#!/usr/bin/env bash
set -eof pipefail

# This script is used to fetch HomeBrew bottles for PCRE and OpenSSL.

function get_gh_pkgs_token() {
    curl --fail -Ls -u "${GITHUB_USER}:${GITHUB_TOKEN}" https://ghcr.io/token | jq -r '.token'
}

function get_bottle_json() {
    brew info --json=v1 "${1}" | jq '.[0].bottle.stable.files.mojave'
}

function fetch_bottle() {
    if [[ -n "${BEARER_TOKEN}" ]]; then
        AUTH=("-H" "Authorization: Bearer ${BEARER_TOKEN}")
    else
        AUTH=("-u" "_:_") # WARNING: Unauthorized requests can be throttled.
    fi
    curl --fail -Ls "${AUTH[@]}" -o "${1}" "${2}"
}

if [[ $(uname) != "Darwin" ]]; then
    echo "This script is intended for use on macOS!" >&2
    exit 1
fi

if [[ $# -ne 1 ]]; then
    echo "usage: $0 <bottle_name>" >&2
    exit 1
fi
BOTTLE_NAME="${1}"
BOTTLE_PATH="/tmp/${BOTTLE_NAME}.tar.gz"

# GitHub Packages requires authentication.
GITHUB_USER="${GITHUB_USER:-_}"
GITHUB_TOKEN="${GITHUB_TOKEN:-_}"
if [[ "${GITHUB_USER}" == "_" ]] || [[ "${GITHUB_TOKEN}" == "_" ]]; then
    echo "No GITHUB_USER or GITHUB_TOKEN variable set!" >&2
    echo "GitHub Packages can throttle unauthorized requests." >&2
else
    echo "${BOTTLE_NAME} - Fetching GH Pkgs Token"
    BEARER_TOKEN=$(get_gh_pkgs_token)
fi

# We want the most recent available version of the package.
if [[ $(stat -f %u /usr/local/var/homebrew) -ne "${UID}" ]]; then
    echo "Missing permissions to update Homebrew formulae!" >&2
else
    echo "${BOTTLE_NAME} - Updating HomeBrew repository"
    brew update >/dev/null
fi

echo "${BOTTLE_NAME} - Finding bottle URL"
BOTTLE_JSON=$(get_bottle_json "${BOTTLE_NAME}")
BOTTLE_URL=$(echo "${BOTTLE_JSON}" | jq -r .url)
BOTTLE_SHA=$(echo "${BOTTLE_JSON}" | jq -r .sha256)

echo "${BOTTLE_NAME} - Fetching bottle for macOS"
fetch_bottle "${BOTTLE_PATH}" "${BOTTLE_URL}"
trap "rm -fr ${BOTTLE_PATH}" EXIT ERR INT QUIT

echo "${BOTTLE_NAME} - Checking SHA256 checksum"
BOTTLE_LOCAL_SHA=$(shasum -a 256 "${BOTTLE_PATH}" | awk '{print $1}')

if [[ "${BOTTLE_LOCAL_SHA}" != "${BOTTLE_SHA}" ]]; then
    echo "The SHA256 of downloaded bottle did not match!" >&2
    exit 1;
fi

echo "${BOTTLE_NAME} - Unpacking bottle tarball"
mkdir -p "bottles/${BOTTLE_NAME}"
tar xzf "${BOTTLE_PATH}" --strip-components 2 -C "bottles/${BOTTLE_NAME}"