/*
 * Copyright (c) 2016 Zibin Zheng <znbin@qq.com>
 * All rights reserved.
 */

#include "multi_button.h"

/* 回调执行宏，包含空值检查，传递user_data */
#define EVENT_CB(ev)   do { if (handle->cb[ev]) handle->cb[ev](handle, handle->user_data); } while(0)

/* 按键句柄链表头 */
static Button* head_handle = NULL;

/* 前向声明 */
static void button_handler(Button* handle);
static inline uint8_t button_read_level(Button* handle);

/*
 * 函数功能：初始化按键结构体句柄
 * 入口参数：handle - 按键句柄结构体指针
 *           pin_level - 读取按键GPIO电平的函数指针
 *           active_level - 按下时的有效电平
 *           button_id - 按键标识符
 * 返回值：无
 * 函数说明：初始化按键状态机和所有参数
 */
void button_init(Button* handle, uint8_t(*pin_level)(uint8_t), uint8_t active_level, uint8_t button_id)
{
    if (!handle || !pin_level) {
        return;
    }

    memset(handle, 0, sizeof(Button));
    handle->event = (uint8_t)BTN_NONE_PRESS;
    handle->hal_button_level = pin_level;
    handle->button_level = !active_level;
    handle->active_level = active_level;
    handle->button_id = button_id;
    handle->state = BTN_STATE_IDLE;
}

/*
 * 函数功能：绑定按键事件回调函数
 * 入口参数：handle - 按键句柄结构体指针
 *           event - 触发事件类型
 *           cb - 回调函数
 *           user_data - 传递给回调的用户上下文指针
 * 返回值：无
 * 函数说明：为指定事件注册回调函数
 */
void button_attach(Button* handle, ButtonEvent event, BtnCallback cb, void* user_data)
{
    if (!handle || event >= BTN_EVENT_COUNT) {
        return;
    }
    handle->cb[event] = cb;
    handle->user_data = user_data;
}

/*
 * 函数功能：解绑按键事件回调函数
 * 入口参数：handle - 按键句柄结构体指针
 *           event - 触发事件类型
 * 返回值：无
 * 函数说明：移除指定事件的回调函数
 */
void button_detach(Button* handle, ButtonEvent event)
{
    if (!handle || event >= BTN_EVENT_COUNT) {
        return;
    }
    handle->cb[event] = NULL;
}

/*
 * 函数功能：获取按键事件
 * 入口参数：handle - 按键句柄结构体指针
 * 返回值：按键事件
 * 函数说明：返回当前发生的按键事件
 */
ButtonEvent button_get_event(Button* handle)
{
    if (!handle) {
        return BTN_NONE_PRESS;
    }
    return (ButtonEvent)(handle->event);
}

/*
 * 函数功能：获取按键重复按下次数
 * 入口参数：handle - 按键句柄结构体指针
 * 返回值：重复按下次数
 * 函数说明：返回连击次数
 */
uint8_t button_get_repeat_count(Button* handle)
{
    if (!handle) {
        return 0;
    }
    return handle->repeat;
}

/*
 * 函数功能：重置按键状态到空闲
 * 入口参数：handle - 按键句柄结构体指针
 * 返回值：无
 * 函数说明：将按键状态机重置为初始状态
 */
void button_reset(Button* handle)
{
    if (!handle) {
        return;
    }
    handle->state = BTN_STATE_IDLE;
    handle->ticks = 0;
    handle->repeat = 0;
    handle->event = (uint8_t)BTN_NONE_PRESS;
    handle->debounce_cnt = 0;
}

/*
 * 函数功能：检查按键是否按下
 * 入口参数：handle - 按键句柄结构体指针
 * 返回值：1 - 按下，0 - 未按下，-1 - 错误
 * 函数说明：检查当前按键是否处于按下状态
 */
int button_is_pressed(Button* handle)
{
    if (!handle) {
        return -1;
    }
    return (handle->button_level == handle->active_level) ? 1 : 0;
}

/*
 * 函数功能：读取按键电平
 * 入口参数：handle - 按键句柄结构体指针
 * 返回值：按键电平
 * 函数说明：通过HAL函数读取GPIO电平
 */
static inline uint8_t button_read_level(Button* handle)
{
    return handle->hal_button_level(handle->button_id);
}

/*
 * 函数功能：按键驱动核心函数，驱动状态机
 * 入口参数：handle - 按键句柄结构体指针
 * 返回值：无
 * 函数说明：实现按键消抖和事件检测的状态机
 */
static void button_handler(Button* handle)
{
    uint8_t read_gpio_level = button_read_level(handle);

    /* 非空闲状态下增加tick计数器（饱和处理） */
    if (handle->state > BTN_STATE_IDLE) {
        if (handle->ticks < UINT16_MAX) {
            handle->ticks++;
        }
    }

    /* 按键消抖处理 */
    if (read_gpio_level != handle->button_level) {
        if (++(handle->debounce_cnt) >= DEBOUNCE_TICKS) {
            handle->button_level = read_gpio_level;
            handle->debounce_cnt = 0;
        }
    } else {
        handle->debounce_cnt = 0;
    }

