/*
 * 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_ctrl_cmd_t — parameters for can_bus_send_control_cmd().
 *
 * CAN ID 0x75  DLC=8  little-endian:
 *   bytes 0-1 : throttle_limit_command (uint16_t, little-endian)
 *   bytes 2-5 : 0x00
 *   byte  6   : bit 0 = led_enable  (1=on, 0=off)
 *   byte  7   : bit 0 = led_r (LED right, 1=on), bit 7 = led_l (LED left, 1=on)
 *
 * keepalive_interval_ms: >0 updates the keepalive period; 0 = no change.
 */
typedef struct {
    uint16_t speed;               /* bytes 0-1: throttle_limit_command, little-endian */
    uint8_t  led_enable;          /* bit 48 (byte 6 bit 0): LED enable 1=on, 0=off   */
    uint8_t  led_r;               /* bit 56 (byte 7 bit 0): LED right  1=on, 0=off   */
    uint8_t  led_l;               /* bit 63 (byte 7 bit 7): LED left   1=on, 0=off   */
    int      keepalive_interval_ms; /* >0 updates keepalive period; 0 = no change    */
} can_ctrl_cmd_t;

/*
 * can_bus_send_control_cmd — send one 8-byte CAN control frame immediately
 * and update the keepalive state to maintain the new values.
 */
void can_bus_send_control_cmd(const can_ctrl_cmd_t *ctrl);

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

/*
 * can_ecu_status_t — parsed signals from ECU CAN ID 0x50 (throttle_status frame).
 *
 * Frame layout (Intel byte order):
 *   frame[0..1] = throttle_status     (bits  0-15, uint16)
 *   frame[2..3] = throttle_pedal_volt (bits 16-31, uint16)
 *   frame[4..5] = led_flash_timer     (bits 32-47, uint16)
 *   frame[6] bit 0 = can_lose_ecu     (bit 48)
 *   frame[6] bit 7 = throttle_limit_off (bit 55)
 *   frame[7]       = heart_beam       (bits 56-63, uint8)
 *
 * can_lose_timeout: KL630 self-detected, set to 1 when no ECU frame for >100ms.
 */
typedef struct {
    uint16_t throttle_status;     /* bits  0-15: current throttle value, 0-8191 */
    uint16_t throttle_pedal_volt; /* bits 16-31: pedal voltage                  */
    uint16_t led_flash_timer;     /* bits 32-47: LED flash timer                */
    uint8_t  can_lose_ecu;        /* bit  48:    ECU-reported CAN loss (0/1)    */
    uint8_t  throttle_limit_off;  /* bit  55:    throttle limit off flag (0/1)  */
    uint8_t  heart_beam;          /* bits 56-63: heartbeat counter              */
    int      can_lose_timeout;    /* KL630 self-detected: 1 if ECU silent >100ms*/
} can_ecu_status_t;

/* can_bus_get_ecu_status — thread-safe snapshot of latest ECU status. */
void can_bus_get_ecu_status(can_ecu_status_t *out);

#endif /* CAN_BUS_H */