# Copyright 1999-2017 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Id: $

DESCRIPTION="Manage Python interpreter preferences"
MAINTAINER="python@gentoo.org"
VERSION=@VERSION@

CONFIG_PATH="${EROOT%/}/etc/python-exec/python-exec.conf"
ENV_D_PATH="${EROOT%/}/etc/env.d"
INTERPRETER_DIR="${EROOT%/}/usr/bin"
MAN_PATH="${EROOT%/}/usr/share/man/man1"

# Get list of all installed Python interpreters, in lexical order.
# $1 can be --pyN to filter results to pythonN.?.
get_installed_pythons() {
	local i

	# get complete list from python-exec
	while read i; do
		# filter by type
		[[ ${1} == --py* && ${i} != python${1:4}* ]] && continue
		# filter to installed only
		if [[ -x ${INTERPRETER_DIR}/${i} ]]; then
			echo "${i}"
		fi
	done < <(python-exec2c -l)
}

# Get list of all preference values from python-exec.conf. This
# includes both preferred implementations (in preference order)
# and disabled interpreters.
get_all_preferences() {
	[[ -e ${CONFIG_PATH} ]] || return

	local l
	while read l; do
		# skip comments
		[[ ${l} == '#'* ]] && continue

		# note: empty lines are stripped through word splitting
		echo "${l}"
	done <"${CONFIG_PATH}"
}

# Get list of preferred Python interpreters, from python-exec.conf,
# in preference order.
# $1 can be --pyN to filter results to pythonN.?.
get_preferred_pythons() {
	local i
	for i in $(get_all_preferences); do
		# skip negative entries
		[[ ${i} == -* ]] && continue
		# apply filters
		[[ ${1} == --py* && ${i} != python${1:4}* ]] && continue

		echo "${i}"
	done
}

# Get list of explicitly disabled Python interpreters, from
# python-exec.conf, in file order.
get_disabled_pythons() {
	local i
	for i in $(get_all_preferences); do
		# process only negative entries
		[[ ${i} == -* ]] || continue

		echo "${i#-}"
	done
}

# Get combined list of preferred, installed and disabled Python
# interpreters, in preference order.
# $1 can be --pyN to filter results to pythonN.?.
get_all_pythons() {
	local targets=( $(get_installed_pythons "${@}") )
	local preferred=( $(get_preferred_pythons "${@}") )
	local disabled=( $(get_disabled_pythons "${@}") )
	local i

	# preferred first
	for i in "${preferred[@]}"; do
		echo "${i}"
	done
	# active then
	for i in "${targets[@]}"; do
		has "${i}" "${preferred[@]}" && continue
		has "${i}" "${disabled[@]}" && continue
		echo "${i}"
	done
	# disabled last
	for i in "${targets[@]}"; do
		has "${i}" "${disabled[@]}" || continue
		echo "${i}"
	done
}

# Write new preference list. Preferences need to be passed
# as parameters (${@}).
write_preferences() {
	if [[ -e ${CONFIG_PATH} ]]; then
		sed -n -e '/^#/p' "${CONFIG_PATH}" > "${CONFIG_PATH}".new || die
	fi

	local IFS=$'\n'
	echo "${*}" >> "${CONFIG_PATH}".new || die

	mv "${CONFIG_PATH}".new "${CONFIG_PATH}" || die
}

# Set a man page symlink
set_man_symlink() {
	local target=${1}

	rm -f "${MAN_PATH}"/python.1{,.{gz,bz2,lzma,xz,lz,zst{,d}}} || die
	echo ".so ${target}.1" > "${MAN_PATH}"/python.1 || die
}

# Set OSX framework symlinks
set_osx_framework() {
	local target=${1}

	# Files of Mac OS X framework
	local framework_dir="${INTERPRETER_DIR%/bin}"/lib/Python.framework
	if [[ -d ${framework_dir} ]]; then
		local version=${target#python}
		pushd "${framework_dir}" >/dev/null || die
		rm -f Headers Python Resources || die
		ln -nfs "Versions/${version}/Headers" || die
		ln -nfs "Versions/${version}/Python" || die
		ln -nfs "Versions/${version}/Resources" || die
		popd >/dev/null || die
	fi
}

# Set the content of /etc/env.d/65python-docs
set_python_docs() {
	local path target=${1#python} variable
	rm -f "${ENV_D_PATH}/65python-docs" || die
	if [[ -f ${ENV_D_PATH}/60python-docs-${target} ]]; then
		variable="PYTHONDOCS_${target//./_}"
		path="$(. "${ENV_D_PATH}/60python-docs-${target}"; echo "${!variable}")"
		if [[ -d ${path} ]]; then
			echo "PYTHONDOCS=\"${path}\"" > "${ENV_D_PATH}/65python-docs"
		fi
	fi
}

