sm_chat

defmodule SmChat do
  @moduledoc """
  Provides utility functions for interacting with the SuperMaker AI Chat service.

  This module focuses on building URLs and providing data transformations
  specific to the SuperMaker AI Chat API.  It assumes the base URL
  is `https://supermaker.ai/chat/`.
  """

  @base_url "https://supermaker.ai/chat/"

  @doc """
  Builds a URL from the base URL and a path, optionally adding query parameters.

  ## Examples

      iex> SmChat.build_url("messages")
      "https://supermaker.ai/chat/messages"

      iex> SmChat.build_url("messages", page: 2, limit: 50)
      "https://supermaker.ai/chat/messages?page=2&limit=50"
  """
  def build_url(path, params \\ []) when is_list(params) do
    url = @base_url <> path

    if params == [] do
      url
    else
      query_string =
        params
        |> Enum.map(fn {key, value} -> "#{key}=#{value}" end)
        |> Enum.join("&")

      url <> "?" <> query_string
    end
  end

  @doc """
  Formats a timestamp (as a string or integer) into a human-readable date string.
  Handles both string and integer timestamps.

  ## Examples

      iex> SmChat.format_timestamp(1678886400)
      {:ok, "2023-03-15 00:00:00 UTC"}

      iex> SmChat.format_timestamp("1678886400")
      {:ok, "2023-03-15 00:00:00 UTC"}

      iex> SmChat.format_timestamp("invalid")
      :error
  """
  def format_timestamp(timestamp) when is_integer(timestamp) do
    case :calendar.universal_time_to_datetime({timestamp, 0, 0}) do
      {:ok, datetime} ->
        {:ok, DateTime.from_naive_datetime(NaiveDateTime.from_erl(datetime), "Etc/UTC") |> DateTime.to_string()}
      {:error, _} ->
        :error
    end
  end

  def format_timestamp(timestamp) when is_binary(timestamp) do
    case Integer.parse(timestamp) do
      {int_timestamp, _} ->
        format_timestamp(int_timestamp)
      :error ->
        :error
    end
  end

  @doc """
  Filters a list of messages, returning only those sent by a specific user ID.

  ## Examples

      iex> messages = [%{user_id: 1, text: "Hello"}, %{user_id: 2, text: "World"}, %{user_id: 1, text: "Again"}]
      iex> SmChat.filter_by_user_id(messages, 1)
      [%{user_id: 1, text: "Hello"}, %{user_id: 1, text: "Again"}]
  """
  def filter_by_user_id(messages, user_id) when is_list(messages) and is_integer(user_id) do
    Enum.filter(messages, fn message -> message[:user_id] == user_id end)
  end

  @doc """
  Truncates a message to a maximum length, adding an ellipsis if truncated.

  ## Examples

      iex> SmChat.truncate_message("This is a very long message", 20)
      "This is a very long..."

      iex> SmChat.truncate_message("Short message", 20)
      "Short message"
  """
  def truncate_message(message, max_length) when is_binary(message) and is_integer(max_length) do
    if String.length(message) > max_length do
      String.slice(message, 0..max_length - 1) <> "..."
    else
      message
    end
  end

  @doc """
  Sorts a list of messages by timestamp in ascending or descending order.

  ## Examples

      iex> messages = [%{timestamp: 2}, %{timestamp: 1}, %{timestamp: 3}]
      iex> SmChat.sort_by_timestamp(messages, :asc)
      [%{timestamp: 1}, %{timestamp: 2}, %{timestamp: 3}]

      iex> SmChat.sort_by_timestamp(messages, :desc)
      [%{timestamp: 3}, %{timestamp: 2}, %{timestamp: 1}]
  """
  def sort_by_timestamp(messages, order) when is_list(messages) and order in [:asc, :desc] do
    Enum.sort(messages, fn a, b ->
      case order do
        :asc -> a[:timestamp] <= b[:timestamp]
        :desc -> a[:timestamp] >= b[:timestamp]
      end
    end)
  end
end