defmodule Stellar.Horizon.PaymentPaths do
  @moduledoc """
  Exposes functions to interact with Paths in Horizon.

  You can:
  * Lists the paths a payment can take based on the amount of an asset you want the recipient to receive.
  * Lists the paths a payment can take based on the amount of an asset you want to send.

  Horizon API reference: https://developers.stellar.org/api/aggregations/paths/
  """

  alias Stellar.Horizon.{Error, Paths, Request, RequestParams, Server}

  @type server :: Server.t()
  @type args :: Keyword.t()
  @type opt :: atom()
  @type path :: String.t()
  @type resource :: Paths.t()
  @type response :: {:ok, resource()} | {:error, Error.t()}

  @endpoint "paths"

  @doc """
    List Payment Paths

  ## Parameters

    * `server`: The Horizon server to query.
    * `source_account`: The Stellar address of the sender.
    * `destination_asset`: `:native` or `[code: "destination_asset_code", issuer: "destination_asset_issuer"]`
    * `destination_amount`: The amount of the destination asset that should be received.

  ## Options

    * `destination_account`: The Stellar address of the reciever.

  ## Examples

      iex> PaymentPaths.list_paths(
        Stellar.Horizon.Server.testnet(),
        source_account: "GBRSLTT74SKP62KJ7ENTMP5V4R7UGB6E5UQESNIIRWUNRCCUO4ZMFM4C",
        destination_asset: :native,
        destination_amount: 5
      )
      {:ok, %Paths{records: [%Path{}, ...]}}

      # list with `destination_account`
      iex> PaymentPaths.list_paths(Stellar.Horizon.Server.testnet(),
        source_account: "GBRSLTT74SKP62KJ7ENTMP5V4R7UGB6E5UQESNIIRWUNRCCUO4ZMFM4C",
        destination_asset: :native,
        destination_amount: 5,
        destination_account: "GBRSLTT74SKP62KJ7ENTMP5V4R7UGB6E5UQESNIIRWUNRCCUO4ZMFM4C"
      )
      {:ok, %Paths{records: [%Path{}, ...]}}

      # list with more options
      iex> PaymentPaths.list_paths(
        Stellar.Horizon.Server.testnet(),
          source_account: "GBRSLTT74SKP62KJ7ENTMP5V4R7UGB6E5UQESNIIRWUNRCCUO4ZMFM4C",
          destination_asset: [
            code: "TEST",
            issuer: "GA654JC6QLA3ZH4O5V7X5NPM7KEWHKRG5GJA4PETK4SOFBUJLCCN74KQ"
          ],
          destination_amount: 5,
          destination_account: "GBRSLTT74SKP62KJ7ENTMP5V4R7UGB6E5UQESNIIRWUNRCCUO4ZMFM4C"
        )
      {:ok, %Paths{records: [%Path{}, ...]}}
  """

  @spec list_paths(server :: server(), args :: args()) :: response()
  def list_paths(server, args \\ []) do
    destination_asset = RequestParams.build_assets_params(args, :destination_asset)

    params =
      args
      |> Keyword.delete(:destination_asset)
      |> Keyword.merge(destination_asset)

    server
    |> Request.new(:get, @endpoint)
    |> Request.add_query(params, extra_params: allowed_query_options(:list_paths))
    |> Request.perform()
    |> Request.results(as: Paths)
  end

  @doc """
  List Strict Receive Payment Paths

  ## Parameters

    * `server`: The Horizon server to query.

    Using either `source_account` or `source_assets` as an argument is required for strict receive path payments.
    * `destination_asset`: `:native` or `[code: "destination_asset_code", issuer: "destination_asset_issuer"]`
    * `destination_amount`: The amount of the destination asset that should be received.

  ## Options

    * `source_account`: The Stellar address of the sender.
    * `source_assets`: A comma-separated list of assets available to the sender.

