Add shell completions for bash, zsh and fish (#50)

This PR aims to introduce basic shell completions for bash, zsh and fish for the zaman command.

Makefile

@@ -10,6 +10,11 @@ install:
 	# Install the main script
 	install -Dm 755 "src/script/${pkgname}.sh" "${DESTDIR}${PREFIX}/bin/${pkgname}"
 
+	# Install shell completions
+	install -Dm 644 "res/completions/${pkgname}.bash" "${DESTDIR}${PREFIX}/share/bash-completion/completions/${pkgname}"
+	install -Dm 644 "res/completions/${pkgname}.zsh" "${DESTDIR}${PREFIX}/share/zsh/site-functions/_${pkgname}"
+	install -Dm 644 "res/completions/${pkgname}.fish" "${DESTDIR}${PREFIX}/share/fish/vendor_completions.d/${pkgname}.fish"
+
 	# Archive and install man pages
 	gzip -c "doc/man/${pkgname}.1" > "${pkgname}.1.gz"
 	install -Dm 644 "${pkgname}.1.gz" "${DESTDIR}${PREFIX}/share/man/man1/${pkgname}.1.gz"

res/completions/zaman.bash

@@ -0,0 +1,13 @@
+_zaman() {
+	local arg="${2}"
+	local -a opts 
+	opts=('-m --menu
+	       -o --output
+	       -O --save
+	       -h --help
+	       -V --version')
+
+	COMPREPLY=( $(compgen -W "${opts[*]}" -- "${arg}") )
+}
+
+complete -F _zaman zaman

res/completions/zaman.fish

@@ -0,0 +1,7 @@
+complete -c zaman -f
+
+complete -c zaman -s m -l menu -d 'Print a menu via rofi or dmenu that lists every man pages to choose from (default operation)'
+complete -c zaman -s o -l output -d '(Args <man page> <file>) Save <man page> into the <file> PDF file'
+complete -c zaman -s O -l save -d '(Arg <man page>) Save <man page> into the "man_<man page>.pdf" file in the current directory'
+complete -c zaman -s h -l help -d 'Display the help message'
+complete -c zaman -s V -l version -d 'Display version information'

res/completions/zaman.zsh

@@ -0,0 +1,12 @@
+#compdef zaman
+
+local -a opts
+opts=(
+    {-m,--menu}'[Print a menu via rofi or dmenu that lists every man pages to choose from (default operation)]'
+    {-o,--output}'[(Args <man page> <file>) Save <man page> into the <file> PDF file]'
+    {-O,--save}'[(Arg <man page>) Save <man page> into the "man_<man page>.pdf" file in the current directory]'
+    {-h,--help}'[Display the help message]'
+    {-V,--version}'[Display version information]'
+)
+
+_arguments $opts