#ifndef JLINK_H
#define JLINK_H

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

/*
 * JLink — Jetson serial binary protocol over USART1 (PB6=TX, PB7=RX).
 *
 * Issue #120: replaces jetson_cmd ASCII-over-USB-CDC with a dedicated
 * hardware UART at 921600 baud using DMA circular RX and IDLE interrupt.
 *
 * Frame format (both directions):
 *   [STX=0x02][LEN][CMD][PAYLOAD...][CRC16_hi][CRC16_lo][ETX=0x03]
 *
 *   STX   : frame start sentinel (0x02)
 *   LEN   : count of CMD + PAYLOAD bytes (1 + payload_len)
 *   CMD   : command/telemetry type byte
 *   PAYLOAD: 0..N bytes depending on CMD
 *   CRC16 : CRC16-XModem over CMD+PAYLOAD (poly 0x1021, init 0), big-endian
 *   ETX   : frame end sentinel (0x03)
 *
 * Jetson → STM32 commands:
 *   0x01  HEARTBEAT  — no payload; refreshes heartbeat timer
 *   0x02  DRIVE      — int16 speed (-1000..+1000), int16 steer (-1000..+1000)
 *   0x03  ARM        — no payload; request arm (same interlock as CDC 'A')
 *   0x04  DISARM     — no payload; disarm immediately
 *   0x05  PID_SET    — float kp, float ki, float kd (12 bytes, IEEE-754 LE)
 *   0x06  DFU_ENTER  — no payload; request OTA DFU reboot (denied while armed)
 *   0x07  ESTOP      — no payload; engage emergency stop
 *
 * STM32 → Jetson telemetry:
 *   0x80  STATUS     — jlink_tlm_status_t (20 bytes), sent at JLINK_TLM_HZ
 *
 * Priority: CRSF RC always takes precedence. Jetson steer/speed only applied
 * when mode_manager_active() == MODE_AUTONOMOUS (CH6 high). In RC_MANUAL and
 * RC_ASSISTED modes the Jetson speed offset and steer are injected via
 * mode_manager_set_auto_cmd() and blended per the existing blend ramp.
 *
 * Heartbeat: if no valid frame arrives within JLINK_HB_TIMEOUT_MS (1000ms),
 * jlink_is_active() returns false and the main loop clears the auto command.
 */

/* ---- Frame constants ---- */
#define JLINK_STX               0x02u
#define JLINK_ETX               0x03u

/* ---- Command IDs (Jetson → STM32) ---- */
#define JLINK_CMD_HEARTBEAT     0x01u
#define JLINK_CMD_DRIVE         0x02u
#define JLINK_CMD_ARM           0x03u
#define JLINK_CMD_DISARM        0x04u
#define JLINK_CMD_PID_SET       0x05u
#define JLINK_CMD_DFU_ENTER     0x06u
#define JLINK_CMD_ESTOP         0x07u
#define JLINK_CMD_AUDIO         0x08u  /* PCM audio chunk: int16 samples, up to 126 */

/* ---- Telemetry IDs (STM32 → Jetson) ---- */
#define JLINK_TLM_STATUS        0x80u

/* ---- Telemetry STATUS payload (20 bytes, packed) ---- */
typedef struct __attribute__((packed)) {
    int16_t  pitch_x10;     /* pitch degrees ×10 */
    int16_t  roll_x10;      /* roll  degrees ×10 */
    int16_t  yaw_x10;       /* yaw   degrees ×10 (gyro-integrated) */
    int16_t  motor_cmd;     /* ESC output -1000..+1000 */
    uint16_t vbat_mv;       /* battery millivolts */
    int8_t   rssi_dbm;      /* CRSF RSSI (dBm, negative) */
    uint8_t  link_quality;  /* CRSF LQ 0-100 */
    uint8_t  balance_state; /* 0=DISARMED, 1=ARMED, 2=TILT_FAULT */
    uint8_t  rc_armed;      /* crsf_state.armed (1=armed) */
    uint8_t  mode;          /* robot_mode_t: 0=RC_MANUAL,1=ASSISTED,2=AUTONOMOUS */
    uint8_t  estop;         /* EstopSource value */
    uint8_t  soc_pct;       /* state-of-charge 0-100, 255=unknown */
    uint8_t  fw_major;
    uint8_t  fw_minor;
    uint8_t  fw_patch;
} jlink_tlm_status_t;  /* 20 bytes */

/* ---- Volatile state (read from main loop) ---- */
typedef struct {
    /* Drive command — updated on JLINK_CMD_DRIVE */
    volatile int16_t  speed;        /* -1000..+1000 */
    volatile int16_t  steer;        /* -1000..+1000 */

    /* Heartbeat timer — updated on any valid frame */
    volatile uint32_t last_rx_ms;   /* HAL_GetTick() of last valid frame; 0=none */

    /* One-shot request flags — set by parser, cleared by main loop */
    volatile uint8_t  arm_req;
    volatile uint8_t  disarm_req;
    volatile uint8_t  estop_req;

    /* PID update — set by parser, cleared by main loop */
    volatile uint8_t  pid_updated;
    volatile float    pid_kp;
    volatile float    pid_ki;
    volatile float    pid_kd;

    /* DFU reboot request — set by parser, cleared by main loop */
    volatile uint8_t  dfu_req;
} JLinkState;

extern volatile JLinkState jlink_state;

/* ---- API ---- */

/*
 * jlink_init() — configure USART1 (PB6=TX, PB7=RX) at 921600 baud with
 * DMA2_Stream2_Channel4 circular RX (128-byte buffer) and IDLE interrupt.
 * Call once before safety_init().
 */
void jlink_init(void);

/*
 * jlink_is_active(now_ms) — returns true if a valid frame arrived within
 * JLINK_HB_TIMEOUT_MS. Returns false if no frame ever received.
 */
bool jlink_is_active(uint32_t now_ms);

/*
 * jlink_send_telemetry(status) — build and transmit a JLINK_TLM_STATUS frame
 * over USART1 TX (blocking, ~0.2ms at 921600). Call at JLINK_TLM_HZ.
 */
void jlink_send_telemetry(const jlink_tlm_status_t *status);

/*
 * jlink_process() — drain DMA circular buffer and parse frames.
 * Call from main loop every iteration (not ISR). Lightweight: O(bytes_pending).
 */
void jlink_process(void);

#endif /* JLINK_H */