/**
 * @file   global_nav.c
 * @brief  赛道级总控 — 混合导航状态机实现
 *
 *         实现 6 条垄沟 S 型遍历:
 *           IDLE → ENTRY → TURN_IN → REACQUIRE → CORRIDOR_TRACK →
 *           TURN_OUT → LINK → TURN_IN_NEXT → REACQUIRE → ...
 *           → EXIT → DOCK → FINISHED
 */

#include "global_nav.h"
#include "est/corridor_filter.h"
#include "preproc/corridor_preproc.h"
#include "robot_params.h"
#include <math.h>
#include <string.h>

/* =========================================================
 * 内部状态
 * ========================================================= */
static struct {
    GlobalNavStage_t stage;
    bool             running;
    bool             initialized;

    /* 赛道级 */
    uint8_t  current_corridor_id;
    uint8_t  corridors_completed;

    /* 转向 */
    float    turn_start_yaw_deg;        /* IMU yaw_continuous at turn start */
    float    turn_target_delta_deg;     /* 90° */
    int8_t   turn_sign;                 /* +1 (CCW) or -1 (CW) */

    /* 里程 (用里程计积分距离) */
    float    stage_entry_odom_vx_accum; /* 进入阶段时的里程计累计距离 */
    float    odom_distance_accum;       /* 运行中持续积分的里程 */

    /* 超时 */
    uint32_t stage_start_ms;

    /* 重捕获 */
    uint8_t  reacquire_ok_count;

    /* 出场 */
    bool     exit_vl53_lost;
    float    exit_lost_distance;

    /* 航向保持 */
    float    heading_ref_deg;

    /* EKF 进度保存 */
    float    corridor_entry_s;

    /* 配置 */
    GlobalNavConfig_t cfg;
} s_nav;

/* 上一个周期的里程计速度，用于积分 */
static float s_last_odom_vx = 0.0f;
static uint32_t s_last_update_ms = 0;

/* =========================================================
 * 辅助函数
 * ========================================================= */
static inline float gnav_clampf(float val, float lo, float hi)
{
    if (val < lo) return lo;
    if (val > hi) return hi;
    return val;
}

static inline float gnav_fabsf(float x)
{
    return x < 0.0f ? -x : x;
}

/** 简单 P 控制航向保持，输入偏差 (deg)，输出角速度 (rad/s) */
static float heading_hold_pd(float current_yaw_deg, float ref_yaw_deg, float kp)
{
    float err_deg = ref_yaw_deg - current_yaw_deg;
    float w = kp * err_deg;  /* kp 把 ° 映射到 rad/s */
    return gnav_clampf(w, -1.0f, 1.0f);
}

/** 检查侧向 VL53 是否探到壁 (至少有一侧的前后都有效) */
static bool side_walls_detected(const CorridorObs_t* obs)
{
    bool left_ok  = (obs->valid_mask & CORRIDOR_OBS_MASK_LF) &&
                    (obs->valid_mask & CORRIDOR_OBS_MASK_LR);
    bool right_ok = (obs->valid_mask & CORRIDOR_OBS_MASK_RF) &&
                    (obs->valid_mask & CORRIDOR_OBS_MASK_RR);
    return left_ok || right_ok;
}

/** 检查侧向 VL53 是否全丢 */
static bool all_side_lost(const CorridorObs_t* obs)
{
    uint8_t side_mask = CORRIDOR_OBS_MASK_LF | CORRIDOR_OBS_MASK_LR |
                        CORRIDOR_OBS_MASK_RF | CORRIDOR_OBS_MASK_RR;
    return (obs->valid_mask & side_mask) == 0U;
}

/** 检查重捕获条件 */
static bool check_reacquire(const CorridorObs_t* obs, const CorridorState_t* state)
{
    /* 条件 1: 至少 3 个侧向传感器有效 */
    uint8_t side_mask = CORRIDOR_OBS_MASK_LF | CORRIDOR_OBS_MASK_LR |
                        CORRIDOR_OBS_MASK_RF | CORRIDOR_OBS_MASK_RR;
    uint8_t active = obs->valid_mask & side_mask;
    int count = 0;
    for (int i = 0; i < 4; i++) {
        if (active & (1U << i)) count++;
    }
    if (count < 3) return false;

