From 633ae5540f1a798e33b474aac1edb696e34994e9 Mon Sep 17 00:00:00 2001
From: Dave Steinberg <dave@steinberg.dev>
Date: Sun, 12 Jul 2020 22:01:26 -0400
Subject: [PATCH] Support if on tasks.

Just like on a link action, the value is executed in the shell. If
it has a non-zero exit code (failure), the whole task is skipped.
This allows tasks to group actions that only apply in certain
conditions (e.g. on certain OSes or in certain configurations),
and allows all actions (not just link) to be conditional.
---
 dotbot/dispatcher.py    | 7 +++++++
 dotbot/plugins/link.py  | 8 +-------
 dotbot/util/__init__.py | 2 +-
 dotbot/util/common.py   | 6 ++++++
 4 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/dotbot/dispatcher.py b/dotbot/dispatcher.py
index 10e4293..f945d54 100644
--- a/dotbot/dispatcher.py
+++ b/dotbot/dispatcher.py
@@ -2,6 +2,7 @@ import os
 from .plugin import Plugin
 from .messenger import Messenger
 from .context import Context
+from .util import test_success
 
 class Dispatcher(object):
     def __init__(self, base_directory, only=None, skip=None):
@@ -21,7 +22,13 @@ class Dispatcher(object):
     def dispatch(self, tasks):
         success = True
         for task in tasks:
+            test = task.get('if', None)
+            if test is not None and not test_success(test, cwd=self._context.base_directory(), log=self._log):
+                self._log.lowinfo('Skipping task')
+                continue
             for action in task:
+                if action == 'if':
+                    continue
                 if self._only is not None and action not in self._only \
                         or self._skip is not None and action in self._skip:
                     self._log.info('Skipping action %s' % action)
diff --git a/dotbot/plugins/link.py b/dotbot/plugins/link.py
index 6f2b562..1c5beb8 100644
--- a/dotbot/plugins/link.py
+++ b/dotbot/plugins/link.py
@@ -47,7 +47,7 @@ class Link(dotbot.Plugin):
                 path = self._default_source(destination, source.get('path'))
             else:
                 path = self._default_source(destination, source)
-            if test is not None and not self._test_success(test):
+            if test is not None and not dotbot.util.test_success(test, cwd=self._context.base_directory(), log=self._log):
                 self._log.lowinfo('Skipping %s' % destination)
                 continue
             path = os.path.expandvars(os.path.expanduser(path))
@@ -105,12 +105,6 @@ class Link(dotbot.Plugin):
             self._log.error('Some links were not successfully set up')
         return success
 
-    def _test_success(self, command):
-        ret = dotbot.util.shell_command(command, cwd=self._context.base_directory())
-        if ret != 0:
-            self._log.debug('Test \'%s\' returned false' % command)
-        return ret == 0
-
     def _default_source(self, destination, source):
         if source is None:
             basename = os.path.basename(destination)
diff --git a/dotbot/util/__init__.py b/dotbot/util/__init__.py
index 0c5a8f5..2a33abe 100644
--- a/dotbot/util/__init__.py
+++ b/dotbot/util/__init__.py
@@ -1 +1 @@
-from .common import shell_command
+from .common import shell_command, test_success
diff --git a/dotbot/util/common.py b/dotbot/util/common.py
index d1e2000..9c871ca 100644
--- a/dotbot/util/common.py
+++ b/dotbot/util/common.py
@@ -32,3 +32,9 @@ def shell_command(command, cwd=None, enable_stdin=False, enable_stdout=False, en
             stderr=stderr,
             cwd=cwd
         )
+
+def test_success(command, cwd=None, log=None):
+    ret = shell_command(command, cwd=cwd)
+    if ret != 0 and log != None:
+        log.debug('Test \'%s\' returned false' % command)
+    return ret == 0