contentful

defmodule Contentful.Delivery.Entries do
  @moduledoc """
  Entries allows for querying the entries of a space via `Contentful.Query`.

  ## Fetching a single entry

      import Contentful.Query
      alias Contentful.Delivery.Entries

      {:ok, entry} = Entries |> fetch_one("my_entry_id")

  ## Simple querying of a collection of entries

      import Contentful.Query
      alias Contentful.Delivery.Entries

      # fetches the entries based on the `space_id`, `environment` and `access_token` in config/config.exs
      {:ok, entries, total: _total_count_of_entries} =
        Entries |> fetch_all

      # fetches the entries by passing  `space_id`, `environment` and `access_token`
      space_id = "<my_space_id>"
      environment = "<my_environment>"
      access_token = "<my_access_token>"

      {:ok, entries, total: _total_count_of_entries} =
        Entries |> fetch_all(space_id, environment, access_token)

  ## More advanced query with included assets

  Entries can have assets included, which limits the amount of times a client has to request data from the server:

      import Contentful.Query
      alias Contentful.{Asset, Entry}
      alias Contentful.Delivery.Entries

      # The default include depth is 1 (max 10)
      {:ok, [ %Entry{assets: assets} = entry | _ ], total: _total_count_of_entries} =
        Entries |> include |> fetch_all

      assets |> Enum.map(fn %Asset{fields: fields} -> {fields.title, fields.file} end)

      # you can also just get the assets belonging to an entry lazily:

      Entries |> include |> stream |> Stream.flat_map(fn entry -> entry.assets end) |> Enum.take(2)


  """

  alias Contentful.{Asset, Entry, Queryable, SysData}
  alias Contentful.Delivery.Assets
  alias Contentful.Entry.AssetResolver

  @behaviour Queryable

  @endpoint "/entries"

  @impl Queryable
  def endpoint do
    @endpoint
  end

  @doc """
  specifies the collection resolver for the case when assets are included within the entries response
  """
  def resolve_collection_response(%{
        "total" => total,
        "items" => items,
        "includes" => %{"Asset" => assets}
      }) do
    {:ok, entries, total: total} =
      resolve_collection_response(%{"total" => total, "items" => items})

    {:ok, entries |> Enum.map(fn entry -> entry |> resolve_assets(assets) end), total: total}
  end

  @doc """
  maps a standard API response for queries compliant with the `Contentful.Queryable` behaviour.


  """
  @impl Queryable
  def resolve_collection_response(%{"total" => total, "items" => items}) do
    entries =
      items
      |> Enum.map(&resolve_entity_response/1)
      |> Enum.map(fn {:ok, entry} -> entry end)

    {:ok, entries, total: total}
  end

  @impl Queryable
  @doc """

  maps a standard API response for a single entry returned, compliant with the `Contentful.Queryable` behaviour.
  """
  def resolve_entity_response(%{
        "fields" => fields,
        "sys" => %{"id" => id, "revision" => rev}
      }) do
    {:ok,
     %Entry{
       fields: fields,
       sys: %SysData{id: id, revision: rev}
     }}
  end

  @spec resolve_assets(Entry.t(), list(Asset.t())) :: Entry.t()
  defp resolve_assets(%Entry{} = entry, assets) do
    asset_ids = entry |> AssetResolver.find_linked_asset_ids()

    assets_for_entry =
      assets
      |> Enum.map(&Assets.resolve_entity_response/1)
      |> Enum.map(fn {:ok, asset} -> asset end)
      |> Enum.filter(fn %Asset{sys: %SysData{id: id}} -> asset_ids |> Enum.member?(id) end)

    entry |> Map.put(:assets, assets_for_entry)
  end
end