defmodule ExOpenAI do
  @moduledoc """
  Provides API wrappers for OpenAI API
  See https://beta.openai.com/docs/api-reference/introduction for further info on REST endpoints
  """

  use Application

  alias ExOpenAI.Config

  def start(_type, _args) do
    children = [Config]
    opts = [strategy: :one_for_one, name: ExOpenAI.Supervisor]

    # TODO: find something more elegant for doing this
    # force allocate all possible keys / atoms that are within all available components
    # this allows us to use String.to_existing_atom without having to worry that those
    # atoms aren't allocated yet
    # with {:ok, mods} <- :application.get_key(:ex_openai, :modules) do
    #   mods
    #   |> Enum.filter(&(&1 |> Module.split() |> Enum.at(1) == "Components"))
    #   |> IO.inspect()

    #   # |> Enum.map(& &1.unpack_ast)
    # end

    Supervisor.start_link(children, opts)
  end

  @doc """
  Modules provided by this package that are not in the openapi docs provided by OpenAI
  So instead of generating those, we just provide a fallback
  """
  def module_overwrites, do: [ExOpenAI.Components.Model]

  defp parse_type(%{
         "type" => "object",
         "properties" => properties
       }) do
    parsed_obj =
      properties
      |> Enum.map(fn {name, obj} ->
        case obj do
          %{"type" => type} ->
            {name, type}

          %{"$ref" => ref} ->
            {name, {:component, String.replace(ref, "#/components/schemas/", "")}}
        end
      end)
      |> Enum.into(%{})

    parsed_obj
  end

  defp parse_type(%{
         "type" => "array",
         "items" => items
       }) do
    case items do
      # on nested array, recurse deeper
      %{"type" => "array", "items" => nested} ->
        {:array, parse_type(nested)}

      %{"type" => "object"} ->
        {:object, parse_type(items)}

      %{"type" => _type} ->
        parse_type(items)

      %{"$ref" => ref} ->
        {:component, String.replace(ref, "#/components/schemas/", "")}

      %{} ->
        :object

      x ->
        IO.puts("invalid type: #{inspect(x)}")
    end
  end

  defp parse_type(%{"type" => type}), do: type

  defp parse_property(
         %{
           "type" => "array",
           "items" => _items
         } = args
       ) do
    parse_property(Map.put(args, "type", {:array, parse_type(args)}))
  end

  defp parse_property(%{"name" => name, "description" => desc, "oneOf" => oneOf}) do
    # parse oneOf array into a list of schemas
    #    "oneOf" => [
    #      %{
    #        "default" => "",
    #        "example" => "I want to kill them.",
    #        "type" => "string"
    #      },
    #      %{
    #        "items" => %{
    #          "default" => "",
    #          "example" => "I want to kill them.",
    #          "type" => "string"
    #        },
    #        "type" => "array"
    #      }
    #    ],

    %{
      name: name,
      description: desc,
      type: "oneOf",
      oneOf:
        Enum.map(oneOf, fn item -> Map.put(parse_get_schema(item), :default, item["default"]) end)
    }
  end

  defp parse_property(
         %{
           "type" => "object",
           "properties" => _properties
         } = args
       ) do
    parse_property(Map.put(args, "type", {:object, parse_type(args)}))
  end

  defp parse_property(
         %{
           "type" => type,
           "name" => name
         } = args
       ) do
    %{
      type: type,
      name: name,
      # optional
      description: Map.get(args, "description", ""),
      # optional
      example: Map.get(args, "example", "")
    }
  end

  defp parse_property(args) do
    IO.puts("Unknown property: #{inspect(args)}")
  end

  defp parse_properties(props) when is_list(props) do
    Enum.map(props, &parse_property(&1))
  end

  defp parse_component_schema(%{"properties" => props, "required" => required}) do
    # turn required stuf into hashmap for quicker access and merge into actual properties
    required_map = required |> Enum.reduce(%{}, fn item, acc -> Map.put(acc, item, true) end)

    merged_props =
      props
      |> Enum.map(fn {key, val} ->
        case Map.has_key?(required_map, key) do
          is_required -> Map.put(val, "required", is_required) |> Map.put("name", key)
        end
      end)

    required_props = merged_props |> Enum.filter(&(Map.get(&1, "required") == true))
    optional_props = merged_props |> Enum.filter(&(Map.get(&1, "required") == false))

