# This class generates a compatible `bash_completion` script file.
#
# On some Linux systems `bash_completion` allow the program to control command line behaviour.
#
# ~~~sh
# $ nitls [TAB][TAB]
# file1.nit              file2.nit              file3.nit
#
# $ nitls --[TAB][TAB]
# --bash-toolname        --keep                 --path                 --tree
# --depends              --log                  --package              --verbose
# --disable-phase        --log-dir              --quiet                --version
# --gen-bash-completion  --no-color             --recursive            --warn
# --help                 --only-metamodel       --source
# --ignore-visibility    --only-parse           --stop-on-first-error
# ~~~
#
# Generated file can be placed in system bash_completion directory `/etc/bash_completion.d/`
# or source it in `~/.bash_completion`.
class BashCompletion
	super Template

	var toolcontext: ToolContext

	private fun extract_options_names: Array[String] do
		var names = new Array[String]
		for option in toolcontext.option_context.options do
			for name in option.names do
				if name.has_prefix("--") then names.add name
			end
		end
		return names
	end

	redef fun rendering do
		var name = toolcontext.toolname
		var option_names = extract_options_names
		addn "# generated bash completion file for {name} {toolcontext.version}"
		addn "_{name}()"
		addn "\{"
		addn "	local cur prev opts"
		addn "	COMPREPLY=()"
		addn "	cur=\"$\{COMP_WORDS[COMP_CWORD]\}\""
		addn "	prev=\"$\{COMP_WORDS[COMP_CWORD-1]\}\""
		if not option_names.is_empty then
			addn "	opts=\"{option_names.join(" ")}\""
			addn "	if [[ $\{cur\} == -* ]] ; then"
			addn "		COMPREPLY=( $(compgen -W \"$\{opts\}\" -- $\{cur\}) )"
			addn "		return 0"
			addn "	fi"
		end
		addn "\} &&"
		addn "complete -o default -F _{name} {name}"
	end
end