#!/bin/bash
# Print some basic info about fediverse instances.

# Version: 2022-05-25_1

if [[ -z "${1}" ]]; then
    echo "usage: ${0} DOMAIN" >&2
    exit 1
fi

if ! command -v curl > /dev/null; then
    echo "You need to install curl (https://curl.haxx.se/)" >&2
    exit 2
fi

if ! command -v jq > /dev/null; then
    echo "You need to install jq (https://stedolan.github.com/jq/)" >&2
    exit 2
fi

mycurl="curl -sk"

function striphtml()
{
    local extract="${*}"
    echo "${extract}" | sed 's/\\u003c/</g' | sed 's/\\u003e/>/g' | sed -E 's/<[^>]+>//g' | sed 's/\\r\\n/ /g' | sed -E 's/(^"|"$)//g'
}

function parse_nodeinfo()
{
    local instance="${1}"
    local nodeinfo="${2}"
    # shellcheck disable=SC2155
    local json=$(${mycurl} "${nodeinfo}")

    # shellcheck disable=SC2155
    local implementation=$(jq -r ".software.name" <<<"${json}")

    # shellcheck disable=SC2155
    local version=$(jq -r ".software.version" <<<"${json}")
    echo "${implementation} ${version} detected."

    # shellcheck disable=SC2155
    local description=$(jq -r ".metadata.nodeDescription" <<<"${json}")
    if [[ "${description}" == "null" ]]; then
        description=$(jq -r ".metadata.shortDescription" <<<"${json}")
    fi
    if [[ "${description}" == "null" ]]; then
        description=$(jq -r ".metadata.nodeName" <<<"${json}")
    fi
    [[ "${description}" != "null" ]] && echo "Description: ${description}"

    # shellcheck disable=SC2155
    local admins=$(jq -r ".metadata.staffAccounts" <<<"${json}")
    if [[ "${admins}" == "null" ]]; then
        admins=$(jq -r ".metadata.adminAccount" <<<"${json}")
    fi
    [[ "${admins}" != "null" ]] && echo "Admins: ${admins}"

    echo -n "Number of users: "
    jq -r ".usage.users.total" <<<"${json}"

    # shellcheck disable=SC2155
    local active=$(jq -r ".usage.users.activeMonth" <<<"${json}")
    [[ "${active}" != "null" ]] && echo "Active users (month): ${active}"

    echo -n "Open registrations: "
    jq -r ".openRegistrations" <<<"${json}"

    if [[ "${implementation}" == "activityrelay" ]]; then
        # shellcheck disable=SC2155
        local peers=$(jq -r ".metadata.peers" <<<"${json}")
        [[ "${peers}" != "null" ]] && echo "Peers: ${peers}"
    fi

    # shellcheck disable=SC2155
    local restrictions=$(jq -r ".metadata.federation.mrf_simple" <<<"${json}")
    if [[ "${restrictions}" == "null" ]]; then
        restrictions=$(jq -r ".federation" <<<"${json}")
    fi
    [[ "${restrictions}" != "null" ]] && echo "Federation restrictions: ${restrictions}"

    if [[ "${implementation}" == "pleroma" ]]; then
        echo "Further info, maybe: https://${instance}/about"
    elif [[ "${implementation}" == "funkwhale" ]]; then
        echo -n "Artists / tracks: "
        jq -rj ".metadata.library.artists.total" <<<"${json}"
        echo -n " / "
        jq -r ".metadata.library.tracks.total" <<<"${json}"
    elif [[ "${implementation}" == "mastodon" ]] ||
             [[ "${implementation}" =~ don$ ]] ||
             [[ "${implementation}" =~ ^masto ]] ||
             [[ "${implementation}" == "bookwyrm" ]]; then
        echo -e "\nUsing Mastodon API additionally."
        parse_mastodon ${instance} "https://${instance}/api/v1/instance"
    elif [[ "${implementation}" == "pixelfed" ]]; then
        echo "Further info, maybe: https://${instance}/site/terms"
    elif [[ "${implementation}" == "peertube" ]]; then
        echo "Further info, maybe: https://${instance}/about/instance"
    elif [[ "${implementation}" == "friendica" ]]; then
        echo "Further info, maybe: https://${instance}/friendica"
    fi
}

function parse_mastodon()
{
    local instance="${1}"
    local mastoinfo="${2}"
    # shellcheck disable=SC2155
    local json=$(${mycurl} "${mastoinfo}")
    local implementation=""

