#!/bin/sh
# ---------------------------------------------------------------------------
# rmuser - tilde.club user removal helper
# Usage: rmuser [-h|--help] <username>
# ---------------------------------------------------------------------------

PROGNAME=${0##*/}
VERSION="0.2"
SIGNUPS_FILE="/var/signups"

error_exit() {
    printf "%s: %s\n" "$PROGNAME" "${1:-"Unknown Error"}" >&2
    exit 1
}

usage() {
    printf "usage: %s %s [-h|--help] <username>\n" "$PROGNAME" "$VERSION"
}

lookup_email_from_signups() {
    user="$1"

    if [ ! -r "$SIGNUPS_FILE" ]; then
        printf "warning: cannot read %s to discover email\n" "$SIGNUPS_FILE" >&2
        return 0
    fi

    awk -v u="$user" '
        /^[[:space:]]*#/ { next }
        {
            n = split($0, fields, /[\t ,;:]+/)
            found_user = 0
            for (i = 1; i <= n; i++) {
                if (fields[i] == u) {
                    found_user = 1
                }
            }
            if (found_user) {
                for (i = 1; i <= n; i++) {
                    if (fields[i] ~ /^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$/) {
                        print fields[i]
                        exit
                    }
                }
            }
        }
    ' "$SIGNUPS_FILE"
}

comment_out_signup() {
    user="$1"

    if [ ! -f "$SIGNUPS_FILE" ]; then
        printf "warning: %s does not exist, skipping signup comment\n" "$SIGNUPS_FILE" >&2
        return 0
    fi

    if ! sudo test -w "$SIGNUPS_FILE"; then
        printf "warning: %s is not writable, skipping signup comment\n" "$SIGNUPS_FILE" >&2
        return 0
    fi

    tmpfile=$(mktemp) || return 1

    awk -v u="$user" '
        /^[[:space:]]*#/ {
            print
            next
        }
        {
            line = $0
            n = split($0, fields, /[\t ,;:]+/)
            found_user = 0
            for (i = 1; i <= n; i++) {
                if (fields[i] == u) {
                    found_user = 1
                }
            }
            if (found_user) {
                print "# " line
            } else {
                print
            }
        }
    ' "$SIGNUPS_FILE" > "$tmpfile" || {
        rm -f "$tmpfile"
        return 1
    }

    sudo cp "$tmpfile" "$SIGNUPS_FILE" || {
        rm -f "$tmpfile"
        return 1
    }

    rm -f "$tmpfile"
}

maybe_unsubscribe_list() {
    email="$1"

    if [ -z "$email" ]; then
        printf "skipping mailing list unsubscribe (email not found)\n"
        return 0
    fi

    printf "sending mailing list unsubscribe request\n"
    sendmail tildeclub-join@lists.tildeverse.org << MAIL || return 1
From: $email
Subject: unsubscribe
MAIL
}

case $1 in
    -h | --help)
        usage; exit 0 ;;
    -* | --*)
        usage; error_exit "unknown option $1" ;;
    *)
        if [ $# -ne 1 ]; then
            usage
            error_exit "invalid args"
        fi

        user="$1"

        if ! id "$user" > /dev/null 2>&1; then
            error_exit "user $user does not exist"
        fi

        email=$(lookup_email_from_signups "$user")
        if [ -n "$email" ]; then
            printf "found email for %s: %s\n" "$user" "$email"
        else
            printf "warning: email for %s not found in %s\n" "$user" "$SIGNUPS_FILE" >&2
        fi

        printf "commenting out %s from %s\n" "$user" "$SIGNUPS_FILE"
        comment_out_signup "$user" \
            || printf "warning: failed to comment out %s in %s\n" "$user" "$SIGNUPS_FILE" >&2

        printf "removing user from Helpdesk\n"
        /usr/local/bin/helpdesk_admin.sh "del" "$user" \
            || printf "warning: failed to remove %s from Helpdesk\n" "$user" >&2

        printf "removing user from ZNC\n"
        /usr/local/bin/zncdelete.py "$user" \
            || printf "warning: failed to remove %s from ZNC\n" "$user" >&2

        maybe_unsubscribe_list "$email" \
            || printf "warning: failed to send mailing list unsubscribe\n" >&2

        printf "deleting unix account and home directory\n"
        sudo userdel -r "$user" || error_exit "couldn't delete user"

        printf "fix sorting in /etc/passwd\n"
        sudo pwck -s || printf "warning: pwck -s reported an issue\n" >&2

        printf "done removing %s\n" "$user"
        ;;
esac