/**
 * @file    btn_fsm.c
 * @brief   按键 FSM 实现 — 参考 MultiButton 设计
 *
 * 5 状态 FSM:
 *   IDLE → PRESS → RELEASE → IDLE (单击/双击)
 *                → LONG_HOLD → IDLE (长按)
 *
 * 驱动方式: 外部 5ms 定时器调用 Btn_Tick()
 *           Btn_Tick() 遍历全局链表，对每个按键执行 handler
 */
#include "btn_fsm.h"
#include <string.h>

/* ======== 全局链表头 ======== */
static Btn_FSM* g_head = (void*)0;

/* ======== 内部: 触发回调 ======== */
static inline void btn_fire(Btn_FSM* btn, BtnEvent_E evt) {
    btn->event = (uint8_t)evt;
    if (btn->cb[evt] != (void*)0) {
        btn->cb[evt](btn, btn->user_data);
    }
}

/* ======== 内部: 单按键 FSM 处理 ======== */
static void btn_handler(Btn_FSM* btn) {
    uint8_t read_gpio = btn->hal_read(btn->button_id);

    /* 非 IDLE 状态时递增节拍 */
    if (btn->state != BTN_STATE_IDLE) {
        if (btn->ticks < 0xFFFF) {
            btn->ticks++;
        }
    }

    /* ---- 去抖处理 ---- */
    if (read_gpio != btn->button_level) {
        btn->debounce_cnt++;
        if (btn->debounce_cnt >= BTN_DEBOUNCE_TICKS) {
            btn->button_level = read_gpio;
            btn->debounce_cnt = 0;
        }
    } else {
        btn->debounce_cnt = 0;
    }

    /* ---- FSM 状态机 ---- */
    switch ((BtnState_E)btn->state) {

    case BTN_STATE_IDLE:
        if (btn->button_level == btn->active_level) {
            /* 检测到有效按下 */
            btn->ticks = 0;
            btn->repeat = 1;
            btn_fire(btn, BTN_EVT_PRESS_DOWN);
            btn->state = BTN_STATE_PRESS;
        }
        break;

    case BTN_STATE_PRESS:
        if (btn->button_level != btn->active_level) {
            /* 按键释放 */
            btn->ticks = 0;
            btn_fire(btn, BTN_EVT_PRESS_UP);
            btn->state = BTN_STATE_RELEASE;
        } else if (btn->ticks >= BTN_LONG_TICKS) {
            /* 长按 */
            btn->ticks = 0;
            btn_fire(btn, BTN_EVT_LONG_PRESS_START);
            btn->state = BTN_STATE_LONG_HOLD;
        }
        break;

    case BTN_STATE_RELEASE:
        if (btn->button_level == btn->active_level) {
            /* 短时间内再次按下 → 连击/双击 */
            btn->ticks = 0;
            btn->repeat++;
            btn_fire(btn, BTN_EVT_PRESS_DOWN);
            btn->state = BTN_STATE_REPEAT;
        } else if (btn->ticks >= BTN_SHORT_TICKS) {
            /* 超时未再次按下 → 判定单击或双击 */
            if (btn->repeat == 1) {
                btn_fire(btn, BTN_EVT_SINGLE_CLICK);
            } else if (btn->repeat == 2) {
                btn_fire(btn, BTN_EVT_DOUBLE_CLICK);
            }
            btn->state = BTN_STATE_IDLE;
        }
        break;

    case BTN_STATE_REPEAT:
        if (btn->button_level != btn->active_level) {
            /* 再次释放 */
            btn->ticks = 0;
            btn_fire(btn, BTN_EVT_PRESS_UP);
            btn->state = BTN_STATE_RELEASE;
        } else if (btn->ticks >= BTN_SHORT_TICKS) {
            /* 超时 → 重新进入 PRESS 态 */
            btn->state = BTN_STATE_PRESS;
        }
        break;

    case BTN_STATE_LONG_HOLD:
        if (btn->button_level != btn->active_level) {
            /* 长按释放 */
            btn->ticks = 0;
            btn_fire(btn, BTN_EVT_PRESS_UP);
            btn->state = BTN_STATE_IDLE;
        } else {
            /* 持续触发长按保持 */
            if (btn->ticks >= BTN_LONG_TICKS) {
                btn->ticks = 0;
                btn_fire(btn, BTN_EVT_LONG_PRESS_HOLD);
            }
        }
        break;
    }
}

/* ======== 公开 API ======== */

void Btn_Init(Btn_FSM* btn,
              uint8_t (*hal_read)(uint8_t button_id),
              uint8_t button_id,
              uint8_t active_level) {
    if (btn == (void*)0 || hal_read == (void*)0) return;

    memset(btn, 0, sizeof(Btn_FSM));
    btn->hal_read      = hal_read;
    btn->button_id     = button_id;
    btn->active_level  = active_level;
    btn->button_level  = (active_level == 0) ? 1 : 0; /* 初始为未按下 */
    btn->state         = BTN_STATE_IDLE;
    btn->next          = (void*)0;
}

void Btn_Attach(Btn_FSM* btn, BtnEvent_E event, BtnCallback cb, void* user_data) {
    if (btn == (void*)0 || event >= BTN_EVT_COUNT) return;
    btn->cb[event]  = cb;
    btn->user_data  = user_data;
}

void Btn_Start(Btn_FSM* btn) {
    if (btn == (void*)0) return;

    /* 头插法加入链表 */
    btn->next = g_head;
    g_head    = btn;
}

void Btn_Stop(Btn_FSM* btn) {
    if (btn == (void*)0) return;

    /* 二级指针遍历摘除 */
    Btn_FSM** cur = &g_head;
    while (*cur != (void*)0) {
        if (*cur == btn) {
            *cur = btn->next;
            btn->next = (void*)0;
            return;
        }
        cur = &(*cur)->next;
    }
}

void Btn_Tick(void) {
    Btn_FSM* btn = g_head;
    while (btn != (void*)0) {
        btn_handler(btn);
        btn = btn->next;
    }
}

BtnState_E Btn_GetState(const Btn_FSM* btn) {
    if (btn == (void*)0) return BTN_STATE_IDLE;
    return (BtnState_E)btn->state;
}