From fcd49d67e5fe6c1695b7fd31b6f3f6c180da75d3 Mon Sep 17 00:00:00 2001
From: Tim Bolender <git@timbolender.de>
Date: Wed, 10 Dec 2014 00:49:58 +0100
Subject: [PATCH] Implemented an exceptions class for every kind of error.

---
 overpass/__init__.py |  3 +++
 overpass/api.py      | 54 ++++++++++++--------------------------------
 overpass/errors.py   | 37 ++++++++++++++++++++++++++++++
 overpass/queries.py  |  3 +--
 4 files changed, 56 insertions(+), 41 deletions(-)
 create mode 100644 overpass/errors.py

diff --git a/overpass/__init__.py b/overpass/__init__.py
index abaf7e0664f..267865a7b4d 100644
--- a/overpass/__init__.py
+++ b/overpass/__init__.py
@@ -8,3 +8,6 @@
 
 from .api import API
 from .queries import MapQuery, WayQuery
+from .errors import (
+    OverpassError, OverpassSyntaxError, TimeoutError, MultipleRequestsError, ServerLoadError, UnknownOverpassError
+)
diff --git a/overpass/api.py b/overpass/api.py
index 72e422f29cd..0764f85d681 100644
--- a/overpass/api.py
+++ b/overpass/api.py
@@ -1,8 +1,9 @@
-import sys
 import requests
 import json
 import geojson
 
+from .errors import OverpassSyntaxError, TimeoutError, MultipleRequestsError, ServerLoadError, UnknownOverpassError
+
 
 class API(object):
     """A simple Python wrapper for the OpenStreetMap Overpass API"""
@@ -40,20 +41,12 @@ def __init__(self, *args, **kwargs):
     def Get(self, query, asGeoJSON=False):
         """Pass in an Overpass query in Overpass QL"""
 
-        response = ""
+        full_query = self._ConstructQLQuery(query, asGeoJSON=asGeoJSON)
+        raw_response = self._GetFromOverpass(full_query)
+        response = json.loads(raw_response)
 
-        try:
-            response = json.loads(self._GetFromOverpass(
-                self._ConstructQLQuery(query, asGeoJSON=asGeoJSON)))
-        except OverpassException as oe:
-            print(oe)
-            sys.exit(1)
-
-        if "elements" not in response or len(response["elements"]) == 0:
-            raise OverpassException(
-                204,
-                'No OSM features satisfied your query'
-            )
+        if "elements" not in response:
+            raise UnknownOverpassError("Received an invalid answer from Overpass.")
 
         if not asGeoJSON:
             return response
@@ -63,7 +56,7 @@ def Get(self, query, asGeoJSON=False):
 
     def Search(self, feature_type, regex=False):
         """Search for something."""
-        pass
+        raise NotImplementedError()
 
     def _ConstructQLQuery(self, userquery, asGeoJSON=False):
         raw_query = str(userquery)
@@ -96,23 +89,18 @@ def _GetFromOverpass(self, query):
                 timeout=self.timeout
             )
         except requests.exceptions.Timeout:
-            raise OverpassException(
-                408,
-                'Query timed out. API instance is set to time out in {timeout}'
-                ' seconds. Try passing in a higher value when instantiating'
-                ' this API: api = Overpass.API(timeout=60)'.format(
-                    timeout=self.timeout
-                )
-            )
+            raise TimeoutError(self._timeout)
 
         self._status = r.status_code
 
         if self._status != 200:
             if self._status == 400:
-                message = 'Query syntax error'
-            else:
-                message = 'Error from Overpass API'
-            raise OverpassException(self._status, message)
+                raise OverpassSyntaxError(query)
+            elif self._status == 429:
+                raise MultipleRequestsError()
+            elif self._status == 504:
+                raise ServerLoadError(self._timeout)
+            raise UnknownOverpassError("The request returned status code {code}".format(code = self._status))
         else:
             return r.text
 
@@ -139,15 +127,3 @@ def _asGeoJSON(self, elements):
             features.append(feature)
 
         return geojson.FeatureCollection(features)
-
-
-class OverpassException(Exception):
-    def __init__(self, status_code, message):
-        self.status_code = status_code
-        self.message = message
-
-    def __str__(self):
-        return json.dumps({
-            'status': self.status_code,
-            'message': self.message
-        })
diff --git a/overpass/errors.py b/overpass/errors.py
new file mode 100644
index 00000000000..b0249f7908c
--- /dev/null
+++ b/overpass/errors.py
@@ -0,0 +1,37 @@
+class OverpassError(Exception):
+    """An error during your request occurred. Super class for all Overpass api errors."""
+    pass
+
+
+class OverpassSyntaxError(OverpassError, ValueError):
+    """The request contains a syntax error."""
+
+    def __init__(self, request):
+        self.request = request
+
+
+class TimeoutError(OverpassError):
+    """A request timeout occurred."""
+
+    def __init__(self, timeout):
+        self.timeout = timeout
+
+
+class MultipleRequestsError(OverpassError):
+    """You are trying to run multiple requests at the same time."""
+    pass
+
+
+class ServerLoadError(OverpassError):
+    """The Overpass server is currently under load and declined the request. Try again later or retry with reduced
+    timeout value."""
+
+    def __init__(self, timeout):
+        self.timeout = timeout
+
+
+class UnknownOverpassError(OverpassError):
+    """An unknown kind of error happened during the request."""
+
+    def __init__(self, message):
+        self.message = message
\ No newline at end of file
diff --git a/overpass/queries.py b/overpass/queries.py
index 2d98ddb10c0..f673950d2a3 100644
--- a/overpass/queries.py
+++ b/overpass/queries.py
@@ -29,8 +29,7 @@ def __str__(self):
 
 class WayQuery(object):
 
-    """Query to retrieve a set of ways and their dependent nodes satisfying
-    the input parameters"""
+    """Query to retrieve a set of ways and their dependent nodes satisfying the input parameters"""
 
     _QUERY_TEMPLATE = "(way{query_parameters});(._;>;);"