    %{
      required_props: parse_properties(required_props),
      optional_props: parse_properties(optional_props)
    }
  end

  defp parse_component_schema(%{"properties" => props}),
    do: parse_component_schema(%{"properties" => props, "required" => []})

  @spec parse_get_schema(map()) :: %{type: String.t(), example: String.t()}
  defp parse_get_schema(%{"type" => type, "example" => example}) do
    %{type: type, example: example}
  end

  defp parse_get_schema(%{"type" => _type} = args),
    do: parse_get_schema(Map.put(args, "example", ""))

  defp parse_request_body(%{"required" => required, "content" => content}, component_mapping) do
    {content_type, rest} =
      content
      |> Map.to_list()
      |> List.first()

    # resolve the object ref to the actual component to get the schema
    ref =
      rest["schema"]["$ref"]
      |> String.replace_prefix("#/components/schemas/", "")

    case content_type do
      "application/json" ->
        %{
          required?: required,
          content_type: String.to_atom(content_type),
          # rest: rest,
          # ref: ref,
          request_schema: Map.get(component_mapping, ref)
        }

      # TODO: other types like multipart/form-data is not supported yet
      _ ->
        :unsupported_content_type
    end
  end

  defp parse_request_body(nil, _) do
    nil
  end

  @spec parse_get_arguments(any()) :: %{
          name: String.t(),
          in: String.t(),
          type: String.t(),
          example: String.t(),
          required?: boolean()
        }
  defp parse_get_arguments(%{"name" => name, "schema" => schema, "in" => inarg} = args) do
    Map.merge(
      %{name: name, in: inarg, required?: Map.get(args, "required", false)},
      parse_get_schema(schema)
    )
  end

  defp extract_response_type(%{"200" => %{"content" => content}}) do
    case content
         # [["application/json", %{}]]
         |> Map.to_list()
         # ["application/json", %{}]
         |> List.first()
         # %{}
         |> Kernel.elem(1)
         |> Map.get("schema") do
      # no ref
      %{"type" => type} -> String.to_atom(type)
      %{"$ref" => ref} -> {:component, String.replace(ref, "#/components/schemas/", "")}
    end
  end

  defp parse_path(
         path,
         %{
           "post" =>
             %{
               "operationId" => id,
               "summary" => summary,
               "requestBody" => body,
               "responses" => responses,
               "x-oaiMeta" => %{"group" => group}
             } = args
         },
         component_mapping
       ) do
    %{
      endpoint: path,
      name: Macro.underscore(id),
      summary: summary,
      deprecated?: Map.has_key?(args, "deprecated"),
      arguments: Map.get(args, "parameters", []) |> Enum.map(&parse_get_arguments(&1)),
      method: :post,
      request_body: parse_request_body(body, component_mapping),
      group: group,
      response_type: extract_response_type(responses)
    }
  end

  defp parse_path(
         path,
         %{
           "post" =>
             %{
               "operationId" => _id,
               "summary" => _summary,
               "responses" => _responses,
               "x-oaiMeta" => _meta
             } = args
         },
         component_mapping
       ) do
    parse_path(path, %{"post" => Map.put(args, "requestBody", nil)}, component_mapping)
  end

  defp parse_path(_path, %{"post" => _args}, _component_mapping) do
    # IO.puts("unhandled POST: #{inspect(path)} - #{inspect(args)}")
    nil
  end

  defp parse_path(_path, %{"delete" => _post}, _component_mapping) do
    # IO.puts("unhandled DELETE: #{inspect(path)} - #{inspect(post)}")
    nil
  end

  # "parse GET functions and generate function definition"
  defp parse_path(
         path,
         %{
           "get" =>
             %{
               "operationId" => id,
               "summary" => summary,
               "responses" => responses,
               "x-oaiMeta" => %{"group" => group}
             } = args
         },
         _component_mapping
       ) do
    %{
      endpoint: path,
      name: Macro.underscore(id),
      summary: summary,
      deprecated?: Map.has_key?(args, "deprecated"),
      arguments: Map.get(args, "parameters", []) |> Enum.map(&parse_get_arguments(&1)),
      method: :get,
      group: group,
      response_type: extract_response_type(responses)
    }
  end

  def get_documentation do
    {:ok, yml} =
      File.read!("docs.yaml")
      |> YamlElixir.read_from_string()

    component_mapping =
      yml["components"]["schemas"]
      |> Enum.reduce(%{}, fn {name, value}, acc ->
        Map.put(acc, name, parse_component_schema(value))
      end)

