package devices

import (
	"context"

	"xiaomihome/xiaomi"
)

// Switch 开关统一控制接口。
// 单通道：TurnOn/TurnOff/Toggle/IsOn 操作唯一通道。
// 多通道：ChannelCount > 1 时，TurnOn 等操作通道 1，或使用带 channel 参数的方法。
type Switch interface {
	Device
	TurnOn(ctx context.Context) error
	TurnOff(ctx context.Context) error
	Toggle(ctx context.Context) error
	IsOn(ctx context.Context) (bool, error)

	// 多通道开关支持（单通道时自动回退到上述方法）
	ChannelCount() int
	TurnOnChannel(ctx context.Context, ch int) error
	TurnOffChannel(ctx context.Context, ch int) error
	ToggleChannel(ctx context.Context, ch int) error
	IsChannelOn(ctx context.Context, ch int) (bool, error)

	OnStateChanged(handler func(ch int, on bool)) (string, error)
}

// switchDevice is the concrete Switch implementation.
type switchDevice struct {
	BaseDevice
	channels   []siidPiid // "on" property per channel (index 0 = channel 1)
	stateCache []bool      // MQTT 推送维护的本地缓存，索引 0 = 通道 1
}

type siidPiid struct {
	siid, piid int
	valid      bool
}

// NewSwitch creates a Switch control for the given device.
func NewSwitch(client *xiaomi.Client, info *xiaomi.DeviceInfo) (Switch, error) {
	d := &switchDevice{
		BaseDevice: NewBaseDevice(client, info),
	}

	// Use the full SPEC to find all "on" properties (supports multi-channel)
	miotDev := d.getMIoTDevice()
	if miotDev == nil || miotDev.SpecInstance() == nil {
		return nil, xiaomi.ErrNoSPEC
	}

	spec := miotDev.SpecInstance()
	var channels []siidPiid
	for _, svc := range spec.Services {
		for _, prop := range svc.Properties {
			if propertyShortName(prop.Type) == "on" {
				channels = append(channels, siidPiid{prop.SIID, prop.PIID, true})
			}
		}
	}

	if len(channels) == 0 {
		return nil, xiaomi.ErrNotSupported
	}
	d.channels = channels
	d.stateCache = make([]bool, len(channels))

	return d, nil
}

func (d *switchDevice) ChannelCount() int {
	return len(d.channels)
}

func (d *switchDevice) TurnOn(ctx context.Context) error {
	return d.TurnOnChannel(ctx, 1)
}

func (d *switchDevice) TurnOff(ctx context.Context) error {
	return d.TurnOffChannel(ctx, 1)
}

func (d *switchDevice) Toggle(ctx context.Context) error {
	return d.ToggleChannel(ctx, 1)
}

func (d *switchDevice) IsOn(ctx context.Context) (bool, error) {
	return d.IsChannelOn(ctx, 1)
}

func (d *switchDevice) TurnOnChannel(ctx context.Context, ch int) error {
	p, ok := d.channel(ch)
	if !ok {
		return xiaomi.ErrNotSupported
	}
	return d.SetProp(ctx, p.siid, p.piid, true)
}

func (d *switchDevice) TurnOffChannel(ctx context.Context, ch int) error {
	p, ok := d.channel(ch)
	if !ok {
		return xiaomi.ErrNotSupported
	}
	return d.SetProp(ctx, p.siid, p.piid, false)
}

func (d *switchDevice) ToggleChannel(ctx context.Context, ch int) error {
	on, err := d.IsChannelOn(ctx, ch)
	if err != nil {
		return err
	}
	if on {
		return d.TurnOffChannel(ctx, ch)
	}
	return d.TurnOnChannel(ctx, ch)
}

func (d *switchDevice) IsChannelOn(ctx context.Context, ch int) (bool, error) {
	p, ok := d.channel(ch)
	if !ok {
		return false, xiaomi.ErrNotSupported
	}
	prop, err := d.GetProp(ctx, p.siid, p.piid)
	if err != nil {
		return false, err
	}
	if b, ok := prop.Value.(bool); ok {
		return b, nil
	}
	return false, nil
}

func (d *switchDevice) OnStateChanged(handler func(ch int, on bool)) (string, error) {
	if len(d.channels) == 0 {
		return "", xiaomi.ErrNotSupported
	}
	// 构建 siid/piid → channel index 的快速查找表
	type chField struct{ siid, piid int }
	lookup := make(map[chField]int) // key → channel index (0-based)
	for i, c := range d.channels {
		lookup[chField{c.siid, c.piid}] = i
	}
	return d.SubProp(0, 0, func(did string, prop *xiaomi.PropertyValue) {
		for k, idx := range lookup {
			if k.siid == prop.SIID && k.piid == prop.PIID {
				if b, ok := prop.Value.(bool); ok {
					d.stateCache[idx] = b
					handler(idx+1, b) // ch = idx+1
				}
				return
			}
		}
	})
}

func (d *switchDevice) channel(ch int) (siidPiid, bool) {
	i := ch - 1 // channel 1 → index 0
	if i < 0 || i >= len(d.channels) {
		return siidPiid{}, false
	}
	return d.channels[i], true
}