defmodule PhaseDB.Client.Session do
  alias PhaseDB.Client.{CLI, Connection, Request, Session}
  defstruct connection_pid: nil, database_name: nil

  @moduledoc """
  Implements a CLI session for users to interact with the server.
  """

  def create uri do
    IO.puts CLI.version
    case Connection.find_or_create uri do
      {:ok, connection_pid} ->
        repl %Session{connection_pid: connection_pid}

      {:error, message} ->
        CLI.halt_with_message message
    end
  end

  def repl %Session{database_name: db}=state do
    IO.write "#{db}> "
    state = :line
    |> IO.read
    |> do_request(state)
    |> handle_response
    repl state
  end

  defp do_request query, %Session{connection_pid: pid}=state do
    query = String.strip query
    case Request.create query, pid do
      {:ok, request_pid} ->
        {Request.await(request_pid), state}
      {:error, reason} ->
        CLI.halt_with_message reason
    end
  end


  defp handle_response({%{status: :ok, rows: [], count: nil}, %Session{}=state}) do
    IO.puts "OK."
    state
  end

  defp handle_response({%{status: :ok, rows: [], count: i}, %Session{}=state}) do
    IO.puts "OK, #{i} rows."
    state
  end

  defp handle_response({%{status: :ok, fields: fields, rows: rows, count: i}=r, %Session{}=state}) do
    rows = Enum.map(rows, &rewrite_tags(&1))

    TableRex.quick_render!(rows, fields) |> IO.puts
    IO.puts "OK, #{i} rows."
    state
  end

  defp handle_response({%{status: :error, message: nil}, %Session{}=state}) do
    IO.puts "ERROR."
    state
  end

  defp handle_response({%{status: :error, message: m}, %Session{}=state}) do
    IO.puts "ERROR, #{m}."
    state
  end

  defp rewrite_tags row do
    Enum.map row, fn
      map when is_map(map) ->
        Enum.map(map, fn {l,r} -> "#{l}=#{r}" end) |> Enum.join(", ")
      other -> other
    end
  end
end