/**
 * @file pcan_abi.h
 * @brief Stable C ABI for desktop, Android and other foreign runtimes.
 *
 * The firmware-facing API remains allocation free.  This header exposes
 * scalar arguments and explicitly sized buffers so ctypes/JNI/Swift can use
 * the same C99 implementation without reproducing the wire protocol.
 */
#ifndef PCAN_ABI_H
#define PCAN_ABI_H

#include <stddef.h>
#include <stdint.h>

#if defined(_WIN32) && defined(PCAN_ABI_BUILD_DLL)
#  define PCAN_ABI_API __declspec(dllexport)
#elif defined(_WIN32) && defined(PCAN_ABI_USE_DLL)
#  define PCAN_ABI_API __declspec(dllimport)
#elif defined(__GNUC__) && (__GNUC__ >= 4)
#  define PCAN_ABI_API __attribute__((visibility("default")))
#else
#  define PCAN_ABI_API
#endif

#ifdef __cplusplus
extern "C" {
#endif

#define PCAN_ABI_VERSION 1U

typedef struct {
    uint32_t can_id;
    uint8_t sequence;
    uint8_t flags;
    uint8_t dlc;
    uint8_t data[8];
} pcan_abi_frame_t;

#define PCAN_ABI_GUI_PAYLOAD_MAX 512U

typedef struct {
    uint16_t sequence;
    uint16_t size;
    uint8_t message_type;
    uint8_t payload[PCAN_ABI_GUI_PAYLOAD_MAX];
} pcan_abi_gui_frame_t;

PCAN_ABI_API uint32_t pcan_abi_version(void);

PCAN_ABI_API uint32_t pcan_abi_id_pack(uint8_t priority, uint8_t route,
                                       uint8_t device_type, uint8_t device_id,
                                       uint8_t message_type, uint16_t body);

PCAN_ABI_API void pcan_abi_id_unpack(uint32_t raw, uint8_t *priority,
                                     uint8_t *route, uint8_t *device_type,
                                     uint8_t *device_id, uint8_t *message_type,
                                     uint16_t *body);

PCAN_ABI_API uint16_t pcan_abi_crc16(const uint8_t *data, size_t size);

PCAN_ABI_API size_t pcan_abi_frame_encode(uint8_t sequence, uint8_t flags,
                                          uint32_t can_id,
                                          const uint8_t *data, uint8_t dlc,
                                          uint8_t *output,
                                          size_t output_size);

/* The caller owns parser_storage; no allocation is performed by the core. */
PCAN_ABI_API size_t pcan_abi_parser_size(void);
PCAN_ABI_API int pcan_abi_parser_init(void *parser_storage,
                                      size_t storage_size);
PCAN_ABI_API int pcan_abi_parser_push(void *parser_storage, uint8_t byte,
                                      pcan_abi_frame_t *output);
PCAN_ABI_API int pcan_abi_parser_stats(const void *parser_storage,
                                       uint32_t *frames,
                                       uint32_t *crc_errors,
                                       uint32_t *bad_length,
                                       uint32_t *stray_bytes);

PCAN_ABI_API uint32_t pcan_abi_gui_crc32(const uint8_t *data, size_t size);
PCAN_ABI_API size_t pcan_abi_gui_frame_encode(
    uint8_t message_type, uint16_t sequence,
    const uint8_t *payload, uint16_t payload_size,
    uint8_t *output, size_t output_size);
PCAN_ABI_API size_t pcan_abi_gui_parser_size(void);
PCAN_ABI_API int pcan_abi_gui_parser_init(void *parser_storage,
                                          size_t storage_size);
PCAN_ABI_API int pcan_abi_gui_parser_push(void *parser_storage, uint8_t byte,
                                          pcan_abi_gui_frame_t *output);
PCAN_ABI_API int pcan_abi_gui_parser_stats(
    const void *parser_storage, uint32_t *frames, uint32_t *crc_errors,
    uint32_t *version_errors, uint32_t *length_errors,
    uint32_t *stray_bytes);

#ifdef __cplusplus
}
#endif

#endif /* PCAN_ABI_H */