defmodule Sutra.Cardano.Asset do
  @moduledoc """
  A module for handling Cardano Assets (Values).

  Cardano Assets are represented as a nested map structure:
  `%{policy_id => %{asset_name => quantity}}`

  Lovelace (ADA) is a special case where the policy ID is `"lovelace"` and the structure is simplified in some contexts, but when fully normalized in this module, it is treated as a top-level key `"lovelace"` with an integer value, or implicitly as policy ID `""` and asset name `""` in Plutus encoded forms.

  This module provides utility functions for creating, merging, diffing, and inspecting these asset structures, as well as encoding/decoding them to/from Plutus Data (CBOR).

  ## Asset Structure

      %{
        "lovelace" => 1000000,
        "policy_id_hex" => %{
          "asset_name_hex" => 100
        }
      }

  """
  @type policy_id() :: String.t()
  @type asset_name() :: String.t()
  @type quantity() :: integer()

  @typedoc """
  A map representing a MultiAsset value.
  Keys are policy IDs (hex string) or "lovelace".
  Values are either the integer amount (for lovelace) or a map of asset names to quantities.
  """
  @type t() :: %{
          optional(policy_id()) => quantity() | %{asset_name() => quantity()}
        }

  alias Sutra.Data
  alias Sutra.Data.Cbor

  import Sutra.Data.Cbor, only: [extract_value: 1]

  @doc """
  Creates a new Asset structure.

  ## Examples

      # Create Lovelace asset
      iex> new("lovelace", 100)
      %{"lovelace" => 100}

      # Create Token
      iex> new("policy_id", "asset_name", 100)
      %{"policy_id" => %{"asset_name" => 100}}

  """
  def new(policy_id, asset_name, amount) do
    add(%{}, policy_id, asset_name, amount)
  end

  def new("lovelace", amount) do
    add(%{}, "lovelace", amount)
  end

  def new(amount) when is_integer(amount), do: from_lovelace(amount)

  @doc """
  Decodes Asset from Plutus Data (CBOR).

  Handles both the flat integer (Lovelace only) and the nested map structure for MultiAssets.

  ## Examples

      iex> from_plutus(%{"" => %{"" => 200}, "policy-1" => %{"asset-1" => 100}})
      {:ok, %{"lovelace" => 200, "policy-1" => %{"asset-1" => 100}}}

      iex> from_plutus("A140A1401A000F4240")
      {:ok, %{"lovelace" => 1_000_000}}

      # Token CBOR example
      iex> token_cbor = "A340A1401A000F42404B706F6C6963792D69642D31A244746B6E31186444746B6E3218C84B706F6C6963792D69642D32A144746B6E3319012C"
      iex> {:ok, asset} = from_plutus(token_cbor)
      iex> asset["lovelace"]
      1_000_000
      iex> asset["706f6c6963792d69642d31"]
      %{"746b6e31" => 100, "746b6e32" => 200}

  """
  def from_plutus(cbor) when is_binary(cbor) do
    case Data.decode(cbor) do
      {:ok, data} -> from_plutus(data)
      {:error, _} -> {:error, :invalid_cbor}
    end
  end

  def from_plutus(plutus_data) when is_map(plutus_data) do
    result =
      Enum.reduce(plutus_data, %{}, fn {key, val}, acc ->
        key =
          case extract_value(key) do
            {:ok, ""} -> "lovelace"
            {:ok, value} -> value
          end

        Map.put(acc, key, to_asset_class(key, val))
      end)

    {:ok, result}
  end

  defp to_asset_class("lovelace", %{%CBOR.Tag{tag: :bytes, value: ""} => lovelace}),
    do: lovelace

  defp to_asset_class("lovelace", %{"" => lovelace}),
    do: lovelace

  defp to_asset_class(_, value) when is_map(value) do
    Enum.reduce(value, %{}, fn {key, val}, acc ->
      {:ok, key} = extract_value(key)
      Map.put(acc, key, val)
    end)
  end

  @doc """
  Encodes an Asset structure to Plutus Data format (as a Map).

