ccxt_client

defmodule CCXT.Order.Sanity do
  @moduledoc """
  Pre-submit order validation that catches common mistakes before they hit the exchange.

  Runs pure checks against market metadata (limits, precision, features, `has` map)
  so users discover invalid orders locally instead of after exchange rejection.

  ## Usage

      market = hd(CCXT.Bybit.fetch_markets!())

      CCXT.Order.Sanity.validate(
        %{symbol: "BTC/USDT", type: "limit", side: "buy", amount: 0.001, price: 50_000},
        market,
        precision_mode: CCXT.Bybit.__ccxt_precision_mode__()
      )

  ## Return Values

  - `{:ok, order_params}` — all checks pass, no warnings
  - `{:ok, order_params, warnings}` — checks pass but price deviation triggered
  - `{:error, {:sanity_check, reasons}}` — one or more hard failures

  Where `reasons` and `warnings` are lists of `{check_name_atom, message_string}`.

  ## Individual Checks

  Each `check_*` function returns `:ok | {:error, String.t()}` (except
  `check_price_deviation` which returns `:ok | {:warning, String.t()}`).
  """

  use Descripex, namespace: "/order/sanity"

  alias CCXT.MarketPrecision
  alias CCXT.Order.Builder

  # Maps order type strings to the corresponding `has` capability key
  @type_to_has %{
    "limit" => :create_limit_order,
    "market" => :create_market_order,
    "stop" => :create_stop_order,
    "stop_limit" => :create_stop_limit_order,
    "stop_market" => :create_stop_market_order,
    "stop_loss" => :create_stop_loss_order,
    "trigger" => :create_trigger_order
  }

  @valid_sides ~w(buy sell)
  @valid_sides_atoms [:buy, :sell]

  # Default deviation threshold: 10% from reference price
  @default_deviation_threshold 0.10

  # Epsilon multiplier for floating-point precision comparisons
  @epsilon_multiplier 1.0e-6

  # Atom equivalents of limit category/bound strings for dual-key map lookups
  @limit_key_atoms %{
    "amount" => :amount,
    "price" => :price,
    "cost" => :cost,
    "min" => :min,
    "max" => :max
  }

  # ============================================================================
  # Main entry point
  # ============================================================================

  api(:validate, "Run all applicable sanity checks on order parameters.",
    params: [
      order_params: [
        kind: :value,
        description: "Plain map or %CCXT.Order.Builder{} with symbol, type/order_type, side, amount, price"
      ],
      market: [kind: :exchange_data, description: "Market map from fetch_markets (or nil to skip market checks)"],
      opts: [
        kind: :value,
        default: [],
        description:
          "Options: reference_price, deviation_threshold, has, features, precision_mode, market_type, warnings (:normal | :strict)"
      ]
    ],
    returns: %{
      type: :result_tuple,
      description: "{:ok, params} | {:ok, params, warnings} | {:error, {:sanity_check, [{check, msg}, ...]}}"
    },
    errors: [:sanity_check]
  )

  @doc """
  Runs all applicable checks and collects ALL failures (not short-circuit).

  Accepts either a plain map or `%CCXT.Order.Builder{}` struct.

  ## Options

  - `:reference_price` — reference price for deviation check
  - `:deviation_threshold` — threshold for price deviation (default 0.10 = 10%)
  - `:has` — exchange `has` map for order type capability check
  - `:features` — full exchange `features`, market-specific wrapper, or flat `create_order` flags
  - `:precision_mode` — integer precision mode (required for raw market maps)
  - `:market_type` — market type override when resolving nested `features` without a market
  - `:warnings` — `:normal` (default) or `:strict` (promotes warnings to errors)
  """
  @spec validate(map() | Builder.t(), map() | nil, keyword()) ::
          {:ok, map()} | {:ok, map(), [{atom(), String.t()}]} | {:error, {:sanity_check, [{atom(), String.t()}]}}
  def validate(order_params, market, opts \\ []) do
    params = normalize_order_params(order_params)
    runtime_opts = normalize_runtime_opts(opts, market)
    {errors, warnings} = run_checks(params, market, runtime_opts)
    format_result(params, errors, warnings, runtime_opts)
  end

