#pragma once

#include <experimental/optional>
#include <variant>
#include <vector>

#include "ble/ByteBuffer.h"
#include "ble/misc.h"

namespace trygvis {
namespace bluetooth {

template<typename T>
using o = std::experimental::optional<T>;

/**
 * BLUETOOTH SPECIFICATION Version 4.0 [Vol 3] - Attribute Protocol (ATT) - 3.4.8 Attribute Opcode Summary
 * Table 3.37
 */
enum AttPduType {
    ERROR = 0x01,
    EXCHANGE_MTU_REQ = 0x02,
    EXCHANGE_MTU_RES = 0x03,
    FIND_INFORMATION_REQ = 0x04,
    FIND_INFORMATION_RES = 0x05,
    FIND_BY_TYPE_VALUE_REQ = 0x06,
    FIND_BY_TYPE_VALUE_RES = 0x07,
    READ_BY_TYPE_REQ = 0x08,
    READ_BY_TYPE_RES = 0x09,
    READ_REQ = 0x0a,
    READ_RES = 0x0b,
    READ_BLOB_REQ = 0x0c,
    READ_BLOB_RES = 0x0d,
    READ_MULTIPLE_REQ = 0x0e,
    READ_MULTIPLE_RES = 0x0f,
    READ_BY_GROUP_TYPE_REQ = 0x10,
    READ_BY_GROUP_TYPE_RES = 0x11,
    WRITE_REQ = 0x12,
    WRITE_RES = 0x13,

    WRITE_CMD = 0x52,
    PREPARE_WRITE_REQ = 0x16,
    PREPARE_WRITE_RES = 0x17,
    EXECUTE_WRITE_REQ = 0x18,
    EXECUTE_WRITE_RES = 0x19,
    HANDLE_VALUE_NOTIFICATION = 0x1b,
    HANDLE_VALUE_INDICATION = 0x1d,
    HANDLE_VALUE_CONFIRMATION = 0x1e,
    SIGNED_WRITE_COMMAND = 0xd2,
};

std::string to_string(AttPduType t);

class AttributeData;

/**
 * Application Error 0x80 – 0xFF Application error code defined by a higher layer specification.
 *
 * BLUETOOTH SPECIFICATION Version 4.0 [Vol 3] - 3.4.1.1 Error Response - Table 3.3
 */
enum ErrorCode : uint8_t {
    INVALID_HANDLE = 0x01,     ///< The attribute handle given was not valid on this server.
    READ_NOT_PERMITTED = 0x02,///< The attribute cannot be read.
    WRITE_NOT_PERMITTED = 0x03,///< The attribute cannot be written.
    INVALID_PDU = 0x04, ///<The attribute PDU was invalid.
    INSUFFICIENT_AUTHENTICATION = 0x05, ///<The attribute requires authentication before it can be read or written.
    REQUEST_NOT_SUPPORTED = 0x06, ///<Attribute server does not support the request received from the client.
    INVALID_OFFSET = 0x07, ///<Offset specified was past the end of the attribute.
    INSUFFICIENT_AUTHORIZATION = 0x08, ///<The attribute requires authorization before it can be read or written.
    PREPARE_QUEUE_FULL = 0x09, ///<Too many prepare writes have been queued.
    ATTRIBUTE_NOT_FOUND = 0x0a, ///<No attribute found within the given attribute handle range.
    ATTRIBUTE_NOT_LONG = 0x0b, ///<The attribute cannot be read or written using the Read Blob Request
    INSUFFICIENT_ENCRYPTION_KEY_SIZE = 0x0c, ///<The Encryption Key Size used for encrypting this link is insufficient.
    INVALID_ATTRIBUTE_VALUE_LENGTH = 0x0d, ///<The attribute value length is invalid for the operation
    UNLIKELY_ERROR = 0x0e, ///<The attribute request that was requested has encountered an error that was unlikely, and therefore could not be completed as requested.
    INSUFFICIENT_ENCRYPTION = 0x0f, ///<The attribute requires encryption before it can be read or written.
    UNSUPPORTED_GROUP_TYPE = 0x10, ///<The attribute type is not a supported grouping attribute as defined by a higher layer specification.
    INSUFFICIENT_RESOURCES = 0x11, ///<Insufficient Resources to complete the request Reserved 0x012 – 0x7F Reserved for future use.
};

struct ErrorRes {
    static constexpr auto att_pdu_type = AttPduType::EXCHANGE_MTU_REQ;

    /**
     * The request that generated this error response.
     */
    uint8_t requestOpcode;

    /**
     * The attribute handle that generated this error response.
     */
    uint16_t attributeHandle;

    /**
     * The reason why the request has generated an error response.
     */
    uint8_t errorCode;

    static ErrorRes parse(ByteBuffer& buffer) {
        return {buffer.read8(), buffer.read16le(), buffer.read8()};
    }
};

struct ExchangeMtuReq {
    static constexpr auto att_pdu_type = AttPduType::EXCHANGE_MTU_REQ;

    uint16_t clientRxMtu;
};

struct ExchangeMtuRes {
    static constexpr auto att_pdu_type = AttPduType::EXCHANGE_MTU_RES;

    uint16_t serverRxMtu;
};

struct ReadByGroupTypeRes {
    static constexpr auto att_pdu_type = AttPduType::READ_BY_GROUP_TYPE_RES;

    std::vector<AttributeData> attributes;
};

struct ReadByTypeRes {
    static constexpr auto att_pdu_type = AttPduType::READ_BY_TYPE_RES;

    std::vector<AttributeData> attributes;
};

using AttVariant = std::variant<std::monostate,
    ErrorRes,
    ExchangeMtuReq, ExchangeMtuRes,
    ReadByGroupTypeRes, ReadByTypeRes>;

o<AttPduType> attPduType(const AttVariant& v);

class AttPdu {
public:
    explicit AttPdu(ByteBuffer &bytes);

    AttPdu(ByteBuffer &bytes, AttPduType type);

    AttPduType getType();

    static AttVariant parse(ByteBuffer &bytes);

    static ExchangeMtuReq parseExchangeMtuReq(ByteBuffer &bytes);
    static ExchangeMtuRes parseExchangeMtuRes(ByteBuffer &bytes);

    static void parseRead(ByteBuffer &bytes);

    static void parseWrite(ByteBuffer &bytes);

    static void makeExchangeMtuRes(ByteBuffer &bytes, uint16_t serverRxMtu);

    static void makeReadByGroupType(ByteBuffer &bytes, uint16_t startHandle, uint16_t endHandle, ShortUuid uuid);

    static void makeReadByType(ByteBuffer &bytes, uint16_t startHandle, uint16_t endHandle, ShortUuid uuid);

    static void makeRead(ByteBuffer &bytes, uint16_t handle);

    static void makeWrite(ByteBuffer &req, uint16_t handle, const ByteBuffer &bytes);

private:
//    static void checkType(ByteBuffer &bytes, AttPduType type);

    static std::vector<AttributeData> parseAttributeData(ByteBuffer &bytes);

    ByteBuffer &bytes;
};

class AttributeData {
public:
    ~AttributeData();

    static AttributeData fromByteBuffer(ByteBuffer &value);

    const uint16_t handle;
    ByteBuffer value;

private:
    AttributeData(uint16_t handle, ByteBuffer value, std::shared_ptr<uint8_t[]> raw);

    std::shared_ptr<uint8_t[]> raw;
};

} // namespace bluetooth
} // namespace trygvis