    %{
      components: component_mapping,
      functions:
        yml["paths"]
        |> Enum.map(fn {path, field_data} -> parse_path(path, field_data, component_mapping) end)
        |> Enum.filter(&(!is_nil(&1)))
        # TODO: implement form-data
        |> Enum.filter(&Kernel.!=(Map.get(&1, :request_body, nil), :unsupported_content_type))
    }
  end

  def type_to_spec("number"), do: quote(do: float())
  def type_to_spec("integer"), do: quote(do: integer())
  def type_to_spec("boolean"), do: quote(do: boolean())
  def type_to_spec("string"), do: quote(do: String.t())
  # TODO: handle these types here better
  def type_to_spec("array"), do: quote(do: list())
  def type_to_spec("object"), do: quote(do: map())
  def type_to_spec("oneOf"), do: quote(do: any())

  def type_to_spec({:array, {:object, nested_object}}) do
    parsed = type_to_spec({:object, nested_object})
    [parsed]
  end

  def type_to_spec({:array, nested}) do
    quote(do: unquote([type_to_spec(nested)]))
  end

  def type_to_spec({:object, nested}) when is_map(nested) do
    parsed =
      nested
      |> Enum.map(fn {name, type} ->
        {String.to_atom(name), type_to_spec(type)}
      end)

    # manually construct correct AST for maps
    {:%{}, [], parsed}
  end

  # nested component reference
  def type_to_spec({:component, component}) when is_binary(component),
    do: quote(do: unquote(string_to_component(component)).t())

  # fallbacks
  def type_to_spec(i) when is_atom(i), do: type_to_spec(Atom.to_string(i))

  def type_to_spec(x) do
    IO.puts("unhandled: #{inspect(x)}")
    quote(do: any())
  end

  def string_to_component(comp), do: Module.concat(ExOpenAI.Components, comp)

  def keys_to_atoms(string_key_map) when is_map(string_key_map) do
    for {key, val} <- string_key_map,
        into: %{},
        do: {
          try do
            String.to_existing_atom(key)
          rescue
            ArgumentError ->
              IO.puts(
                "Warning! Found non-existing atom returning by OpenAI API: :#{key}.\nThis may mean that OpenAI has updated it's API, or that the key was not included in their official openapi reference.\nGoing to load this atom now anyway, but as converting a lot of unknown data into atoms can result in a memory leak, watch out for these messages. If you see a lot of them, something may be wrong."
              )

              String.to_atom(key)
          end,
          keys_to_atoms(val)
        }
  end

  def keys_to_atoms(value) when is_list(value), do: Enum.map(value, &keys_to_atoms/1)
  def keys_to_atoms(value), do: value
end

docs = ExOpenAI.get_documentation()

# Generate structs from schema
docs
|> Map.get(:components)
# generate module name: ExOpenAI.Components.X
|> Enum.map(fn {name, c} ->
  {name
   |> ExOpenAI.string_to_component(), c}
end)
# ignore stuff that's overwritten
|> Enum.filter(fn {name, _c} -> name not in ExOpenAI.module_overwrites() end)
|> Enum.each(fn {name, component} ->
  struct_fields =
    [component.required_props, component.optional_props]
    |> Enum.map(fn i ->
      Enum.reduce(
        i,
        %{},
        fn item, acc ->
          name = item.name
          type = item.type

          Map.merge(acc, %{
            String.to_atom(name) => quote(do: unquote(ExOpenAI.type_to_spec(type)))
          })
        end
      )
    end)

  # module start
  defmodule name do
    @type t :: %unquote(name){
            unquote_splicing(
              struct_fields
              |> Enum.map(&Map.to_list(&1))
              |> Enum.reduce(&Kernel.++/2)
            )
          }

    with l <- List.first(struct_fields),
         is_empty? <- Enum.empty?(l),
         false <- is_empty? do
      # @enforce_keys Map.keys(l)
    end

    defstruct(struct_fields |> Enum.map(&Map.keys(&1)) |> List.flatten())