  @doc false
  # Builds and runs all applicable checks, collecting errors and warnings
  defp run_checks(params, market, opts) do
    side = params[:side]
    order_type = params[:type]
    amount = params[:amount]
    price = params[:price]

    checks = [
      {:check_side, fn -> check_side(side) end},
      {:check_order_type, fn -> check_order_type(order_type, opts) end},
      {:check_symbol, fn -> run_symbol_check(params[:symbol], market) end},
      {:check_amount, fn -> run_amount_check(amount, order_type, side, market, opts) end},
      {:check_price, fn -> check_price(price, order_type, side, market, opts) end},
      {:check_cost, fn -> check_cost(amount, price, order_type, side, market, opts) end},
      {:check_price_deviation, fn -> run_deviation_check(price, opts) end}
    ]

    {errors, warnings} =
      Enum.reduce(checks, {[], []}, fn {name, check_fn}, {errs, warns} ->
        case check_fn.() do
          :ok -> {errs, warns}
          :skip -> {errs, warns}
          {:error, msg} -> {[{name, msg} | errs], warns}
          {:warning, msg} -> {errs, [{name, msg} | warns]}
        end
      end)

    {Enum.reverse(errors), Enum.reverse(warnings)}
  end

  @doc false
  # Applies strict mode promotion and selects the appropriate return shape
  defp format_result(params, errors, warnings, opts) do
    {errors, warnings} =
      if opts[:warnings] == :strict do
        {errors ++ warnings, []}
      else
        {errors, warnings}
      end

    cond do
      errors != [] -> {:error, {:sanity_check, errors}}
      warnings != [] -> {:ok, params, warnings}
      true -> {:ok, params}
    end
  end

  # ============================================================================
  # Individual checks
  # ============================================================================

  api(:check_side, ~s(Validate order side is :buy/:sell or "buy"/"sell".),
    params: [side: [kind: :value, description: "Order side — atom or string"]],
    returns: %{type: :ok_or_error, description: ":ok | {:error, message}"},
    errors: [:invalid_side]
  )

  @spec check_side(any()) :: :ok | {:error, String.t()}
  def check_side(side) when side in @valid_sides or side in @valid_sides_atoms, do: :ok
  def check_side(side), do: {:error, "Invalid side: #{inspect(side)}. Must be :buy, :sell, \"buy\", or \"sell\""}

  api(:check_order_type, "Validate order type is known and supported by the exchange.",
    params: [
      type: [kind: :value, description: ~s{Order type string (e.g., "limit", "market")}],
      opts: [kind: :value, default: [], description: "Options: has"]
    ],
    returns: %{type: :ok_or_error, description: ":ok | {:error, message}"},
    errors: [:unknown_type, :unsupported_type]
  )

  @spec check_order_type(any(), keyword()) :: :ok | {:error, String.t()}
  def check_order_type(type, opts \\ [])

  def check_order_type(type, opts) when is_binary(type) do
    case Map.get(@type_to_has, type) do
      nil ->
        known = @type_to_has |> Map.keys() |> Enum.join(", ")
        {:error, "Unknown order type: #{inspect(type)}. Known types: #{known}"}

      has_key ->
        check_has_capability(type, has_key, opts)
    end
  end

  def check_order_type(type, _opts), do: {:error, "Order type must be a string, got: #{inspect(type)}"}

  api(:check_symbol, "Validate order symbol matches market and market is active.",
    params: [
      order_symbol: [kind: :value, description: "Symbol from order params"],
      market: [kind: :exchange_data, description: "Market map with symbol and active fields"]
    ],
    returns: %{type: :ok_or_error, description: ":ok | {:error, message}"},
    errors: [:symbol_mismatch, :inactive_market]
  )

