package devices

import (
	"context"
	"fmt"

	"xiaomihome/xiaomi"
)

// OccupancySensor 人在传感器读取接口（只读）。
type OccupancySensor interface {
	Device
	IsOccupied(ctx context.Context) (bool, error)
	GetIlluminance(ctx context.Context) (float64, error)

	OnStateChanged(handler func(occupied bool, illuminance float64)) (string, error)
	GetState() (bool, float64)
	FetchState(ctx context.Context) (bool, float64, error)
}

type occupancyDevice struct {
	BaseDevice
	propOccupancy   siidPiid
	propIlluminance siidPiid
	stateCache      [2]interface{} // [0]=bool occupied, [1]=float64 lux
}

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
}

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
}

func (d *occupancyDevice) OnStateChanged(handler func(occupied bool, illuminance float64)) (string, error) {
	if !d.propOccupancy.valid && !d.propIlluminance.valid { return "", xiaomi.ErrNotSupported }
	return d.SubProp(0, 0, func(did string, prop *xiaomi.PropertyValue) {
		switch {
		case d.propOccupancy.valid && prop.SIID == d.propOccupancy.siid && prop.PIID == d.propOccupancy.piid:
			if b, ok := prop.Value.(bool); ok { d.stateCache[0] = b }
		case d.propIlluminance.valid && prop.SIID == d.propIlluminance.siid && prop.PIID == d.propIlluminance.piid:
			d.stateCache[1] = toFloat(prop.Value)
		}
		occ, _ := d.stateCache[0].(bool)
		lux, _ := d.stateCache[1].(float64)
		handler(occ, lux)
	})
}

func (d *occupancyDevice) GetState() (bool, float64) { 
	b, _ := d.stateCache[0].(bool)
	f, _ := d.stateCache[1].(float64)
	return b, f
}
func (d *occupancyDevice) FetchState(ctx context.Context) (bool, float64, error) {
	keys := []xiaomi.PropKey{}
	if d.propOccupancy.valid { keys = append(keys, xiaomi.PropKey{DID: d.info.DID, SIID: d.propOccupancy.siid, PIID: d.propOccupancy.piid}) }
	if d.propIlluminance.valid { keys = append(keys, xiaomi.PropKey{DID: d.info.DID, SIID: d.propIlluminance.siid, PIID: d.propIlluminance.piid}) }
	props, err := d.client.GetProps(ctx, keys)
	if err != nil {
		b, _ := d.stateCache[0].(bool)
		f, _ := d.stateCache[1].(float64)
		return b, f, err
	}
	var occupied bool
	var illuminance float64
	for _, p := range props {
		switch {
		case d.propOccupancy.valid && p.SIID == d.propOccupancy.siid && p.PIID == d.propOccupancy.piid:
			occupied, _ = p.Value.(bool)
		case d.propIlluminance.valid && p.SIID == d.propIlluminance.siid && p.PIID == d.propIlluminance.piid:
			illuminance = toFloat(p.Value)
		}
	}
	d.stateCache = [2]interface{}{occupied, illuminance}
	return occupied, illuminance, nil
}