feat(completion): add bash completion

Still missing a few options and cannot complete dates inside string
delimiters, but mostly works.

Makefile

@@ -7,11 +7,13 @@ PREFIX := /usr/local
 install: ./agenda.1.gz
 	install -m 755 -D ./agenda $(PREFIX)/bin/agenda
 	install -m 644 -D ./agenda.1.gz $(PREFIX)/share/man/man1/agenda.1.gz
+	install -m 644 -D ./completion.bash $(PREFIX)/share/bash-completion/completions/agenda
 
 .PHONY: uninstall
 uninstall:
-	rm $(PREFIX)/bin/agenda
+	rm -f $(PREFIX)/bin/agenda
-	rm $(PREFIX)/share/man/man1/agenda.1.gz
+	rm -f $(PREFIX)/share/man/man1/agenda.1.gz
+	rm -f $(PREFIX)/share/bash-completion/completions/agenda
 
 .PHONY: clean
 clean:

completion.bash

@@ -0,0 +1,190 @@
+#!/usr/bin/env bash
+
+# Bash completion script for the agenda(1) script.
+
+# TODO: Maybe its easier to add an api to the agenda script to query for the
+#       available -t option values?
+if [ -z "$AGENDA_DIR" ]; then
+	if type xdg-user-dir >/dev/null 2>&1; then
+		AGENDA_DIR="$(xdg-user-dir DOCUMENTS)/agenda"
+	else
+		AGENDA_DIR="$HOME/.agenda"
+	fi
+fi
+
+AGENDA_COMP_DATE_MOD=("next" "last")
+AGENDA_COMP_DATE_UNIT=("day" "week" "month" "year")
+AGENDA_COMP_DATE_DAY=("monday" "tuesday" "wednesday" "thursday" "friday" "saturday" "sunday")
+AGENDA_COMP_DATE_REL=("yesterday" "today" "tomorrow")
+
+AGENDA_COMP_DATE=(
+	"${AGENDA_COMP_DATE_MOD[@]}" 
+	"${AGENDA_COMP_DATE_UNIT[@]}" 
+	"${AGENDA_COMP_DATE_DAY[@]}" 
+	"${AGENDA_COMP_DATE_REL[@]}"
+)
+
+__agenda_comp() {
+	# Pointer to current and last completion words.
+	local cur last
+
+	cur=${COMP_WORDS[COMP_CWORD]}
+	last=${COMP_WORDS[COMP_CWORD - 1]}
+
+	# All subcommands take a date (or parts of a date) as their final arguments.
+	if __agenda_comp_is_date_word "${COMP_WORDS[-2]}"; then
+		return
+	fi
+
+	if __agenda_comp_is_date_mod "$last"; then
+		local words=("${AGENDA_COMP_DATE_UNIT[@]}" "${AGENDA_COMP_DATE_DAY[@]}")
+		mapfile -t COMPREPLY < <(compgen -W "${words[*]}" -- "$cur")
+		return
+	fi
+
+	case ${COMP_WORDS[1]} in
+		"edit")
+			mapfile -t COMPREPLY < <(__agenda_comp_edit "$last" "$cur")
+			;;
+		"list"|"ls")
+			mapfile -t COMPREPLY < <(__agenda_comp_list "$last" "$cur")
+			;;
+		*)
+			if (( COMP_CWORD == 1 )); then
+				local dates
+				mapfile -t dates < <(__agenda_comp_iso_date "$cur")
+
+				local words=(
+					"edit"
+					"list"
+					"${dates[@]}"
+					"${AGENDA_COMP_DATE[@]}"
+					"${AGENDA_COMP_DATE_DAY[@]}"
+				)
+
+				mapfile -t COMPREPLY < <(compgen -W "${words[*]}" -- "${COMP_WORDS[1]}")
+			else
+				# The "edit" subcommand is implicit.
+				mapfile -t COMPREPLY < <(__agenda_comp_edit "$last" "$cur")
+			fi
+			;;
+	esac
+}
+complete -F __agenda_comp agenda
+
+__agenda_comp_edit() {
+	local last="$1" cur="$2"
+
+	case $last in
+		"-"*"t")
+			compgen -W "$(__agenda_comp_names)" -- "$cur"
+			;;
+		*)
+			__agenda_comp_opt "c" "$cur"
+			__agenda_comp_opt "E" "$cur"
+			__agenda_comp_opt "t" "$cur"
+
+			compgen -W "${AGENDA_COMP_DATE[*]} $(__agenda_comp_iso_date "$cur")" -- "$cur"
+			;;
+	esac
+}
+
+__agenda_comp_list() {
+	local last="$1" cur="$2"
+
+	case $last in
+		# TODO: Somehow complete date wrapped in a string?
+		"-"*"u")
+			local year
+			year=$(printf '%(%Y)T' -1)
+			compgen -W "$(__agenda_comp_iso_date "$cur" "$year")" -- "$cur"
+			;;
+		"-"*"t")
+			compgen -W "$(__agenda_comp_names)" -- "$cur"
+			;;
+		*)
+			__agenda_comp_opt "a" "$cur"
+			__agenda_comp_opt "c" "$cur"
+			__agenda_comp_opt "u" "$cur"
+			__agenda_comp_opt "t" "$cur"
+
+			compgen -W "${AGENDA_COMP_DATE[*]} $(__agenda_comp_iso_date "$cur")" -- "$cur"
+			;;
+	esac
+}
+
+__agenda_comp_is_date_mod() {
+	[[ $last == "next" ]] || [[ $last == "last" ]] || [[ $last =~ ^[-+]?[0-9]+$ ]]
+}
+
+__agenda_comp_is_date_word() {
+	local word words=(
+		"${AGENDA_COMP_DATE_DAY[@]}"
+		"${AGENDA_COMP_DATE_UNIT[@]}"
+		"${AGENDA_COMP_DATE_REL[@]}"
+	)
+	for word in "${words[@]}"; do
+		if [[ $1 == "$word" ]]; then
+			return 0
+		fi
+	done
+
+	if [[ $1 =~ ^[0-9]{4}-[0-9]{2}-[0-9]{2}$ ]]; then
+		return 0
+	fi
+
+	return 1
+}
+
+__agenda_comp_names() {
+	local dir
+	for dir in "$AGENDA_DIR"/*; do
+		if [ -e "$dir" ]; then
+			echo "${dir##*/}"
+		fi
+	done
+}
+
+# TODO: Complete years only without appending a space on completion (If
+#       possible, idk)?
+__agenda_comp_iso_date() {
+	local year month day
+
+	if [[ $1 =~ ^[0-9]{4}-? ]]; then
+		year=${1%%-*}
+	elif [[ -n ${2:-} ]]; then
+		year=$2
+	else
+		return
+	fi
+
+	for month in {1..12}; do
+		case $month in
+			1|3|5|7|8|10|12)
+				for day in {1..31}; do
+					printf "%04d-%02d-%02d\n" "$year" "$month" "$day"
+				done
+				;;
+			4|6|9|11)
+				for day in {1..30}; do
+					printf "%04d-%02d-%02d\n" "$year" "$month" "$day"
+				done
+				;;
+			2)
+				# TODO: Leap years.
+				for day in {1..28}; do
+					printf "%04d-%02d-%02d\n" "$year" "$month" "$day"
+				done
+				;;
+		esac
+	done
+}
+
+__agenda_comp_opt() {
+	local regex="^.*[[:space:]]-.*$1.*.*$"
+	if ! [[ $COMP_LINE =~ $regex ]]; then
+		compgen -W "-$1" -- "$2"
+	fi
+}
+
+# vi: noet sts=4 sw=4 tw=84