  @spec check_symbol(String.t(), map()) :: :ok | {:error, String.t()}
  def check_symbol(order_symbol, market) when is_binary(order_symbol) and is_map(market) do
    market_symbol = get_field(market, "symbol", :symbol)

    cond do
      market_symbol != order_symbol ->
        {:error, "Symbol mismatch: order has #{inspect(order_symbol)} but market is #{inspect(market_symbol)}"}

      get_field(market, "active", :active) == false ->
        {:error, "Market #{inspect(order_symbol)} is inactive (active: false)"}

      true ->
        :ok
    end
  end

  def check_symbol(order_symbol, _market), do: {:error, "Invalid symbol: #{inspect(order_symbol)}"}

  api(:check_amount, "Validate order amount against limits and precision.",
    params: [
      amount: [kind: :value, description: "Order amount (positive number)"],
      market: [kind: :exchange_data, description: "Market map or %MarketPrecision{} (or nil)"],
      opts: [kind: :value, default: [], description: "Options: precision_mode"]
    ],
    returns: %{type: :ok_or_error, description: ":ok | {:error, message}"},
    errors: [:invalid_amount, :below_min, :above_max, :precision_violation]
  )

  @spec check_amount(any(), map() | MarketPrecision.t() | nil, keyword()) :: :ok | {:error, String.t()}
  def check_amount(amount, market, opts \\ [])

  def check_amount(amount, _market, _opts) when not is_number(amount) or amount <= 0 do
    {:error, "Amount must be a positive number, got: #{inspect(amount)}"}
  end

  def check_amount(_amount, nil, _opts), do: :ok

  def check_amount(amount, market, opts) do
    with :ok <- check_limit(amount, "amount", "min", market, :>=),
         :ok <- check_limit(amount, "amount", "max", market, :<=) do
      check_precision(amount, "amount", market, opts)
    end
  end

  api(:check_price, "Validate order price against type requirements, limits, and precision.",
    params: [
      price: [kind: :value, description: "Order price (or nil for market orders)"],
      order_type: [kind: :value, description: "Order type string"],
      side: [kind: :value, description: "Order side (atom or string)"],
      market: [kind: :exchange_data, description: "Market map or %MarketPrecision{} (or nil)"],
      opts: [
        kind: :value,
        default: [],
        description: "Options: precision_mode, features, market_type"
      ]
    ],
    returns: %{type: :ok_or_error, description: ":ok | {:error, message}"},
    errors: [:missing_price, :invalid_price, :below_min, :above_max, :precision_violation]
  )

  @spec check_price(any(), String.t() | nil, any(), map() | MarketPrecision.t() | nil, keyword()) ::
          :ok | {:error, String.t()}
  def check_price(price, order_type, side, market, opts \\ [])

  def check_price(nil, "limit", _side, _market, _opts) do
    {:error, "Limit orders require a price"}
  end

  def check_price(nil, "market", side, market, opts) do
    features = normalize_create_order_features(opts[:features], market, opts)
    requires_price = get_in_map(features, "market_buy_requires_price", :market_buy_requires_price)

    if requires_price && side_is_buy?(side) do
      {:error, "This exchange requires a price for market buy orders (market_buy_requires_price)"}
    else
      :ok
    end
  end

  def check_price(nil, _type, _side, _market, _opts), do: :ok

  def check_price(price, _type, _side, _market, _opts) when not is_number(price) or price <= 0 do
    {:error, "Price must be a positive number, got: #{inspect(price)}"}
  end

  def check_price(price, _type, _side, nil, _opts) when is_number(price), do: :ok

  def check_price(price, _type, _side, market, opts) when is_number(price) do
    with :ok <- check_limit(price, "price", "min", market, :>=),
         :ok <- check_limit(price, "price", "max", market, :<=) do
      check_precision(price, "price", market, opts)
    end
  end

  api(:check_cost, "Validate order notional or quote-cost against cost limits.",
    params: [
      amount: [kind: :value, description: "Order amount"],
      price: [kind: :value, description: "Order price (required unless market_buy_by_cost applies)"],
      order_type: [kind: :value, description: "Order type string"],
      side: [kind: :value, description: "Order side (atom or string)"],
      market: [kind: :exchange_data, description: "Market map (or nil)"],
      opts: [
        kind: :value,
        default: [],
        description: "Options: features, market_type"
      ]
    ],
    returns: %{type: :ok_or_error, description: ":ok | {:error, message}"},
    errors: [:below_min_cost, :above_max_cost]
  )

