blog.ex

defmodule FormUrlRecipe.Blog do
  @moduledoc """
  The Blog context.
  """

  import Ecto.Query, warn: false
  alias FormUrlRecipe.Repo

  alias FormUrlRecipe.Blog.Post

  @doc """
  Returns the list of posts.

  ## Examples

      iex> list_posts()
      [%Post{}, ...]

  """
  def list_posts do
    Repo.all(Post)
  end

  def list_authors do
    query = from p in Post, select: p.author, distinct: true

    Repo.all(query)
  end

  @doc """
  Returns the list of posts based on a search map.

  ## Examples

      iex> search_posts(%{"title" => "foo"})
      [%Post{}, ...]

  """
  def search_posts(params) do
    conditions =
      params
      |> Map.take(["title", "author"])
      |> Enum.reduce(true, fn
        {_key, value}, acc when value in ["", nil] ->
          acc

        {key, value}, acc ->
          atomized_key = String.to_atom(key)
          dynamic([p], field(p, ^atomized_key) == ^value and ^acc)
      end)

    query = from p in Post, where: ^conditions

    Repo.all(query)
  end

  @doc """
  Gets a single post.

  Raises `Ecto.NoResultsError` if the Post does not exist.

  ## Examples

      iex> get_post!(123)
      %Post{}

      iex> get_post!(456)
      ** (Ecto.NoResultsError)

  """
  def get_post!(id), do: Repo.get!(Post, id)

  @doc """
  Creates a post.

  ## Examples

      iex> create_post(%{field: value})
      {:ok, %Post{}}

      iex> create_post(%{field: bad_value})
      {:error, %Ecto.Changeset{}}

  """
  def create_post(attrs \\ %{}) do
    %Post{}
    |> Post.changeset(attrs)
    |> Repo.insert()
  end

  @doc """
  Updates a post.

  ## Examples

      iex> update_post(post, %{field: new_value})
      {:ok, %Post{}}

      iex> update_post(post, %{field: bad_value})
      {:error, %Ecto.Changeset{}}

  """
  def update_post(%Post{} = post, attrs) do
    post
    |> Post.changeset(attrs)
    |> Repo.update()
  end

  @doc """
  Deletes a post.

  ## Examples

      iex> delete_post(post)
      {:ok, %Post{}}

      iex> delete_post(post)
      {:error, %Ecto.Changeset{}}

  """
  def delete_post(%Post{} = post) do
    Repo.delete(post)
  end

  @doc """
  Returns an `%Ecto.Changeset{}` for tracking post changes.

  ## Examples

      iex> change_post(post)
      %Ecto.Changeset{data: %Post{}}

  """
  def change_post(%Post{} = post, attrs \\ %{}) do
    Post.changeset(post, attrs)
  end
end