#!/bin/bash
# Print some basic info about fediverse instances. Install json_pp for prettier
# output.

# Version: 2019-06-24_1

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

function pretty()
{
    local extract="${*}"
    if command -v json_pp > /dev/null; then
        echo "{${extract}}" | json_pp
    else
        echo "${extract}"
    fi
}

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

function main()
{
    local instance="${1}"
    local nodeinfo="https://${instance}/nodeinfo/2.0.json"
    local mastoinfo="https://${instance}/api/v1/instance"
    local misskeyinfo="https://${instance}/api/meta"

    if curl -sIf "${nodeinfo}" | grep -q 'Content-Type: application/json'; then
        echo "Nodeinfo found."
        json=$(curl -s "${nodeinfo}")
        local implementation=""

        if grep -q pleroma <<<"${json}"; then
            implementation="Pleroma"
        fi
        [[ -n "${implementation}" ]] && echo "${implementation} detected."

        echo -n "Description: "
        grep -Eo '"nodeDescription":"[^"]+"' <<<"${json}" | cut -d: -f2

        echo "Admins: "
        # shellcheck disable=SC2046
        pretty $(grep -Eo '"staffAccounts":\[[^]]+\]' <<<"${json}")

        echo -n "Number of users: "
        grep -Eo '"total":[0-9]+' <<<"${json}" | cut -d: -f2

        echo "Blocked instances: "
        # shellcheck disable=SC2046
        pretty $(grep -Eo '"reject":\[[^]]+\]' <<<"${json}" | head -n1)

        if [[ "${implementation}" == "Pleroma" ]]; then
            echo "Further info, maybe: https://${instance}/static/terms-of-service.html"
        fi
    elif curl -sIf "${mastoinfo}" > /dev/null; then
        echo "Mastodon API found."
        json=$(curl -s "${mastoinfo}")
        local implementation=""

        if grep -q '"is_pro"' <<<"${json}"; then
            implementation="Gab"
        elif grep -Eq '"version":"[0-9]+\.[0-9]+\.[0-9]+"' <<<"${json}"; then
            implementation="Mastodon"
        fi
        [[ -n "${implementation}" ]] && echo "${implementation} detected."

        echo -n "Description: "
        # shellcheck disable=SC2046
        striphtml $(grep -Eo '"description":"[^,]+",' <<<"${json}") | cut -d: -f2,3,4,5,6,7,8,9

        # shellcheck disable=SC2155
        local admin=$(grep -Eo '"acct":"[^"]+"' <<<"${json}" | cut -d: -f2 | sed 's/"//g')
        [[ -n "${admin}" ]] && echo "Admin: https://${instance}/users/${admin}"

        # shellcheck disable=SC2155
        local email=$(grep -Eo '"email":"[^"]+"' <<<"${json}" | cut -d: -f2)
        [[ -n "${email}" ]] && echo "E-Mail: ${email}"

        echo -n "Number of users: "
        grep -Eo '"user_count":[0-9]+' <<<"${json}" | cut -d: -f2

        if [[ "${implementation}" == "Mastodon" ]]; then
            echo "Further info, maybe: https://${instance}/about/more"
        fi
    elif curl -sIf -X POST "${misskeyinfo}" | grep -q 'Content-Type: application/json'; then
        echo "Misskey API found."
        json=$(curl -s -X POST "${misskeyinfo}")

        # shellcheck disable=SC2155
        local email=$(grep -Eo '"maintainerEmail":"[^"]+"' <<<"${json}" | cut -d: -f2 | sed 's/"//g')
        [[ -n "${email}" ]] && echo "E-Mail: ${email}"

        # shellcheck disable=SC2155
        local users=$(curl -s -X POST "https://${instance}/api/stats" | grep -Eo '"usersCount":[0-9]+' | cut -d: -f2)
        [[ -n ${users} ]] && echo "Number of users: ${users}"

        # NOTE: I'm not sure what the returned data means exactly and I couldn't find the API-documentation. So I commented it out for now.
        # # shellcheck disable=SC2155
        # local federation=$(curl -s -X POST "https://${instance}/api/federation/instances" | grep -Eo '"host":"[^"]+",' | sed 's/"host"://g')
        # # shellcheck disable=SC2046
        # [[ -n ${federation} ]] && echo -n "Federates with: " && pretty '"":['"${federation}"'""]'

        # shellcheck disable=SC2155
        local tos=$(grep -Eo '"ToSUrl":"[^"]+"' <<<"${json}" | cut -d: -f2,3 | sed 's/"//g')
        [[ -n "${tos}" ]] && echo "ToS: ${tos}"
    else
        echo "Could not detect type of server."
        curl -I "https://${instance}/"
    fi

    echo "See also: https://fediverse.network/${instance}"
}

main "${1}"