Implement GET /statuses/user_timeline.json.

Almost identical to GET /statuses/home_timeline.json (see #570), but
the user is explicitly specified by the caller.

Added a bit of error handling guff relating to users that can't be found
and/or when the caller provides us with questionable input.

[#562]

app/controllers/api/statuses_controller.rb

@@ -40,8 +40,67 @@ def update
     end
 
     def home_timeline
-      options = home_timeline_options
-      updates = current_user.timeline(options)
+      timeline_for current_user
+    rescue => e
+      handle_error e
+    end
+
+    def user_timeline
+      timeline_for requested_user!
+    rescue => e
+      handle_error e
+    end
+
+    protected
+
+    def handle_error(e)
+      respond_to do |fmt|
+        fmt.json do
+          status = {
+            NotFound => :not_found,
+            BadRequest => :bad_request
+          }[e.class]
+          raise e if status.nil?
+          render :status => status, :json => [e.message]
+        end
+      end
+    end
+
+    def requested_user!
+      if params[:user_id].blank? && params[:screen_name].blank?
+        #
+        # TODO this is an assumption. Verify against Twitter API.
+        #
+        raise BadRequest, "You must specify either user_id or screen_name"
+      elsif !params[:user_id].blank? && !params[:screen_name].blank?
+        #
+        # TODO verify if/how Twitter deals with this. Edge case, anyway.
+        #
+        raise BadRequest, "You can't specify both user_id and screen_name"
+      end
+
+      #
+      # Try to find a user by user_id first, then screen_name
+      #
+      user = nil
+      user = User.first(params[:user_id]) if !params[:user_id].blank?
+      if user.nil?
+        if !params[:screen_name].blank?
+          user = User.first(:username => params[:screen_name])
+          if user.nil?
+            raise NotFound, "User does not exist: #{params[:screen_name]}"
+          end
+        else
+          raise NotFound, "User ID does not exist: #{params[:user_id]}"
+        end
+      end
+
+      user
+    end
+
+    def timeline_for(user)
+      options = timeline_options
+      updates = user.timeline(options)
       respond_to do |fmt|
         fmt.json do
           json = updates.map do |update|
@@ -54,8 +113,6 @@ def home_timeline
       end
     end
 
-    protected
-
     def format_errors(errors)
       errors = errors.full_messages.map do |error|
         #
@@ -72,7 +129,7 @@ def format_errors(errors)
       {:errors => errors}.to_json
     end
 
-    def home_timeline_options
+    def timeline_options
       options = {}
       attrs = [
         [:count,               :int],
@@ -110,6 +167,9 @@ def update_options
         :twitter => (params[:tweet] == "true")
       }
     end
+
+    class BadRequest < StandardError; end
+    class NotFound < StandardError; end
   end
 end
 

config/routes.rb

@@ -75,5 +75,6 @@
   namespace :api do
     match 'statuses/update.:format', :to => "statuses#update", :via => :post, :constraints => { :format => "json" }
     match 'statuses/home_timeline.:format', :to => "statuses#home_timeline", :via => :get, :constraints => { :format => "json" }
+    match 'statuses/user_timeline.:format', :to => "statuses#user_timeline", :via => :get, :constraints => { :format => "json" }
   end
 end