defmodule IRC.Account do
  alias IRC.UserTrack.User

  @moduledoc """
  Account registry....

  Maps a network predicate:
    * `{net, {:nick, nickname}}`
    * `{net, {:account, account}}`
    * `{net, {:mask, user@host}}`
  to an unique identifier, that can be shared over multiple networks.

  If a predicate cannot be found for an existing account, a new account will be made in the database.

  To link two existing accounts from different network onto a different one, a merge operation is provided.

  """

  # FIXME: Ensure uniqueness of name?

  defstruct [:id, :name, :token]
  @type t :: %__MODULE__{id: id(), name: String.t()}
  @type id :: String.t()

  defimpl Inspect, for: __MODULE__ do
    import Inspect.Algebra

    def inspect(%{id: id, name: name}, opts) do
      concat(["#IRC.Account[", id, " ", name, "]"])
    end
  end

  def file(base) do
    to_charlist(LSG.data_path() <> "/account_#{base}.dets")
  end

  defp from_struct(%__MODULE__{id: id, name: name, token: token}) do
    {id, name, token}
  end

  defp from_tuple({id, name, token}) do
    %__MODULE__{id: id, name: name, token: token}
  end

  def start_link() do
    GenServer.start_link(__MODULE__, [], [name: __MODULE__])
  end

  def init(_) do
    {:ok, accounts} = :dets.open_file(file("db"), [])
    {:ok, meta} = :dets.open_file(file("meta"), [])
    {:ok, predicates} = :dets.open_file(file("predicates"), [{:type, :set}])
    {:ok, %{accounts: accounts, meta: meta, predicates: predicates}}
  end

  def get(id) do
    case :dets.lookup(file("db"), id) do
      [account] -> from_tuple(account)
      _ -> nil
    end
  end

  def get_by_name(name) do
    spec = [{{:_, :"$1", :_}, [{:==, :"$1", {:const, name}}], [:"$_"]}]
    case :dets.select(file("db"), spec) do
      [account] -> from_tuple(account)
      _ -> nil
    end
  end

  def get_meta(%__MODULE__{id: id}, key, default \\ nil) do
    case :dets.lookup(file("meta"), {id, key}) do
      [{_, value}] -> (value || default)
      _ -> default
    end
  end

  @spec find_meta_accounts(String.t()) :: [{account :: t(), value :: String.t()}, ...]
  @doc "Find all accounts that have a meta of `key`."
  def find_meta_accounts(key) do
    spec = [{{{:"$1", :"$2"}, :"$3"}, [{:==, :"$2", {:const, key}}], [{{:"$1", :"$3"}}]}]
    for {id, val} <- :dets.select(file("meta"), spec), do: {get(id), val}
  end

  @doc "Find an account given a specific meta `key` and `value`."
  @spec find_meta_account(String.t(), String.t()) :: t() | nil
  def find_meta_account(key, value) do
    #spec = [{{{:"$1", :"$2"}, :"$3"}, [:andalso, {:==, :"$2", {:const, key}}, {:==, :"$3", {:const, value}}], [:"$1"]}]
    spec = [{{{:"$1", :"$2"}, :"$3"}, [{:andalso, {:==, :"$2", {:const, key}}, {:==, {:const, value}, :"$3"}}], [:"$1"]}]
    case :dets.select(file("meta"), spec) do
      [id] -> get(id)
      _ -> nil
    end
  end

  def get_all_meta(%__MODULE__{id: id}) do
    spec = [{{{:"$1", :"$2"}, :"$3"}, [{:==, :"$1", {:const, id}}], [{{:"$2", :"$3"}}]}]
    :dets.select(file("meta"), spec)
  end

  def put_user_meta(account = %__MODULE__{}, key, value) do
    put_meta(account, "u:"<>key, value)
  end

  def put_meta(%__MODULE__{id: id}, key, value) do
    :dets.insert(file("meta"), {{id, key}, value})
  end

