/* ============================================================
 * 实验二：计数信号量应用 - 资源管理
 * ============================================================*/
#include <Arduino.h>
#include <freertos/FreeRTOS.h>
#include <freertos/task.h>
#include <freertos/semphr.h>

#define BUTTON_ENTER 0    // 进入按键
#define BUTTON_EXIT 15    // 退出按键（GPIO15）
#define LED_GREEN 2       // 有空位指示灯
#define LED_RED 4         // 满位指示灯

#define TOTAL_PARKING 5   // 总车位数

SemaphoreHandle_t xParkingSemaphore;
int currentCars = 0;

// 显示当前车位状态
void displayStatus() {
    UBaseType_t available = uxSemaphoreGetCount(xParkingSemaphore);
    Serial.printf("当前车位: %d/%d (剩余: %d)\n", 
                  TOTAL_PARKING - available, TOTAL_PARKING, available);
    
    if(available > 0) {
        digitalWrite(LED_GREEN, HIGH);
        digitalWrite(LED_RED, LOW);
    } else {
        digitalWrite(LED_GREEN, LOW);
        digitalWrite(LED_RED, HIGH);
    }
}

// 车辆进入任务
void vCarEnterTask(void *pvParameters) {
    bool lastButtonState = HIGH;
    
    while(1) {
        bool currentButtonState = digitalRead(BUTTON_ENTER);
        
        if(lastButtonState == HIGH && currentButtonState == LOW) {
            // 尝试获取车位（信号量）
            if(xSemaphoreTake(xParkingSemaphore, 0) == pdTRUE) {
                currentCars++;
                Serial.print("🚗 车辆进入 → ");
                displayStatus();
            } else {
                Serial.println("❌ 车位已满，车辆无法进入！");
            }
            vTaskDelay(pdMS_TO_TICKS(300)); // 消抖
        }
        
        lastButtonState = currentButtonState;
        vTaskDelay(pdMS_TO_TICKS(10));
    }
}

// 车辆离开任务
void vCarExitTask(void *pvParameters) {
    bool lastButtonState = HIGH;
    
    while(1) {
        bool currentButtonState = digitalRead(BUTTON_EXIT);
        
        if(lastButtonState == HIGH && currentButtonState == LOW) {
            // 释放车位（信号量）
            if(uxSemaphoreGetCount(xParkingSemaphore) < TOTAL_PARKING) {
                xSemaphoreGive(xParkingSemaphore);
                currentCars--;
                Serial.print("🚙 车辆离开 → ");
                displayStatus();
            } else {
                Serial.println("⚠️  停车场已空，无车辆离开！");
            }
            vTaskDelay(pdMS_TO_TICKS(300)); // 消抖
        }
        
        lastButtonState = currentButtonState;
        vTaskDelay(pdMS_TO_TICKS(10));
    }
}

void setup() {
    Serial.begin(115200);
    delay(1000);
    Serial.println("\n=== 实验二：计数信号量应用 - 停车场管理系统 ===");
    Serial.printf("总车位: %d\n\n", TOTAL_PARKING);
    
    pinMode(BUTTON_ENTER, INPUT_PULLUP);
    pinMode(BUTTON_EXIT, INPUT_PULLUP);
    pinMode(LED_GREEN, OUTPUT);
    pinMode(LED_RED, OUTPUT);
    
    // 创建计数信号量：最大计数TOTAL_PARKING，初始值TOTAL_PARKING（全部空闲）
    xParkingSemaphore = xSemaphoreCreateCounting(TOTAL_PARKING, TOTAL_PARKING);
    
    if(xParkingSemaphore == NULL) {
        Serial.println("信号量创建失败！");
        while(1);
    }
    
    displayStatus();
    
    // 创建任务
    xTaskCreate(vCarEnterTask, "CarEnter", 2048, NULL, 2, NULL);
    xTaskCreate(vCarExitTask, "CarExit", 2048, NULL, 2, NULL);
}

void loop() {
    vTaskDelay(pdMS_TO_TICKS(1000));
}