From b11ab480b9bdd43f3d9ee32dfe50b8f77ebec540 Mon Sep 17 00:00:00 2001
From: Fabio Salvini <salvini.fabio001@gmail.com>
Date: Mon, 26 Jun 2017 16:27:53 +0200
Subject: [PATCH] Use group receivers when sending email, custom subject

---
 apps/log_monitor/src/mailer.erl | 46 ++++++++++++++++++++++++++++-----
 config/log_monitor.config       |  5 ++++
 2 files changed, 45 insertions(+), 6 deletions(-)

diff --git a/apps/log_monitor/src/mailer.erl b/apps/log_monitor/src/mailer.erl
index 8e0e71f..796b0ad 100644
--- a/apps/log_monitor/src/mailer.erl
+++ b/apps/log_monitor/src/mailer.erl
@@ -6,6 +6,7 @@
 -export([start_link/0, init/1, terminate/2]).
 -export([handle_info/2, handle_cast/2, handle_call/3]).
 -export([code_change/3]).
+-export([email_subject/2]).
 
 start_link() ->
     gen_server:start_link(?MODULE, [], []).
@@ -75,13 +76,24 @@ send_email(File, Text) ->
     {ok, EmailConfig} = application:get_env(log_monitor, email_config),
     Sender = proplists:get_value(sender, EmailConfig),
     DefaultReceiver = proplists:get_value(default_receiver, EmailConfig),
+    RawSubject = proplists:get_value(subject, EmailConfig),
     Connection = proplists:get_value(connection, EmailConfig),
-    error_logger:info_msg("Sending email for file ~s with text: ~n~s~n", [File, Text]),
-    gen_smtp_client:send_blocking(
-      {Sender, [DefaultReceiver],
-       io_lib:format("Subject: Error notification\r\nFrom: Fabio\r\n\r\nLogfile: ~s~nError: ~n~s~n", [File, Text])},
-      Connection
-     ).
+    try receivers(File) of
+        GroupReceivers ->
+            Receivers = if GroupReceivers == []
+                           -> [DefaultReceiver];
+                           true -> GroupReceivers
+                        end,
+            Subject = email_subject(RawSubject, File),
+            gen_smtp_client:send_blocking(
+              {Sender, Receivers,
+               io_lib:format("Subject: ~s\r\nFrom: ~s\r\n\r\nLogfile: ~s~nError: ~n~s~n", [Subject, Sender, File, Text])},
+              Connection
+             )
+    catch
+        _Throw ->
+            ok
+    end.
 
 remove_email(Id) ->
     mnesia:activity(
@@ -90,3 +102,25 @@ remove_email(Id) ->
               mnesia:delete({log_monitor_error, Id})
       end),
     ok.
+
+receivers(File) ->
+    mnesia:activity(
+      transaction,
+      fun() ->
+              case mnesia:read(log_monitor_file, File) of
+                  [{log_monitor_file, File, _, _, Group}] ->
+                      case mnesia:read(log_monitor_group, Group) of
+                          [{log_monitor_group, Group, EmailReceivers}] ->
+                              EmailReceivers
+                      end;
+                  _ -> throw(file_not_found)
+              end
+      end).
+
+email_subject(Text, File) ->
+    Text1 = re:replace(Text, "%f", File, [global, {return, list}]),
+    re:replace(Text1, "%F", file_name_from_path(File), [global, {return, list}]).
+
+file_name_from_path(File) ->
+    {match, [_, Basename]} = re:run(File, "^.*\/(.*)\\..*$", [{capture, all, list}]),
+    Basename.
diff --git a/config/log_monitor.config b/config/log_monitor.config
index 0d117c7..ec7653b 100644
--- a/config/log_monitor.config
+++ b/config/log_monitor.config
@@ -5,6 +5,11 @@
         [
           {sender, "log@monitor.com"},
           {default_receiver, "salvini.fabio001@gmail.com"},
+          %% Subject of the email.
+          %% Placeholders:
+          %% %f: the full path of the log file (ex. /var/log/myapp.log).
+          %% %F: the basename of the log file (ex. myapp).
+          {subject, "[%F] Error notification"},
           {connection, [
             {relay, "smtp.fabiosalvinii.com"},
             {username, "salvini.fabio001@gmail.com"},