defmodule LSG.IRC.PreumsPlugin do
  @moduledoc """
  # preums !!!

  * `!preums`: affiche le preums du jour
  * `.preums`: stats des preums
  """

  require Logger

  @perfects [~r/preum(s|)/i]

  # dets {{chan, day = {yyyy, mm, dd}}, nick, now, perfect?, text}

  def all(dets) do
    :dets.foldl(fn(i, acc) -> [i|acc] end, [], dets)
  end

  def all(dets, channel) do
    fun = fn({{chan, date}, nick, time, perfect, text}, acc) ->
      if channel == chan do
        [%{date: date, nick: nick, time: time, perfect: perfect, text: text} | acc]
      else
        acc
      end
    end
    :dets.foldl(fun, [], dets)
  end

  def topnicks(dets, channel) do
    fun = fn(x = {{chan, date}, nick, _time, _perfect, _text}, acc) ->
      if (channel == nil and chan) or (channel == chan) do
        count = Map.get(acc, nick, 0)
        Map.put(acc, nick, count + 1)
      else
        acc
      end
    end
    :dets.foldl(fun, %{}, dets)
    |> Enum.sort_by(fn({nick, count}) -> count end, &>=/2)
  end

  def irc_doc, do: @moduledoc
  def start_link() do
    GenServer.start_link(__MODULE__, [])
  end

  def dets do
    (LSG.data_path() <> "/preums.dets") |> String.to_charlist()
  end

  def init([]) do
    {:ok, _} = Registry.register(IRC.PubSub, "account", [])
    {:ok, _} = Registry.register(IRC.PubSub, "message", [])
    {:ok, _} = Registry.register(IRC.PubSub, "triggers", [])
    {:ok, dets} = :dets.open_file(dets(), [{:repair, :force}])
    Util.ets_mutate_select_each(:dets, dets, [{:"$1", [], [:"$1"]}], fn(table, obj) ->
      {key, nick, now, perfect, text} = obj
      case key do
        {{net, {bork,chan}}, date} ->
          :dets.delete(table, key)
          nick = if IRC.Account.get(nick) do
            nick
          else
            if acct = IRC.Account.find_always_by_nick(net, nil, nick) do
              acct.id
            else
              nick
            end
          end
          :dets.insert(table, { { {net,chan}, date }, nick, now, perfect, text})
        {{_net, nil}, _} ->
          :dets.delete(table, key)
        {{net, chan}, date} ->
          if !IRC.Account.get(nick) do
            if acct = IRC.Account.find_always_by_nick(net, chan, nick) do
              :dets.delete(table, key)
              :dets.insert(table, { { {net,chan}, date }, acct.id, now, perfect, text})
            end
          end
        _ ->
          Logger.debug("DID NOT FIX: #{inspect key}")
      end
    end)
    {:ok, %{dets: dets}}
  end

  # Latest
  def handle_info({:irc, :trigger, "preums", m = %IRC.Message{trigger: %IRC.Trigger{type: :bang}}}, state) do
    channelkey = {m.network, m.channel}
    state = handle_preums(m, state)
    tz = timezone(channelkey)
    {:ok, now} = DateTime.now(tz, Tzdata.TimeZoneDatabase)
    date = {now.year, now.month, now.day}
    key = {channelkey, date}
    chan_cache = Map.get(state, channelkey, %{})
    item = if i = Map.get(chan_cache, date) do
      i
    else
      case :dets.lookup(state.dets, key) do
        [item = {^key, _nick, _now, _perfect, _text}] -> item
        _ -> nil
      end
    end

    if item do
      {_, nick, date, _perfect, text} = item
      h = "#{date.hour}:#{date.minute}:#{date.second}"
      m.replyfun.("preums: #{nick} à #{h}: “#{text}”")
    end
    {:noreply, state}
  end