  ## Examples

      # list with `source_account`
      iex> PaymentPaths.list_receive_paths(
        Stellar.Horizon.Server.testnet(),
          destination_asset: :native,
          destination_amount: 5,
          source_account: "GBTKSXOTFMC5HR25SNL76MOVQW7GA3F6CQEY622ASLUV4VMLITI6TCOO"
        )
      {:ok, %Paths{records: [%Path{}, ...]}}


      # list with `source_assets`
      iex> PaymentPaths.list_receive_paths(
        Stellar.Horizon.Server.testnet(),
          destination_asset: :native,
          destination_amount: 5,
          source_assets: :native
        )
      {:ok, %Paths{records: [%Path{}, ...]}}

      # list with more options
      iex> PaymentPaths.list_receive_paths(
        Stellar.Horizon.Server.testnet(),
          source_assets: "CNY:GAREELUB43IRHWEASCFBLKHURCGMHE5IF6XSE7EXDLACYHGRHM43RFOX",
          destination_asset: [
            code: "BB1",
            issuer: "GD5J6HLF5666X4AZLTFTXLY46J5SW7EXRKBLEYPJP33S33MXZGV6CWFN"
          ],
          destination_amount: 5
        )
      {:ok, %Paths{records: [%Path{}, ...]}}
  """

  @spec list_receive_paths(server :: server(), args :: args()) :: response()
  def list_receive_paths(server, args \\ []) do
    destination_asset = RequestParams.build_assets_params(args, :destination_asset)

    params =
      args
      |> Keyword.delete(:destination_asset)
      |> Keyword.merge(destination_asset)

    server
    |> Request.new(:get, @endpoint, path: "strict-receive")
    |> Request.add_query(params, extra_params: allowed_query_options(:list_receive))
    |> Request.perform()
    |> Request.results(as: Paths)
  end

  @doc """
  List Strict Send Payment Paths

  ## Parameters

    * `server`: The Horizon server to query.

    Using either `destination_account` or `destination_assets` as an argument is required for strict send path payments.
    * `source_asset`: `:native` or `[code: "source_asset_code", issuer: "source_asset_issuer"]`
    * `source_amount`: The amount of the source asset that should be sent.

  ## Options

    * `destination_account`: The Stellar address of the reciever.
    * `destination_assets`: A comma-separated list of assets that the recipient can receive.

  ## Examples

      * list with `destination_account`
      iex> PaymentPaths.list_send_paths(
        Stellar.Horizon.Server.testnet(),
          source_asset: :native,
          source_amount: 5,
          destination_account: "GBTKSXOTFMC5HR25SNL76MOVQW7GA3F6CQEY622ASLUV4VMLITI6TCOO"
        )
      {:ok, %Paths{records: [%Path{}, ...]}}

      * list with `destination_assets`
      iex> PaymentPaths.list_send_paths(
        Stellar.Horizon.Server.testnet(),
          source_asset: :native,
          source_amount: 5,
          destination_assets: "TEST:GA654JC6QLA3ZH4O5V7X5NPM7KEWHKRG5GJA4PETK4SOFBUJLCCN74KQ"
        )
      {:ok, %Paths{records: [%Path{}, ...]}}

      # list with more options
      iex> PaymentPaths.list_send_paths(
        Stellar.Horizon.Server.testnet(),
          destination_account: "GAYOLLLUIZE4DZMBB2ZBKGBUBZLIOYU6XFLW37GBP2VZD3ABNXCW4BVA",
          source_asset: [
            code: "BRL",
            issuer: "GDVKY2GU2DRXWTBEYJJWSFXIGBZV6AZNBVVSUHEPZI54LIS6BA7DVVSP"
          ],
          source_amount: 400
        )
      {:ok, %Paths{records: [%Path{}, ...]}}
  """

  @spec list_send_paths(server :: server(), args :: args()) :: response()
  def list_send_paths(server, args \\ []) do
    source_asset = RequestParams.build_assets_params(args, :source_asset)

    params =
      args
      |> Keyword.delete(:source_asset)
      |> Keyword.merge(source_asset)

    server
    |> Request.new(:get, @endpoint, path: "strict-send")
    |> Request.add_query(params, extra_params: allowed_query_options(:list_send))
    |> Request.perform()
    |> Request.results(as: Paths)
  end

  @spec allowed_query_options(opt :: opt()) :: list()
  defp allowed_query_options(:list_paths) do
    [
      :source_account,
      :destination_asset_type,
      :destination_amount,
      :destination_account,
      :destination_asset_issuer,
      :destination_asset_code
    ]
  end

  defp allowed_query_options(:list_receive) do
    [
      :destination_asset_type,
      :destination_amount,
      :source_account,
      :source_assets,
      :destination_asset_issuer,
      :destination_asset_code
    ]
  end

  defp allowed_query_options(:list_send) do
    [
      :source_asset_type,
      :source_amount,
      :source_asset_issuer,
      :source_asset_code,
      :destination_account,
      :destination_assets
    ]
  end
end