  ## Examples

      iex> asset = %{"lovelace" => 300}
      iex> to_plutus(asset)
      %{%CBOR.Tag{tag: :bytes, value: ""} => %{%CBOR.Tag{tag: :bytes, value: ""} => 300}}

      iex> asset = %{"lovelace" => 200, "policy-1" => %{"asset-1" => 300}}
      iex> plutus_data = to_plutus(asset)
      iex> Map.keys(plutus_data) |> length()
      2

      iex> asset = %{"lovelace" => 1_000_000}
      iex> to_plutus(asset) |> Cbor.encode_hex()
      "A140A1401A000F4240"
  """

  def to_plutus(data) when is_map(data) do
    Enum.reduce(data, %{}, fn {key, val}, acc ->
      key_val =
        case key do
          "lovelace" -> ""
          _ -> key
        end

      acc
      |> Map.put(Cbor.as_byte(key_val), from_asset_class(val))
    end)
  end

  def to_plutus(_val), do: {:error, :invalid_data}

  defp from_asset_class(lovelace_value) when is_integer(lovelace_value),
    do: %{%CBOR.Tag{tag: :bytes, value: ""} => lovelace_value}

  defp from_asset_class(asset_map) when is_map(asset_map) do
    Enum.reduce(asset_map, %{}, fn {key, val}, acc ->
      Map.put(acc, Cbor.as_byte(key), val)
    end)
  end

  @doc """
  Creates an Asset structure purely containing Lovelace.

  ## Examples

      iex> from_lovelace(100)
      %{"lovelace" => 100}

  """
  def from_lovelace(value) when is_number(value), do: %{"lovelace" => value}
  def from_lovelace(_), do: nil

  @doc """
  Returns lovelace amount from asset. returns 0 if no lovelace is found in asset.

  ## Examples

      iex> lovelace_of(%{"policy" => %{"asset" => 1}})
      0

      iex> lovelace_of(%{"lovelace" => 134_000})
      134_000

  """
  def lovelace_of(asset) when is_map(asset), do: Map.get(asset, "lovelace", 0)
  def lovelace_of(_), do: 0

  @doc """
  Returns quantity of specific token from asset. returns 0 if no such token is found.

  ## Examples

      iex> asset = %{"policy-1" => %{"asset-1" => 500, "asset-2" => 300}}
      iex> get_quantity(asset, "policy-1", "asset-1")
      500

      iex> get_quantity(%{"policy-1" => %{"asset-1" => 100}}, "policy-1", "asset-3")
      0

      iex> get_quantity(%{"policy-1" => %{"asset-1" => 100}}, "policy-2", "asset-1")
      0

      iex> get_quantity(%{"lovelace" => 1000}, "lovelace")
      1000

      iex> get_quantity(%{}, "lovelace")
      0

  """
  def get_quantity(asset, policy_id, asset_name)
      when is_map(asset) and is_binary(policy_id) and is_binary(asset_name) do
    asset
    |> Map.get(policy_id, %{})
    |> Map.get(asset_name, 0)
  end

  def get_quantity(asset, "lovelace"), do: lovelace_of(asset)

  @doc """
  Merge two asset values into one.

  ## Examples

      iex> asset1 = %{"lovelace" => 123}
      iex> asset2 = %{"policy-1" => %{"asset1" => 600}}
      iex> merge(asset1, asset2)
      %{"lovelace" => 123, "policy-1" => %{"asset1" => 600}}

  Adds Qty of token for similar policies:

      iex> asset1 = %{"lovelace" => 100, "policy-1" => %{"asset1" => 600}}
      iex> asset2 = %{"policy-1" => %{"asset1" => 400}}
      iex> merge(asset1, asset2)
      %{"lovelace" => 100, "policy-1" => %{"asset1" => 1000}}

  """
  def merge(asset1, asset2) when is_map(asset1) and is_map(asset2) do
    merge(asset1, asset2, fn _k, v1, v2 -> v1 + v2 end)
  end

  def merge(asset1, asset2, with_func) when is_function(with_func, 3) do
    Map.merge(asset1, asset2, fn k, v1, v2 ->
      if is_number(v1), do: with_func.(k, v1, v2), else: merge(v1, v2, with_func)
    end)
  end

  @doc """
  Subtract value of asset (asset1 - asset2).

  ## Examples

      iex> asset1 = from_lovelace(500)
      iex> asset2 = from_lovelace(600)
      iex> diff(asset1, asset2)
      %{"lovelace" => 100}

      iex> asset1 = %{"policy-1" => %{"asset1" => 200}}
      iex> asset2 = %{"policy-1" => %{"asset1" => 50, "asset2" => 200 }}
      iex> diff(asset1, asset2)
      %{"policy-1" => %{"asset1" => -150, "asset2" => 200 }}

  """
  def diff(asset1, asset2) when is_map(asset1) and is_map(asset2) do
    Enum.map(asset2, fn {k, v} ->
      if is_map(v),
        do: {k, Map.get(asset1, k, %{}) |> diff(v)},
        else: {k, v - Map.get(asset1, k, 0)}
    end)
    |> Enum.into(%{})
  end

  def zero?(asset) when is_map(asset), do: asset == %{}

  @doc """
  Checks if asset has positive amount.

