#! /usr/bin/awk -f

function print_title(title,    _i) {
    print title
    for (_i = 1; _i <= length(title); _i++)
        printf "="
    printf "\n"
}

function print_decoded_field(field,    _i, _decode) {
    _decode = "base64 -d | json_pp"
    print $field | _decode
    close(_decode)
}

BEGIN {
    FS = "."
}

{
    print_title("Header")
    print_decoded_field(1)
    print_title("Payload")
    print_decoded_field(2)
    print_title("Signature")
    print $3
}