  # Stats
  def handle_info({:irc, :trigger, "preums", m = %IRC.Message{trigger: %IRC.Trigger{type: :dot}}}, state) do
    channel = {m.network, m.channel}
    state = handle_preums(m, state)
    top = topnicks(state.dets, channel)
          |> Enum.map(fn({nick, count}) ->
            "#{nick} (#{count})"
          end)
          |> Enum.filter(fn(x) -> x end)
          |> Enum.intersperse(", ")
          |> Enum.join("")
    msg = unless top == "" do
      "top preums: #{top}"
    else
      "vous êtes tous nuls"
    end
    m.replyfun.(msg)
    {:noreply, state}
  end

  # Help
  def handle_info({:irc, :trigger, "preums", m = %IRC.Message{trigger: %IRC.Trigger{type: :query}}}, state) do
    state = handle_preums(m, state)
    msg = "!preums - preums du jour, .preums top preumseurs"
    m.replymsg.(msg)
    {:noreply, state}
  end

  # Trigger fallback
  def handle_info({:irc, :trigger, _, m = %IRC.Message{}}, state) do
    state = handle_preums(m, state)
    {:noreply, state}
  end

  # Message fallback
  def handle_info({:irc, :text, m = %IRC.Message{}}, state) do
    {:noreply, handle_preums(m, state)}
  end

  # Account
  def handle_info({:account_change, old_id, new_id}, state) do
    spec = [{{:_, :"$1", :_, :_, :_}, [{:==, :"$1", {:const, old_id}}], [:"$_"]}]
    Util.ets_mutate_select_each(:dets, state.dets, spec, fn(table, obj) ->
      rename_object_owner(table, obj, new_id)
    end)
    {:noreply, state}
  end

  # Account: move from nick to account id
  # FIXME: Doesn't seem to work.
  def handle_info({:accounts, accounts}, state) do
    for x={:account, _net, _chan, _nick, _account_id} <- accounts do
      handle_info(x, state)
    end
    {:noreply, state}
  end
  def handle_info({:account, _net, _chan, nick, account_id}, state) do
    nick = String.downcase(nick)
    spec = [{{:_, :"$1", :_, :_, :_}, [{:==, :"$1", {:const, nick}}], [:"$_"]}]
    Util.ets_mutate_select_each(:dets, state.dets, spec, fn(table, obj) ->
      Logger.debug("account:: merging #{nick} -> #{account_id}")
      rename_object_owner(table, obj, account_id)
    end)
    {:noreply, state}
  end

  def handle_info(_, dets) do
    {:noreply, dets}
  end


  defp rename_object_owner(table, object = {key, _, now, perfect, time}, new_id) do
    :dets.delete_object(table, key)
    :dets.insert(table, {key, new_id, now, perfect, time})
  end

  defp timezone(channel) do
    env = Application.get_env(:lsg, LSG.IRC.PreumsPlugin, [])
    channels = Keyword.get(env, :channels, %{})
    channel_settings = Map.get(channels, channel, [])
    default = Keyword.get(env, :default_tz, "Europe/Paris")
    Keyword.get(channel_settings, :tz, default) || default
  end

  defp handle_preums(%IRC.Message{channel: nil}, state) do
    state
  end

  defp handle_preums(m = %IRC.Message{text: text, sender: sender}, state) do
    channel = {m.network, m.channel}
    tz = timezone(channel)
    {:ok, now} = DateTime.now(tz, Tzdata.TimeZoneDatabase)
    date = {now.year, now.month, now.day}
    key = {channel, date}
    chan_cache = Map.get(state, channel, %{})
    unless i = Map.get(chan_cache, date) do
      case :dets.lookup(state.dets, key) do
        [item = {^key, _nick, _now, _perfect, _text}] ->
          # Preums lost, but wasn't cached
          Map.put(state, channel, %{date => item})
        [] ->
          # Preums won!
          perfect? = Enum.any?(@perfects, fn(perfect) -> Regex.match?(perfect, text) end)
          item = {key, m.account.id, now, perfect?, text}
          :dets.insert(state.dets, item)
          :dets.sync(state.dets)
          Map.put(state, channel, %{date => item})
        {:error, _} = error ->
          Logger.error("#{__MODULE__} dets lookup failed: #{inspect error}")
          state
      end
    else
      state
    end
  end

end