FIX: Support $HOME and $TODOTXT_ACTIONS_DIR containing spaces.

And document a minor discrepancy in action completion to todo.sh.

Makefile

@@ -13,7 +13,7 @@ VERSION-FILE: .FORCE-VERSION-FILE
 todo.sh: VERSION-FILE
 
 # For packaging
-DISTFILES := todo.cfg
+DISTFILES := todo.cfg todo_completion
 
 DISTNAME=todo.txt_cli-$(VERSION)
 dist: $(DISTFILES) todo.sh

todo_completion

@@ -0,0 +1,64 @@
+#!/bin/bash source-this-script
+[ "$BASH_VERSION" ] || return
+
+_todo()
+{
+    local cur prev opts
+    COMPREPLY=()
+    cur="${COMP_WORDS[COMP_CWORD]}"
+    prev="${COMP_WORDS[COMP_CWORD-1]}"
+
+    local -r OPTS="-@ -@@ -+ -++ -d -f -h -p -P -PP -a -n -t -v -vv -V -x"
+    local -r COMMANDS="\
+        add a addto addm append app archive command del  \
+        rm depri dp do help list ls listall lsa listcon  \
+        lsc listfile lf listpri lsp listproj lsprj move \
+        mv prepend prep pri p replace report shorthelp"
+
+    # Add custom commands from add-ons, if installed.
+    # TODO: Filter for executable flag of files found in $TODO_ACTIONS_DIR.
+    local allCommands="$COMMANDS $('ls' "${TODO_ACTIONS_DIR:-$HOME/.todo.actions.d}/" 2>/dev/null)"
+
+    local completions
+    if [ $COMP_CWORD -eq 1 ]; then
+        completions="$allCommands $OPTS"
+    else
+        case "$prev" in
+            command)
+                completions=$COMMANDS;;
+            -*) completions="$allCommands $OPTS";;
+            *)  case "$cur" in
+                    +*) completions=$(TODOTXT_VERBOSE=0 todo.sh command listproj);;
+                    @*) completions=$(TODOTXT_VERBOSE=0 todo.sh command listcon);;
+                    *)  if [[ "$cur" =~ ^[0-9]+$ ]]; then
+                            local item=$(TODOTXT_VERBOSE=0 todo.sh -@ -+ -p -x command ls "^ *${cur} " | head -n 1)
+
+                            # Remove the (padded) task number; we prepend the
+                            # user-provided $cur.
+                            item=${item#* }
+
+                            # Remove the timestamp prepended by the -t option;
+                            # there's no todo.txt option for that yet.
+                            item=${item#[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9] }
+
+                            # Append task text as a shell comment. This
+                            # completion can be a safety check before a
+                            # destructive todo.txt operation.
+                            [ "$item" ] && COMPREPLY[0]="$cur # $item"
+                            return 0
+                        else
+                            return 0
+                        fi
+                        ;;
+                esac
+                ;;
+        esac
+    fi
+
+    COMPREPLY=( $( compgen -W "$completions" -- $cur ))
+    return 0
+}
+complete -F _todo todo.sh
+# If you define an alias (e.g. "t") to todo.sh, you need to explicitly enable
+# completion for it, too:
+#complete -F _todo t