  ## Examples

      iex> is_positive_asset(%{"lovelace" => 100})
      true

      iex> is_positive_asset(%{"lovelace" => 50, "policy" => %{"asset" => -100}})
      true

      iex> is_positive_asset(%{"lovelace" => 0, "policy" => %{"asset" => -100}})
      false

      iex> is_positive_asset(%{"lovelace" => -10, "policy" => %{"asset" => -100}})
      false

  """
  def is_positive_asset(asset) when is_map(asset) do
    Enum.any?(asset, fn {_k, v} ->
      if is_number(v), do: v > 0, else: is_positive_asset(v)
    end)
  end

  @doc """
  Returns only Positive Assets.

  ## Examples

      iex> only_positive(%{"lovelace" => 200, "policy" => %{"asset" => -10}})
      %{"lovelace" => 200}

      iex> only_positive(%{"lovelace" => 0, "policy" => %{"asset" => -10}})
      %{}

      iex> only_positive(%{"lovelace" => 0, "policy" => %{"asset" => 10}})
      %{"policy" => %{"asset" => 10}}

  """
  def only_positive(asset) when is_map(asset) do
    filter_by_value(asset, &(&1 > 0))
  end

  @doc """
  Filter Asset by applying functions against Asset value.

  ## Examples

      iex> asset = %{"lovelace" => 100, "policy" => %{"asset1" => -10, "asset2" => 10}}
      iex> filter_by_value(asset, fn v -> v > 0 end)
      %{"lovelace" => 100, "policy" => %{"asset2" => 10}}

      iex> asset = %{"lovelace" => 10, "policy" => %{"asset1" => -10, "asset2" => 10}}
      iex> filter_by_value(asset, &(&1 == 10))
      %{"lovelace" => 10, "policy" => %{"asset2" => 10}}

      iex> asset = %{"lovelace" => 10, "policy" => %{"asset1" => -10, "asset2" => 10}}
      iex> filter_by_value(asset, &(&1 < 0))
      %{"policy" => %{"asset1" => -10}}

  """

  def filter_by_value(asset, func) when is_function(func, 1) and is_map(asset) do
    Enum.reduce(asset, %{}, fn {k, v}, acc ->
      if is_map(v) do
        result = filter_by_value(v, func)
        if map_size(result) > 0, do: Map.put(acc, k, result), else: acc
      else
        # credo:disable-for-next-line Credo.Check.Refactor.Nesting
        if func.(v), do: Map.put(acc, k, v), else: acc
      end
    end)
  end

  @doc """
  Returns Asset with absolute values (all positive).

  ## Examples

      iex> abs_value(%{"lovelace" => -100})
      %{"lovelace" => 100 }

      iex> abs_value(%{"lovelace" => 100})
      %{"lovelace" => 100 }

  """
  def abs_value(asset) when is_map(asset) do
    Enum.map(asset, fn {k, v} ->
      if is_map(v), do: {k, abs_value(v)}, else: {k, abs(v)}
    end)
    |> Enum.into(%{})
  end

  @doc """
  Add quantity of single token to Assets.

  ## Examples

      iex> add(from_lovelace(100), "lovelace", 200)
      %{"lovelace" => 300}

      iex> add(from_lovelace(100), "policy", "asset", 10)
      %{"lovelace" => 100, "policy" => %{"asset" => 10}}

  """
  def add(asset, "lovelace", amount) when is_map(asset) and is_number(amount),
    do: Map.put(asset, "lovelace", lovelace_of(asset) + amount)

  def add(asset, policy_id, asset_name, qty)
      when is_map(asset) and is_binary(policy_id) and is_binary(asset_name) and is_number(qty) do
    merge(asset, Map.put(%{}, policy_id, Map.new([{asset_name, qty}])))
  end

  @doc """
  Returns an empty asset.
  """
  def zero, do: %{}

  @doc """
  Negates quantities of all Assets.

  ## Examples

      iex> negate(from_lovelace(100))
      %{"lovelace" => -100}

      iex> negate(%{"lovelace" => 10, "policy" => %{"asset" => 70}})
      %{"lovelace" => -10, "policy" => %{"asset" => -70}}

  """
  def negate(assets) do
    Enum.map(assets, fn {k, v} ->
      if is_map(v), do: {k, negate(v)}, else: {k, -v}
    end)
    |> Enum.into(%{})
  end

  @doc """
  Returns Asset without Ada.