    /* 条件 2: 左右距离和 ≈ 走廊宽度 */
    bool left_ok  = (obs->valid_mask & CORRIDOR_OBS_MASK_LF) &&
                    (obs->valid_mask & CORRIDOR_OBS_MASK_LR);
    bool right_ok = (obs->valid_mask & CORRIDOR_OBS_MASK_RF) &&
                    (obs->valid_mask & CORRIDOR_OBS_MASK_RR);

    if (left_ok && right_ok) {
        float d_left  = (obs->d_lf + obs->d_lr) * 0.5f;
        float d_right = (obs->d_rf + obs->d_rr) * 0.5f;
        float total_width = d_left + d_right + PARAM_ROBOT_WIDTH;
        float err = gnav_fabsf(total_width - s_nav.cfg.corridor_width);
        if (err > s_nav.cfg.reacquire_width_tol) return false;
    }

    /* 条件 3: EKF 置信度 */
    if (state->conf < s_nav.cfg.reacquire_conf_thresh) return false;

    return true;
}

/** 获取当前阶段的已行驶里程 */
static float odom_since_entry(void)
{
    return s_nav.odom_distance_accum - s_nav.stage_entry_odom_vx_accum;
}

/** 阶段转移 — 通用初始化 */
static void transition_to(GlobalNavStage_t next, const RobotBlackboard_t* board);

/* =========================================================
 * 阶段名称表
 * ========================================================= */
static const char* const s_stage_names[] = {
    "IDLE",
    "ENTRY_STRAIGHT",
    "TURN_INTO_CORRIDOR",
    "REACQUIRE",
    "CORRIDOR_TRACK",
    "TURN_OUT",
    "LINK_STRAIGHT",
    "TURN_INTO_NEXT",
    "EXIT_STRAIGHT",
    "DOCK",
    "FINISHED",
    "ERROR"
};

/* =========================================================
 * 转向执行 (统一的 90° 转向逻辑)
 * ========================================================= */
static void execute_turn(const CorridorObs_t* obs,
                         const CorridorState_t* state,
                         const RobotBlackboard_t* board,
                         uint32_t now_ms,
                         GlobalNavOutput_t* out)
{
    float imu_yaw = board->imu_yaw_continuous.is_valid
                    ? board->imu_yaw_continuous.value : 0.0f;

    /* 已转过的角度 (取绝对值) */
    float delta = (imu_yaw - s_nav.turn_start_yaw_deg) * s_nav.turn_sign;
    float target = s_nav.turn_target_delta_deg;
    float remaining_deg = target - delta;

    float omega = s_nav.cfg.turn_omega;

    /* 接近目标时减速 */
    float decel_zone_deg = PARAM_RAD2DEG(s_nav.cfg.turn_decel_zone_rad);
    if (remaining_deg < decel_zone_deg && decel_zone_deg > 0.01f) {
        float ratio = remaining_deg / decel_zone_deg;
        if (ratio < 0.0f) ratio = 0.0f;
        omega = s_nav.cfg.turn_min_omega +
                ratio * (s_nav.cfg.turn_omega - s_nav.cfg.turn_min_omega);
    }

    out->override_v = 0.0f;
    out->override_w = (float)s_nav.turn_sign * omega;
    out->use_override = true;
    out->request_corridor = false;
    out->safety_mode = SAFETY_MODE_TURN;

    /* 转向完成判定 */
    float tolerance_deg = PARAM_RAD2DEG(s_nav.cfg.turn_tolerance_rad);
    if (delta >= target - tolerance_deg) {
        switch (s_nav.stage) {
        case GNAV_TURN_INTO_CORRIDOR:
        case GNAV_TURN_INTO_NEXT:
            transition_to(GNAV_REACQUIRE, board);
            break;
        case GNAV_TURN_OUT_OF_CORRIDOR:
            if (TrackMap_IsLastCorridor(s_nav.current_corridor_id)) {
                transition_to(GNAV_EXIT_STRAIGHT, board);
            } else {
                transition_to(GNAV_LINK_STRAIGHT, board);
            }
            break;
        default:
            break;
        }
        return;
    }

    /* 超时保护 */
    if (now_ms - s_nav.stage_start_ms > s_nav.cfg.turn_timeout_ms) {
        transition_to(GNAV_ERROR, board);
    }
}

/* =========================================================
 * 阶段转移
 * ========================================================= */
static void transition_to(GlobalNavStage_t next, const RobotBlackboard_t* board)
{
    float imu_yaw = (board != NULL && board->imu_yaw_continuous.is_valid)
                    ? board->imu_yaw_continuous.value : 0.0f;