    /* 状态机 */
    switch (handle->state) {
    case BTN_STATE_IDLE:
        if (handle->button_level == handle->active_level) {
            /* 检测到按键按下 */
            handle->event = (uint8_t)BTN_PRESS_DOWN;
            EVENT_CB(BTN_PRESS_DOWN);
            handle->ticks = 0;
            handle->repeat = 1;
            handle->state = BTN_STATE_PRESS;
        } else {
            handle->event = (uint8_t)BTN_NONE_PRESS;
        }
        break;

    case BTN_STATE_PRESS:
        if (handle->button_level != handle->active_level) {
            /* 按键释放 */
            handle->event = (uint8_t)BTN_PRESS_UP;
            EVENT_CB(BTN_PRESS_UP);
            handle->ticks = 0;
            handle->state = BTN_STATE_RELEASE;
        } else if (handle->ticks > LONG_TICKS) {
            /* 检测到长按 */
            handle->event = (uint8_t)BTN_LONG_PRESS_START;
            EVENT_CB(BTN_LONG_PRESS_START);
            handle->state = BTN_STATE_LONG_HOLD;
        }
        break;

    case BTN_STATE_RELEASE:
        if (handle->button_level == handle->active_level) {
            /* 按键再次按下 */
            handle->event = (uint8_t)BTN_PRESS_DOWN;
            EVENT_CB(BTN_PRESS_DOWN);
            if (handle->repeat < PRESS_REPEAT_MAX_NUM) {
                handle->repeat++;
            }
            handle->event = (uint8_t)BTN_PRESS_REPEAT;
            EVENT_CB(BTN_PRESS_REPEAT);
            handle->ticks = 0;
            handle->state = BTN_STATE_REPEAT;
        } else if (handle->ticks > SHORT_TICKS) {
            /* 超时，判断点击类型 */
            if (handle->repeat == 1) {
                handle->event = (uint8_t)BTN_SINGLE_CLICK;
                EVENT_CB(BTN_SINGLE_CLICK);
            } else if (handle->repeat == 2) {
                handle->event = (uint8_t)BTN_DOUBLE_CLICK;
                EVENT_CB(BTN_DOUBLE_CLICK);
            }
            handle->state = BTN_STATE_IDLE;
        }
        break;

    case BTN_STATE_REPEAT:
        if (handle->button_level != handle->active_level) {
            /* 按键释放 */
            handle->event = (uint8_t)BTN_PRESS_UP;
            EVENT_CB(BTN_PRESS_UP);
            if (handle->ticks < SHORT_TICKS) {
                handle->ticks = 0;
                handle->state = BTN_STATE_RELEASE;
            } else {
                handle->state = BTN_STATE_IDLE;
            }
        } else if (handle->ticks > SHORT_TICKS) {
            /* 按住时间过长，视为普通按下 */
            handle->ticks = 0;
            handle->repeat = 0;
            handle->state = BTN_STATE_PRESS;
        }
        break;

    case BTN_STATE_LONG_HOLD:
        if (handle->button_level == handle->active_level) {
            /* 继续保持按下 */
            handle->event = (uint8_t)BTN_LONG_PRESS_HOLD;
            EVENT_CB(BTN_LONG_PRESS_HOLD);
        } else {
            /* 从长按中释放 */
            handle->event = (uint8_t)BTN_PRESS_UP;
            EVENT_CB(BTN_PRESS_UP);
            handle->state = BTN_STATE_IDLE;
        }
        break;

    default:
        /* 无效状态，重置为空闲 */
        handle->state = BTN_STATE_IDLE;
        break;
    }
}

/*
 * 函数功能：启动按键工作，将句柄添加到工作链表
 * 入口参数：handle - 目标句柄结构体指针
 * 返回值：0 - 成功，-1 - 已存在，-2 - 无效参数
 * 函数说明：将按键添加到轮询链表中
 */
int button_start(Button* handle)
{
    if (!handle) {
        return -2;
    }

    Button* target = head_handle;
    while (target) {
        if (target == handle) {
            return -1;
        }
        target = target->next;
    }

    handle->next = head_handle;
    head_handle = handle;
    return 0;
}

/*
 * 函数功能：停止按键工作，从工作链表移除句柄
 * 入口参数：handle - 目标句柄结构体指针
 * 返回值：无
 * 函数说明：将按键从轮询链表中移除
 */
void button_stop(Button* handle)
{
    if (!handle) {
        return;
    }

    Button** curr;
    for (curr = &head_handle; *curr; ) {
        Button* entry = *curr;
        if (entry == handle) {
            *curr = entry->next;
            entry->next = NULL;
            return;
        } else {
            curr = &entry->next;
        }
    }
}

/*
 * 函数功能：后台tick处理，定时器重复调用，间隔5ms
 * 入口参数：无
 * 返回值：无
 * 函数说明：遍历链表调用每个按键的状态机处理函数
 */
void button_ticks(void)
{
    Button* target;
    Button* next;

    target = head_handle;
    while (target) {
        next = target->next;
        button_handler(target);
        target = next;
    }
}