Add sdkman_selfupdate_feature flag to disable selfupdate functionality for Homebrew (#44)

* Implement support for sdkman_selfupdate_feature and sdkman_auto_update
* Use .bak suffix for temporary file
* Inject timestamp into filename
* Backup config file before modification

Author: Oliver Weiler

app/views/install_beta.scala.txt

@@ -230,6 +230,7 @@ else
     echo "sdkman_auto_complete=true" >> "$sdkman_config_file"
 fi
 echo "sdkman_auto_env=false" >> "$sdkman_config_file"
+echo "sdkman_auto_update=true" >> "$sdkman_config_file"
 echo "sdkman_beta_channel=true" >> "$sdkman_config_file"
 echo "sdkman_checksum_enable=true" >> "$sdkman_config_file"
 echo "sdkman_colour_enable=true" >> "$sdkman_config_file"
@@ -238,7 +239,7 @@ echo "sdkman_curl_max_time=10" >> "$sdkman_config_file"
 echo "sdkman_debug_mode=false" >> "$sdkman_config_file"
 echo "sdkman_insecure_ssl=false" >> "$sdkman_config_file"
 echo "sdkman_rosetta2_compatible=false" >> "$sdkman_config_file"
-echo "sdkman_selfupdate_enable=true" >> "$sdkman_config_file"
+echo "sdkman_selfupdate_feature=true" >> "$sdkman_config_file"
 
 echo "Download script archive..."
 curl --location --progress-bar "${SDKMAN_SERVICE}/broker/download/sdkman/install/${SDKMAN_VERSION}/${SDKMAN_PLATFORM}" > "$sdkman_zip_file"

app/views/selfupdate_beta.scala.txt

@@ -1,3 +1,4 @@
+@import java.time.LocalDate
 @(cliVersion: String, baseUrl: String)#!/bin/bash
 #
 #   Copyright 2017 Marco Vermeulen
@@ -156,6 +157,10 @@ if [[ -z $(cat ${sdkman_config_file} | grep 'sdkman_checksum_enable') ]]; then
 	echo "sdkman_checksum_enable=true" >> "$sdkman_config_file"
 fi
 
+if [[ -z $(cat ${sdkman_config_file} | grep 'sdkman_selfupdate_feature') ]]; then
+	echo "sdkman_selfupdate_feature=true" >> "$sdkman_config_file"
+fi
+
 if [[ -z $(cat ${sdkman_config_file} | grep 'sdkman_auto_complete') ]]; then
     if [ -z "$ZSH_VERSION" -a -z "$BASH_VERSION" ]; then
         echo "sdkman_auto_complete=false" >> "$sdkman_config_file"
@@ -164,6 +169,18 @@ if [[ -z $(cat ${sdkman_config_file} | grep 'sdkman_auto_complete') ]]; then
     fi
 fi
 
+# migrate deprecated sdkman_selfupdate_enable configuration
+@defining(LocalDate.now()) { now =>
+cp "$sdkman_config_file" "${sdkman_config_file}-@{now}.bak"
+
+sed 's/sdkman_selfupdate_enable/sdkman_auto_update/' "$sdkman_config_file" > "${sdkman_config_file}.tmp" &&
+    mv "${sdkman_config_file}.tmp" "$sdkman_config_file"
+}
+
+if [[ -z $(cat ${sdkman_config_file} | grep 'sdkman_auto_update') ]]; then
+	echo "sdkman_auto_update=true" >> "$sdkman_config_file"
+fi
+
 # drop version token
 echo "$SDKMAN_VERSION" > "${SDKMAN_DIR}/var/version"