# -*-eselect-*-  vim: ft=eselect
# Copyright 2014 Gentoo Foundation
# Distributed under the terms of the GNU GPL version 2 or later

DESCRIPTION="Manage the rust compiler versions"
MAINTAINER="jauhien@gentoo.org"
VERSION="0.1"

inherit package-manager path-manipulation

SITELISP=/usr/share/emacs/site-lisp
SITEVIM=/usr/share/vim/vimfiles
SITEZSH=/usr/share/zsh/site-functions

# find a list of installed rust compilers
find_targets() {
	local f
	local version
	for f in "${EROOT}"/usr/bin/rustc-*; do
		version=""
		[[ -x ${f} ]] && version=`basename "${f}" | awk -F"-" '{ print $2 }'`
		has_version "=dev-lang/rust-${version}" && echo ${version}
	done
}

# remove symlink if exists

remove_symlink() {
	local symlink=$1

	if [[ -L ${symlink} ]]; then
		# existing symlink
		rm ${symlink} || die -q "Couldn't remove existing symlink ${symlink}"
	elif [[ -e ${symlink} ]]; then
		# we have something strange
		die -q "${symlink} exists but is not a symlink"
	fi
}

# Regenerate the site-gentoo.el file, based on packages' site
# initialisation files in the /usr/share/emacs/site-lisp/site-gentoo.d/
# directory.
# A slightly changed function from elisp-common.eclass

elisp-site-regen() {
	local sitelisp=${EROOT}${SITELISP}
	local sf i ret=0 null="" page=$'\f'
	local -a sflist
	local T=${EROOT}/tmp/eselect

	mkdir -p "${T}" || die -q "temporary directory creation failed for ${T}"

	[[ -d ${sitelisp} ]] \
		|| die -q "elisp-site-regen: Directory ${sitelisp} does not exist"

	[[ -d ${T} ]] \
		|| die -q "elisp-site-regen: Temporary directory ${T} does not exist"

	for sf in "${sitelisp}"/site-gentoo.d/[0-9][0-9]*.el; do
		[[ -r ${sf} ]] && sflist+=("${sf}")
	done

	cat <<-EOF >"${T}"/site-gentoo.el || ret=$?
	;;; site-gentoo.el --- site initialisation for Gentoo-installed packages

	;;; Commentary:
	;; Automatically generated by eselect-rust
	;; DO NOT EDIT THIS FILE

	;;; Code:
	EOF
	# Use sed instead of cat here, since files may miss a trailing newline.
	sed '$q' "${sflist[@]}" </dev/null >>"${T}"/site-gentoo.el || ret=$?
	cat <<-EOF >>"${T}"/site-gentoo.el || ret=$?

	${page}
	(provide 'site-gentoo)

	;; Local ${null}Variables:
	;; no-byte-compile: t
	;; buffer-read-only: t
	;; End:

	;;; site-gentoo.el ends here
	EOF

	if [[ ${ret} -ne 0 ]]; then
		die -q "elisp-site-regen: Writing site-gentoo.el failed."
	else
		mv "${T}"/site-gentoo.el "${sitelisp}"/site-gentoo.el || \
			die -q "elisp-site-regen: Replacing site-gentoo.el failed"
	fi

	rm -rf "${T}"
	true
}

# set symlink if source exists

set_symlink() {
	local source=$1
	local dest=$2

	if [[ -e ${source} ]]; then
		mkdir -p "$(dirname ${dest})" || die -q "directory creation failed for $(dirname ${dest})"
		ln -s "${source}" "${dest}" || die -q "${dest} symlink setting failed"
	else
		false
	fi
}

