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

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

trap "echo 'Failed to download bottle. Check your authentication token and network connection.'" EXIT ERR INT QUIT

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

function get_bottle_json() {
    brew info --json=v1 "${1}" | jq ".[0].bottle.stable.files[\"${2}\"]"
}

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

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

if [[ $# -ne 2 ]]; then
    echo "usage: $0 <bottle_name> <bottle_filter1|bottle_filter2>" >&2
    exit 1
fi
BOTTLE_NAME="${1}"
BOTTLE_FILTER="${2}"
BOTTLE_PATH="/tmp/${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

echo "${BOTTLE_NAME} - Finding bottle URL"
echo "${BOTTLE_NAME} - Selecting: ${BOTTLE_FILTER}"

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

if [[ -z "${BOTTLE_URL}" ]] || [[ -z "${BOTTLE_SHA}" ]]; then
    echo "Failed to identify bottle URL or SHA256!" >&2
    exit 1
fi

echo "${BOTTLE_NAME} - Fetching bottle for macOS, bottle sha256: ${BOTTLE_SHA}"
fetch_bottle "${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}"