# Copyright (C) 2018 by the Georgia Tech Research Institute (GTRI)
# This software may be modified and distributed under the terms of
# the BSD 3-Clause license. See the LICENSE file for details.

defmodule Helpers do
  @moduledoc """
  Collection of generic helper functions.
  """

  @doc """
  get_slug/1: extracts the slug from the provided URI argument and returns the path

  # Example
      iex(1)> {:ok, slug} = Helpers.get_slug("https://github.com/kitplummer/xmpprails")
      {:ok, "kitplummer/xmpprails"}
      iex(2)> slug
      "kitplummer/xmpprails"
  """
  def get_slug(url) do
    uri = URI.parse(url)

    case uri.path do
      nil ->
        {:error, "invalid source URL"}

      path ->
        path = String.slice(path, 1..-1)
        {:ok, path}
    end
  end

  @doc """
  split_slug/1: splits apart the username and repo from a git slug returning discrete stings.

  ## Examples

      iex(6)> {:ok, org, repo}  = Helpers.split_slug("kitplummer/xmpprails")
      {:ok, "kitplummer", "xmpprails"}
      iex(7)> org
      "kitplummer"
      iex(8)> repo
      "xmpprails"

  """
  def split_slug(slug) do
    if String.contains?(slug, "/") do
      v = String.split(slug, "/")
      {:ok, Enum.at(v, 0), Enum.at(v, 1)}
    else
      {:error, "bad_slug"}
    end
  end

  def count_forward_slashes(url) do
    url |> String.graphemes |> Enum.count(& &1 == "/")
  end

  # def have_config() do
  #   try do
  #     config = Application.fetch_env!(:lowendinsight, :critical_contributor_level)
  #     IO.inspect config
  #     IO.puts "CONFIG: "

  #   rescue
  #     RuntimeError -> raise ArgumentError, message: "No LoweEndInsight configuration found."
  #   end
  # end


  @doc """
  validates field is a valid url

  ## Examples
  iex> "https:://www.url.com"
  ...> |> Helpers.validate_url()
  {:error, "invalid URI"}

  iex> "http://zipbooks.com/"
  ...> |> Helpers.validate_url()
  :ok

  iex> "https://https://www.google.com"
  ...> |> Helpers.validate_url()
  {:error, "invalid URI"}

  iex> '"https://"https://www.google.com"'
  ...> |> Helpers.validate_url()
  {:error, "invalid URI"}

  iex> "zipbooks.com"
  ...> |> Helpers.validate_url()
  {:error, "invalid URI"}

  iex> "https://zipbooks..com"
  ...> |> Helpers.validate_url()
  {:error, "invalid URI"}
  """
  def validate_url(url) do
    try do
      with :ok <- validate_scheme(url),
          :ok <- validate_host(url),
          do: :ok
    rescue
      FunctionClauseError ->
        {:error, "invalid URI"}
    end
  end

  @doc """
  iex> ["http://www.google.com","http://www.test.com"]
  ...> |> Helpers.validate_urls()
  :ok

  iex> ["https://zipbooks..com", "http://www.test.com"]
  ...> |> Helpers.validate_urls()
  {:error, "invalid URI"}

  iex> ["https://https://github.com/kitplummer/xmpp4rails","https://www.zipbooks.com", "http://www.test.com"]
  ...> |> Helpers.validate_urls()
  {:error, "invalid URI"}

  iex> "https://zipbooks.com"
  ...> |> Helpers.validate_urls()
  {:error, "invalid URI"}
  """
  def validate_urls(urls) do
    try do
      if !is_list(urls), do: throw(:break)
      Enum.each urls, fn url ->
        if :ok == validate_url(url), do: :ok, else: throw(:break)
      end
    catch
      :break -> {:error, "invalid URI"}
    end
  end

  defp validate_host(url) do
    case URI.parse(url) do
      %URI{host: nil} -> {:error, "invalid URI"}
      %URI{host: host} ->
        case :inet.gethostbyname(Kernel.to_charlist host) do
          {:ok, _} -> :ok
          {:error, _} -> {:error, "invalid URI"}
        end
    end 
  end

  defp validate_scheme(url) do
    case URI.parse(url) do
      %URI{scheme: nil} -> {:error, "invalid URI"}
      %URI{scheme: scheme} ->
        case URI.default_port(scheme) do
          nil -> {:error, "invalid URI"}
          p when p > 0 -> :ok
        end
    end
  end
end