add todo.txt-cli as a plugin

Since it is referenced in the default .bash_profile and in aliases and
themes, why not make it an official plugin?

This creates a 'todo/' directory in /plugins/available, and installs
todo.sh and friends there.  Tab completion and the 't' alias should work
out of the box.

Note: it was also necessary to modify .gitignore to ignore the files
todo.sh generates in custom/.

plugins/available/todo/todo_completion

@@ -0,0 +1,107 @@
+#!/bin/bash source-this-script
+[ "$BASH_VERSION" ] || return
+
+_todo()
+{
+    local cur prev opts
+    COMPREPLY=()
+    cur="${COMP_WORDS[COMP_CWORD]}"
+    prev="${COMP_WORDS[COMP_CWORD-1]}"
+
+    local -r OPTS="-@ -@@ -+ -++ -d -f -h -p -P -PP -a -n -t -v -vv -V -x"
+    local -r COMMANDS="\
+        add a addto addm append app archive command del  \
+        rm depri dp do help list ls listaddons listall lsa listcon  \
+        lsc listfile lf listpri lsp listproj lsprj move \
+        mv prepend prep pri p replace report shorthelp"
+
+    local _todo_sh=${_todo_sh:-todo.sh}
+    local completions
+    if [ $COMP_CWORD -eq 1 ]; then
+        completions="$COMMANDS $(eval TODOTXT_VERBOSE=0 $_todo_sh command listaddons) $OPTS"
+    elif [[ $COMP_CWORD -gt 2 && ( \
+        "${COMP_WORDS[COMP_CWORD-2]}" =~ ^(move|mv)$ || \
+        "${COMP_WORDS[COMP_CWORD-3]}" =~ ^(move|mv)$ ) ]]; then
+        # "move ITEM# DEST [SRC]" has file arguments on positions 2 and 3.
+        completions=$(eval TODOTXT_VERBOSE=0 $_todo_sh command listfile)
+    else
+        case "$prev" in
+            command)
+                completions=$COMMANDS;;
+            addto|listfile|lf)
+                completions=$(eval TODOTXT_VERBOSE=0 $_todo_sh command listfile);;
+            -*) completions="$COMMANDS $(eval TODOTXT_VERBOSE=0 $_todo_sh command listaddons) $OPTS";;
+            *)  case "$cur" in
+                    +*) completions=$(eval TODOTXT_VERBOSE=0 $_todo_sh command listproj)
+                        COMPREPLY=( $( compgen -W "$completions" -- $cur ))
+                        [ ${#COMPREPLY[@]} -gt 0 ] && return 0
+                        # Fall back to projects extracted from done tasks.
+                        completions=$(eval 'TODOTXT_VERBOSE=0 TODOTXT_SOURCEVAR=\$DONE_FILE' $_todo_sh command listproj)
+                        ;;
+                    @*) completions=$(eval TODOTXT_VERBOSE=0 $_todo_sh command listcon)
+                        COMPREPLY=( $( compgen -W "$completions" -- $cur ))
+                        [ ${#COMPREPLY[@]} -gt 0 ] && return 0
+                        # Fall back to contexts extracted from done tasks.
+                        completions=$(eval 'TODOTXT_VERBOSE=0 TODOTXT_SOURCEVAR=\$DONE_FILE' $_todo_sh command listcon)
+                        ;;
+                    *)  if [[ "$cur" =~ ^[0-9]+$ ]]; then
+                            # Remove the (padded) task number; we prepend the
+                            # user-provided $cur instead.
+                            # Remove the timestamp prepended by the -t option,
+                            # and the done date (for done tasks); there's no
+                            # todo.txt option for that yet.
+                            # But keep priority and "x"; they're short and may
+                            # provide useful context.
+                            # Remove any trailing whitespace; the Bash
+                            # completion inserts a trailing space itself.
+                            # Finally, limit the output to a single line just as
+                            # a safety check of the ls action output.
+                            local todo=$( \
+                                eval TODOTXT_VERBOSE=0 $_todo_sh '-@ -+ -p -x command ls "^ *${cur} "' | \
+                                sed -e 's/^ *[0-9]\{1,\} //' -e 's/\((.) \)[0-9]\{2,4\}-[0-9]\{2\}-[0-9]\{2\} /\1/' \
+                                    -e 's/\([xX] \)\([0-9]\{2,4\}-[0-9]\{2\}-[0-9]\{2\} \)\{1,2\}/\1/' \
+                                    -e 's/[[:space:]]*$//' \
+                                    -e '1q' \
+                            )
+                            # Append task text as a shell comment. This
+                            # completion can be a safety check before a
+                            # destructive todo.txt operation.
+                            [ "$todo" ] && COMPREPLY[0]="$cur # $todo"
+                            return 0
+                        else
+                            return 0
+                        fi
+                        ;;
+                esac
+                ;;
+        esac
+    fi
+
+    COMPREPLY=( $( compgen -W "$completions" -- $cur ))
+    return 0
+}
+complete -F _todo todo.sh
+
+# If you define an alias (e.g. "t") to todo.sh, you need to explicitly enable
+# completion for it, too:
+#complete -F _todo t
+
+# If you have renamed the todo.sh executable, or if it is not accessible through
+# PATH, you need to add and use a wrapper completion function, like this:
+#_todoElsewhere()
+#{
+#    local _todo_sh='/path/to/todo2.sh'
+#    _todo "$@"
+#}
+#complete -F _todoElsewhere /path/to/todo2.sh
+
+# If you use aliases to use different configuration(s), you need to add and use
+# a wrapper completion function for each configuration if you want to complete
+# fron the actual configured task locations:
+#alias todo2='todo.sh -d "$HOME/todo2.cfg"'
+#_todo2()
+#{
+#    local _todo_sh='todo.sh -d "$HOME/todo2.cfg"'
+#    _todo "$@"
+#}
+#complete -F _todo2 todo2