from machine import SPI, Pin
import os
import sdcard

# Wokwi Pico + SD 模块 标准引脚
SPI_ID = 0
SCK_PIN = 2
MOSI_PIN = 3
MISO_PIN = 4
CS_PIN = 5
MOUNT_PATH = "/sd"

sd_dev = None
vfs = None

def sd_mount():
    global sd_dev, vfs
    try:
        spi = SPI(SPI_ID, baudrate=10000000, sck=Pin(SCK_PIN), mosi=Pin(MOSI_PIN), miso=Pin(MISO_PIN))
        cs = Pin(CS_PIN, Pin.OUT)
        sd_dev = sdcard.SDCard(spi, cs)
        vfs = os.VfsFat(sd_dev)
        os.mount(vfs, MOUNT_PATH)
        return True
    except Exception as e:
        print("挂载失败：", e)
        return False

def sd_unmount():
    try:
        os.umount(MOUNT_PATH)
        return True
    except:
        return False

def file_append(path, data):
    try:
        with open(MOUNT_PATH + path, "a") as f:
            f.write(data + "\n")
        return True
    except:
        return False

def file_read(path):
    try:
        with open(MOUNT_PATH + path, "r") as f:
            return f.read()
    except:
        return ""

# ===================== 测试 =====================
if __name__ == "__main__":
    if sd_mount():
        print("✅ SD 卡挂载成功！")
        
        file_append("/data.txt", "Hello Wokwi!")
        file_append("/data.txt", "Temp:25C Humidity:60%")
        
        print("--- 文件内容 ---")
        print(file_read("/data.txt"))

        statvfs = os.statvfs(MOUNT_PATH)
        total_kb = (statvfs[0] * statvfs[2]) // 1024
        free_kb = (statvfs[0] * statvfs[3]) // 1024
        print(f"总容量：{total_kb} KB | 剩余：{free_kb} KB")
        
        sd_unmount()
        print("✅ 已卸载")
    else:
        print("❌ 挂载失败，请检查接线")