    if grep -Eq '"is_(pro|verified)"' <<<"${json}"; then
        implementation="Gab"
    elif grep -Pq '"version":"\d+\.\d+\.\d+\.\d+\."' <<<"${json}"; then
        implementation="Florence"
    elif grep -Pq '"version":"\d+\.\d+\.\d+(rc\d+)?"' <<<"${json}"; then
        implementation="Mastodon"
    elif grep -Pq '"version":"\d+\.\d+\.\d+[\._\-\+]?[\w\_\+\-]+"' <<<"${json}"
    then
        implementation="Mastodon fork"
    fi
    if [[ -n "${implementation}" ]]; then
        # shellcheck disable=SC2155
        local version=$(jq -r ".version" <<<"${json}")
        echo "${implementation} ${version} detected."
    fi

    echo -n "Description: "
    # shellcheck disable=SC2046
    striphtml $(jq ".description" <<<"${json}")

    # shellcheck disable=SC2155
    local admin=$(jq -r ".contact_account.acct" <<<"${json}")
    [[ "${admin}" != "null" ]] && echo "Admin: https://${instance}/users/${admin}"

    # shellcheck disable=SC2155
    local email=$(jq -r ".email" <<<"${json}")
    [[ -n "${email}" ]] && echo "E-Mail: ${email}"

    echo -n "Number of users: "
    jq -r ".stats.user_count" <<<"${json}"

    echo -n "Open registrations: "
    jq -r ".registrations" <<<"${json}"

    if [[ "${implementation}" == "Mastodon"
                    || "${implementation}" == "Mastodon fork"
                    || "${implementation}" == "Florence" ]]; then
        echo "Further info, maybe: https://${instance}/about/more"
    elif [[ "${implementation}" == "Gab" ]]; then
        echo "Further info, maybe: https://${instance}/about"
    fi
}

function parse_misskey()
{
    local instance="${1}"
    local misskeyinfo="${2}"
    # shellcheck disable=SC2155
    local json=$(${mycurl} -X POST "${misskeyinfo}")

    # shellcheck disable=SC2155
    local version=$(jq -r ".version" <<<"${json}")
    [[ "${version}" != "null" ]] && echo "Misskey ${version} detected."

    local description=$(jq -r ".description" <<<"${json}")
    [[ "${description}" != "null" ]] && echo "Description: ${description}"

    # shellcheck disable=SC2155
    local email=$(jq -r ".maintainerEmail" <<<"${json}")
    [[ "${email}" != "null" ]] && echo "E-Mail: ${email}"

    # shellcheck disable=SC2155
    local users=$(${mycurl} -X POST "https://${instance}/api/stats" | jq -r ".originalUsersCount")
    [[ ${users} != "null" ]] && echo "Number of users: ${users}"

    echo -n "Open registrations: "
    jq -r ".features.registration" <<<"${json}"

    # shellcheck disable=SC2155
    local tos=$(jq -r ".ToSUrl" <<<"${json}")
    [[ "${tos}" != "null" ]] && echo "ToS: ${tos}"
}

function main()
{
    local instance="${1}"
    # shellcheck disable=SC2155
    local nodeinfo=$(${mycurl} -L "https://${instance}/.well-known/nodeinfo" | jq -r '.links[].href' 2> /dev/null | sort | tail -n 1)
    local mastoinfo="https://${instance}/api/v1/instance"
    local misskeyinfo="https://${instance}/api/meta"

    if ${mycurl} -ILf -X POST "${misskeyinfo}" | grep -iq 'HTTP.*200'; then
        echo "Misskey API found."
        parse_misskey "${instance}" "${misskeyinfo}"
    elif ${mycurl} -ILf "${nodeinfo}" | grep -iq 'Content-Type: application/json' \
            || ${mycurl} -s "${nodeinfo}" | jq -e '.software' > /dev/null; then
        # ↑ Bookwyrm doesn't answer to HEAD requests ↑.
        echo "Nodeinfo found."
        parse_nodeinfo "${instance}" "${nodeinfo}"
    elif ${mycurl} -ILf "${mastoinfo}" | grep -iq 'Content-Type: application/json'; then
        echo "Mastodon API found."
        parse_mastodon "${instance}" "${mastoinfo}"
    else
        echo "Could not detect type of server."
        ${mycurl} -I "https://${instance}/"
    fi

    if ${mycurl} -ILf "${instance}" | grep -q 'Server: cloudflare'; then
        echo "Uses CloudFlare."
    fi

    echo "See also: https://fedi.ninja/${instance}"
}

main "${1}"