#!/bin/bash

set -e
set -u
set -o pipefail

snapshot_tmp_dir=$(mktemp -d)
mkdir -p "${snapshot_tmp_dir}"

get_latest_month_query() {
    local -r snapshot_archive_tmp_file="${snapshot_tmp_dir}/archive.html"

    curl -sSfL "https://snapshot.debian.org/archive/debian/" > "$snapshot_archive_tmp_file"

    local -r month_query_regex="(\?year=\d\d\d\d&month=\d+)"
    local -r month_query=$(grep -Po "${month_query_regex}" "${snapshot_archive_tmp_file}" | tail -1)

    [[ -z "$month_query" ]] && echo "Not found snapshots using the following regex: ${month_query_regex}" && return 1

    echo "$month_query"
}

get_latest_debian_snapshot_id() {
    local -r snapshot_list_tmp_file="${snapshot_tmp_dir}/month-snapshots.html"

    ! month_query=$(get_latest_month_query) && return 1
    month_query=${month_query/&month=/&month=}

    curl -sSfL "https://snapshot.debian.org/archive/debian/$month_query" > "$snapshot_list_tmp_file"

    local -r snapshot_id_regex="(\d+T.*Z)"
    local -r snapshot_id=$(grep -Po "${snapshot_id_regex}" "${snapshot_list_tmp_file}" | tail -1)

    [[ -z "$snapshot_id" ]] && echo "Not found snapshot id using the following regex: ${snapshot_id_regex}" && return 1

    echo "$snapshot_id"
}

get_latest_debian_snapshot_id
rm -rf "${snapshot_tmp_dir}"