package models

import (
	"math"
	"math/rand"
	"sort"
	"strings"
)

type Scene struct {
	ID         int         `json:"id"`
	Name       string      `json:"name"`
	IntervalMS int64       `json:"interval"`
	Roles      []SceneRole `json:"roles"`
}

func (s *Scene) Validate() error {
	if s.IntervalMS < 0 {
		return ErrSceneInvalidInterval
	}
	if len(s.Roles) == 0 {
		return ErrSceneNoRoles
	}

	for _, role := range s.Roles {
		err := role.Validate()
		if err != nil {
			return err
		}
	}

	return nil
}

func (s *Scene) Role(device *Device) *SceneRole {
	index := s.RoleIndex(device)
	if index == -1 {
		return nil
	}

	return &s.Roles[index]
}

func (s *Scene) RoleIndex(device *Device) int {
	for i, role := range s.Roles {
		if role.TargetKind.Matches(device, role.TargetValue) {
			return i
		}
	}

	return -1
}

type SceneEffect string

const (
	SEStatic     SceneEffect = "Plain"
	SERandom     SceneEffect = "Random"
	SEGradient   SceneEffect = "Gradient"
	SETransition SceneEffect = "Transition"
)

type SceneRole struct {
	Effect      SceneEffect      `json:"effect"`
	PowerMode   ScenePowerMode   `json:"overridePower"`
	TargetKind  ReferenceKind    `json:"targetKind"`
	TargetValue string           `json:"targetValue"`
	Interpolate bool             `json:"interpolate"`
	Order       string           `json:"order"`
	States      []NewDeviceState `json:"states"`
}

func (r *SceneRole) Validate() error {
	if len(r.States) == 0 {
		return ErrSceneRoleNoStates
	}

	switch r.TargetKind {
	case RKTag, RKBridgeID, RKDeviceID, RKName, RKAll:
	default:
		return ErrBadInput
	}

	switch r.PowerMode {
	case SPScene, SPDevice, SPOverride:
	default:
		return ErrSceneRoleUnknownPowerMode
	}

	switch r.Effect {
	case SEStatic, SERandom, SEGradient, SETransition:
	default:
		return ErrSceneRoleUnknownEffect
	}

	switch r.Order {
	case "", "-name", "name", "+name", "-id", "id", "+id":
	default:
		return ErrSceneRoleUnsupportedOrdering
	}

	return nil
}

func (r *SceneRole) ApplyOrder(devices []Device) {
	if r.Order == "" {
		return
	}

	desc := strings.HasPrefix(r.Order, "-")

	orderKey := r.Order
	if desc || strings.HasPrefix(r.Order, "+") {
		orderKey = orderKey[1:]
	}

	switch orderKey {
	case "id":
		sort.Slice(devices, func(i, j int) bool {
			if desc {
				return devices[i].ID > devices[j].ID
			}

			return devices[i].ID < devices[j].ID
		})
	case "name":
		sort.Slice(devices, func(i, j int) bool {
			if desc {
				return strings.Compare(devices[i].Name, devices[j].Name) < 0
			}

			return strings.Compare(devices[i].Name, devices[j].Name) > 0
		})
	}
}

func (r *SceneRole) ApplyEffect(device *Device, intervalFac float64, positionFac float64) (newState NewDeviceState, deviceChanged bool) {
	switch r.Effect {
	case SEStatic:
		newState = r.States[0]
	case SERandom:
		newState = r.State(rand.Float64())
	case SEGradient:
		newState = r.State(positionFac)
	case SETransition:
		newState = r.State(intervalFac)
	}

	switch r.PowerMode {
	case SPDevice:
		newState.Power = nil
	case SPScene:
		// Do nothing
	case SPOverride:
		if newState.Power != nil && device.State.Power != *newState.Power {
			device.State.Power = *newState.Power
			deviceChanged = true
		}
	}

	return
}

func (r *SceneRole) State(fac float64) NewDeviceState {
	if len(r.States) == 0 {
		return NewDeviceState{}
	} else if len(r.States) == 1 {
		return r.States[0]
	}

	if r.Interpolate {
		if len(r.States) == 2 {
			return r.States[0].Interpolate(r.States[1], fac)
		} else {
			pos := fac * float64(len(r.States)-1)
			start := math.Floor(pos)
			localFac := pos - start

			return r.States[int(start)].Interpolate(r.States[int(start)+1], localFac)
		}
	} else {
		index := int(fac * float64(len(r.States)))
		if index == len(r.States) {
			index = len(r.States) - 1
		}

		return r.States[index]
	}
}

type ScenePowerMode string

const (
	SPDevice   ScenePowerMode = "Device"   // Device state decides power. Scene state may only power off.
	SPScene    ScenePowerMode = "Scene"    // Scene state decide power.
	SPOverride ScenePowerMode = "Override" // Same as above, but Scene state set Device state' power. This is good for "wake up" scenes.
)

type SceneAssignment struct {
	Scene  *Scene
	Device *Device
	Tag    string
}