# This code has originally been a part of https://github.com/elixir-lsp/elixir_sense

# Copyright (c) 2017 Marlus Saraiva
# Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
# The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

defmodule ElixirLS.LanguageServer.Providers.Completion.Reducers.TypeSpecs do
  @moduledoc false

  alias ElixirSense.Core.Binding
  alias ElixirSense.Core.Introspection
  alias ElixirSense.Core.Metadata
  alias ElixirSense.Core.Source
  alias ElixirSense.Core.State
  alias ElixirSense.Core.TypeInfo
  alias ElixirLS.Utils.Matcher

  @type type_spec :: %{
          type: :type_spec,
          name: String.t(),
          arity: non_neg_integer,
          origin: String.t() | nil,
          args_list: list(String.t()),
          spec: String.t(),
          doc: String.t(),
          signature: String.t(),
          metadata: map
        }

  @doc """
  A reducer that adds suggestions of type specs.
  """

  # We only list type specs when inside typespec scope
  def add_types(
        hint,
        env,
        file_metadata,
        %{at_module_body?: _, cursor_position: cursor_position},
        acc
      ) do
    if match?({_, _}, env.typespec) do
      %State.Env{
        aliases: aliases,
        module: module
      } = env

      %Metadata{mods_funs_to_positions: mods_funs, types: metadata_types} = file_metadata

      binding_env = Binding.from_env(env, file_metadata, cursor_position)

      {mod, hint} =
        hint
        |> Source.split_module_and_hint(module, aliases)
        |> expand(binding_env, aliases)

      list =
        find_typespecs_for_mod_and_hint(
          {mod, hint},
          env,
          mods_funs,
          metadata_types
        )
        |> Kernel.++(find_builtin_types({mod, hint}))

      {:cont, %{acc | result: acc.result ++ list}}
    else
      {:cont, acc}
    end
  end

  def add_types(_hint, _env, _buffer_metadata, _context, acc) do
    {:cont, acc}
  end

  defp expand({{:attribute, _} = type, hint}, env, aliases) do
    # TODO Binding should return expanded aliases
    # TODO use Macro.Env
    case Binding.expand(env, type) do
      {:atom, module} -> {Introspection.expand_alias(module, aliases), hint}
      _ -> {nil, ""}
    end
  end

  defp expand({type, hint}, _env, _aliases) do
    {type, hint}
  end

  defp find_typespecs_for_mod_and_hint(
         {mod, hint},
         env,
         mods_funs,
         metadata_types
       ) do
    # alias already expanded by Source.split_module_and_hint
    case Introspection.actual_module(mod, env, mods_funs, false) do
      {actual_mod, true} ->
        find_module_types(actual_mod, {mod, hint}, metadata_types, env.module)

      {nil, false} ->
        find_module_types(env.module, {mod, hint}, metadata_types, env.module)

      {_, false} ->
        []
    end
  end

  defp find_builtin_types({nil, hint}) do
    TypeInfo.find_all_builtin(&Matcher.match?("#{&1.name}", hint))
    |> Enum.map(&type_info_to_suggestion(&1, nil))
    |> Enum.sort_by(fn %{name: name, arity: arity} -> {name, arity} end)
  end

  defp find_builtin_types({_mod, _hint}), do: []

  defp find_module_types(actual_mod, {mod, hint}, metadata_types, module) do
    find_metadata_types(actual_mod, {mod, hint}, metadata_types, module)
    |> Kernel.++(TypeInfo.find_all(actual_mod, &Matcher.match?("#{&1.name}", hint)))
    |> Enum.map(&type_info_to_suggestion(&1, actual_mod))
    |> Enum.uniq_by(fn %{name: name, arity: arity} -> {name, arity} end)
    |> Enum.sort_by(fn %{name: name, arity: arity} -> {name, arity} end)
  end

  defp find_metadata_types(actual_mod, {mod, hint}, metadata_types, module) do
    # local types are hoisted, no need to check position
    include_private = mod == nil and actual_mod == module

    for {{^actual_mod, type, arity}, type_info} when is_integer(arity) <- metadata_types,
        type |> Atom.to_string() |> Matcher.match?(hint),
        include_private or type_info.kind != :typep,
        do: type_info
  end

  defp type_info_to_suggestion(type_info, module) do
    origin = if module, do: inspect(module)

    case type_info do
      %ElixirSense.Core.State.TypeInfo{args: [args]} ->
        args_stringified = Enum.join(args, ", ")

        spec =
          case type_info.kind do
            :opaque -> "@opaque #{type_info.name}(#{args_stringified})"
            _ -> List.last(type_info.specs)
          end

        %{
          type: :type_spec,
          name: type_info.name |> Atom.to_string(),
          arity: length(args),
          args_list: args,
          signature: "#{type_info.name}(#{args_stringified})",
          origin: origin,
          doc: Introspection.extract_summary_from_docs(type_info.doc),
          spec: spec,
          metadata: type_info.meta
        }

      _ ->
        args_list =
          if type_info.signature do
            part =
              type_info.signature
              |> String.split("(")
              |> Enum.at(1)

            if part do
              part
              |> String.split(")")
              |> Enum.at(0)
              |> String.split(",")
              |> Enum.map(&String.trim/1)
            else
              []
            end
          else
            []
          end

        %{
          type: :type_spec,
          name: type_info.name |> Atom.to_string(),
          arity: type_info.arity,
          args_list: args_list,
          signature: type_info.signature,
          origin: origin,
          doc: type_info.doc,
          spec: type_info.spec,
          metadata: type_info.metadata
        }
    end
  end
end
