feat: add utility to copy files and handle diffs based on user input

bootstrap.sh

@@ -41,6 +41,47 @@ pre_substep() {
     echo -e "\e[1m[$STEP_COUNT.$SUBSTEP_COUNT] <====== $1 =======>\e[0m"
 }
 
+# Copies a file from $1 to $2.
+#
+# If $2 exists, checks if $1 == $2 and asks what to do.
+# From there, the user providing "O" will overwrite (proceed with copy),
+# "S" will skip the file and leave the destination as-is, and anyting else
+# will skip the copy altogether (i.e. "S").
+copy_file() {
+    source_path=$1
+    dest_path=$2
+
+    if [ ! -e "$dest_path" ]; then
+        cp $source_path $dest_path
+        echo "Copied $source_path > $dest_path"
+        return 0
+    fi
+
+    difference="$(diff $source_path $dest_path)"
+
+    if [ -z "$difference" ]; then
+        echo "$dest_path already exists, but is the same as $source_path - skipping."
+        return 0
+    fi
+
+    echo "Differences detected between $source_path and $dest_path:"
+    diff --color $source_path $dest_path
+    read -p "$dest_path already exists. What should be done? [O:overwrite,S:skip] " action
+
+    if [[ $action == "O" ]]; then
+        cp $source_path $dest_path
+        echo "Overwrote $source_path > $dest_path"
+        return 0
+    fi
+
+    if [[ $action == "S" ]]; then
+        echo "Skipped and left $dest_path as is."
+        return 0
+    fi
+
+    echo "Unrecognized action, doing nothing."
+}
+
 ##########################################################
 #
 # 2. Steps
@@ -113,10 +154,10 @@ install_and_configure_starship() {
     pre_substep "Copy configuration in configuration directory"
     STARSHIP_CONFIGURATION_PATH=~/.config/starship.toml
     if [ -f $STARSHIP_CONFIGURATION_PATH ]; then
-        cp $STARSHIP_CONFIGURATION_PATH $STARSHIP_CONFIGURATION_PATH.old
+        copy_file $STARSHIP_CONFIGURATION_PATH $STARSHIP_CONFIGURATION_PATH.old
     fi
 
-    cp ./files/starship.toml $STARSHIP_CONFIGURATION_PATH
+    copy_file ./files/starship.toml $STARSHIP_CONFIGURATION_PATH
 }
 
 install_nvm() {