    /* 通用: 记录进入时间和里程 */
    s_nav.stage_start_ms = s_last_update_ms;
    s_nav.stage_entry_odom_vx_accum = s_nav.odom_distance_accum;
    s_nav.reacquire_ok_count = 0;

    switch (next) {
    case GNAV_ENTRY_STRAIGHT:
        s_nav.heading_ref_deg = imu_yaw;
        s_nav.current_corridor_id = TrackMap_Get()->entry_corridor_id;
        break;

    case GNAV_TURN_INTO_CORRIDOR: {
        const CorridorDescriptor_t* cd = TrackMap_GetCorridor(s_nav.current_corridor_id);
        s_nav.turn_sign = (int8_t)cd->entry_turn_dir;
        s_nav.turn_start_yaw_deg = imu_yaw;
        s_nav.turn_target_delta_deg = 90.0f;
        break;
    }
    case GNAV_TURN_OUT_OF_CORRIDOR: {
        const CorridorDescriptor_t* cd = TrackMap_GetCorridor(s_nav.current_corridor_id);
        s_nav.turn_sign = (int8_t)cd->exit_turn_dir;
        s_nav.turn_start_yaw_deg = imu_yaw;
        s_nav.turn_target_delta_deg = 90.0f;
        break;
    }
    case GNAV_TURN_INTO_NEXT: {
        uint8_t next_id = TrackMap_GetNextCorridorId(s_nav.current_corridor_id);
        const CorridorDescriptor_t* cd = TrackMap_GetCorridor(next_id);
        s_nav.turn_sign = (int8_t)cd->entry_turn_dir;
        s_nav.turn_start_yaw_deg = imu_yaw;
        s_nav.turn_target_delta_deg = 90.0f;
        s_nav.current_corridor_id = next_id;
        break;
    }
    case GNAV_REACQUIRE:
        /* EKF 重置: 新沟的 e_y 参考不同，必须重建 */
        CorridorFilter_Reset();
        s_nav.heading_ref_deg = imu_yaw;
        break;

    case GNAV_CORRIDOR_TRACK:
        s_nav.corridor_entry_s = 0.0f;  /* EKF 已 reset, s 从 0 开始 */
        break;

    case GNAV_LINK_STRAIGHT:
        s_nav.heading_ref_deg = imu_yaw;
        break;

    case GNAV_EXIT_STRAIGHT:
        s_nav.heading_ref_deg = imu_yaw;
        s_nav.exit_vl53_lost = false;
        s_nav.exit_lost_distance = 0.0f;
        break;

    case GNAV_DOCK:
        break;

    case GNAV_FINISHED:
        s_nav.running = false;
        break;

    case GNAV_ERROR:
        break;

    default:
        break;
    }

    s_nav.stage = next;
}

/* =========================================================
 * 公开 API
 * ========================================================= */

void GlobalNav_Init(const GlobalNavConfig_t* cfg)
{
    memset(&s_nav, 0, sizeof(s_nav));
    s_nav.cfg = *cfg;
    s_nav.stage = GNAV_IDLE;
    s_nav.running = false;
    s_nav.initialized = true;
    s_last_odom_vx = 0.0f;
    s_last_update_ms = 0;
}

void GlobalNav_Start(void)
{
    if (!s_nav.initialized) return;
    s_nav.running = true;
    s_nav.corridors_completed = 0;
    s_nav.odom_distance_accum = 0.0f;
    s_nav.stage_entry_odom_vx_accum = 0.0f;
    s_nav.current_corridor_id = TrackMap_Get()->entry_corridor_id;
    /* 不在这里 transition_to，因为还没有 board 数据。
       下一个 Update 周期里发现 running && IDLE 时再 transition。 */
    s_nav.stage = GNAV_IDLE;
}

void GlobalNav_Stop(void)
{
    s_nav.running = false;
    s_nav.stage = GNAV_FINISHED;
}

void GlobalNav_Reset(void)
{
    s_nav.stage = GNAV_IDLE;
    s_nav.running = false;
    s_nav.corridors_completed = 0;
    s_nav.odom_distance_accum = 0.0f;
}

GlobalNavStage_t GlobalNav_GetStage(void)
{
    return s_nav.stage;
}

const char* GlobalNav_GetStageName(GlobalNavStage_t stage)
{
    if (stage <= GNAV_ERROR) {
        return s_stage_names[stage];
    }
    return "UNKNOWN";
}

