click-app.eclass: new eclass

Signed-off-by: Anna (cybertailor) Vyalkova <cyber+gentoo@sysrq.in>

eclass/click-app.eclass

@@ -0,0 +1,129 @@
+# Copyright 2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: click-app.eclass
+# @MAINTAINER:
+# Anna <cyber+gentoo@sysrq.in>
+# @AUTHOR:
+# Anna <cyber+gentoo@sysrq.in>
+# @SUPPORTED_EAPIS: 8
+# @BLURB: eclass for Click-based Python applications
+# @DESCRIPTION:
+# This eclass provides a streamlined way to generate and install shell
+# completions for Python applications based on the Click library
+# (dev-python/click package).
+
+case ${EAPI} in
+	8) ;;
+	*) die "${ECLASS}: EAPI ${EAPI:-0} not supported" ;;
+esac
+
+if [[ ! ${_CLICK_APP_ECLASS} ]]; then
+_CLICK_APP_ECLASS=1
+
+inherit distutils-r1 shell-completion
+
+# @FUNCTION: click-app_enable_completions
+# @USAGE: <script...>
+# @DESCRIPTION:
+# Set up IUSE, BDEPEND and python_install() to generate and install shell
+# completions for the given scripts.
+#
+# This function does not overwrite python_install() if it is already defined.
+# If you need to extend python_install(), you can call the original
+# implementation as click-app_python_install.
+#
+# This function must be called in global scope.
+#
+# See also: https://click.palletsprojects.com/en/stable/shell-completion/
+click-app_enable_completions() {
+	debug-print-function "${FUNCNAME}" "${@}"
+	(( $# >= 1 )) ||
+		die "${FUNCNAME} takes at least one argument"
+
+	IUSE+=" bash-completion"
+	BDEPEND+=" bash-completion? ( ${RDEPEND} )"
+
+	readonly -a _CLICK_SHELLCOMP_SCRIPTS=( "${@}" )
+
+	click-app_python_install() {
+		debug-print-function "${FUNCNAME}" "${@}"
+		use bash-completion || return 0
+
+		local script_name
+		for script_name in "${_CLICK_SHELLCOMP_SCRIPTS[@]?}"; do
+			click_install_completions "${script_name:?}"
+		done
+	}
+
+	if ! declare -f python_install; then
+		python_install() {
+			click-app_python_install
+			distutils-r1_python_install
+		}
+	fi
+
+	# we need to ensure successful return in case we're called last,
+	# otherwise Portage may wrongly assume sourcing failed
+	return 0
+}
+
+# @FUNCTION: click-app_python_install
+# @USAGE: <script...>
+# @DESCRIPTION:
+# Generate and install shell completions for the given scripts.
+#
+# Note that this function checks if USE="bash-completion" is enabled, and if
+# not automatically exits. Therefore, there is no need to wrap this function
+# in an "if" statement.
+#
+# This function needs to be called before distutils-r1_python_install.
+
+# @FUNCTION: click_install_completions
+# @USAGE: <script>
+# @DESCRIPTION:
+# Generate and install shell completions for a single script.
+#
+# Note that if a shell completions directory already exists in the install tree,
+# generation and installation steps will be skipped for this shell.
+#
+# This function needs to be called before distutils-r1_python_install.
+click_install_completions() {
+	debug-print-function "${FUNCNAME}" "${@}"
+	(( $# == 1 )) ||
+		die "${FUNCNAME} takes exactly one argument"
+
+	_gen_click_completions() {
+		local shell=${1:?}
+
+		echo "${env_var_name:?}=${shell:?}_source ${script_path:?}" >&2
+		local -x "${env_var_name:?}"="${shell:?}_source" || die
+		"${script_path:?}" || die
+	}
+
+	local env_var_name script_name script_path
+
+	script_name=${1:?}
+	script_path="${BUILD_DIR}/install${EPREFIX}/usr/bin/${script_name:?}"
+	[[ -f "${script_path}" ]] ||
+		die "${script_path} not found, click_install_completions call wrong"
+
+	# convert to screaming snake case
+	env_var_name="_${script_name:?}_COMPLETE"
+	env_var_name=${env_var_name^^}
+	env_var_name=${env_var_name//-/_}
+
+	if [[ ! -d "${D}/$(get_bashcompdir)" ]]; then
+		_gen_click_completions bash | newbashcomp - "${script_name:?}"
+	fi
+	if [[ ! -d "${D}/$(get_fishcompdir)" ]]; then
+		_gen_click_completions fish | newfishcomp - "${script_name:?}.fish"
+	fi
+	if [[ ! -d "${D}/$(get_zshcompdir)" ]]; then
+		_gen_click_completions zsh | newzshcomp - "_${script_name:?}"
+	fi
+
+	unset -f _gen_click_completions
+}
+
+fi