#!/bin/sh
# Download a published Drum release without a compiler or sudo.
set -eu

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

for tool in curl tar uname mktemp awk; do
    command -v "$tool" >/dev/null 2>&1 || fail "$tool is required."
done

# Choose a release for this operating system and architecture.
case "$(uname -s)" in
    Darwin) os=apple-darwin ;;
    Linux) os=unknown-linux-musl ;;
    *) fail 'Supported platforms: macOS and Linux.' ;;
esac

case "$(uname -m)" in
    arm64|aarch64) arch=aarch64 ;;
    x86_64|amd64) arch=x86_64 ;;
    *) fail 'Supported architectures: Intel/AMD 64-bit and ARM64.' ;;
esac

target="$arch-$os"
base=https://github.com/drumhq/drum-cli/releases

fetch() {
    curl --fail --silent --show-error --location \
        --proto '=https' --proto-redir '=https' --tlsv1.2 \
        --connect-timeout 10 --max-time 180 --max-filesize 100000000 \
        "$1" -o "$2"
}

work=$(mktemp -d "${TMPDIR:-/tmp}/drum-install.XXXXXXXX") || fail 'Could not create a temporary directory.'
staged=

cleanup() {
    rm -rf "$work"

    if [ -n "$staged" ]; then
        rm -f "$staged"
    fi
}

trap cleanup EXIT
trap 'exit 1' HUP INT TERM

# Resolve the latest published version, then pin all downloads to its tag.
fetch "$base/latest/download/version.txt" "$work/version.txt" || fail 'No published CLI release is available. Please try again later.'

[ "$(wc -c < "$work/version.txt")" -le 128 ] || fail 'Invalid release version.'
version=$(cat "$work/version.txt")

case "$version" in
    *[!0-9.]*) fail 'Invalid release version.' ;;
esac

printf '%s\n' "$version" | LC_ALL=C grep -Eq '^[0-9]+\.[0-9]+\.[0-9]+$' || fail 'Invalid release version.'

asset="drum-$target.tar.gz"

fetch "$base/download/v$version/$asset" "$work/$asset" || fail 'Could not download this platform’s release.'
fetch "$base/download/v$version/$asset.sha256" "$work/checksum" || fail 'Could not download the checksum.'

# Verify the archive before extracting or replacing an installed binary.
expected=$(awk -v file="$asset" '$2 == file { print $1 }' "$work/checksum")
[ "${#expected}" -eq 64 ] || fail 'Invalid checksum file.'

case "$expected" in
    *[!0-9a-fA-F]*) fail 'Invalid checksum.' ;;
esac

if command -v sha256sum >/dev/null 2>&1; then
    actual=$(sha256sum "$work/$asset" | awk '{print $1}')
elif command -v shasum >/dev/null 2>&1; then
    actual=$(shasum -a 256 "$work/$asset" | awk '{print $1}')
else
    fail 'sha256sum or shasum is required.'
fi

[ "$actual" = "$expected" ] || fail 'Checksum verification failed; nothing was installed.'

# The release archive must contain exactly one regular file named drum.
[ "$(tar -tzf "$work/$asset")" = drum ] || fail 'Invalid release archive.'
[ "$(tar -tvzf "$work/$asset" | cut -c 1)" = '-' ] || fail 'Invalid release entry type.'

tar -xzf "$work/$asset" -C "$work" drum

[ -f "$work/drum" ] && [ ! -L "$work/drum" ] || fail 'Invalid binary.'
chmod 755 "$work/drum"

[ "$("$work/drum" --version)" = "drum $version" ] || fail 'Downloaded binary has an unexpected version.'

# Update an existing user installation, or install into ~/.local/bin.
: "${HOME:?HOME is required}"
install_dir=${DRUM_INSTALL_DIR:-}

if [ -z "$install_dir" ]; then
    existing=$(command -v drum 2>/dev/null || true)

    case "$existing" in
        "$HOME"/*)
            if [ -f "$existing" ] && [ ! -L "$existing" ] && [ -w "$(dirname "$existing")" ]; then
                install_dir=$(dirname "$existing")
            fi
            ;;
    esac
fi

install_dir=${install_dir:-"$HOME/.local/bin"}

case "$install_dir" in
    /*) ;;
    *) fail 'Install directory must be an absolute path.' ;;
esac

mkdir -p "$install_dir"
[ ! -L "$install_dir/drum" ] || fail 'Refusing to overwrite a symlink named drum.'

staged=$(mktemp "$install_dir/.drum.XXXXXXXX") || fail 'Install directory is not writable.'

cp "$work/drum" "$staged"
chmod 755 "$staged"
mv -f "$staged" "$install_dir/drum"
staged=

printf 'Installed Drum %s to %s/drum\n' "$version" "$install_dir"

case ":${PATH:-}:" in
    *":$install_dir:"*)
        printf 'Get started: drum init\n'
        ;;
    *)
        printf 'Add this directory to PATH in your shell configuration:\n  export PATH="%s:$PATH"\n' "$install_dir"
        ;;
esac