  def delete_meta(%__MODULE__{id: id}, key) do
    :dets.delete(file("meta"), {id, key})
  end

  def all_accounts() do
    :dets.traverse(file("db"), fn(obj) -> {:continue, from_tuple(obj)} end)
  end

  def all_predicates() do
    :dets.traverse(file("predicates"), fn(obj) -> {:continue, obj} end)
  end

  def all_meta() do
    :dets.traverse(file("meta"), fn(obj) -> {:continue, obj} end)
  end

  def merge_account(old_id, new_id) do
    if old_id != new_id do
      spec = [{{:"$1", :"$2"}, [{:==, :"$2", {:const, old_id}}], [:"$1"]}]
      predicates = :dets.select(file("predicates"), spec)
      for pred <- predicates, do: :ok = :dets.insert(file("predicates"), {pred, new_id})
      spec = [{{{:"$1", :"$2"}, :"$3"}, [{:==, :"$1", {:const, old_id}}], [{{:"$2", :"$3"}}]}]
      metas = :dets.select(file("meta"), spec)
      for {k,v} <- metas do
        :dets.delete(file("meta"), {{old_id, k}})
        :ok = :dets.insert(file("meta"), {{new_id, k}, v})
      end
      :dets.delete(file("db"), old_id)
      IRC.Membership.merge_account(old_id, new_id)
      IRC.UserTrack.merge_account(old_id, new_id)
      IRC.Connection.dispatch("account", {:account_change, old_id, new_id})
      IRC.Connection.dispatch("conn", {:account_change, old_id, new_id})
    end
    :ok
  end

  @doc "Find an account by a logged in user"
  def find_by_nick(network, nick) do
    do_lookup(%ExIRC.SenderInfo{nick: nick, network: network}, false)
  end

  @doc "Always find an account by nickname, even if offline. Uses predicates and then account name."
  def find_always_by_nick(network, chan, nick) do
    with \
      nil <- find_by_nick(network, nick),
         nil <- do_lookup(%User{network: network, nick: nick}, false),
         nil <- get_by_name(nick)
    do
      nil
    else
      %__MODULE__{} = account ->
        memberships = IRC.Membership.of_account(account)
        if Enum.any?(memberships, fn({net, ch}) -> (net == network) or (chan && chan == ch) end) do
          account
        else
          nil
        end
    end
  end

  def find(something) do
    do_lookup(something, false)
  end

  def lookup(something, make_default \\ true) do
    account = do_lookup(something, make_default)
    if account && Map.get(something, :nick) do
      IRC.Connection.dispatch("account", {:account_auth, Map.get(something, :nick), account.id})
    end
    account
  end

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

  def handle_cast(_, state) do
    {:noreply, state}
  end

  def handle_call(_, _, state) do
    {:noreply, state}
  end

  def terminate(_, state) do
    for {_, dets} <- state do
      :dets.sync(dets)
      :dets.close(dets)
    end
  end

  defp do_lookup(message = %IRC.Message{account: account_id}, make_default) when is_binary(account_id) do
    get(account_id)
  end

  defp do_lookup(sender = %ExIRC.Who{}, make_default) do
    if user = IRC.UserTrack.find_by_nick(sender) do
      lookup(user, make_default)
    else
      #FIXME this will never work with continued lookup by other methods as Who isn't compatible
      lookup_by_nick(sender, :dets.lookup(file("predicates"), {sender.network,{:nick, sender.nick}}), make_default)
    end
  end

  defp do_lookup(sender = %ExIRC.SenderInfo{}, make_default) do
    lookup(IRC.UserTrack.find_by_nick(sender), make_default)
  end

  defp do_lookup(user = %User{account: id}, make_default) when is_binary(id) do
    get(id)
  end

  defp do_lookup(user = %User{network: server, nick: nick}, make_default) do
    lookup_by_nick(user, :dets.lookup(file("predicates"), {server,{:nick, nick}}), make_default)
  end

