imapfilter: auto sort mailing list

gistfile1.lua

bool = function(o)
    if not o then
        return false
    elseif o == '' then
        return false
    elseif o == 0 then
        return false
    elseif #o == 0 then
        return false
    end
    return true
end

pyor = function(o)
    if not bool(o) then
        return false
    end
    return o
end

function process()
    ML = 'MailingLists/'
    AUTO_ML = ML..'Auto/'
    -- now make a generic filtering on mailing lists...
    messages = mbox:contain_field('List-Id', '')

    mls = {}
    for msgid, listid in pairs(mbox:fetch_fields({'List-Id'}, messages) or {}) do
        if bool(listid) then
            -- imapfilter bug: the search is also done inside the message body
            -- and thus also match the forwarded emails.
        
            s, m1, m2 = regex_search('^List-Id: (.*) ?<(.*)>$', listid)
            if s then
                m = pyor(m1) or pyor(m2)
            else
                m2 = string.sub(listid, 10)
                m = m2
            end
            if bool(m2) then
                -- get the first part of a split on .
                s, _ = m:find('.', 1, true)
                if s then
                    m = m:sub(1, s-1)
                end
                mls[m2] = m:gsub('"', ''):gsub('/', '-')
            end
        end
    end
    for listid, listtitle in pairs(mls) do
        dest = AUTO_ML..listtitle
        account:create_mailbox(dest)
        account:subscribe_mailbox(dest)
        messages:contain_field('List-Id', listid):move_messages(account[dest])
    end
end