# Completion for eselect [<global options>] <module> <action> [<options>]
# Author: Wilke Schwiedop <w.schwiedop@web.de>
# Distributed under the terms of the GNU General Public License v2

_eselect() {
	local curr=${COMP_WORDS[COMP_CWORD]} possibles="" module_index=1

	# Unset default completion
	COMPREPLY=()

	# Unfortunatly we can't source eselect to get to the variables directly, so this is a bit more complicated
	local ESELECT_DATA_PATH ESELECT_MODULES_PATH

	# Obtain ESELECT_DATA_PATH and ESELECT_MODULES_PATH . See eselect for more info
	ESELECT_DATA_PATH=$(sed -n -e 's/^ESELECT_DATA_PATH="\(.\+\)"$/\1/p' $(which eselect))
	ESELECT_MODULES_PATH=( "${HOME}/.eselect/modules" "${ESELECT_DATA_PATH}/modules" )

	# Hard-coded Actions.
	# Note: list-modules is hardcoded aswell, but not used in the modules. list-modules is added only when needed.
	ESELECT_KNOWN_ACTIONS="help usage version"
	# Hard-coded Options
	# TODO These could be read from ESELECT_KNOWN_OPTIONS
	ESELECT_KNOWN_OPTIONS="--no-colour"

	# If any word in ${COMP_WORDS[@]} is a default-action, we don't need further completion
	for i in ${COMP_WORDS[@]} ; do
		[[ $i == @(${ESELECT_KNOWN_ACTIONS//[[:space:]]/"|"}|list-modules) ]] && return 0
	done

	# Skip all global-options
	while [[ ${COMP_WORDS[module_index]} == -* ]] ; do
		((++module_index))
	done

	# If this is true we're looking for a module name or an eselect-option. In short: "eselect <wearehere>"
	# Since we're skipping the global options, this may be < 0 if we have nothing but options in COMP_WORDS.
	if [[ $((COMP_CWORD-module_index)) -le 0 ]] ; then
		local path file
		for path in "${ESELECT_MODULES_PATH[@]}" ; do
			[[ -d ${path} ]] || continue
			for file in ${path}/*.eselect ; do
				[[ -f ${file} ]] || continue
				file=${file##*/}       # strip path
				file=${file%%.eselect} # strip extension
				possibles+=" ${file}"
			done
		done
		
		possibles+=" list-modules ${ESELECT_KNOWN_ACTIONS}" # Include default actions and list-modules
		possibles+=" ${ESELECT_KNOWN_OPTIONS}" # Include default options

	# We already have a module, so we're looking for an action or even and option
	# In short: "eselect somemodule <wearehere> <orevenhere>"
	else
		local modname=${COMP_WORDS[module_index]} modpath="" modfile=""
		for modpath in "${ESELECT_MODULES_PATH[@]}" ; do
			modfile="${modpath}/${modname}.eselect"
			[[ -f ${modfile} ]] && break
		done
		[[ -f ${modfile} ]] || return 1 # 404 File not found, so theres no way we get the info we need

		
		# We're looking for an action; In short: "eselect somemodule <wearehere>"
		if [[ $((COMP_CWORD-module_index)) -eq 1 ]] ; then
			possibles+=" ${ESELECT_KNOWN_ACTIONS}" # Include default actions
		
			# module-actions are simple bash functions in the module-file.
			# They follow the pattern "do_${action}()" and "do_${action} ()" respectively
			possibles+=" "
			possibles+=$(sed -n -e 's/^do_\([^ _\(]\+\).*/\1/p' ${modfile})

		# We're looking for an option.
		# In short: "eselect somemodule someaction <wearehere>"
		else
			local action=${COMP_WORDS[module_index+1]}

			possibles+=" "
			possibles+=$(
				source ${modfile} &> /dev/null
				# functions describing options follow the pattern "describe_${action}_options()"
				if [[ $(type -t "describe_${action}_options" ) == "function" ]] ; then
					# we're only interested in --options-like-this
					# TODO The regexp could be improved to match only single "-" between letters
					echo $(describe_${action}_options | sed -n -e 's/^.*--\([[:alpha:]-]\+\).*/--\1/p')
					if [[ $(type -t "find_targets") == "function" ]] ; then
						$(describe_${action}_options | grep -q '/^<target>') | find_targets
					fi
				fi
			)
		fi
	fi

	# If we already completed something, remove already used words from completion.
	if [[ ${COMP_CWORD} -ge 2 ]] ; then
		# Our delete candidates are ${COMP_WORDS[@] without the first ("eselect") and last word ("$curr")
		local delete_candidates="${COMP_WORDS[@]:1:${COMP_CWORD}-1}" 
		# Convert delete candidates to regexp
		delete_candidates=${delete_candidates//[[:space:]]/"|"}
		# Delete candidates begone!
		possibles=${possibles//@($delete_candidates)/""}
		# When removing a word, the delimiting spaces remain. Remove them aswell
		possibles=${possibles//"  "/" "}
	fi

	COMPREPLY=( $(compgen -W "${possibles}" -- ${curr}) )

	return 0
}

complete -F _eselect eselect