  defp do_lookup(nil, _) do
    nil
  end

  defp lookup_by_nick(_, [{_, id}], _make_default) do
    get(id)
  end

  defp lookup_by_nick(user, _, make_default) do
    #authenticate_by_host(user)
    if make_default, do: new_account(user), else: nil
  end

  defp new_account(%{nick: nick, network: server}) do
    id = EntropyString.large_id()
    :dets.insert(file("db"), {id, nick, EntropyString.token()})
    :dets.insert(file("predicates"), {{server, {:nick, nick}}, id})
    get(id)
  end

  def update_account_name(account = %__MODULE__{id: id}, name) do
    account = %__MODULE__{account | name: name}
    :dets.insert(file("db"), from_struct(account))
    get(id)
  end

  def get_predicates(%__MODULE__{} = account) do
    spec = [{{:"$1", :"$2"}, [{:==, :"$2", {:const, account.id}}], [:"$1"]}]
    :dets.select(file("predicates"), spec)
  end

  defmodule AccountPlugin do
    @moduledoc """
    # Account

    * **account** Get current account id and token
    * **auth `<account-id>` `<token>`** Authenticate and link the current nickname to an account
    * **auth** list authentications methods
    * **whoami** list currently authenticated users
    * **enable-sms** Link a SMS number
    * **enable-telegram** Link a Telegram account
    """

    def irc_doc, do: @moduledoc
    def start_link(), do: GenServer.start_link(__MODULE__, [], name: __MODULE__)
    def init(_) do
      {:ok, _} = Registry.register(IRC.PubSub, "message:private", [])
      {:ok, nil}
    end

    def handle_info({:irc, :text, m = %IRC.Message{account: account, text: "help"}}, state) do
      text = [
        "account: show current account and auth token",
        "auth: show authentications methods",
        "whoami: list authenticated users",
        "set-name <name>: set account name",
        "web: login to web",
        "enable-sms | disable-sms: enable/change or disable sms",
        "enable-telegram: link/change telegram",
        "enable-untappd: link untappd account",
        "getmeta: show meta datas",
        "setusermeta: set user meta",
      ]
      m.replyfun.(text)
      {:noreply, state}
    end

    def handle_info({:irc, :text, m = %IRC.Message{account: account, text: "auth"}}, state) do
      spec = [{{:"$1", :"$2"}, [{:==, :"$2", {:const, account.id}}], [:"$1"]}]
      predicates = :dets.select(IRC.Account.file("predicates"), spec)
      text = for {net, {key, value}} <- predicates, do: "#{net}: #{to_string(key)}: #{value}"
      m.replyfun.(text)
      {:noreply, state}
    end

    def handle_info({:irc, :text, m = %IRC.Message{account: account, text: "whoami"}}, state) do
      users = for user <- IRC.UserTrack.find_by_account(m.account) do
        chans = Enum.map(user.privileges, fn({chan, _}) -> chan end)
                |> Enum.join(" ")
        "#{user.network} - #{user.nick}!#{user.username}@#{user.host} - #{chans}"
      end
      m.replyfun.(users)
      {:noreply, state}
    end

    def handle_info({:irc, :text, m = %IRC.Message{account: account, text: "account"}}, state) do
      account = IRC.Account.lookup(m.sender)
      text = ["Account Id: #{account.id}",
        "Authenticate to this account from another network: \"auth #{account.id} #{account.token}\" to the other bot!"]
      m.replyfun.(text)
      {:noreply, state}
    end

    def handle_info({:irc, :text, m = %IRC.Message{sender: sender, text: "auth"<>_}}, state) do
      #account = IRC.Account.lookup(m.sender)
      case String.split(m.text, " ") do
        ["auth", id, token] ->
          join_account(m, id, token)
        _ ->
          m.replyfun.("Invalid parameters")
      end
      {:noreply, state}
    end