# unset the rust version

unset_version() {
	remove_symlink "${EROOT}"/usr/bin/rustc
	remove_symlink "${EROOT}"/usr/bin/rustdoc
	remove_symlink "${EROOT}/${SITELISP}"/rust-mode
	remove_symlink "${EROOT}/${SITELISP}"/site-gentoo.d/50rust-mode-gentoo.el

	for i in after/syntax autoload ftdetect ftplugin indent plugin syntax; do
		remove_symlink "${EROOT}/${SITEVIM}/${i}/rust.vim"
	done
	for i in compiler syntax_checkers/rust; do
		remove_symlink "${EROOT}/${SITEVIM}/${i}/rustc.vim"
	done
	remove_symlink "${EROOT}/${SITEVIM}/doc/rust.txt"

	remove_symlink "${EROOT}/${SITEZSH}/_rust"
}

# set the rust version

set_version() {
	local target=$1

	if is_number "${target}"; then
		local targets=( $(find_targets) )
		target=${targets[target-1]}
	fi

	[[ -z ${target} || ! -x "${EROOT}/usr/bin/rustc-${target}" ]] \
		&& die -q "Target \"$1\" doesn't appear to be valid!"

	unset_version

	ln -s "${EROOT}/usr/bin/rustc-${target}" "${EROOT}/usr/bin/rustc" || die -q "rustc symlink setting failed"
	ln -s "${EROOT}/usr/bin/rustdoc-${target}" "${EROOT}/usr/bin/rustdoc" || die -q "rustdoc symlink setting failed"

	local datadir="${EROOT}/usr/share/rust-${target}"

	set_symlink "${datadir}/emacs/site-lisp/rust-mode" "${EROOT}/${SITELISP}/rust-mode" && \
		set_symlink "${datadir}/emacs/site-lisp/site-gentoo.d/50rust-mode-gentoo.el" \
		"${EROOT}/${SITELISP}/site-gentoo.d/50rust-mode-gentoo.el" && \
		elisp-site-regen

	local rustvimdir="${datadir}/vim/vimfiles"
	for i in after/syntax autoload ftdetect ftplugin indent plugin syntax; do
		set_symlink "${rustvimdir}/${i}/rust.vim" "${EROOT}/${SITEVIM}/${i}/rust.vim"
	done
	for i in compiler syntax_checkers/rust; do
		set_symlink "${rustvimdir}/${i}/rustc.vim" "${EROOT}/${SITEVIM}/${i}/rustc.vim"
	done
	set_symlink "${rustvimdir}/doc/rust.txt" "${EROOT}/${SITEVIM}/doc/rust.txt"

	set_symlink "${datadir}/zsh/site-functions/_rust" "${EROOT}/${SITEZSH}/_rust"

	true
}

### list action ###

describe_list() {
	echo "List available rust versions"
}

do_list() {
	local i targets=( $(find_targets) )

	write_list_start "Available rust versions:"
    for (( i = 0; i < ${#targets[@]}; i++ )); do
        # highlight the target where the symlink is pointing to
        [[ rustc-${targets[i]} = \
            $(basename "$(canonicalise "${EROOT}/usr/bin/rustc")") ]] \
            && targets[i]=$(highlight_marker "${targets[i]}")
    done
    write_numbered_list -m "(none found)" "${targets[@]}"
}

### set action ###

describe_set() {
	echo "Set active rust version"
}

describe_set_parameters() {
    echo "<target>"
}

describe_set_options() {
    echo "target : Target number (from 'list' action)"
}

do_set() {
    [[ -z $1 ]] && die -q "You didn't tell me what to set the version to"
    [[ $# -gt 1 ]] && die -q "Too many parameters"

	set_version "$1" || die -q "Couldn't set new active version"
}

### update action ###

describe_update() {
	echo "Switch to the most recent rust compiler"
}

describe_update_options() {
	echo "--if-unset    : Do not override existing implementation"
}

do_update() {
	local if_unset="0"
	while [[ $# > 0 ]]; do
		case "$1" in
			--if-unset)
				if_unset="1"
				;;
			*)
				die -q "Unrecognized argument '$1'"
				;;
		esac
		shift
	done

	if [[ "${if_unset}" == "1" && -f "${EROOT}"/usr/bin/rustc ]]; then
		return
	fi

	local targets=( $(find_targets) )
	do_set ${#targets[@]}
}

### unset action ###

describe_unset() {
	echo "Unset active rust version"
}

do_unset() {
    [[ $# -gt 0 ]] && die -q "Too many parameters"

	unset_version || die -q "Couldn't unset active version"
}