defmodule Cache.Redis.JSON do
  @moduledoc false

  alias Cache.{Redis, TermEncoder}

  def get(pool_name, key, nil, opts) do
    with {:ok, data} <- json_command(pool_name, key, "GET", [], opts) do
      {:ok, TermEncoder.decode_json(data)}
    end
  end

  def get(pool_name, key, path, opts) do
    with {:ok, data} <- json_command(pool_name, key, "GET", [serialize_path(path)], opts) do
      {:ok, TermEncoder.decode_json(data)}
    end
  end

  def set(pool_name, key, path, value, opts) do
    json_command(
      pool_name,
      key,
      "SET",
      [serialize_path(path), TermEncoder.encode_json(value)],
      opts
    )
  end

  def delete(pool_name, key, path, opts) do
    json_command(pool_name, key, "DEL", [serialize_path(path)], opts)
  end

  def incr(pool_name, key, path, value, opts) do
    with {:ok, value} <-
           json_command(
             pool_name,
             key,
             "NUMINCRBY",
             [serialize_path(path), to_string(value)],
             opts
           ) do
      {:ok, String.to_integer(value)}
    end
  end

  def clear(pool_name, key, path, opts) do
    json_command(
      pool_name,
      key,
      "CLEAR",
      [serialize_path(path)],
      opts
    )
  end

  def array_append(pool_name, key, path, values, opts) when is_list(values) do
    json_command(
      pool_name,
      key,
      "ARRAPPEND",
      [serialize_path(path) | Enum.map(values, &TermEncoder.encode_json/1)],
      opts
    )
  end

  def array_append(pool_name, key, path, value, opts) do
    json_command(
      pool_name,
      key,
      "ARRAPPEND",
      [serialize_path(path), TermEncoder.encode_json(value)],
      opts
    )
  end

  def serialize_path(nil) do
    "$"
  end

  def serialize_path(path_list) do
    Enum.reduce(path_list, "", &append_to_path(&2, &1))
  end

  def append_to_path("", field) do
    to_string(field)
  end

  def append_to_path(path, field) when is_atom(field) do
    append_to_path(path, to_string(field))
  end

  def append_to_path(path, index) when is_integer(index) do
    "#{path}[#{index}]"
  end

  def append_to_path(path, field) when is_binary(field) do
    "#{path}.#{field}"
  end

  defp json_command(pool_name, key, command, commands, opts) do
    Redis.Global.command(
      pool_name,
      [
        "JSON.#{command}",
        Redis.Global.cache_key(pool_name, key) | commands
      ],
      opts
    )
  end
end