  @spec check_cost(number() | nil, number() | nil, String.t() | nil, any(), map() | nil, keyword()) ::
          :ok | {:error, String.t()}
  def check_cost(amount, price, order_type, side, market, opts \\ [])

  def check_cost(_amount, _price, _order_type, _side, nil, _opts), do: :ok
  def check_cost(nil, _price, _order_type, _side, _market, _opts), do: :ok

  def check_cost(amount, price, order_type, side, market, opts)
      when is_number(amount) and is_map(market) and is_binary(order_type) do
    cond do
      market_buy_by_cost_order?(order_type, side, market, opts) ->
        with :ok <- check_cost_limit(amount, "min", market, :>=) do
          check_cost_limit(amount, "max", market, :<=)
        end

      is_number(price) ->
        notional = calculate_notional(amount, price, market)

        with :ok <- check_cost_limit(notional, "min", market, :>=) do
          check_cost_limit(notional, "max", market, :<=)
        end

      true ->
        :ok
    end
  end

  def check_cost(_amount, _price, _order_type, _side, _market, _opts), do: :ok

  api(:check_price_deviation, "Check if price deviates significantly from a reference price.",
    params: [
      price: [kind: :value, description: "Order price"],
      reference_price: [kind: :value, description: "Reference/market price for comparison"],
      opts: [kind: :value, default: [], description: "Options: deviation_threshold (default 0.10 = 10%)"]
    ],
    returns: %{type: :ok_or_warning, description: ":ok | {:warning, message}"},
    errors: []
  )

  @spec check_price_deviation(number(), number(), keyword()) :: :ok | {:warning, String.t()}
  def check_price_deviation(price, reference_price, opts \\ [])

  def check_price_deviation(price, reference_price, opts)
      when is_number(price) and is_number(reference_price) and reference_price > 0 do
    threshold = opts[:deviation_threshold] || @default_deviation_threshold
    deviation = abs(price - reference_price) / reference_price

    if deviation > threshold do
      pct = Float.round(deviation * 100, 2)

      {:warning,
       "Price #{price} deviates #{pct}% from reference #{reference_price} (threshold: #{Float.round(threshold * 100, 2)}%)"}
    else
      :ok
    end
  end

  def check_price_deviation(_price, _reference_price, _opts), do: :ok

  # ============================================================================
  # Input normalization
  # ============================================================================

  @doc false
  # Normalizes order params from Builder struct or plain map to a canonical map
  @spec normalize_order_params(Builder.t() | map()) :: map()
  defp normalize_order_params(%Builder{} = b) do
    %{
      symbol: b.symbol,
      type: to_string_safe(b.order_type),
      side: to_string_safe(b.side),
      amount: b.amount,
      price: b.price
    }
  end

  defp normalize_order_params(params) when is_map(params) do
    type = params[:type] || params[:order_type] || params["type"] || params["order_type"]
    side = params[:side] || params["side"]

    %{
      symbol: params[:symbol] || params["symbol"],
      type: to_string_safe(type),
      side: to_string_safe(side),
      amount: params[:amount] || params["amount"],
      price: params[:price] || params["price"]
    }
  end

  # ============================================================================
  # Private helpers
  # ============================================================================

  @doc false
  # Safely converts atoms/strings to strings, passes nil through
  defp to_string_safe(nil), do: nil
  defp to_string_safe(val) when is_atom(val), do: Atom.to_string(val)
  defp to_string_safe(val) when is_binary(val), do: val

  @doc false
  # Checks if side is a buy
  defp side_is_buy?(:buy), do: true
  defp side_is_buy?("buy"), do: true
  defp side_is_buy?(_), do: false

