defmodule Scrypath.Meilisearch.Client do
  @moduledoc false

  alias Scrypath.Config
  alias Scrypath.Document
  alias Scrypath.Meilisearch.Query, as: MeilisearchQuery
  alias Scrypath.Query, as: CommonQuery
  alias Scrypath.Telemetry

  @spec create_index(String.t(), String.t() | atom() | nil, keyword()) ::
          {:ok, map()} | {:error, term()}
  def create_index(index_name, primary_key, config) do
    payload =
      %{"uid" => index_name}
      |> maybe_put_primary_key(primary_key)

    run_request(:post, "/indexes", [json: payload], config, index: index_name)
  end

  @spec update_settings(String.t(), map(), keyword()) :: {:ok, map()} | {:error, term()}
  def update_settings(index_name, settings, config) when is_map(settings) do
    run_request(
      :patch,
      "/indexes/#{index_name}/settings",
      [json: settings],
      config,
      index: index_name
    )
  end

  @spec get_settings(String.t(), keyword()) :: {:ok, map()} | {:error, term()}
  def get_settings(index_name, config) do
    run_request(
      :get,
      "/indexes/#{index_name}/settings",
      [],
      config,
      index: index_name
    )
  end

  @spec swap_indexes({String.t(), String.t()}, keyword()) :: {:ok, map()} | {:error, term()}
  def swap_indexes({source_index, target_index}, config) do
    payload = [%{"indexes" => [source_index, target_index]}]

    run_request(
      :post,
      "/swap-indexes",
      [json: payload],
      config,
      source_index: source_index,
      target_index: target_index
    )
  end

  @spec upsert_documents(String.t(), [Document.t()], keyword()) :: {:ok, map()} | {:error, term()}
  def upsert_documents(index_name, documents, config) when is_list(documents) do
    document_id_field = Keyword.get(config, :document_id_field, :id)

    run_request(
      :post,
      "/indexes/#{index_name}/documents",
      [json: Enum.map(documents, &document_payload(&1, document_id_field))],
      config,
      index: index_name
    )
  end

  @spec delete_documents(String.t(), [term()], keyword()) :: {:ok, map()} | {:error, term()}
  def delete_documents(index_name, document_ids, config) when is_list(document_ids) do
    run_request(
      :post,
      "/indexes/#{index_name}/documents/delete-batch",
      [json: document_ids],
      config,
      index: index_name
    )
  end

  @spec task(term(), keyword()) :: {:ok, map()} | {:error, term()}
  def task(task_uid, config) do
    run_request(:get, "/tasks/#{task_uid}", [], config, task_uid: task_uid)
  end

  @spec tasks(keyword(), keyword()) :: {:ok, map()} | {:error, term()}
  def tasks(filters, config) when is_list(filters) do
    run_request(:get, "/tasks", [params: encode_task_filters(filters)], config, filters: filters)
  end

  @spec search(String.t(), CommonQuery.t() | map() | String.t(), keyword()) ::
          {:ok, map()} | {:error, term()}
  def search(index_name, query, config) do
    run_request(
      :post,
      "/indexes/#{index_name}/search",
      [json: search_payload(query)],
      config,
      index: index_name
    )
  end

  @spec multi_search(map(), keyword()) :: {:ok, map()} | {:error, term()}
  def multi_search(payload, config) when is_map(payload) do
    run_request(
      :post,
      "/multi-search",
      [json: payload],
      config,
      operation: :multi_search
    )
  end

  defp run_request(method, path, req_opts, config, extra_metadata) do
    metadata =
      extra_metadata
      |> Map.new()
      |> Map.merge(%{method: method, path: path})

    Telemetry.span([:scrypath, :meilisearch, :request], metadata, fn ->
      response =
        request(config)
        |> Req.request([method: method, url: path] ++ req_opts)

      {normalize_response(response), response_metadata(response)}
    end)
  end

  defp request(config) do
    options =
      config
      |> Keyword.get(:req_options, [])
      |> Keyword.put_new(:base_url, base_url!(config))
      |> Keyword.update(:headers, default_headers(config), &(default_headers(config) ++ &1))

    Req.new(options)
  end

  defp normalize_response({:ok, %Req.Response{status: status, body: body}})
       when status >= 200 and status < 300 and is_map(body) do
    {:ok, body}
  end

  defp normalize_response({:ok, %Req.Response{status: status, body: body}}) do
    {:error, {:http_error, status, body}}
  end

  defp normalize_response({:error, exception}) do
    {:error, {:transport_error, exception}}
  end

  defp response_metadata({:ok, %Req.Response{status: status}}), do: %{status_code: status}
  defp response_metadata({:error, exception}), do: %{error: inspect(exception)}

  defp document_payload(%Document{id: id, data: data}, document_id_field) when is_map(data) do
    Map.put(data, document_id_field, id)
  end

  defp search_payload(%CommonQuery{} = query), do: MeilisearchQuery.to_payload(query)
  defp search_payload(query) when is_binary(query), do: %{q: query}
  defp search_payload(query) when is_map(query), do: query

  defp maybe_put_primary_key(payload, nil), do: payload

  defp maybe_put_primary_key(payload, primary_key),
    do: Map.put(payload, "primaryKey", to_string(primary_key))

  defp encode_task_filters(filters) do
    Enum.reduce(filters, %{}, fn
      {_key, nil}, acc ->
        acc

      {key, value}, acc when is_list(value) ->
        Map.put(acc, camelize_filter(key), Enum.map_join(value, ",", &to_string/1))

      {key, value}, acc ->
        Map.put(acc, camelize_filter(key), to_string(value))
    end)
  end

  defp camelize_filter(key) do
    key
    |> to_string()
    |> Macro.camelize()
    |> then(&String.replace_prefix(&1, String.first(&1), String.downcase(String.first(&1))))
  end

  defp default_headers(config) do
    case Config.meilisearch_api_key(config) do
      nil -> []
      api_key -> [{"x-meili-api-key", api_key}]
    end
  end

  defp base_url!(config) do
    case Config.fetch_meilisearch_url!(config) do
      url when is_binary(url) and url != "" -> url
      _ -> raise ArgumentError, "meilisearch_url is required"
    end
  end
end