    def handle_info({:irc, :text, m = %IRC.Message{account: account, text: "set-name "<>name}}, state) do
      IRC.Account.update_account_name(account, name)
      m.replyfun.("Name changed: #{name}")
      {:noreply, state}
    end

    def handle_info({:irc, :text, m = %IRC.Message{text: "disable-sms"}}, state) do
      if IRC.Account.get_meta(m.account, "sms-number") do
        IRC.Account.delete_meta(m.account, "sms-number")
        m.replfyun.("SMS disabled.")
      else
        m.replyfun.("SMS already disabled.")
      end
      {:noreply, state}
    end

    def handle_info({:irc, :text, m = %IRC.Message{text: "web"}}, state) do
      auth_url = Untappd.auth_url()
      login_url = LSG.AuthToken.new_url(m.account.id, nil)
      m.replyfun.("-> " <> login_url)
      {:noreply, state}
    end

    def handle_info({:irc, :text, m = %IRC.Message{text: "enable-sms"}}, state) do
      code = String.downcase(EntropyString.small_id())
      IRC.Account.put_meta(m.account, "sms-validation-code", code)
      IRC.Account.put_meta(m.account, "sms-validation-target", m.network)
      number = LSG.IRC.SmsPlugin.my_number()
      text = "To enable or change your number for SMS messaging, please send:"
             <> " \"enable #{code}\" to #{number}"
      m.replyfun.(text)
      {:noreply, state}
    end

    def handle_info({:irc, :text, m = %IRC.Message{text: "enable-telegram"}}, state) do
      code = String.downcase(EntropyString.small_id())
      IRC.Account.delete_meta(m.account, "telegram-id")
      IRC.Account.put_meta(m.account, "telegram-validation-code", code)
      IRC.Account.put_meta(m.account, "telegram-validation-target", m.network)
      text = "To enable or change your number for telegram messaging, please open #{LSG.Telegram.my_path()} and send:"
             <> " \"/enable #{code}\""
      m.replyfun.(text)
      {:noreply, state}
    end

    def handle_info({:irc, :text, m = %IRC.Message{text: "enable-untappd"}}, state) do
      auth_url = Untappd.auth_url()
      login_url = LSG.AuthToken.new_url(m.account.id, {:external_redirect, auth_url})
      m.replyfun.(["To link your Untappd account, open this URL:", login_url])
      {:noreply, state}
    end

    def handle_info({:irc, :text, m = %IRC.Message{text: "getmeta"<>_}}, state) do
      result = case String.split(m.text, " ") do
        ["getmeta"] ->
          for {k, v} <- IRC.Account.get_all_meta(m.account) do
            case k do
              "u:"<>key -> "(user) #{key}: #{v}"
              key -> "#{key}: #{v}"
            end
          end
        ["getmeta", key] ->
          value = IRC.Account.get_meta(m.account, key)
          text = if value do
            "#{key}: #{value}"
          else
            "#{key} is not defined"
          end
        _ ->
          "usage: getmeta [key]"
      end
      m.replyfun.(result)
      {:noreply, state}
    end

    def handle_info({:irc, :text, m = %IRC.Message{text: "setusermet"<>_}}, state) do
      result = case String.split(m.text, " ") do
        ["setusermeta", key, value] ->
          IRC.Account.put_user_meta(m.account, key, value)
          "ok"
        _ ->
          "usage: setusermeta <key> <value>"
      end
      m.replyfun.(result)
      {:noreply, state}
    end

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

    defp join_account(m, id, token) do
      old_account = IRC.Account.lookup(m.sender)
      new_account = IRC.Account.get(id)
      if new_account && token == new_account.token do
        case IRC.Account.merge_account(old_account.id, new_account.id) do
          :ok ->
            if old_account.id == new_account.id do
              m.replyfun.("Already authenticated, but hello")
            else
              m.replyfun.("Accounts merged!")
            end
          _ -> m.replyfun.("Something failed :(")
        end
      else
        m.replyfun.("Invalid token")
      end
    end

  end

end