#!/bin/sh
# Installs LuaXE on Linux x86_64 from https://luaxe.dev
#
#   curl -fsSL https://luaxe.dev/install | sh
#
# Puts lxe in ${LXE_HOME:-$HOME/.lxe}/bin and symlinks ~/.local/bin/lxe,
# installing the LuaJIT runtime (libluajit-5.1.so) next to it. Run it again to
# update; no root privileges are needed. Remove everything again with:
#
#   rm -f ~/.local/bin/lxe "$HOME/.lxe/bin/lxe" "$HOME/.lxe/bin/libluajit-5.1.so"
#
# Optional environment variables (they belong on sh's side of the pipe):
#   curl -fsSL https://luaxe.dev/install | LUAXE_URL=http://localhost:4321 sh
#   LUAXE_URL=http://localhost:4321  download from another server
#   LXE_HOME=/opt/lxe                  lxe's home (bin/), as lxe itself reads it
set -eu

base=${LUAXE_URL:-https://luaxe.dev}
case "$base" in
    */) base=$(expr "$base" : '\(.*[^/]\)/*$' || true) ;;
esac

fail() {
    printf '%s\n' "install: $*" >&2
    exit 1
}

[ "$(uname -s 2>/dev/null || echo unknown)" = Linux ] || \
    fail "LuaXE's Linux build only runs on Linux x86_64"
[ "$(uname -m 2>/dev/null || echo unknown)" = x86_64 ] || \
    fail "LuaXE's Linux build only runs on Linux x86_64"

if command -v curl >/dev/null 2>&1; then
    fetch() { curl -fsSL --max-time 120 "$1" -o "$2"; }
elif command -v wget >/dev/null 2>&1; then
    fetch() { wget -q -O "$2" "$1"; }
else
    fail "need curl or wget to download LuaXE"
fi

if command -v sha256sum >/dev/null 2>&1; then
    file_hash() { sha256sum "$1" | cut -d ' ' -f 1; }
elif command -v shasum >/dev/null 2>&1; then
    file_hash() { shasum -a 256 "$1" | cut -d ' ' -f 1; }
else
    fail "need sha256sum or shasum to verify the download"
fi

home=${LXE_HOME:-${HOME:?'install: HOME is not set'}/.lxe}
case "$home" in
    /*) : ;;
    *) fail "LXE_HOME must be an absolute path" ;;
esac
bin_dir=$home/bin
link_dir=$HOME/.local/bin
link=$link_dir/lxe

printf 'Installing LuaXE to %s\n' "$bin_dir"
mkdir -p "$bin_dir" "$link_dir" || fail "could not create $bin_dir or $link_dir"

tmp_dir=$(mktemp -d 2>/dev/null || mktemp -d -t luaxe) || fail "could not make a temporary directory"
trap 'rm -rf "$tmp_dir"' EXIT INT TERM HUP

sha_lxe=$tmp_dir/lxe.sha256
sha_rt=$tmp_dir/libluajit.sha256
bin_tmp=$tmp_dir/lxe
rt_tmp=$tmp_dir/libluajit-5.1.so

# Every checksum first: a server that is half updated changes nothing.
fetch "$base/get/linux-x86_64/sha256" "$sha_lxe" || fail "could not download the lxe checksum"
fetch "$base/runtime/linux-x86_64/libluajit-5.1.so/sha256" "$sha_rt" || fail "could not download the runtime checksum"
want_lxe=$(tr -d ' \t\r\n' < "$sha_lxe")
want_rt=$(tr -d ' \t\r\n' < "$sha_rt")
case "$want_lxe" in
    *[!0-9a-fA-F]*|'') fail "$base/get/linux-x86_64/sha256 did not return a checksum" ;;
esac
case "$want_rt" in
    *[!0-9a-fA-F]*|'') fail "$base/runtime/linux-x86_64/libluajit-5.1.so/sha256 did not return a checksum" ;;
esac
case ${#want_lxe} in
    64) : ;;
    *) fail "$base/get/linux-x86_64/sha256 did not return a checksum" ;;
esac
case ${#want_rt} in
    64) : ;;
    *) fail "$base/runtime/linux-x86_64/libluajit-5.1.so/sha256 did not return a checksum" ;;
esac

printf '  downloading lxe\n'
fetch "$base/get/linux-x86_64" "$bin_tmp" || fail "could not download lxe"
printf '  downloading libluajit-5.1.so\n'
fetch "$base/runtime/linux-x86_64/libluajit-5.1.so" "$rt_tmp" || fail "could not download libluajit-5.1.so"

got_lxe=$(file_hash "$bin_tmp")
got_rt=$(file_hash "$rt_tmp")
[ "$(printf '%s' "$got_lxe" | tr 'A-Z' 'a-z')" = "$(printf '%s' "$want_lxe" | tr 'A-Z' 'a-z')" ] || \
    fail "lxe failed its checksum (expected $want_lxe, got $got_lxe)"
[ "$(printf '%s' "$got_rt" | tr 'A-Z' 'a-z')" = "$(printf '%s' "$want_rt" | tr 'A-Z' 'a-z')" ] || \
    fail "libluajit-5.1.so failed its checksum (expected $want_rt, got $got_rt)"

if [ -f "$bin_dir/lxe" ] && [ "$(file_hash "$bin_dir/lxe")" = "$got_lxe" ] && \
    [ -f "$bin_dir/libluajit-5.1.so" ] && [ "$(file_hash "$bin_dir/libluajit-5.1.so")" = "$got_rt" ]; then
    printf '  lxe is up to date\n'
else
    mv -f "$bin_tmp" "$bin_dir/lxe" || fail "could not install $bin_dir/lxe"
    mv -f "$rt_tmp" "$bin_dir/libluajit-5.1.so" || fail "could not install $bin_dir/libluajit-5.1.so"
fi
chmod +x "$bin_dir/lxe" || fail "could not make $bin_dir/lxe executable"

if [ -e "$link" ] && [ ! -L "$link" ]; then
    fail "$link exists and is not a symlink; move it aside and run this again"
fi
ln -sf "$bin_dir/lxe" "$link" || fail "could not link $link"

printf '\nLuaXE is installed.\n'
printf '  lxe --help    show the toolchain commands\n'
printf '  docs: %s/docs\n' "$base"
case ":$PATH:" in
    *":$link_dir:"*) : ;;
    *) printf 'Add %s to PATH, for example:\n  export PATH="%s:$PATH"\n' "$link_dir" "$link_dir" ;;
esac
printf 'Uninstall: rm -f %s %s %s\n' "$link" "$bin_dir/lxe" "$bin_dir/libluajit-5.1.so"
trap - EXIT INT TERM HUP
rm -rf "$tmp_dir"