/* =========================================================
 * 核心 Update
 * ========================================================= */
void GlobalNav_Update(const CorridorObs_t*      obs,
                      const CorridorState_t*     state,
                      const RobotBlackboard_t*   board,
                      GlobalNavOutput_t*         out)
{
    if (!s_nav.initialized) {
        memset(out, 0, sizeof(*out));
        return;
    }

    uint32_t now_ms = s_last_update_ms;
    /* 用 HAL_GetTick 代理 — 实际上 app_tasks 会传入 board 里的时间 */
    {
        /* 里程计积分: Δd = vx * dt */
        float odom_vx = board->odom_vx;
        if (s_last_update_ms > 0) {
            /* 使用 board 中的时间戳估计当前时间 */
            uint32_t cur_ms = board->imu_wz.timestamp_ms;
            if (cur_ms == 0) cur_ms = s_last_update_ms + 20U;
            float dt = (float)(cur_ms - s_last_update_ms) * 0.001f;
            if (dt > 0.0f && dt < 0.5f) {
                s_nav.odom_distance_accum += gnav_fabsf(odom_vx) * dt;
            }
            now_ms = cur_ms;
        } else {
            now_ms = board->imu_wz.timestamp_ms;
            if (now_ms == 0) now_ms = 1;
        }
        s_last_update_ms = now_ms;
        s_last_odom_vx = odom_vx;
    }

    float imu_yaw_deg = board->imu_yaw_continuous.is_valid
                        ? board->imu_yaw_continuous.value : 0.0f;

    /* 默认输出 */
    out->use_override     = true;
    out->request_corridor = false;
    out->override_v       = 0.0f;
    out->override_w       = 0.0f;
    out->safety_mode      = SAFETY_MODE_IDLE;
    out->stage            = s_nav.stage;
    out->corridor_id      = s_nav.current_corridor_id;
    out->corridors_done   = s_nav.corridors_completed;
    out->active           = s_nav.running;
    out->stage_name       = GlobalNav_GetStageName(s_nav.stage);

    if (!s_nav.running) return;

    /* IDLE → 自动进入 ENTRY_STRAIGHT */
    if (s_nav.stage == GNAV_IDLE) {
        transition_to(GNAV_ENTRY_STRAIGHT, board);
        out->stage      = s_nav.stage;
        out->stage_name = GlobalNav_GetStageName(s_nav.stage);
    }

    uint32_t elapsed_ms = now_ms - s_nav.stage_start_ms;

    switch (s_nav.stage) {

    /* ============================================================
     * 入场直线
     * ============================================================ */
    case GNAV_ENTRY_STRAIGHT:
        out->override_v  = s_nav.cfg.entry_v;
        out->override_w  = heading_hold_pd(imu_yaw_deg, s_nav.heading_ref_deg,
                                            s_nav.cfg.heading_kp);
        out->safety_mode = SAFETY_MODE_STRAIGHT;

        if (side_walls_detected(obs) ||
            odom_since_entry() >= s_nav.cfg.entry_distance ||
            elapsed_ms > s_nav.cfg.entry_timeout_ms)
        {
            transition_to(GNAV_TURN_INTO_CORRIDOR, board);
        }
        break;

    /* ============================================================
     * 三种转向状态统一处理
     * ============================================================ */
    case GNAV_TURN_INTO_CORRIDOR:
    case GNAV_TURN_OUT_OF_CORRIDOR:
    case GNAV_TURN_INTO_NEXT:
        execute_turn(obs, state, board, now_ms, out);
        break;

    /* ============================================================
     * 重捕获走廊
     * ============================================================ */
    case GNAV_REACQUIRE:
        out->override_v  = s_nav.cfg.reacquire_v;
        out->override_w  = heading_hold_pd(imu_yaw_deg, s_nav.heading_ref_deg,
                                            s_nav.cfg.heading_kp);
        out->safety_mode = SAFETY_MODE_STRAIGHT;

        if (check_reacquire(obs, state)) {
            s_nav.reacquire_ok_count++;
        } else {
            s_nav.reacquire_ok_count = 0;
        }

        if (s_nav.reacquire_ok_count >= s_nav.cfg.reacquire_confirm_ticks) {
            transition_to(GNAV_CORRIDOR_TRACK, board);
        }
        if (elapsed_ms > s_nav.cfg.reacquire_timeout_ms) {
            transition_to(GNAV_ERROR, board);
        }
        break;