  @doc false
  # Runs symbol check only when market is provided
  defp run_symbol_check(_symbol, nil), do: :skip
  defp run_symbol_check(symbol, market), do: check_symbol(symbol, market)

  @doc false
  # Runs amount checks only when `amount` is a base amount, not a quote cost.
  defp run_amount_check(amount, order_type, side, market, opts) do
    cond do
      not is_number(amount) or amount <= 0 ->
        check_amount(amount, market, opts)

      market_buy_by_cost_order?(order_type, side, market, opts) ->
        :skip

      true ->
        check_amount(amount, market, opts)
    end
  end

  @doc false
  # Runs deviation check only when reference_price is provided
  defp run_deviation_check(price, opts) do
    case opts[:reference_price] do
      nil -> :skip
      ref when is_number(price) -> check_price_deviation(price, ref, opts)
      _ref -> :skip
    end
  end

  @doc false
  # Checks if exchange `has` map supports the order type
  defp check_has_capability(type, has_key, opts) do
    has = opts[:has]

    case has do
      nil ->
        :ok

      %{} ->
        val = map_get_dual(has, has_key, Atom.to_string(has_key))

        if val == false do
          {:error, "Exchange does not support #{inspect(type)} orders (has.#{has_key} == false)"}
        else
          :ok
        end
    end
  end

  @doc false
  # Normalizes runtime opts so downstream checks see flattened create_order flags.
  defp normalize_runtime_opts(opts, market) do
    normalized_features = normalize_create_order_features(opts[:features], market, opts)
    Keyword.put(opts, :features, normalized_features)
  end

  @doc false
  # Extracts create_order feature flags from full `spec.features`, market wrappers,
  # subtype wrappers, or already-flattened maps.
  defp normalize_create_order_features(nil, _market, _opts), do: nil

  defp normalize_create_order_features(features, _market, _opts) when not is_map(features), do: nil

  defp normalize_create_order_features(features, market, opts) do
    market_type = resolve_market_type(market, opts)
    market_features = get_market_feature_map(features, market_type)
    default_features = get_in_map(features, "default", :default)

    cond do
      create_order_feature_map?(features) ->
        features

      resolved = resolve_create_order_features(features, features, market, opts) ->
        resolved

      resolved = resolve_create_order_features(market_features, features, market, opts) ->
        resolved

      resolved = resolve_create_order_features(default_features, features, market, opts) ->
        resolved

      true ->
        nil
    end
  end

  @doc false
  defp resolve_create_order_features(nil, _root_features, _market, _opts), do: nil

  defp resolve_create_order_features(features, root_features, market, opts) when is_map(features) do
    if create_order_feature_map?(features) do
      features
    else
      create_order = get_in_map(features, "create_order", :create_order)
      sub_type_features = get_sub_type_feature_map(features, market, opts)
      extends = get_in_map(features, "extends", :extends)

      cond do
        is_map(create_order) ->
          resolve_create_order_features(create_order, root_features, market, opts)

        is_map(sub_type_features) ->
          resolve_create_order_features(sub_type_features, root_features, market, opts)

        is_binary(extends) ->
          root_features
          |> get_feature_alias_target(extends)
          |> resolve_create_order_features(root_features, market, opts)

        true ->
          nil
      end
    end
  end

  @doc false
  defp create_order_feature_map?(features) when is_map(features) do
    Enum.any?(
      [
        "market_buy_requires_price",
        :market_buy_requires_price,
        "market_buy_by_cost",
        :market_buy_by_cost,
        "time_in_force",
        :time_in_force
      ],
      &Map.has_key?(features, &1)
    )
  end

  @doc false
  defp get_market_feature_map(features, nil), do: features

  defp get_market_feature_map(features, market_type) when is_map(features) and is_atom(market_type) do
    map_get_dual(features, market_type, Atom.to_string(market_type))
  end

