# Copyright 1999-2020 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

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

ENV_D_PATH="${EROOT%/}/etc/env.d"
BIN_DIR="${EROOT%/}/usr/bin"

inherit package-manager path-manipulation

# find a list of missing or broken symlinks
# each compiler installs a list of provided programs.
# this function checks if a symlink for a provided program
# is missing or broken for the current active Rust implementation
find_missing_broken_symlinks() {
	local -a missing_symlinks
	local required_symlinks=( "/usr/bin/rustc" $(get_last_set_symlinks) )

	local target=$(get_current_target)
	if [ "${target}" != "NOT_SET" ]; then
		# make sure we add new symlinks for new targets,
		# i.e. after changed USE flags
		required_symlinks+=( $(get_symlinks ${target}) )
	fi

	required_symlinks=( $(printf "%s\n" "${required_symlinks[@]}" | sort -u) )

	local i
	for i in "${required_symlinks[@]}"; do
		local symlink="${EROOT%/}${i}"

		if [[ -L "${symlink}" && -e "${symlink}" ]]; then
			# existing symlink
			continue
		else
			missing_symlinks+=( "${symlink}" )
		fi
	done

	echo "${missing_symlinks[@]}"
}

# find a list of installed rust compilers
# each compiler provider should install
# a config file named provider-$pkgname-$pkgver
# in "${ENV_D_PATH}/rust" directory
# this function prints list of $pkgname-$pkgver values
find_targets() {
	local f fn
	local -a providers
	local -a providers_unsorted
	local -a providers_sorted
	for f in "${ENV_D_PATH}"/rust/provider-*; do
		[[ -f ${f} ]] || continue
		fn="${f##*/provider-}"
		if [[ "${fn}" == rust-bin-* ]]; then
			providers_unsorted+=( "${fn##rust-bin-}-mysortA" )
		elif [[ "${fn}" == rust-* ]]; then
			providers_unsorted+=( "${fn##rust-}-mysortZ" )
		else
			die -q "Unsupported rust provider file '${f}' found."
		fi
	done

	IFS=$'\n' LC_COLLATE=C providers_sorted=( $(sort <<<"${providers_unsorted[*]}") )

	for fn in "${providers_sorted[@]}"; do
		if [[ "${fn}" == *-mysortA ]]; then
			providers+=( "rust-bin-${fn%%-mysortA}" )
		else
			providers+=( "rust-${fn%%-mysortZ}" )
		fi
	done

	echo "${providers[@]}"
}

#get rustc postfix
get_postfix() {
	local target=$1
	echo "${target}" | cut -d- -f2-
}

#get current target
get_current_target() {
	local i targets=( $(find_targets) )
	for (( i = 0; i < ${#targets[@]}; i++ )); do
		if [[ rustc-$(get_postfix ${targets[i]}) = \
			$(basename "$(canonicalise "${BIN_DIR}/rustc")") ]]; then
			echo $i
			return 0
		fi
	done
	echo "NOT_SET"
}

#get symlinks list from file or the default value
get_symlinks_from_file() {
	local filename=$1
	local symlinks=()
	local i
	if [[ -e ${filename} ]]; then
		for i in $(cat "${filename}"); do
			symlinks+=($i)
		done
	fi

	if [ ${#symlinks[@]} -eq 0 ]; then
		echo /usr/bin/rustdoc
	else
		echo "${symlinks[@]}"
	fi

}

#get last set symlinks
get_last_set_symlinks() {
	local symlinks=( $(get_symlinks_from_file "${ENV_D_PATH}/rust/last-set") )
	echo "${symlinks[@]}"
}

#get lists of symlinks
get_symlinks() {
	local target=$1
	if [ "${target}" == "NOT_SET" ]; then
		echo /usr/bin/rustdoc
		return
	fi
	if is_number "${target}"; then
		local targets=( $(find_targets) )
		target=${targets[target]}
	fi

	local symlinks=( $(get_symlinks_from_file "${ENV_D_PATH}/rust/provider-${target}") )
	echo "${symlinks[@]}"
}

# 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
}

# set symlink if source exists
set_symlink() {
	local source=$1
	local dest=$2

	remove_symlink "${dest}"

	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() {
	local symlinks=( $(get_last_set_symlinks) )
	for i in "${symlinks[@]}"; do
		remove_symlink "${EROOT%/}${i}"
	done
	remove_symlink "${BIN_DIR}/rustc"
	rm -f "${ENV_D_PATH}/rust/last-set" \
		|| die -q "rm -f ${ENV_D_PATH}/rust/last-set failed"
}

# set the rust version
# each compiler provider should install
# files named rustc-$postfix and rustdoc-$postfix
# in ${BIN_DIR} directory
# $postfix is defined as the part of $pkgname-$pkgver after the first -
# for dev-lang/rust-bin-9999 ebuild it would be bin-9999
set_version() {
	local target=$1

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

	target_postfix=$(get_postfix ${target})

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

	unset_version

	set_symlink "${BIN_DIR}/rustc-${target_postfix}" "${BIN_DIR}/rustc"

	local symlinks=( $(get_symlinks ${target}) )
	for i in "${symlinks[@]}"; do
		set_symlink "${EROOT%/}${i}-${target_postfix}" "${EROOT%/}${i}"
	done

	cp "${ENV_D_PATH}/rust/provider-${target}" \
		"${ENV_D_PATH}/rust/last-set" \
		|| die -q "symlink list copying failed"
}

### cleanup action ###
describe_cleanup() {
	echo "This action is not to be called manually."
}

do_cleanup() {
	[[ -z ${@} ]] || die -q "This function does not expect any arguments"

	# Do we need to clean up?
	local missing_symlinks=( $(find_missing_broken_symlinks) )
	if [[ ${#missing_symlinks[@]} -eq 0 ]]; then
		echo "Nothing to clean up."
		return
	fi

	unset_version

	local targets=( $(find_targets) )

	if [[ ${#targets[@]} -ne 0 ]]; then
		echo "Marking the latest still installed version as default..."
		do_set ${#targets[@]}
	else
		echo "No Rust profiles left on the system. Stale symlinks removed."
	fi
}

### list action ###

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

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

	if is_number "${target}"; then
		targets[target]=$(highlight_marker "${targets[target]}")
	fi

	write_list_start "Available Rust versions:"
	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"
}

### show action ###

describe_show() {
	echo "Show the current Rust implementation"
}

do_show() {
	[[ -z "${@}" ]] || die -q "Too many parameters"
	write_list_start "Current Rust implementation:"

	local targets=( $(find_targets) )
	local target=$(get_current_target)

	if is_number "${target}"; then
		write_kv_list_entry "${targets[target]}" ""
	else
		write_kv_list_entry "(unset)" ""
	fi
}

### 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" ]]; then
		local missing_symlinks=( $(find_missing_broken_symlinks) )
		if [[ ${#missing_symlinks[@]} -eq 0 ]]; then
			return
		else
			echo "Not all symlinks set. Will switch to the most recent Rust compiler!"
		fi
	fi

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

### unset action ###

describe_unset() {
	echo 'DEPRECATED: Use "cleanup" action instead!'
}

do_unset() {
	do_cleanup
}

# vim: set ft=eselect :