    /* ============================================================
     * 沟内闭环跟踪 (交给 corridor_ctrl)
     * ============================================================ */
    case GNAV_CORRIDOR_TRACK:
        out->use_override     = false;
        out->request_corridor = true;
        out->safety_mode      = SAFETY_MODE_CORRIDOR;

        /* 到端检测 */
        {
            bool front_valid = (obs->valid_mask & CORRIDOR_OBS_MASK_FRONT) != 0U;
            if (front_valid && obs->d_front <= s_nav.cfg.corridor_end_detect_dist) {
                /* 里程下限保护: 至少走了 1.0m 才允许认定到端，避免假阳性 */
                float corridor_odom = odom_since_entry();
                if (corridor_odom > 1.0f) {
                    s_nav.corridors_completed++;
                    transition_to(GNAV_TURN_OUT_OF_CORRIDOR, board);
                }
            }
        }
        /* 里程超长保护 */
        if (odom_since_entry() > s_nav.cfg.corridor_length_max) {
            s_nav.corridors_completed++;
            transition_to(GNAV_TURN_OUT_OF_CORRIDOR, board);
        }
        break;

    /* ============================================================
     * 连接段直行
     * ============================================================ */
    case GNAV_LINK_STRAIGHT:
        out->override_v  = s_nav.cfg.link_v;
        out->override_w  = heading_hold_pd(imu_yaw_deg, s_nav.heading_ref_deg,
                                            s_nav.cfg.heading_kp);
        out->safety_mode = SAFETY_MODE_STRAIGHT;

        if (odom_since_entry() >= s_nav.cfg.link_distance ||
            side_walls_detected(obs))
        {
            transition_to(GNAV_TURN_INTO_NEXT, board);
        }
        if (elapsed_ms > s_nav.cfg.link_timeout_ms) {
            transition_to(GNAV_ERROR, board);
        }
        break;

    /* ============================================================
     * 出场直行
     * ============================================================ */
    case GNAV_EXIT_STRAIGHT:
        out->override_v  = s_nav.cfg.exit_v;
        out->override_w  = heading_hold_pd(imu_yaw_deg, s_nav.heading_ref_deg,
                                            s_nav.cfg.heading_kp);
        out->safety_mode = SAFETY_MODE_STRAIGHT;

        /* 检测侧向全丢 */
        if (!s_nav.exit_vl53_lost && all_side_lost(obs)) {
            s_nav.exit_vl53_lost = true;
            s_nav.exit_lost_distance = s_nav.odom_distance_accum;
        }
        if (s_nav.exit_vl53_lost) {
            float since_lost = s_nav.odom_distance_accum - s_nav.exit_lost_distance;
            if (since_lost >= s_nav.cfg.exit_runout) {
                transition_to(GNAV_DOCK, board);
            }
        }
        /* 里程上限保护 */
        if (odom_since_entry() >= s_nav.cfg.exit_max_dist) {
            transition_to(GNAV_DOCK, board);
        }
        if (elapsed_ms > s_nav.cfg.exit_timeout_ms) {
            transition_to(GNAV_DOCK, board);
        }
        break;

    /* ============================================================
     * 回停启动区
     * ============================================================ */
    case GNAV_DOCK:
        out->override_v  = s_nav.cfg.dock_v;
        out->override_w  = 0.0f;
        out->safety_mode = SAFETY_MODE_STRAIGHT;

        if (odom_since_entry() >= s_nav.cfg.dock_distance ||
            elapsed_ms > 5000U)
        {
            transition_to(GNAV_FINISHED, board);
        }
        break;

    /* ============================================================
     * 终态
     * ============================================================ */
    case GNAV_FINISHED:
        out->override_v = 0.0f;
        out->override_w = 0.0f;
        out->safety_mode = SAFETY_MODE_IDLE;
        out->active = false;
        break;

    /* ============================================================
     * 异常态
     * ============================================================ */
    case GNAV_ERROR:
        out->override_v = 0.0f;
        out->override_w = 0.0f;
        out->safety_mode = SAFETY_MODE_IDLE;

        if (elapsed_ms > 2000U) {
            transition_to(GNAV_FINISHED, board);
        }
        break;

    default:
        out->override_v = 0.0f;
        out->override_w = 0.0f;
        break;
    }

    /* 更新输出阶段 (可能在 switch 内已经 transition) */
    out->stage       = s_nav.stage;
    out->stage_name  = GlobalNav_GetStageName(s_nav.stage);
    out->corridor_id = s_nav.current_corridor_id;
    out->corridors_done = s_nav.corridors_completed;
    out->active      = s_nav.running;
}