#!/bin/sh
set -eu

BASE_URL=${DTR_BASE_URL:-https://dtr.dtrm.tech}
TARGET=${DTR_TARGET:-/usr/local/bin/dtr}
TMP_FILE=$(mktemp)

cleanup() {
    rm -f "$TMP_FILE"
}
trap cleanup EXIT HUP INT TERM

fetch() {
    if command -v curl >/dev/null 2>&1; then
        curl -fsSL "$BASE_URL/dtr" -o "$TMP_FILE"
    elif command -v wget >/dev/null 2>&1; then
        wget -qO "$TMP_FILE" "$BASE_URL/dtr"
    else
        printf '%s\n' 'error: curl or wget is required' >&2
        exit 1
    fi
}

install_dtr() {
    if [ "$(id -u)" -eq 0 ]; then
        install -Dm755 "$TMP_FILE" "$TARGET"
    elif command -v sudo >/dev/null 2>&1; then
        sudo install -Dm755 "$TMP_FILE" "$TARGET"
    else
        printf '%s\n' 'error: sudo is required to install into /usr/local/bin' >&2
        exit 1
    fi
}

command -v bash >/dev/null 2>&1 || {
    printf '%s\n' 'error: bash is required' >&2
    exit 1
}
command -v install >/dev/null 2>&1 || {
    printf '%s\n' 'error: install from GNU coreutils is required' >&2
    exit 1
}

fetch
[ -s "$TMP_FILE" ] || {
    printf '%s\n' 'error: downloaded file is empty' >&2
    exit 1
}

bash -n "$TMP_FILE"
install_dtr

printf 'Installed dtr to %s\n' "$TARGET"
"$TARGET" --version