#ifndef CAN_DRIVER_H
#define CAN_DRIVER_H

#include <stdint.h>
#include <stdbool.h>

/* CAN bus driver for BLDC motor controllers (Issue #597)
 * CAN2 on PB12 (RX, AF9) / PB13 (TX, AF9) at 500 kbps
 * APB1 = 54 MHz: PSC=6, BS1=13tq, BS2=4tq, SJW=1tq → 18 tq/bit = 500 kbps
 */

/* Node IDs */
#define CAN_NUM_MOTORS          2u
#define CAN_NODE_LEFT           0u
#define CAN_NODE_RIGHT          1u

/* CAN frame IDs */
#define CAN_ID_VEL_CMD_BASE     0x100u   /* TX: 0x100 + node_id — velocity/torque command */
#define CAN_ID_ENABLE_CMD_BASE  0x110u   /* TX: 0x110 + node_id — enable/disable */
#define CAN_ID_FEEDBACK_BASE    0x200u   /* RX: 0x200 + node_id — position/velocity/current */

/* Filter: accept standard IDs 0x200–0x21F */
#define CAN_FILTER_STDID        0x200u
#define CAN_FILTER_MASK         0x7E0u

/* Bit timing (500 kbps @ 54 MHz APB1) */
#define CAN_PRESCALER           6u

/* TX rate */
#define CAN_TX_RATE_HZ          100u

/* Node alive timeout */
#define CAN_NODE_TIMEOUT_MS     100u

/* TX command frame (8 bytes payload, DLC=4 for vel cmd) */
typedef struct {
    int16_t velocity_rpm;   /* target RPM (+/- = fwd/rev) */
    int16_t torque_x100;    /* torque limit × 100 (0 = unlimited) */
} can_cmd_t;

/* RX feedback frame (DLC=8) */
typedef struct {
    int16_t  velocity_rpm;      /* actual RPM */
    int16_t  current_ma;        /* phase current in mA */
    int16_t  position_x100;     /* position × 100 (degrees or encoder counts) */
    int8_t   temperature_c;     /* controller temperature °C */
    uint8_t  fault;             /* fault flags (0 = healthy) */
    uint32_t last_rx_ms;        /* HAL_GetTick() at last valid frame */
} can_feedback_t;

/* Bus statistics */
typedef struct {
    uint32_t tx_count;   /* frames transmitted */
    uint32_t rx_count;   /* frames received */
    uint16_t err_count;  /* HAL-level errors */
    uint8_t  bus_off;    /* 1 = bus-off state */
    uint8_t  _pad;
} can_stats_t;

/* Initialise CAN2 peripheral, GPIO, and filter bank 14 */
void can_driver_init(void);

/* Send velocity+torque command to one node */
void can_driver_send_cmd(uint8_t node_id, const can_cmd_t *cmd);

/* Send enable/disable command to one node */
void can_driver_send_enable(uint8_t node_id, bool enable);

/* Copy latest feedback snapshot (returns false if node never heard from) */
bool can_driver_get_feedback(uint8_t node_id, can_feedback_t *out);

/* Returns true if node has been heard within CAN_NODE_TIMEOUT_MS */
bool can_driver_is_alive(uint8_t node_id, uint32_t now_ms);

/* Copy bus statistics snapshot */
void can_driver_get_stats(can_stats_t *out);

/* Drain RX FIFO0; call every main-loop tick */
void can_driver_process(void);

#endif /* CAN_DRIVER_H */