  @doc false
  defp get_sub_type_feature_map(features, market, opts) when is_map(features) do
    case resolve_sub_type(market, opts) do
      nil -> nil
      sub_type -> map_get_dual(features, sub_type, Atom.to_string(sub_type))
    end
  end

  @doc false
  defp get_feature_alias_target(features, extends) when is_map(features) and is_binary(extends) do
    underscored = Macro.underscore(extends)

    Enum.find_value(
      [extends, safe_to_existing_atom(extends), underscored, safe_to_existing_atom(underscored)],
      fn key ->
        if is_nil(key), do: nil, else: Map.get(features, key)
      end
    )
  end

  @doc false
  defp resolve_market_type(market, opts) do
    opts[:market_type]
    |> normalize_market_type()
    |> case do
      nil ->
        cond do
          market_type = normalize_market_type(get_field(market, "type", :type)) ->
            market_type

          get_field(market, "spot", :spot) == true ->
            :spot

          get_field(market, "swap", :swap) == true ->
            :swap

          get_field(market, "future", :future) == true ->
            :future

          get_field(market, "option", :option) == true ->
            :option

          true ->
            nil
        end

      market_type ->
        market_type
    end
  end

  @doc false
  defp resolve_sub_type(market, opts) do
    opts[:sub_type]
    |> normalize_market_type()
    |> case do
      nil ->
        cond do
          sub_type = normalize_market_type(get_field(market, "sub_type", :sub_type)) ->
            sub_type

          get_field(market, "linear", :linear) == true ->
            :linear

          get_field(market, "inverse", :inverse) == true ->
            :inverse

          true ->
            nil
        end

      sub_type ->
        sub_type
    end
  end

  @doc false
  defp normalize_market_type(nil), do: nil
  defp normalize_market_type(type) when is_atom(type), do: type

  defp normalize_market_type(type) when is_binary(type) do
    case Macro.underscore(type) do
      "spot" -> :spot
      "swap" -> :swap
      "future" -> :future
      "option" -> :option
      "linear" -> :linear
      "inverse" -> :inverse
      _ -> nil
    end
  end

  @doc false
  defp safe_to_existing_atom(key) when is_binary(key) do
    String.to_existing_atom(key)
  rescue
    ArgumentError -> nil
  end

  @doc false
  defp market_buy_by_cost_order?(order_type, side, market, opts) do
    features = normalize_create_order_features(opts[:features], market, opts)
    market_buy_by_cost = get_in_map(features, "market_buy_by_cost", :market_buy_by_cost)

    order_type == "market" and side_is_buy?(side) and market_buy_by_cost == true
  end

  @doc false
  # Gets a field from either a string-keyed or atom-keyed map (or struct)
  defp get_field(%{__struct__: _} = struct, _string_key, atom_key) do
    Map.get(struct, atom_key)
  end

  defp get_field(map, string_key, atom_key) when is_map(map) do
    map_get_dual(map, string_key, atom_key)
  end

  defp get_field(_, _, _), do: nil

  @doc false
  # Gets a value from a map trying both string and atom keys
  defp get_in_map(nil, _string_key, _atom_key), do: nil

  defp get_in_map(map, string_key, atom_key) when is_map(map) do
    map_get_dual(map, string_key, atom_key)
  end

  @doc false
  # Gets a value from a map trying primary key first, then fallback key.
  # Unlike `||`, correctly handles `false` as a valid value.
  defp map_get_dual(map, primary_key, fallback_key) do
    case Map.fetch(map, primary_key) do
      {:ok, val} -> val
      :error -> Map.get(map, fallback_key)
    end
  end

  @doc false
  # Checks a value against a limit from the market
  defp check_limit(value, category, bound, %MarketPrecision{} = mp, op) do
    limit = get_mp_limit(mp, category, bound)
    compare_limit(value, limit, category, bound, op)
  end

  defp check_limit(value, category, bound, market, op) when is_map(market) do
    limit = get_nested_limit(market, category, bound)
    compare_limit(value, limit, category, bound, op)
  end

