#!/bin/bash

# Function to get the corresponding debian-archive-keyring
get_keyring() {
 date_string=${1:-"20190608T160814Z"}

 echo "${date_string}"
 echo ""

 # Remove the 'SOURCES_DATE=' prefix
 date_string=${date_string#*=}

 echo "${date_string}"
 echo ""

 # Convert the date format
 date_string=$(date -d"${date_string:0:4}-${date_string:4:2}-${date_string:6:2}T${date_string:9:2}:${date_string:11:2}:${date_string:13:2}" +"%Y-%m-%dT%H:%M:%SZ")

 echo "${date_string}"
 echo ""

 # Get the list of keyrings
 keyrings=$(curl -s "https://snapshot.debian.org/mr/package/debian-archive-keyring/")

 echo "${keyrings}" | jq -r '.result[].version'
 echo ""

 # Obtain the available version numbers
 echo "${keyrings}" | jq -r '.result[].version' | sort -rV
 echo ""

 # Find the keyring that was first seen closest to but not later than the given date



 keyring=$(echo "${keyrings}" | jq -r '.result[].version' | sort -V | awk -v date="${date_string}" '$0 <= date {print; exit}')

 echo "debian-archive-keyring_${keyring}"
}

# Call the function
get_keyring "$@"