    @doc """
    Helper function to return the full AST representation of the type and all it's nested types
    This is used so that all atoms in the map are getting allocated recursively.
    Without this, we wouldn't be able to safely do String.to_existing_atom()
    """
    def unpack_ast(partial_tree \\ %{}) do
      resolved_mods = Map.get(partial_tree, :resolved_mods, [])
      partial_tree = Map.put(partial_tree, :resolved_mods, resolved_mods)

      {:ok, x} = Code.Typespec.fetch_types(__MODULE__)

      case Enum.member?(resolved_mods, __MODULE__) do
        true ->
          # IO.puts("already resolved, skipping")
          partial_tree

        false ->
          res =
            x
            |> List.first()
            |> Kernel.elem(1)
            |> Code.Typespec.type_to_quoted()
            # walk through the AST and find all "ExOpenAI.Components"
            # unpack their AST recursively and merge it all together into
            # the accumulator
            |> Macro.prewalk(partial_tree, fn args, acc ->
              r =
                with true <- is_atom(args),
                     ats <- Atom.to_string(args),
                     true <- String.contains?(ats, "ExOpenAI.Components") do
                  tree =
                    args.unpack_ast(%{
                      resolved_mods: acc.resolved_mods ++ [__MODULE__]
                    })

                  {:ok, tree}
                end

              # merge back into accumulator, otherwise just return AST as is
              case r do
                {:ok, res} -> {args, Map.merge(acc, res)}
                _ -> {args, acc}
              end
            end)

          {ast, acc} = res

          acc
          |> Map.put(__MODULE__, ast)
      end
    end
  end

  # module end
end)

# generate modules
docs
|> Map.get(:functions)
|> Enum.reduce(%{}, fn fx, acc ->
  Map.put(acc, fx.group, [fx | Map.get(acc, fx.group, [])])
end)
|> Enum.each(fn {modname, functions} ->
  modname =
    modname
    |> String.replace("-", "_")
    |> Macro.camelize()
    |> String.to_atom()
    |> (&Module.concat(ExOpenAI, &1)).()

  defmodule modname do
    functions
    |> Enum.each(fn fx ->
      %{
        name: name,
        summary: summary,
        arguments: args,
        endpoint: endpoint,
        deprecated?: deprecated,
        method: method,
        response_type: response_type
      } = fx

      name = String.to_atom(name)

      merged_required_args =
        case method do
          :post ->
            args ++
              if(is_nil(fx.request_body),
                do: [],
                else: fx.request_body.request_schema.required_props
              )

          :get ->
            Enum.filter(args, &Map.get(&1, :required?))
        end

      required_args_docstring =
        Enum.map_join(merged_required_args, "\n\n", fn i ->
          s = "- `#{i.name}`"
          s = if Map.has_key?(i, :description), do: "#{s}: #{Map.get(i, :description)}", else: s

          s =
            if Map.get(i, :example, "") != "",
              do: "#{s}\n\n*Example*: `#{Map.get(i, :example)}`",
              else: s

          s
        end)

      merged_optional_args =
        case method do
          :post ->
            Enum.filter(args, &(!Map.get(&1, :required?))) ++
              if(is_nil(fx.request_body),
                do: [],
                else: fx.request_body.request_schema.optional_props
              )

          :get ->
            Enum.filter(args, &(!Map.get(&1, :required?)))
        end

      optional_args_docstring =
        Enum.map_join(merged_optional_args, "\n\n", fn i ->
          s = "- `#{i.name}`"
          s = if Map.has_key?(i, :description), do: "#{s}: #{Map.get(i, :description)}", else: s

          s =
            if Map.get(i, :example, "") != "",
              do: "#{s}\n\n*Example*: `#{inspect(Map.get(i, :example))}`",
              else: s

          s
        end)

      # convert non-optional args into [arg1, arg2, arg3] representation
      arg_names =
        merged_required_args
        |> Enum.map(&(Map.get(&1, :name) |> String.to_atom() |> Macro.var(nil)))

