bootstrap: prune broken links

The links are only removed if they are broken and the target was within
the dotfiles bin directory. This makes it easier to deal with removed
and renamed scripts so I don't have to go hunt for them by hand.

bootstrap

@@ -9,6 +9,8 @@ XDG_CACHE_HOME="${XDG_CACHE_HOME:-$HOME/.cache}"
 XDG_CONFIG_HOME="${XDG_CONFIG_HOME:-$HOME/.config}"
 XDG_DATA_HOME="${XDG_DATA_HOME:-$HOME/.local/share}"
 
+DOTFILES_DIR="$(dirname "$(realpath "$0")")"
+
 DIRS=$(cat <<EOF
 ${HOME}/.local/bin
 ${HOME}/.local/etc/git
@@ -88,6 +90,20 @@ file_touch() {  # Make sure file $1 exists (content is irrelevant).
     fi
 }
 
+prune_link() {  # Remove $1 if it's a broken link to a dotfile script.
+    if [ -h "$1" ]; then  # it's a symbolic link
+        target="$(readlink "$1")"
+        case "$target" in
+            "$DOTFILES_DIR/bin/"*)  # it points into dotfiles bin
+                if [ ! -e "$1" ]; then  # target of the link missing
+                    warn "pruning $1 -> $target"
+                    $DRY_RUN || rm -f "$1"
+                fi
+                ;;
+        esac
+    fi
+}
+
 file_link() {  # Make sure $1 is a link to $2.
     target="$(realpath "$2")"
     if [ "$(readlink "$1")" = "$target" ]; then
@@ -155,7 +171,14 @@ EOF
     file_content "$HOME/.local/etc/git/config.host" "$temp_git"
 }
 
-task_link_local_commands() {
+task_prune_broken_bin() {
+    heading "Prune broken links to commands"
+    for cmd in $HOME/.local/bin/*; do
+        prune_link "$cmd"
+    done
+}
+
+task_link_local_bin() {
     heading "Link local commands"
     for cmd in bin/*; do
         file_link "$HOME/.local/bin/$(basename "$cmd")" "$cmd"
@@ -185,12 +208,14 @@ task_install_nvim_plugins() {
 }
 
 main() {
+    $DRY_RUN && warn "Dry run: no changes will actually be made."
     task_gather_user_info
     task_remove_bash_profile
     task_ensure_directories
     task_link_dotfiles
     task_deploy_templates
-    task_link_local_commands
+    task_prune_broken_bin
+    task_link_local_bin
     task_link_dircolors
     task_make_logins_silent
     task_install_nvim_plugins