package devices

import (
	"context"
	"fmt"

	"xiaomihome/xiaomi"
)

// OccupancySensor 人在传感器读取接口（只读）。
type OccupancySensor interface {
	Device

	// IsOccupied 是否有人。
	IsOccupied(ctx context.Context) (bool, error)

	// GetIlluminance 环境光照度（lux），部分传感器支持。
	GetIlluminance(ctx context.Context) (float64, error)
}

// NewOccupancySensor 创建人在传感器。失败返回错误（含无 SPEC / 无相关属性）。
func NewOccupancySensor(client *xiaomi.Client, info *xiaomi.DeviceInfo) (OccupancySensor, error) {
	if info == nil {
		return nil, xiaomi.ErrDeviceNotFound
	}

	miotDev := client.GetMIoTDevice(info.DID)
	if miotDev == nil {
		return nil, fmt.Errorf("%w: device not initialized", xiaomi.ErrDeviceNotFound)
	}
	spec := miotDev.SpecInstance()
	if spec == nil {
		return nil, fmt.Errorf("%w: device has no SPEC information", xiaomi.ErrNotSupported)
	}

	d := &occupancyDevice{
		BaseDevice: BaseDevice{client: client, info: info},
	}

	for _, svc := range spec.Services {
		for _, prop := range svc.Properties {
			switch propertyShortName(prop.Type) {
			case "occupancy":
				if !d.propOccupancy.valid {
					d.propOccupancy = siidPiid{svc.IID, prop.PIID, true}
				}
			case "illumination":
				if !d.propIlluminance.valid {
					d.propIlluminance = siidPiid{svc.IID, prop.PIID, true}
				}
			}
		}
	}

	if !d.propOccupancy.valid {
		return nil, fmt.Errorf("%w: no occupancy property in SPEC", xiaomi.ErrNotSupported)
	}

	return d, nil
}

type occupancyDevice struct {
	BaseDevice
	propOccupancy   siidPiid
	propIlluminance siidPiid
}

func (d *occupancyDevice) IsOccupied(ctx context.Context) (bool, error) {
	prop, err := d.GetProp(ctx, d.propOccupancy.siid, d.propOccupancy.piid)
	if err != nil {
		return false, err
	}
	if b, ok := prop.Value.(bool); ok {
		return b, nil
	}
	return false, nil
}

func (d *occupancyDevice) GetIlluminance(ctx context.Context) (float64, error) {
	if !d.propIlluminance.valid {
		return 0, xiaomi.ErrNotSupported
	}
	prop, err := d.GetProp(ctx, d.propIlluminance.siid, d.propIlluminance.piid)
	if err != nil {
		return 0, err
	}
	return toFloat(prop.Value), nil
}