  @doc false
  defp compare_limit(_value, nil, _category, _bound, _op), do: :ok

  defp compare_limit(value, limit, category, _bound, :>=) when is_number(limit) do
    if value >= limit do
      :ok
    else
      {:error, "#{category} #{value} is below minimum #{limit}"}
    end
  end

  defp compare_limit(value, limit, category, _bound, :<=) when is_number(limit) do
    if value <= limit do
      :ok
    else
      {:error, "#{category} #{value} exceeds maximum #{limit}"}
    end
  end

  @doc false
  # Gets limit from MarketPrecision struct
  defp get_mp_limit(%MarketPrecision{} = mp, "amount", "min"), do: mp.amount_min
  defp get_mp_limit(%MarketPrecision{} = mp, "amount", "max"), do: mp.amount_max
  defp get_mp_limit(%MarketPrecision{} = mp, "price", "min"), do: mp.price_min
  defp get_mp_limit(%MarketPrecision{} = mp, "price", "max"), do: mp.price_max
  defp get_mp_limit(%MarketPrecision{} = mp, "cost", "min"), do: mp.cost_min
  defp get_mp_limit(%MarketPrecision{} = mp, "cost", "max"), do: mp.cost_max
  defp get_mp_limit(_, _, _), do: nil

  @doc false
  # Gets a nested limit from a raw market map: limits["amount"]["min"]
  # Uses @limit_key_atoms for dual-key lookups (string and atom) without rescue.
  defp get_nested_limit(market, category, bound) do
    limits = get_field(market, "limits", :limits)

    with %{} <- limits,
         %{} = cat <- map_get_dual(limits, category, @limit_key_atoms[category]) do
      map_get_dual(cat, bound, @limit_key_atoms[bound])
    else
      _ -> nil
    end
  end

  @doc false
  # Checks cost against limits (cost is nested under "cost" in limits)
  defp check_cost_limit(notional, bound, %MarketPrecision{} = mp, op) do
    limit = get_mp_limit(mp, "cost", bound)
    compare_limit(notional, limit, "cost", bound, op)
  end

  defp check_cost_limit(notional, bound, market, op) do
    limit = get_nested_limit(market, "cost", bound)
    compare_limit(notional, limit, "cost", bound, op)
  end

  @doc false
  # Calculates notional value, handling contracts
  defp calculate_notional(amount, price, market) do
    contract? = get_field(market, "contract", :contract)
    contract_size = get_field(market, "contractSize", :contract_size) || 1
    inverse? = get_field(market, "inverse", :inverse)

    cond do
      contract? && inverse? -> amount * contract_size / price
      contract? -> amount * contract_size * price
      true -> amount * price
    end
  end

  @doc false
  # Checks precision (increment validation)
  defp check_precision(value, field, %MarketPrecision{} = mp, _opts) do
    increment = get_mp_increment(mp, field)
    validate_increment(value, increment, field)
  end

  defp check_precision(value, field, market, opts) when is_map(market) do
    case opts[:precision_mode] do
      nil ->
        :ok

      mode ->
        case MarketPrecision.from_market(market, mode) do
          {:error, :unsupported_precision_mode} -> :ok
          %MarketPrecision{} = mp -> check_precision(value, field, mp, [])
        end
    end
  end

  @doc false
  defp get_mp_increment(%MarketPrecision{} = mp, "price"), do: mp.price_increment
  defp get_mp_increment(%MarketPrecision{} = mp, "amount"), do: mp.amount_increment
  defp get_mp_increment(_, _), do: nil

  @doc false
  defp validate_increment(_value, nil, _field), do: :ok

  defp validate_increment(value, increment, field) when is_number(increment) and increment > 0 do
    remainder = :math.fmod(value, increment)
    epsilon = increment * @epsilon_multiplier

    if remainder < epsilon or increment - remainder < epsilon do
      :ok
    else
      {:error, "#{field} #{value} does not respect increment #{increment}"}
    end
  end

  defp validate_increment(_value, _increment, _field), do: :ok
end