      # convert non-optional args into spec definition [String.t(), String.t(), etc.] representation
      spec =
        merged_required_args
        |> Enum.map(fn item -> quote do: unquote(ExOpenAI.type_to_spec(item.type)) end)

      # convert optional args into keyword list
      response_spec = ExOpenAI.type_to_spec(response_type)

      optional_args =
        merged_optional_args
        |> Enum.reduce([], fn item, acc ->
          name = item.name
          type = item.type

          case acc do
            [] ->
              quote do: {unquote(String.to_atom(name)), unquote(ExOpenAI.type_to_spec(type))}

            val ->
              quote do:
                      {unquote(String.to_atom(name)), unquote(ExOpenAI.type_to_spec(type))}
                      | unquote(val)
          end
        end)

      @doc """
      Endpoint `#{endpoint}`

      #{summary}

      ---

      ### Required Arguments:

      #{required_args_docstring}


      ### Optional Arguments:

      #{optional_args_docstring}
      """
      if deprecated, do: @deprecated("Deprecated by OpenAI")

      opts_name =
        name |> Atom.to_string() |> Kernel.<>("_opts") |> String.to_atom() |> Macro.var(nil)

      @type unquote(opts_name) :: unquote(optional_args)
      @spec unquote(name)(unquote_splicing(spec)) :: {:ok, any()} | {:error, any()}
      @spec unquote(name)(unquote_splicing(spec), [unquote(optional_args)]) ::
              {:ok, unquote(response_spec)} | {:error, any()}
      def unquote(name)(unquote_splicing(arg_names), opts \\ []) do
        # store binding so we can't access args of the function later
        binding = binding()

        required_arguments = unquote(Macro.escape(merged_required_args))
        optional_arguments = unquote(Macro.escape(merged_optional_args))
        arguments = required_arguments ++ optional_arguments
        url = "#{unquote(endpoint)}"
        method = unquote(method)

        # merge all passed args together, so opts + passed
        all_passed_args = Keyword.merge(binding, opts) |> Keyword.drop([:opts])

        # replace all args in the URL that are specified as 'path'
        # for example: /model/{model_id} -> /model/123
        url =
          arguments
          |> Enum.filter(&Kernel.==(Map.get(&1, :in, ""), "path"))
          |> Enum.reduce(
            url,
            &String.replace(
              &2,
              "{#{&1.name}}",
              Keyword.get(all_passed_args, String.to_atom(&1.name))
            )
          )

        # iterate over all other arguments marked with in: "query", and append them to the query
        # for example /model/123?foo=bar
        query =
          Enum.filter(arguments, &Kernel.==(Map.get(&1, :in, ""), "query"))
          |> Enum.reduce(%{}, fn item, acc ->
            Map.put(acc, item.name, Keyword.get(all_passed_args, String.to_atom(item.name)))
          end)
          |> URI.encode_query()

        url = url <> "?" <> query

        # construct body with the remaining args

        body_params =
          arguments
          # filter by all the rest, so neither query nor path
          |> Enum.filter(&Kernel.==(Map.get(&1, :in, ""), ""))
          |> Enum.filter(&(!is_nil(Keyword.get(all_passed_args, String.to_atom(&1.name)))))
          |> Enum.reduce(
            [],
            &Keyword.merge(&2, [
              {
                String.to_atom(&1.name),
                Keyword.get(all_passed_args, String.to_atom(&1.name))
              }
            ])
          )

        case ExOpenAI.Client.api_call(method, url, body_params, opts) do
          {:ok, res} ->
            case unquote(response_type) do
              {:component, comp} ->
                # calling unpack_ast here so that all atoms of the given struct are
                # getting allocated. otherwise later usage of keys_to_atom will fail
                ExOpenAI.string_to_component(comp).unpack_ast()

                # todo: this is not recursive yet, so nested values won't be correctly identified as struct
                # although the typespec is already recursive, so there can be cases where
                # the typespec says a struct is nested, but there isn't
                {:ok, struct(ExOpenAI.string_to_component(comp), ExOpenAI.keys_to_atoms(res))}

              _ ->
                {:ok, res}
            end

          e ->
            e
        end
      end
    end)
  end
end)