# Perform all necessary updates following preference list change.
post_update() {
	local main_cpython=$(do_show --cpython)

	# TODO: update only when necessary

	set_man_symlink "${main_cpython}"
	set_osx_framework "${main_cpython}"
	set_python_docs "${main_cpython}"
}

### cleanup action ###

describe_cleanup() {
	echo "Remove stale implementations from list"
}

do_cleanup() {
	local installed=( $(get_installed_pythons) )
	local prefs=( $(get_all_preferences) )

	local i target_idx
	local num_prefs=${#prefs[@]}
	for (( i = 0; i < num_prefs; ++i )); do
		# remove preferences for uninstalled interpreters
		if ! has "${prefs[i]#-}" "${installed[@]}"; then
			unset 'prefs[i]'
		fi
	done

	umask 022
	write_preferences "${prefs[@]}"

	post_update
}

### show action ###

describe_show() {
	echo "Show the most preferred Python interpreter"
}

describe_show_options() {
	echo "--cpython     : show the preferred version of CPython"
	echo "--pref-only   : consider only explicitly preferred impls"
	echo "--python2     : show the preferred version of CPython 2"
	echo "--python3     : show the preferred version of CPython 3"
}

do_show() {
	local filter interpreter pref_only
	while [[ ${#} -gt 0 ]]; do
		case ${1} in
			--cpython|--py)
				filter=--py
				;;
			--pref-only)
				pref_only=1
				;;
			--python2|--py2)
				filter=--py2
				;;
			--python3|--py3)
				filter=--py3
				;;
			*)
				die -q "Unrecognized argument '$1'"
				;;
		esac
		shift
	done

	local preferred=( $(get_preferred_pythons ${filter}) )
	local installed=( $(get_installed_pythons ${filter}) )

	local all=( "${preferred[@]}" )
	# preferred are preferred, but fall back to anything
	[[ ${pref_only} ]] || all+=( "${installed[@]}" )

	local i
	for i in "${all[@]}"; do
		# skip if not installed
		has "${i}" "${installed[@]}" || continue
		interpreter=${i}
		break
	done

	echo "${interpreter}"
}

### edit action ###

describe_edit() {
	echo "Edit the interpreter preference list"
}

do_edit() {
	[[ ${EDITOR} ]] || die "EDITOR is not set"

	${EDITOR} "${CONFIG_PATH}"

	post_update
}

### show action ###

describe_show() {
	echo "Show the most preferred Python interpreter"
}

describe_show_options() {
	echo "--cpython     : show the preferred version of CPython"
	echo "--pref-only   : consider only explicitly preferred impls"
	echo "--python2     : show the preferred version of CPython 2"
	echo "--python3     : show the preferred version of CPython 3"
}

do_show() {
	local filter interpreter pref_only
	while [[ ${#} -gt 0 ]]; do
		case ${1} in
			--cpython|--py)
				filter=--py
				;;
			--pref-only)
				pref_only=1
				;;
			--python2|--py2)
				filter=--py2
				;;
			--python3|--py3)
				filter=--py3
				;;
			*)
				die -q "Unrecognized argument '$1'"
				;;
		esac
		shift
	done

	local preferred=( $(get_preferred_pythons ${filter}) )
	local installed=( $(get_installed_pythons ${filter}) )

	local all=( "${preferred[@]}" )
	# preferred are preferred, but fall back to anything
	[[ ${pref_only} ]] || all+=( "${installed[@]}" )

	local i
	for i in "${all[@]}"; do
		# skip if not installed
		has "${i}" "${installed[@]}" || continue
		interpreter=${i}
		break
	done

	echo "${interpreter}"
}

### list action ###

describe_list() {
	echo "List installed Python interpreters"
}

describe_list_options() {
	echo "--cpython     : list only CPython interpreters"
	echo "--python2     : list only CPython 2 interpreters"
	echo "--python3     : list only CPython 3 interpreters"
}

do_list() {
	local filter
	while [[ ${#} -gt 0 ]]; do
		case ${1} in
			--cpython|--py)
				filter=--py
				;;
			--python2|--py2)
				filter=--py2
				;;
			--python3|--py3)
				filter=--py3
				;;
			*)
				die -q "Unrecognized argument '$1'"
				;;
		esac
		shift
	done

