discord-upgrade

#!/bin/sh
set -eux

BRANCH=canary

ICONDIR="${XDG_DATA_HOME:=$HOME/.local/share}/icons"
APPDIR="$XDG_DATA_HOME/applications"
DISCORDDIR="$HOME/.local/opt/discord-$BRANCH"
mkdir -p "$ICONDIR" "$APPDIR" "$DISCORDDIR"

fail() {
    printf '%s: %s\n' "$(basename "$0")" "$1"
}

WORKDIR="$(mktemp -td discord-upgradeXXXXXX)"
trap 'rm -r "$WORKDIR"' EXIT

download_url="https://discord.com/api/download/$BRANCH?platform=linux&format=tar.gz"
etag="$(curl -fsSLI "$download_url" |
        grep -i '^etag:' |
        tail -n 1 |
        # assumes that the etag is hexadecimal, but Discord shouldn't return anything else
        sed 's/^etag:[[:space:]]*"\([[:xdigit:]]\+\)"\r/\1/')"

versionfile="$DISCORDDIR/.discord_upgrade"
touch "$versionfile"
if [ "$(cat "$versionfile")" != "$etag" ]; then
    cd "$WORKDIR"
    curl -fsSLo discord.tar.gz "$download_url"
    mkdir out
    tar -C out -xf discord.tar.gz
    [ "$(echo out/* | wc -l)" -ne 1 ] && fail "discord extracted into more than one top level dir"

    cp -f out/*/*.png "$ICONDIR/"

    sed -i -e '/Path=/d' -e "s%/usr/share/discord[[:alpha:]-]*/%$DISCORDDIR/%" out/*/*.desktop
    mv out/*/*.desktop "$APPDIR/"

    rsync -a out/*/ "$DISCORDDIR/"
    printf '%s\n' "$etag" > "$versionfile"
fi