/*
 * can_bus.h — MCP2515 CAN bus wrapper for KL630 (J15 SPI connector)
 *
 * API mirrors bt_uart.h: both channels carry the same JSON payload.
 *   BLE  channel: bt_uart_send_json(json)
 *   CAN  channel: can_bus_send_json(json)
 *
 * The same JSON string {"class":"car","level":1} is transmitted on both
 * channels simultaneously from fire_json_async() in event_recorder.c.
 *
 * MCP2515 is classic CAN (max 8 bytes per frame).  Long JSON strings are
 * split into sequential 8-byte frames automatically:
 *   Frame N: bytes [N*8 .. N*8+7] of the JSON string (padded with 0x00)
 * The receiver reassembles by concatenating frames until a null byte.
 * If a CAN FD controller is fitted later, switch to single-frame send.
 */

#ifndef CAN_BUS_H
#define CAN_BUS_H

#include <stdint.h>

/*
 * can_bus_init — open MCP2515 via SPI and start writer thread.
 *   spidev        : e.g. "/dev/spidev1.0"
 *   can_speed_kbps: 250 (typical) or 125, 500, 1000
 *   can_id        : 11-bit standard frame ID for outbound frames
 * Returns 0 on success, -1 on error.
 */
int  can_bus_init(const char *spidev, int can_speed_kbps, uint32_t can_id);

/*
 * can_bus_send_json — non-blocking: enqueue a JSON string for CAN transmission.
 *   Same signature as bt_uart_send_json(); call both from fire_json_async().
 *   Long strings are split into multiple 8-byte CAN frames automatically.
 */
void can_bus_send_json(const char *json);

/*
 * can_bus_send_control_cmd — send one classic-CAN control frame.
 * Frame format (compatible with bt_proc.c reference):
 *   CAN ID : 0x75 (11-bit)
 *   DLC    : 8
 *   DATA   : [cmd, 0, 0, 0, 0, 0, 0, 0]
 */
void can_bus_send_control_cmd(uint8_t cmd);

/* can_bus_close — drain queue, join writer thread, close SPI device. */
void can_bus_close(void);

#endif /* CAN_BUS_H */