	local all=( $(get_all_pythons ${filter}) )
	local installed=( $(get_installed_pythons ${filter}) )
	local preferred=( $(get_preferred_pythons ${filter}) )
	local disabled=( $(get_disabled_pythons) )

	write_list_start "Available Python${filter+ ${filter#--py}} interpreters, in order of preference:"

	for (( i = 0; i < ${#all[@]}; ++i )); do
		if has "${all[i]}" "${disabled[@]}"; then
			all[i]=$(highlight_marker "${all[i]}" "$(highlight_warning "(disabled)")")
		elif ! has "${all[i]}" "${installed[@]}"; then
			all[i]=$(highlight_marker "${all[i]}" "$(highlight_warning "(uninstalled)")")
		elif ! has "${all[i]}" "${preferred[@]}"; then
			all[i]=$(highlight_marker "${all[i]}" "(fallback)")
		fi
	done
	write_numbered_list -m "(none found)" "${all[@]}"
}

### set action ###

describe_set() {
	echo "Set the preferred Python interpreter"
}

describe_set_options() {
	echo "--cpython     : update preference for CPython versions only"
	echo "--python2     : update preference for CPython 2 versions only"
	echo "--python3     : update preference for CPython 3 versions only"
}

describe_set_parameters() {
	echo "<target>"
}

do_set() {
	local filter
	while [[ ${#} -gt 0 ]]; do
		case ${1} in
			--cpython|--py)
				filter=--py
				;;
			--python2|--py2)
				filter=--py2
				;;
			--python3|--py3)
				filter=--py3
				;;
			*)
				break
				;;
		esac
		shift
	done

	[[ ${#} -eq 1 ]] || die "Usage: eselect python set <interpreter>"

	local target=${1}
	local targets=( $(get_all_pythons ${filter}) )
	if is_number "${target}" \
		&& [[ ${target} -ge 1 && ${target} -le ${#targets[@]} ]]
	then
		target=${targets[target-1]}
	fi

	has "${target}" "${targets[@]}" || die "Invalid target: ${target}"

	local prefs=( $(get_all_preferences) )

	local i target_idx
	local num_prefs=${#prefs[@]}
	for (( i = 0; i < num_prefs; ++i )); do
		# find first positive preference matching the filter
		if [[ ! ${target_idx} ]]; then
			if [[ ( ${filter} == --py? && ${prefs[i]} == python${filter:4}* ) \
				|| ( ! ${filter} && ${prefs[i]} != -* ) ]]
			then
				target_idx=${i}
			fi
		fi

		# remove all duplicate positive and negative entries for target
		[[ ${prefs[i]#-} == ${target} ]] && unset 'prefs[i]'
	done
	# if none matched, add to the bottom
	: "${target_idx=${num_prefs}}"

	# add between remaining preferences, before the one matching
	# need to do this outta loop in case no pref matches
	prefs=( "${prefs[@]:0:target_idx}" "${target}" "${prefs[@]:target_idx}" )

	umask 022
	write_preferences "${prefs[@]}"
	post_update
}

### update action ###

describe_update() {
	echo "Switch to the most recent Python interpreter"
}

describe_update_options() {
	echo "--if-unset    : do not alter preferences unless there is no valid preference set"
	echo "--ignore SLOT : ignore specified Python slots"
	echo "--cpython     : update only CPython preferences"
	echo "--python2     : update only CPython 2 preferences (ignored)"
	echo "--python3     : update only CPython 3 preferences"
}

do_update() {
	local if_unset ignored_slots=() filter
	while [[ ${#} -gt 0 ]]; do
		case ${1} in
			--if-unset)
				if_unset=1
				;;
			--ignore)
				ignored_slots+=( "${2}" )
				shift
				;;
			--cpython|--py)
				filter=--py
				;;
			--python2|--py2)
				filter=--py2
				echo "Ignoring Python 2 preference update as non-meaningful"
				return 0
				;;
			--python3|--py3)
				filter=--py3
				;;
			*)
				die -q "Unrecognized argument '$1'"
				;;
		esac
		shift
	done

	if [[ ${if_unset} ]]; then
		local current=$(do_show ${filter} --pref-only)

		[[ ${current} ]] && return
	fi

	local targets=( $(get_installed_pythons ${filter}) )

	# Ignore slots
	local slot
	for slot in ${ignored_slots[@]}; do
		targets=( ${targets[@]/python${slot}/} )
	done

	if [[ ${targets[@]} ]]; then
		local target=${targets[0]}
		echo "Switching to ${target}"
		do_set ${filter} "${target}"
	else
		die -q "No Python interpreter available"
	fi
}

# vim: set ft=eselect :