#pragma once

#include <xrpl/basics/Buffer.h>
#include <xrpl/basics/Slice.h>
#include <xrpl/conditions/Condition.h>

namespace xrpl {
namespace cryptoconditions {

struct Fulfillment
{
public:
    /** The largest binary fulfillment we support.

        @note This value will be increased in the future, but it
              must never decrease, as that could cause fulfillments
              that were previously considered valid to no longer
              be allowed.
    */
    static constexpr std::size_t maxSerializedFulfillment = 256;

    /** Load a fulfillment from its binary form

        @param s The buffer containing the fulfillment to load.
        @param ec Set to the error, if any occurred.

        The binary format for a fulfillment is specified in the
        cryptoconditions RFC. See:

        https://tools.ietf.org/html/draft-thomas-crypto-conditions-02#section-7.3
    */
    static std::unique_ptr<Fulfillment>
    deserialize(Slice s, std::error_code& ec);

public:
    virtual ~Fulfillment() = default;

    /** Returns the fulfillment's fingerprint:

        The fingerprint is an octet string uniquely
        representing this fulfillment's condition
        with respect to other conditions of the
        same type.
   */
    virtual Buffer
    fingerprint() const = 0;

    /** Returns the type of this condition. */
    virtual Type
    type() const = 0;

    /** Validates a fulfillment. */
    virtual bool
    validate(Slice data) const = 0;

    /** Calculates the cost associated with this fulfillment. *

        The cost function is deterministic and depends on the
        type and properties of the condition and the fulfillment
        that the condition is generated from.
    */
    virtual std::uint32_t
    cost() const = 0;

    /** Returns the condition associated with the given fulfillment.

        This process is completely deterministic. All implementations
        will, if compliant, produce the identical condition for the
        same fulfillment.
    */
    virtual Condition
    condition() const = 0;
};

inline bool
operator==(Fulfillment const& lhs, Fulfillment const& rhs)
{
    // FIXME: for compound conditions, need to also check subtypes
    return lhs.type() == rhs.type() && lhs.cost() == rhs.cost() &&
        lhs.fingerprint() == rhs.fingerprint();
}

inline bool
operator!=(Fulfillment const& lhs, Fulfillment const& rhs)
{
    return !(lhs == rhs);
}

/** Determine whether the given fulfillment and condition match */
bool
match(Fulfillment const& f, Condition const& c);

/** Verify if the given message satisfies the fulfillment.

    @param f The fulfillment
    @param c The condition
    @param m The message

    @note the message is not relevant for some conditions
          and a fulfillment will successfully satisfy its
          condition for any given message.
*/
bool
validate(Fulfillment const& f, Condition const& c, Slice m);

/** Verify a cryptoconditional trigger.

    A cryptoconditional trigger is a cryptocondition with
    an empty message.

    When using such triggers, it is recommended that the
    trigger be of type preimage, prefix or threshold. If
    a signature type is used (i.e. Ed25519 or RSA-SHA256)
    then the Ed25519 or RSA keys should be single-use keys.

    @param f The fulfillment
    @param c The condition
*/
bool
validate(Fulfillment const& f, Condition const& c);

}  // namespace cryptoconditions
}  // namespace xrpl