  ## Examples

      iex> without_lovelace(%{"lovelace" => 10}) == zero()
      true

      iex> without_lovelace(%{"lovelace" => 10, "policy" => %{"asset" => 1}})
      %{"policy" => %{"asset" => 1}}

  """
  def without_lovelace(assets), do: Map.delete(assets, "lovelace")

  @doc """
  Returns all policies of asset.

  ## Examples

      iex> policies(%{"lovelace" => 100})
      []

      iex> policies(%{"policy1" => %{"asset1" => 1}, "policy2" => %{"asset1" => 2}})
      ["policy1", "policy2"] |> Enum.sort()

  """
  def policies(assets) when is_map(assets) do
    assets
    |> without_lovelace()
    |> Map.keys()
  end

  @doc """
  Get a subset of the assets restricted to the given policies.

  ## Examples

      iex> restricted_to(%{"lovelace" => 100, "policy1" => %{"asset1" => 10}}, ["lovelace"])
      %{"lovelace" => 100}

      iex> restricted_to(%{
      ...>    "lovelace" => 100,
      ...>    "policy1" => %{"asset" => 10},
      ...>    "policy2" => %{"asset" => 50},
      ...>    "policy3" => %{"asset" => 30},
      ...> }, ["policy1", "policy2"])
      %{"policy1" => %{"asset" => 10}, "policy2" => %{"asset" => 50}}

  """
  def restricted_to(assets, policy_ids) when is_map(assets) and is_list(policy_ids) do
    Enum.reduce(policy_ids, %{}, fn policy_id, acc ->
      policy_value = Map.get(assets, policy_id)
      if policy_value, do: Map.put(acc, policy_id, policy_value), else: acc
    end)
  end

  @doc """
  Checks if both asset has similar tokens (share at least one policy ID).

  ## Examples

      iex> asset1 = %{"lovelace" => 1000, "policy1" => %{"asset" => 1}}
      iex> contains_token?(from_lovelace(100), asset1)
      false

      iex> asset1 = %{"policy1" => %{"asset" => 1}, "policy2" => %{"asset" => 1}}
      iex> asset2 = %{"policy3" => %{"asset" => 1}}
      iex> contains_token?(asset2, asset1)
      false
  """
  def contains_token?(asset1, asset2) do
    asset2
    |> policies()
    |> Enum.any?(&Map.has_key?(asset1, &1))
  end

  @doc """
  Encodes Asset to CBOR list format `[lovelace_qty, multi_asset_map]`.

  Note: If the asset only contains Lovelace, it returns the integer amount directly, which corresponds to the compact encoding in some contexts, or the way output values are represented when no multi-assets are present.

  ## Examples

      iex> to_cbor(%{"lovelace" => 100})
      100

      iex> to_cbor(%{"lovelace" => 100, "policy" => %{"asset" => 100}})
      [ 100,
        %{%CBOR.Tag{tag: :bytes, value: "policy"} =>
              %{%CBOR.Tag{tag: :bytes, value: "asset"} => 100}
        }
      ]

  """
  def to_cbor(%{"lovelace" => lovelace} = asset) when map_size(asset) == 1, do: lovelace

  def to_cbor(assets) do
    [Map.get(assets, "lovelace", 0), Map.delete(assets, "lovelace") |> to_plutus()]
  end

  @doc """
  Converts CBOR decoded data back to Asset structure.

  ## Examples

      iex> cbor_list = [
      ...>   100,
      ...>   %{
      ...>     %CBOR.Tag{tag: :bytes, value: "policy"} =>
      ...>       %{
      ...>           %CBOR.Tag{tag: :bytes, value: "asset"} => 1
      ...>       }
      ...>   }
      ...> ]
      iex> from_cbor(cbor_list)
      %{"lovelace" => 100, "706f6c696379" => %{"6173736574" => 1}}

      iex> from_cbor(10)
      %{"lovelace" => 10}
  """
  def from_cbor(lovelace) when is_integer(lovelace), do: from_lovelace(lovelace)

  def from_cbor([lovelace, other_assets]) do
    with {:ok, assets} <- from_plutus(other_assets) do
      Map.put(assets, "lovelace", lovelace)
    end
  end

  def from_seperator(assets, seperator \\ ".") when is_map(assets) do
    Enum.reduce(assets, %{}, fn {k, v}, acc ->
      [policy_id, asset_name] = String.split(k, seperator)
      add(acc, policy_id, asset_name, v)
    end)
  end
end