app-text/bibletime: add option to install offline documentation

All languages for now, with a discrepancy in language support between
the howto and the handbook making these selectable will need some effort
+ the generation overhead is fairly minimal.

Closes: https://bugs.gentoo.org/869875
Signed-off-by: Marek Szuba <marecki@gentoo.org>

app-text/bibletime/bibletime-3.0.3-r4.ebuild

@@ -12,6 +12,7 @@ SRC_URI="https://github.com/${PN}/${PN}/releases/download/v${PV}/${P}.tar.xz"
 LICENSE="GPL-2"
 SLOT="0"
 KEYWORDS="~amd64 ~x86"
+IUSE="doc"
 
 RDEPEND=">=app-text/sword-1.8.1[curl,icu]
 	dev-cpp/clucene
@@ -26,7 +27,13 @@ RDEPEND=">=app-text/sword-1.8.1[curl,icu]
 DEPEND="${RDEPEND}
 	dev-libs/boost
 	dev-qt/qttest:5"
-BDEPEND="dev-qt/linguist-tools:5"
+BDEPEND="dev-qt/linguist-tools:5
+	doc? (
+		app-text/docbook-xml-dtd
+		app-text/docbook-xsl-stylesheets
+		app-text/po4a
+		dev-libs/libxslt
+	)"
 
 PATCHES=(
 	"${FILESDIR}"/${PN}-3.0.3-no_indirect_deps.patch
@@ -41,11 +48,14 @@ src_prepare() {
 		-i cmake/platforms/linux/bibletime.desktop.cmake || die "fixing .desktop file failed"
 }
 
+# TODO: FOO_HTML_LANGUAGES. Current lists for "all languages":
+# handbook: ar br cs de en es fi fr hu it ko lt nl pt_BR ru th uk
+# howto: ar bg br cs da de en es fi fr hu it ja ko lt nl pt_BR ru th uk
 src_configure() {
 	local mycmakeargs=(
-		-DBUILD_HANDBOOK_HTML=no
+		-DBUILD_HANDBOOK_HTML=$(usex doc)
 		-DBUILD_HANDBOOK_PDF=no
-		-DBUILD_HOWTO_HTML=no
+		-DBUILD_HOWTO_HTML=$(usex doc)
 		-DBUILD_HOWTO_PDF=no
 	)
 	cmake_src_configure