interface Order {
  /** Total order value in dollars */
  order_value: number;

  /** Total units in the order */
  quantity: number;

  /** Base margin as decimal (0.40 = 40%) */
  product_margin: number;

  /** Customer tier/segment (optional) */
  customer_segment?: string;
}

interface Policy {
  /** Unique policy identifier */
  id: string;

  /** Human-readable policy name */
  name: string;

  /** Array of policy rules */
  rules: PolicyRule[];
}

interface PolicyRule {
  /** Rule identifier */
  name: string;

  /** Rule conditions */
  conditions: {
    all?: RuleCondition[];
    any?: RuleCondition[];
  };

  /** Event triggered when rule matches */
  event: {
    type: string;
    params?: Record<string, unknown>;
  };

  /** Rule priority (higher = first) */
  priority?: number;
}

type RuleCondition = FactCondition | NestedCondition;

interface FactCondition {
  fact: string;
  operator: string;
  value: unknown;
}

interface NestedCondition {
  all?: RuleCondition[];
  any?: RuleCondition[];
}

interface EvaluationResult {
  /** Whether the discount was approved */
  approved: boolean;

  /** List of policy violations */
  violations: Violation[];

  /** Rules that were triggered */
  applied_rules: string[];

  /** Calculated margin after discount */
  calculated_margin: number;
}

interface Violation {
  /** Rule that was violated */
  rule: string;

  /** Human-readable violation message */
  message: string;

  /** UCP-compatible error code */
  ucp_error_code?: UCPErrorCode;
}

type UCPErrorCode =
  | 'discount_code_expired'
  | 'discount_code_invalid'
  | 'discount_code_already_applied'
  | 'discount_code_combination_disallowed'
  | 'discount_code_user_not_logged_in'
  | 'discount_code_user_ineligible';

interface LineItem {
  item_id: string;
  subtotal: number;
}

interface Allocation {
  item_id: string;
  amount: number;
}