#ifndef JETSON_CMD_H
#define JETSON_CMD_H

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

/*
 * Jetson→STM32 command protocol over USB CDC (bidirectional, same /dev/ttyACM0)
 *
 * Commands (newline-terminated ASCII, sent by Jetson):
 *   H\n              — heartbeat (every 200ms). Must arrive within 500ms or
 *                      jetson_cmd_is_active() returns false → steer reverts to 0.
 *   C<spd>,<str>\n   — drive command: speed -1000..+1000, steer -1000..+1000.
 *                      Also refreshes the heartbeat timer.
 *
 * Speed→setpoint:
 *   Speed is converted to a setpoint offset (degrees) before calling balance_update().
 *   Positive speed → forward tilt → robot moves forward.
 *   Max offset is ±JETSON_SPEED_MAX_DEG (see below).
 *
 * Steer:
 *   Passed directly to motor_driver_update() as steer_cmd.
 *   Motor driver ramps and clamps with balance headroom (see motor_driver.h).
 *
 * Integration pattern in main.c (after the cdc_cmd_ready block):
 *
 *   // Process buffered C command (parsed here, not in ISR)
 *   if (jetson_cmd_ready) { jetson_cmd_ready = 0; jetson_cmd_process(); }
 *
 *   // Apply setpoint offset and steer when active
 *   float base_sp = bal.setpoint;
 *   if (jetson_cmd_is_active(now)) bal.setpoint += jetson_cmd_sp_offset();
 *   balance_update(&bal, &imu, dt);
 *   bal.setpoint = base_sp;
 *
 *   // Steer injection in 50Hz ESC block
 *   int16_t jsteer = jetson_cmd_is_active(now) ? jetson_cmd_steer() : 0;
 *   motor_driver_update(&motors, bal.motor_cmd, jsteer, now);
 */

/* Heartbeat timeout: if no H or C within this window, commands deactivate */
#define JETSON_HB_TIMEOUT_MS    500

/* Max setpoint offset from Jetson speed command (speed=1000 → +N degrees tilt) */
#define JETSON_SPEED_MAX_DEG    4.0f   /* ±4° → enough for ~0.5 m/s */

/*
 * jetson_cmd_process()
 * Call from main loop (NOT ISR) when jetson_cmd_ready is set.
 * Parses jetson_cmd_buf (the C<spd>,<str> frame) with sscanf.
 */
void    jetson_cmd_process(void);

/*
 * jetson_cmd_is_active(now)
 * Returns true if a heartbeat (H or C command) arrived within JETSON_HB_TIMEOUT_MS.
 * If false, main loop should fall back to RC or zero steer.
 */
bool    jetson_cmd_is_active(uint32_t now_ms);

/* Current steer command after latest C frame, clamped to ±1000 */
int16_t jetson_cmd_steer(void);

/* Setpoint offset (degrees) derived from latest speed command. */
float   jetson_cmd_sp_offset(void);

/*
 * Externals — declared here, defined in usbd_cdc_if.c alongside the other
 * CDC volatile flags (cdc_streaming, cdc_arm_request, etc.).
 * Main loop checks jetson_cmd_ready; ISR sets it.
 */
extern volatile uint8_t  jetson_cmd_ready;   /* set by ISR on C frame */
extern volatile char     jetson_cmd_buf[32]; /* C<spd>,<str>\0 from ISR */
extern volatile uint32_t jetson_hb_tick;     /* HAL_GetTick() of last H or C */

#endif /* JETSON_CMD_H */
