defmodule BarrelEx.Document do
  @moduledoc """
  API for interacting with a BarrelDB document.
  """
  alias BarrelEx.Request

  ## TODO: some header args like x-barrel-id-match and ETag
  ## are in headers, accept them too

  ## GET - ALL DOCUMENTS 

  @doc """
  Get all documents from the database `db`, filtered by
  a map of `options`.
  Returns also the response status.
  """
  @spec get(String.t(), list | map | none) :: {atom, map}
  def get(db, options \\ []) do
    case is_map(options) do
      true ->
        with options <- Map.to_list(options),
             opts <- options |> atomize_keys() do
          get(db, opts)
        end

      false ->
        with url <- make_url(db) do
          Request.get(url, [], params: options)
        end
    end
  end

  @doc """
  Get all documents from the
  database `db`, filtered by a map of options or
  a list of `options` tuples.
  """
  @spec get!(String.t(), list | map | none) :: map
  def get!(db, options \\ []) do
    case is_map(options) do
      true ->
        with options <- Map.to_list(options),
             opts <- options |> atomize_keys() do
          get!(db, opts)
        end

      false ->
        with url <- make_url(db) do
          Request.get!(url, [], params: options)
        end
    end
  end

  ## GET - ONE DOCUMENT

  @doc """
  Get the document with a given `doc_id` from the
  database `db`, filtered by an optional list of options.
  Returns also the response status.
  """
  @spec get_one(String.t(), String.t(), list | none) :: {atom, map}
  def get_one(db, doc_id, options \\ []) do
    with url <- make_url(db, doc_id) do
      Request.get(url, [], options)
    end
  end

  @doc """
  Get the document with a given `doc_id` from the
  database `db`, filtered by an optional list of options.
  """
  @spec get_one!(String.t(), String.t(), list | none) :: map
  def get_one!(db, doc_id, options \\ []) do
    with url <- make_url(db, doc_id) do
      Request.get!(url, [], options)
    end
  end

  ## CREATE

  @doc """
  Create a new document `doc` in the database `db`.
  Returns also the response status.
  """
  @spec create(String.t(), map | none) :: {atom, map}
  def create(db, doc \\ %{}) do
    with url <- make_url(db) do
      Request.post(url, doc)
    end
  end

  @doc """
  Create a new document `doc` in the database `db`.
  """
  @spec create!(String.t(), map | none) :: map
  def create!(db, doc \\ %{}) do
    with url <- make_url(db) do
      Request.post!(url, doc)
    end
  end

  ## DELETE

  @doc """
  Delete a document `doc` in the database `db`.
  Returns also the response status.
  """
  @spec delete(String.t(), String.t(), String.t() | none) :: {atom, map}
  def delete(db, doc_id, e_tag \\ "") do
    with url <- make_url(db, doc_id),
         headers <- make_e_tag(e_tag) do
      Request.delete(url, headers)
    end
  end

  @doc """
  Delete a document `doc` in the database `db`.
  """
  @spec delete!(String.t(), String.t(), String.t() | none) :: map
  def delete!(db, doc_id, e_tag \\ "") do
    with url <- make_url(db, doc_id),
         headers <- make_e_tag(e_tag) do
      Request.delete!(url, headers)
    end
  end

  ## UPDATE

  @doc """
  Update a document `doc` in the database `db`.
  Returns also the response status.
  """
  @spec update(String.t(), String.t(), map, String.t(), boolean) :: {atom, map}
  def update(db, doc_id, doc, e_tag \\ "", edit \\ false) do
    with url <- make_url(db, doc_id) do
      # to add doc_id to body if doesn't exist
      doc = Map.put_new(doc, "id", doc_id)
      Request.put(url, doc, make_e_tag(e_tag), edit: edit)
    end
  end

  @doc """
  Update a document `doc` in the database `db`.
  """
  @spec update!(String.t(), String.t(), map, String.t(), boolean) :: map
  def update!(db, doc_id, doc, e_tag \\ "", edit \\ false) do
    with url <- make_url(db, doc_id) do
      # to add doc_id to body if doesn't exist
      doc = Map.put_new(doc, "id", doc_id)
      Request.put!(url, doc, make_e_tag(e_tag), edit: edit)
    end
  end

  ## HISTORY

  @doc """
  Check for differences in documents history in the
  database `db`. Returns also the response status.
  """
  @spec revsdiff(String.t(), map) :: {atom, map}
  def revsdiff(db, doc) do
    with url <- make_revsdiff_url(db) do
      Request.post(url, doc)
    end
  end

  @doc """
  Check for differences in documents history in the
  database `db`.
  """
  @spec revsdiff!(String.t(), map) :: map
  def revsdiff!(db, doc) do
    with url <- make_revsdiff_url(db) do
      Request.post!(url, doc)
    end
  end

  ## UTILS

  defp make_e_tag(e_tag) do
    case is_bitstring(e_tag) do
      true -> ["ETag: " <> e_tag]
      _ -> []
    end
  end

  defp make_id_match(doc_ids) do
    case is_list(doc_ids) do
      # TODO: test this header
      true ->
        ["x-barrel-id-match: " <> Enum.join(doc_ids, ", ")]

      _ ->
        []
    end
  end

  defp make_url(db) do
    "dbs/" <> db <> "/docs/"
  end

  defp make_url(db, doc_id) do
    make_url(db) <> doc_id
  end

  defp make_revsdiff_url(db) do
    "dbs/" <> db <> "/revsdiff/"
  end

  defp atomize_keys(list) do
    Enum.map(list, fn {k, v} -> {String.to_atom(k), v} end)
  end
end