5074, -0.1278, "London", "United Kingdom"
),
"tokyo, japan": Location(35.6762, 139.6503, "Tokyo", "Japan"),
"paris, france": Location(48.8566, 2.3522, "Paris", "France"),
"sydney, australia": Location(-33.8688, 151.2093, "Sydney", "Australia"),
"singapore, singapore": Location(
1.3521, 103.8198, "Singapore", "Singapore"
),
"hong kong, china": Location(22.3193, 114.1694, "Hong Kong", "China"),
"shanghai, china": Location(31.2304, 121.4737, "Shanghai", "China"),
"beijing, china": Location(39.9042, 116.4074, "Beijing", "China"),
"mumbai, india": Location(19.0760, 72.8777, "Mumbai", "India"),
"delhi, india": Location(28.7041, 77.1025, "Delhi", "India"),
"bangalore, india": Location(12.9716, 77.5946, "Bangalore", "India"),
# Countries (capital cities as fallback)
"united states": Location(
39.8283, -98.5795, "Washington DC", "United States", 0.5
),
"china": Location(35.8617, 104.1954, "Beijing", "China", 0.5),
"india": Location(20.5937, 78.9629, "Delhi", "India", 0.5),
"japan": Location(36.2048, 138.2529, "Tokyo", "Japan", 0.5),
"united kingdom": Location(
55.3781, -3.4360, "London", "United Kingdom", 0.5
),
"france": Location(46.2276, 2.2137, "Paris", "France", 0.5),
"germany": Location(51.1657, 10.4515, "Berlin", "Germany", 0.5),
"australia": Location(-25.2744, 133.7751, "Canberra", "Australia", 0.5),
"singapore": Location(1.3521, 103.8198, "Singapore", "Singapore", 0.5),
}
def _normalize_location_key(self, city: str, country: str) -> str:
"""Create a normalized key for location caching."""
return f"{city.lower().strip()}, {country.lower().strip()}"
async def geocode_location(self, city: str, country: str) -> Location | None:
"""
Geocode a city/country combination to coordinates.
Args:
city: City name
country: Country name
Returns:
Location object with coordinates, or None if geocoding fails
"""
if not city or not country:
return None
location_key = self._normalize_location_key(city, country)
# Check cache first
cached_location = self._get_cached_location(location_key)
if cached_location:
return cached_location
# Try online geocoding
location = await self._geocode_online(city, country)
if location:
self._cache_location(location_key, location)
return location
# Fall back to static data
fallback_key = location_key
if fallback_key in self.fallback_locations:
location = self.fallback_locations[fallback_key]
self._cache_location(location_key, location)
return location
# Try country-only fallback
country_key = country.lower().strip()
if country_key in self.fallback_locations:
location = self.fallback_locations[country_key]
# Reduce confidence for country-only matches
location.confidence = 0.3
self._cache_location(location_key, location)
return location
logger.warning(f"Could not geocode location: {city}, {country}")
return None
def _get_cached_location(self, location_key: str) -> Location | None:
"""Retrieve location from cache."""
try:
with sqlite3.connect(self.cache_db_path) as conn:
cursor = conn.execute(
"""
SELECT latitude, longitude, city, country, confidence
FROM geocoding_cache
WHERE location_key = ?
""",
(location_key,),
)
row = cursor.fetchone()
if row:
return Location(
latitude=row[0],
longitude=row[1],
city=row[2],
country=row[3],
confidence=row[4],
)
except Exception as e:
logger.error(f"Error reading from geocoding cache: {e}")
return None
def _cache_location(self, location_key: str, location: Location):
"""Cache location in database."""
try:
with sqlite3.connect(self.cache_db_path) as conn:
conn.execute(
"""
INSERT OR REPLACE INTO geocoding_cache
(location_key, latitude, longitude, city, country, confidence)
VALUES (?, ?, ?, ?, ?, ?)
""",
(
location_key,
location.latitude,
location.longitude,
location.city,
location.country,
location.confidence,
),
)
conn.commit()
except Exception as e:
logger.error(f"Error caching location: {e}")
@circuit_breaker(
"external_api_geocoding",
CircuitBreakerConfig(
failure_threshold=5,
recovery_timeout=120.0,
expected_exception=(
aiohttp.ClientError if aiohttp else Exception,
Exception,
),
),
)
async def _geocode_online(self, city: str, country: str) -> Location | None:
"""Attempt online geocoding using free APIs with circuit breaker protection."""
query = f"{city}, {country}"
# Try OpenStreetMap Nominatim (no API key required)
try:
async with aiohttp.ClientSession() as session:
params = {"q": query, "format": "json", "limit": 1, "addressdetails": 1}
async with session.get(
"https://nominatim.openstreetmap.org/search",
params=params,
headers={"User-Agent": "FraudDetectionApp/1.0"},
) as response:
if response.status == 200:
data = await response.json()
if data:
result = data[0]
return Location(
latitude=float(result["lat"]),
longitude=float(result["lon"]),
city=city,
country=country,
confidence=0.9, # High confidence for OSM
)
except Exception as e:
logger.warning(f"OpenStreetMap geocoding failed: {e}")
return None
async def batch_geocode(
self, locations: list[tuple[str, str]]
) -> dict[tuple[str, str], Location | None]:
"""
Geocode multiple locations in batch.
Args:
locations: List of (city, country) tuples
Returns:
Dictionary mapping (city, country) to Location objects
"""
results = {}
# Process in batches to avoid overwhelming APIs
batch_size = 10
for i in range(0, len(locations), batch_size):
batch = locations[i : i + batch_size]
# Create tasks for concurrent processing
tasks = [self.geocode_location(city, country) for city, country in batch]
batch_results = await asyncio.gather(*tasks, return_exceptions=True)
# Process results
for (city, country), result in zip(batch, batch_results):
if isinstance(result, Exception):
logger.error(f"Error geocoding {city}, {country}: {result}")
results[(city, country)] = None
else:
results[(city, country)] = result
# Small delay between batches to be respectful to APIs
if i + batch_size < len(locations):
await asyncio.sleep(0.1)
return results
def clear_cache(self):
"""Clear the geocoding cache."""
try:
with sqlite3.connect(self.cache_db_path) as conn:
conn.execute("DELETE FROM geocoding_cache")
conn.commit()
logger.info("Geocoding cache cleared")
except Exception as e:
logger.error(f"Error clearing geocoding cache: {e}")
def get_cache_stats(self) -> dict[str, int]:
"""Get cache statistics."""
try:
with sqlite3.connect(self.cache_db_path) as conn:
cursor = conn.execute("SELECT COUNT(*) FROM geocoding_cache")
count = cursor.fetchone()[0]
return {"cached_locations": count}
except Exception as e:
logger.error(f"Error getting cache stats: {e}")
return {"cached_locations": 0}
# Global geocoding service instance
geocoding_service = GeocodingService()
async def geocode_transaction_location(
city: str, country: str
) -> dict[str, float] | None:
"""
Convenience function to geocode a transaction location.
Returns:
Dict with 'lat' and 'lng' keys, or None if geocoding fails
"""
location = await geocoding_service.geocode_location(city, country)
if location:
return {"lat": location.latitude, "lng": location.longitude}
return None
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