Split prerequisites check into three stages

modules/01-system-settings.sh

@@ -1,9 +1,15 @@
 #!/usr/bin/env zsh
 # vi: ft=zsh
 
-function checkPrerequisites() {
+function getQuestionsPrerequisites() {
-  local -A cmds=(
+  cmds=(
-    [docopts]='(with -f option supported)'
+    [systemsetup]=''
+  )
+  requireRootPrivileges
+}
+
+function getExecPrerequisites() {
+  cmds=(
     [osascript]=''
     [scutil]=''
     [systemsetup]=''
@@ -12,8 +18,6 @@ function checkPrerequisites() {
     [defaults]=''
     [launchctl]=''
   )
-  test "`id -u`" -eq 0 || { lop -- -e 'This module requires root access. Please run as root.'; return 11 }
-  checkCommands
 }
 
 function getQuestions() {

modules/02-create-filevault-user.sh

@@ -187,20 +187,30 @@ function configure_system() {
   allowOnlyFileVaultUserToUnlock "${filevault_username}"
 }
 
-function checkPrerequisites() {
+function getHelpPrerequisites() {
-  local -A cmds=(
+  cmds=(
-    [docopts]='(with -f option supported)'
     [tr]=''
-    [cut]=''
+    [scutil]=''
+  )
+  addDocoptsToCmds
+}
+
+function getQuestionsPrerequisites() {
+  cmds=(
+    [find]=''
     [dscl]=''
+    [sysadminctl]=''
+  )
+}
+
+function getExecPrerequisites() {
+  cmds=(
+    [cut]=''
     [fdesetup]=''
     [base64]=''
     [dsimport]=''
-    [sysadminctl]=''
-    [scutil]=''
   )
-  test "`id -u`" -eq 0 || { lop -- -e 'This module requires root access. Please run as root.'; return 11 }
+  requireRootPrivileges
-  checkCommands
 }
 
 function getQuestions() {

modules/03-install-brew.sh

@@ -246,9 +246,8 @@ function configure_system() {
   popd -q
 }
 
-function checkPrerequisites() {
+function getExecPrerequisites() {
-  local -A cmds=(
+  cmds=(
-    [docopts]='(with -f option supported)'
     [dscl]=''
     [dseditgroup]=''
     [chown]=''
@@ -259,8 +258,7 @@ function checkPrerequisites() {
     [awk]=''
     [sysadminctl]=''
   )
-  test "`id -u`" -eq 0 || { lop -- -e 'This module requires root access. Please run as root.'; return 11 }
+  requireRootPrivileges
-  checkCommands
 }
 
 function getDefaultHomebrewUsername() {

modules/04-install-brew-apps.sh

@@ -94,14 +94,11 @@ function configure_system() {
   popd -q
 }
 
-function checkPrerequisites() {
+function getExecPrerequisites() {
-  local -A cmds=(
+  cmds=(
-    [docopts]='(with -f option supported)'
-  )
-  local -A execCmds=(
     [brew]=''
   )
-  test "`id -u`" -eq 0 || { lop -- -e 'This module requires root access. Please run as root.'; return 11 }
+  id -nG | grep admin >&! /dev/null || { lop -- -e 'This module requires the user to be in admin group. Please run again as either root or an admin user.'; return 11 }
   checkCommands
 }
 

modules/lib.sh

@@ -29,17 +29,46 @@ function getModuleAnswerByKeyRegEx() {
 
 function checkCommands() {
   local cmd
-  local varName=$1
+  for cmd in ${(k)cmds}; do
-  for cmd in ${(Pk)varName}; do
     if ! which "${cmd}" >&! /dev/null; then
       local comment=''
-      [ -n "${${(P)varName}[$cmd]}" ] && comment=" ${${(P)varName}[$cmd]}"
+      [ -n "${cmds[$cmd]}" ] && comment=" ${cmds[$cmd]}"
       lop -- -e "This module needs ${cmd}${comment} to work."
       return 11
     fi
   done
 }
 
+function checkHelpPrerequisites() {
+  local -A cmds
+  getHelpPrerequisites || return
+  checkCommands
+}
+
+function addDocoptsToCmds() {
+  cmds+=(docopts '(with -f option supported)')
+}
+
+function requireRootPrivileges() {
+  test "`id -u`" -eq 0 || { lop -- -e 'This module requires root access. Please run as root.'; return 11 }
+}
+
+whence getHelpPrerequisites >&! /dev/null || function $_() {
+  addDocoptsToCmds
+}
+
+function checkQuestionsPrerequisites() {
+  local -A cmds
+  getQuestionsPrerequisites || return
+  checkCommands
+}
+
+function checkExecPrerequisites() {
+  local -A cmds
+  getExecPrerequisites || return
+  checkCommands
+}
+
 function showQuestions() {
   local questions=()
   getQuestions
@@ -52,11 +81,18 @@ function module_main() {
   local cmdName=${1:t}
   shift
   autoloadZShLib || return
-  checkPrerequisites cmds || return
+  checkHelpPrerequisites || return
   configureLogging
   eval "`getUsage $cmdName | docopts -f -V - -h - : "$@"`"
-  [ $# -lt 1 ] && return
+  checkQuestionsPrerequisites || return
   [ "${show_questions}" = true ] && { showQuestions; return }
-  checkPrerequisites execCmds || return
+  checkExecPrerequisites || return
   configure_system
 }
+
+function {
+  local name
+  for name in getQuestionsPrerequisites getExecPrerequisites getQuestions getUsage; do
+    whence ${name} >&! /dev/null || function $_() {}
+  done
+}