package devices

import (
	"bytes"
	"fmt"

	"os"
	"path"
	"strings"
)

// IGPIODevice GPIO 设备操作接口
// /sys/class/gpio/gpio141
// active_low device direction edge power subsystem uevent value
type IGPIODevice interface {
	GetPath() string
	GetValuePath() string
	GetDirectionPath() string
	GetDevicePath() string

	Export() (bool, error)
	UnExport() (bool, error)

	IsExported() bool
	IsUnExported() bool

	Value() (GPIOValue, error)
	ChangeValue(value GPIOValue) error

	Mode() (GPIOMode, error)
	ChangeMode(mode GPIOMode) error
}

// GPIODevice 设备信息
type GPIODevice struct {
	Id   int    // GPIO 编号
	Path string // GPIO 设备目录
}

// NewGPIODevice 实例化一个设备
func NewGPIODevice(id int) *GPIODevice {
	return &GPIODevice{
		Id:   id,
		Path: path.Join(GPIO, fmt.Sprintf("gpio%d", id)),
	}
}

// isSetPath 内置:是否已经设置了路径
func (device *GPIODevice) isSetPath() bool {
	if len(device.Path) > 0 {
		return strings.Contains(device.Path, GPIO)
	}
	return false
}

// GetPath 获取设备目录路径
func (device *GPIODevice) GetPath() string {
	if device.isSetPath() {
		return device.Path
	}
	return path.Join(GPIO, fmt.Sprintf("gpio%d", device.Id))
}

// GetValuePath 获取GPIO设备的 value 路径
func (device *GPIODevice) GetValuePath() string {
	return path.Join(device.GetPath(), "value")
}

// GetDirectionPath 获取GPIO设备的 direction 路径
func (device *GPIODevice) GetDirectionPath() string {
	return path.Join(device.GetPath(), "direction")
}

// GetDevicePath 获取GPIO设备的 device 路径
func (device *GPIODevice) GetDevicePath() string {
	return path.Join(device.GetPath(), "device")
}

// IsExported 检查是否已经导出设备引脚
func (device *GPIODevice) IsExported() bool {
	_, err := os.Stat(device.GetPath())
	return err == nil
}

// IsUnExported 检查是否已经导出设备引脚
func (device *GPIODevice) IsUnExported() bool {
	return !device.IsExported()
}

// Export 导出设备
func (device *GPIODevice) Export() (bool, error) {
	if device.IsExported() {
		return true, nil
	}

	err := GPIOExport(device.Id)
	return err == nil, err
}

// UnExport 取消导出设备
func (device *GPIODevice) UnExport() (bool, error) {
	if device.IsExported() {
		err := GPIOUnExport(device.Id)
		return err == nil, err
	}
	return true, nil
}

// 获取
func (device *GPIODevice) Value() (value GPIOValue, err error) {
	value = LEVEL_LOW // 初始化默认值

	content, err := os.ReadFile(device.GetDirectionPath())
	if err != nil {
		return
	}
	if string(content) == "0" {
		value = LEVEL_LOW
	} else {
		value = LEVEL_HIGH
	}
	return
}

// ChangeValue 改变value值
func (device *GPIODevice) ChangeValue(value GPIOValue) (err error) {
	if value == LEVEL_LOW {
		err = os.WriteFile(device.GetValuePath(), []byte("0"), os.ModePerm)
	}
	if value == LEVEL_HIGH {
		err = os.WriteFile(device.GetValuePath(), []byte("1"), os.ModePerm)
	}
	return
}

// Mode 获取当前工作模式
func (device *GPIODevice) Mode() (mode GPIOMode, err error) {
	mode = DIRECTION_IN

	content, err := os.ReadFile(device.GetDirectionPath())
	if err != nil {
		return
	}

	if bytes.Contains(content, []byte("in")) {
		mode = DIRECTION_IN
	} else {
		mode = DIRECTION_OUT
	}
	return
}

// ChangeMode 改变工作模式
func (device *GPIODevice) ChangeMode(mode GPIOMode) (err error) {
	if mode == DIRECTION_IN {
		err = os.WriteFile(device.GetDirectionPath(), []byte("in"), os.ModePerm)
	} else {
		err = os.WriteFile(device.GetDirectionPath(), []byte("out"), os.ModePerm)
	}
	return
}

// func (device *GPIODevice) ()