From 995025b5728e6c9a8bf833f5cab554b06ed4d60e Mon Sep 17 00:00:00 2001
From: Kjell Winblad <kjellwinblad@gmail.com>
Date: Mon, 29 May 2023 14:22:58 +0200
Subject: [PATCH] feat: add timezone_to_second/1 function to rule engine

This commit adds the functions timezone_to_offset_seconds and its alias
timezone_to_second to the rule engine. As the names suggests, these
functions convert a timzone offset string such as "+02:00", "Z", "local"
to an integer representing how many seconds that the given timezone
differs from UTC. timezone_to_offset_seconds is the one of the two
functions that should be advertised while timezone_to_second in kept for
backwards compatibility with 4.X.

Fixes:
https://emqx.atlassian.net/browse/EMQX-10058
---
 apps/emqx_machine/src/emqx_machine.app.src    |  2 +-
 apps/emqx_rule_engine/src/emqx_rule_funcs.erl | 10 +++++++++-
 .../test/emqx_rule_funcs_SUITE.erl            | 19 +++++++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/apps/emqx_machine/src/emqx_machine.app.src b/apps/emqx_machine/src/emqx_machine.app.src
index 7cf0e4b53..5cfa80369 100644
--- a/apps/emqx_machine/src/emqx_machine.app.src
+++ b/apps/emqx_machine/src/emqx_machine.app.src
@@ -3,7 +3,7 @@
     {id, "emqx_machine"},
     {description, "The EMQX Machine"},
     % strict semver, bump manually!
-    {vsn, "0.2.4"},
+    {vsn, "0.2.5"},
     {modules, []},
     {registered, []},
     {applications, [kernel, stdlib, emqx_ctl]},
diff --git a/apps/emqx_rule_engine/src/emqx_rule_funcs.erl b/apps/emqx_rule_engine/src/emqx_rule_funcs.erl
index 73e2f78e7..a94aa0c8a 100644
--- a/apps/emqx_rule_engine/src/emqx_rule_funcs.erl
+++ b/apps/emqx_rule_engine/src/emqx_rule_funcs.erl
@@ -228,7 +228,9 @@
     format_date/3,
     format_date/4,
     date_to_unix_ts/3,
-    date_to_unix_ts/4
+    date_to_unix_ts/4,
+    timezone_to_second/1,
+    timezone_to_offset_seconds/1
 ]).
 
 %% MongoDB specific date functions. These functions return a date tuple. The
@@ -1104,6 +1106,12 @@ date_to_unix_ts(TimeUnit, Offset, FormatString, InputString) ->
     OffsetDelta = erlang:convert_time_unit(OffsetSecond, second, Unit),
     date_to_unix_ts(Unit, FormatString, InputString) - OffsetDelta.
 
+timezone_to_second(TimeZone) ->
+    timezone_to_offset_seconds(TimeZone).
+
+timezone_to_offset_seconds(TimeZone) ->
+    emqx_calendar:offset_second(TimeZone).
+
 %% @doc This is for sql funcs that should be handled in the specific modules.
 %% Here the emqx_rule_funcs module acts as a proxy, forwarding
 %% the function handling to the worker module.
diff --git a/apps/emqx_rule_engine/test/emqx_rule_funcs_SUITE.erl b/apps/emqx_rule_engine/test/emqx_rule_funcs_SUITE.erl
index 9bb6e2e6f..525d60503 100644
--- a/apps/emqx_rule_engine/test/emqx_rule_funcs_SUITE.erl
+++ b/apps/emqx_rule_engine/test/emqx_rule_funcs_SUITE.erl
@@ -1012,6 +1012,25 @@ prop_format_date_fun() ->
     Args3DTUS = [<<"second">>, <<"+04:00">>, <<"--%m--%d--%Y---%H:%M:%S">>, Formatters3],
     Second == apply_func(date_to_unix_ts, Args3DTUS).
 
+t_timezone_to_offset_seconds(_) ->
+    t_timezone_to_offset_seconds_helper(timezone_to_offset_seconds),
+    %% The timezone_to_second function is kept for compatibility with 4.X.
+    t_timezone_to_offset_seconds_helper(timezone_to_second).
+
+t_timezone_to_offset_seconds_helper(FunctionName) ->
+    ?assertEqual(120 * 60, apply_func(FunctionName, [<<"+02:00:00">>])),
+    ?assertEqual(-120 * 60, apply_func(FunctionName, [<<"-02:00:00">>])),
+    ?assertEqual(102, apply_func(FunctionName, [<<"+00:01:42">>])),
+    ?assertEqual(0, apply_func(FunctionName, [<<"z">>])),
+    ?assertEqual(0, apply_func(FunctionName, [<<"Z">>])),
+    ?assertEqual(42, apply_func(FunctionName, [42])),
+    ?assertEqual(0, apply_func(FunctionName, [undefined])),
+    %% Check that the following does not crash
+    apply_func(FunctionName, [<<"local">>]),
+    apply_func(FunctionName, ["local"]),
+    apply_func(FunctionName, [local]),
+    ok.
+
 %%------------------------------------------------------------------------------
 %% Utility functions
 %%------------------------------------------------------------------------------