#ifndef __SNC_CAN_APP_H
#define __SNC_CAN_APP_H

#ifdef __cplusplus
extern "C" {
#endif

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

#define SNC_ODOM_TIMEOUT_MS        300U

/* ========================= 协议 CAN ID ========================= */
#define SNC_CAN_ID_HEARTBEAT      0x080U
#define SNC_CAN_ID_CMD_VEL        0x100U

#define SNC_CAN_ID_STATUS         0x181U
#define SNC_CAN_ID_ACTUAL_RPM     0x182U
#define SNC_CAN_ID_TARGET_RPM     0x183U
#define SNC_CAN_ID_COMM_DIAG      0x184U
#define SNC_CAN_ID_ODOM           0x200U

/* ========================= 系统状态定义 ========================= */
typedef enum
{
    SNC_SYSTEM_BOOTING = 0,
    SNC_SYSTEM_OPERATIONAL = 1,
    SNC_SYSTEM_SAFE_FAULT = 2
} SNC_SystemState_t;

typedef enum
{
    SNC_SYSTEM_HEALTH_OK = 0,
    SNC_SYSTEM_HEALTH_WARNING = 1,
    SNC_SYSTEM_HEALTH_FAULT = 2
} SNC_SystemHealth_t;

/* ========================= 诊断位定义 ========================= */
typedef enum
{
    SNC_DIAG_COMM_TIMEOUT        = (1UL << 0),
    SNC_DIAG_CAN_BUS_OFF         = (1UL << 1),
    SNC_DIAG_CMD_CRC_STORM       = (1UL << 2),
    SNC_DIAG_CMD_CNT_STORM       = (1UL << 3),
    SNC_DIAG_MOTOR_FL_STALL      = (1UL << 4),
    SNC_DIAG_MOTOR_RL_STALL      = (1UL << 5),
    SNC_DIAG_MOTOR_FR_STALL      = (1UL << 6),
    SNC_DIAG_MOTOR_RR_STALL      = (1UL << 7),
    SNC_DIAG_CONTROL_SATURATION  = (1UL << 8)
} SNC_DiagBits_t;

/* ========================= 下位机状态快照 ========================= */
typedef struct
{
    uint8_t state;
    uint8_t health;
    uint32_t diag_bits;
    uint8_t cmd_age_10ms;
    uint8_t status_counter;
    uint32_t last_update_ms;
    bool online;
} SNC_ChassisStatus_t;

/* ========================= 轮速数据 ========================= */
typedef struct
{
    int16_t fl;
    int16_t rl;
    int16_t fr;
    int16_t rr;
    uint32_t last_update_ms;
} SNC_WheelRpmFrame_t;

/* ========================= 里程增量 ========================= */
typedef struct
{
    int16_t fl_delta;
    int16_t rl_delta;
    int16_t fr_delta;
    int16_t rr_delta;
    uint32_t last_update_ms;
} SNC_OdomDeltaFrame_t;

/**
 * @brief  里程增量累加器
 *
 * 解决 0x200 增量帧的"漏积分/重复积分"问题：
 * - ISR 收到每帧 0x200 时，将增量**累加**到此结构体（不覆盖）
 * - 消费者调用 SNC_CAN_ConsumeOdomDelta() 原子取走累计值并清零
 *
 * 这样即使消费者频率 (100ms) 低于帧到达频率 (~60ms)，
 * 也不会丢失任何增量；也不会重复消费同一份增量。
 */
typedef struct
{
    int32_t  fl_accum;        /**< 左前轮累计增量 ticks (int32 防溢出) */
    int32_t  rl_accum;        /**< 左后轮累计增量 ticks */
    int32_t  fr_accum;        /**< 右前轮累计增量 ticks */
    int32_t  rr_accum;        /**< 右后轮累计增量 ticks */
    uint32_t first_frame_ms;  /**< 本次累加窗口内第一帧的时间戳 [ms] */
    uint32_t last_frame_ms;   /**< 本次累加窗口内最后一帧的时间戳 [ms] */
    uint32_t span_ms;         /**< 本次累计增量实际覆盖的时间窗 [ms] */
    uint8_t  frame_count;     /**< 本次累加窗口内收到的帧数 */
} SNC_OdomDeltaAccum_t;

/* ========================= 通信诊断 ========================= */
typedef struct
{
    uint8_t valid_cmd_total_lsb;
    uint8_t crc_error_total_lsb;
    uint8_t counter_reject_total_lsb;
    uint8_t can_tx_drop_total_lsb;
    uint8_t busoff_total_lsb;
    uint8_t rx_overrun_total_lsb;
    uint8_t last_accepted_counter;
    uint8_t consecutive_counter_errors;
    uint8_t consecutive_crc_errors;
    uint32_t last_update_ms;
} SNC_CommDiagFrame_t;

/* ========================= 上位机应用层总状态 ========================= */
typedef struct
{
    SNC_ChassisStatus_t status;
    SNC_WheelRpmFrame_t actual_rpm;
    SNC_WheelRpmFrame_t target_rpm;
    SNC_OdomDeltaFrame_t odom_delta;       /**< 最近一帧快照 (保留兼容性, 勿用于积分) */
    SNC_OdomDeltaAccum_t odom_accum;      /**< 里程增量累加器 (正确消费入口) */
    SNC_CommDiagFrame_t comm_diag;

    uint8_t tx_counter;
    uint8_t tx_ctrl_flags;
    uint32_t tx_total;
    uint32_t tx_fail_total;
    uint32_t rx_total;
} SNC_CAN_AppContext_t;

/* ========================= 全局上下文 ========================= */
extern SNC_CAN_AppContext_t g_snc_can_app;

/* ========================= 初始化与任务 ========================= */
void SNC_CAN_AppInit(void);
void SNC_CAN_20msTask(void);
void SNC_CAN_100msTask(void);
void SNC_CAN_PollOnlineState(uint32_t now_ms);

/* ========================= 发送接口 ========================= */
HAL_StatusTypeDef SNC_CAN_SendHeartbeat(void);
HAL_StatusTypeDef SNC_CAN_SendCmdVel(float vx_mps, float wz_radps, uint8_t ctrl_flags);

/* ========================= 接收回调 ========================= */
void SNC_CAN_RxFifo0Callback(FDCAN_HandleTypeDef *hfdcan, uint32_t rxFifo0ITs);

/* ========================= 数据读取接口 ========================= */
const SNC_CAN_AppContext_t *SNC_CAN_GetContext(void);

/**
 * @brief  原子取走并清零里程增量累加器
 *
 * 消费者（monitorTask）每周期调用一次，取走自上次消费以来
 * ISR 累积的全部增量帧总和。返回后累加器归零，等待下一批帧。
 *
 * @param[out] fl  左前轮累计增量 ticks (截断为 int16)
 * @param[out] rl  左后轮累计增量 ticks
 * @param[out] fr  右前轮累计增量 ticks
 * @param[out] rr  右后轮累计增量 ticks
 * @param[out] dt_ms  累加增量实际覆盖的时间窗 [ms]
 *                    若无法可靠计算（如系统首帧）则为 0，可用默认帧间隔替代
 * @return     本次取走的帧数；0 表示期间没有新帧到达
 */
uint8_t SNC_CAN_ConsumeOdomDelta(int16_t *fl, int16_t *rl,
                                  int16_t *fr, int16_t *rr,
                                  uint32_t *dt_ms);

/* ========================= 工具接口 ========================= */
uint8_t SNC_CAN_Crc8J1850(const uint8_t *data, uint16_t len);

#ifdef __cplusplus
}
#endif

#endif /* __SNC_CAN_APP_H */