package light

import (
	"context"
	"database/sql"
	"log"
	"net/http"
	"sync"
	"time"

	"git.aiterp.net/lucifer/lucifer/internal/httperr"
	"git.aiterp.net/lucifer/lucifer/models"
	"golang.org/x/sync/errgroup"
)

// ErrUnknownDriver is returned by any function asking for a driver name if the driver specified doesn't exist.
var ErrUnknownDriver = httperr.Error{Status: http.StatusNotImplemented, Kind: "unknown_driver", Message: "Unknown light driver"}

// A Service wraps the repos for lights and bridges and takes care of the business logic.
type Service struct {
	mutex sync.Mutex

	bridges models.BridgeRepository
	lights  models.LightRepository
	buttons models.ButtonRepository
	groups  models.GroupRepository

	buttonActive  map[int]bool
	buttonTargets map[int]int
}

// DirectConnect connects to a bridge directly, without going through the discovery process to find them..
func (s *Service) DirectConnect(ctx context.Context, driver string, addr string, name string) (models.Bridge, error) {
	d, ok := drivers[driver]
	if !ok {
		return models.Bridge{}, ErrUnknownDriver
	}

	bridge := models.Bridge{
		ID:     -1,
		Name:   name,
		Addr:   addr,
		Driver: driver,
	}

	bridge, err := d.Connect(ctx, bridge)
	if err != nil {
		return models.Bridge{}, httperr.Error{Status: http.StatusPreconditionFailed, Kind: "connect_failed", Message: err.Error()}
	}

	bridge, err = s.bridges.Insert(ctx, bridge)
	if err != nil {
		return models.Bridge{}, err
	}

	return bridge, nil
}

// SyncLights syncs all lights in a bridge with the state in the database.
func (s *Service) SyncLights(ctx context.Context, bridge models.Bridge) error {
	d, ok := drivers[bridge.Driver]
	if !ok {
		return ErrUnknownDriver
	}

	bridgeLights, err := d.Lights(ctx, bridge)
	if err != nil {
		return err
	}

	dbLights, err := s.lights.ListByBridge(ctx, bridge)
	if err != nil {
		return err
	}

	// Add unknown lights
	for _, bridgeLight := range bridgeLights {
		found := false
		for _, dbLight := range dbLights {
			if dbLight.InternalID == bridgeLight.InternalID {
				found = true
				break
			}
		}

		// Add unknown lights if it doesn't exist in the databse.
		if !found {
			log.Println("Adding unknown light", bridgeLight.InternalID)
			bridgeLight.SetColor("FFFFFF")
			bridgeLight.Brightness = 254
			bridgeLight.On = true
			_, err := s.lights.Insert(ctx, bridgeLight)
			if err != nil {
				return err
			}
		}
	}

	changedLights, err := d.ChangedLights(ctx, bridge, dbLights...)
	if err != nil {
		return err
	}

	if len(changedLights) > 0 {
		err := d.Apply(ctx, bridge, changedLights...)
		if err != nil {
			log.Printf("Failed to apply one or more of the changes on bridge %d (%s): %s", bridge.ID, bridge.Name, err)
		}
	}

	return nil
}

// SyncButtons syncs all buttons in a bridge with the state in the database.
func (s *Service) SyncButtons(ctx context.Context, bridge models.Bridge) error {
	d, ok := drivers[bridge.Driver]
	if !ok {
		return ErrUnknownDriver
	}

	bridgeButtons, err := d.Buttons(ctx, bridge)
	if err != nil {
		return err
	}

	dbButtons, err := s.buttons.ListByBridge(ctx, bridge)
	if err != nil {
		return err
	}

	changedButtons := make([]models.Button, 0, len(bridgeButtons))
	newButtons := make([]models.Button, 0, len(dbButtons))
	exists := make(map[string]bool, len(dbButtons))

	// Check for new or changed
	for _, bridgeButton := range bridgeButtons {
		found := false

		exists[bridgeButton.InternalID] = true

		for _, dbButton := range dbButtons {
			if bridgeButton.InternalID == dbButton.InternalID {
				if dbButton.InternalIndex != bridgeButton.InternalIndex || dbButton.Missing {
					dbButton.InternalIndex = bridgeButton.InternalIndex
					dbButton.Missing = false
					changedButtons = append(changedButtons, dbButton)

					log.Println("Updating button", dbButton.ID)
				}

				found = true

				break
			}
		}

		if !found {
			newButtons = append(newButtons, bridgeButton)
		}
	}

	// Check for missing buttons
	for _, dbButton := range dbButtons {
		if !exists[dbButton.InternalID] {
			dbButton.Missing = true
			changedButtons = append(changedButtons, dbButton)

			log.Println("Marking button", dbButton.ID, "as missing")
		}
	}

	// Insert new buttons
	for _, newButton := range newButtons {
		button, err := s.buttons.Insert(ctx, newButton)
		if err != nil {
			log.Printf("Failed to insert button %s (%s): %s", button.Name, button.InternalID, err)
			continue
		}

		dbButtons = append(dbButtons, button)
	}

	// Update changed buttons
	for _, changedButton := range changedButtons {
		err := s.buttons.Update(ctx, changedButton)
		if err != nil {
			log.Printf("Failed to change button %s (%d): %s", changedButton.Name, changedButton.ID, err)
			continue
		}

		for i := range dbButtons {
			if dbButtons[i].ID == changedButton.ID {
				dbButtons[i] = changedButton

				break
			}
		}
	}

	// Start polling buttons
	for _, dbButton := range dbButtons {
		s.mutex.Lock()
		if exists[dbButton.InternalID] && !s.buttonActive[dbButton.ID] {
			s.buttonActive[dbButton.ID] = true
			go s.pollButton(ctx, bridge, dbButton)

			log.Printf("Polling button %s (%d)", dbButton.Name, dbButton.ID)
		}

		s.buttonTargets[dbButton.ID] = dbButton.TargetGroupID
		s.mutex.Unlock()
	}

	return nil
}

// UpdateLight updates the light immediately.
func (s *Service) UpdateLight(ctx context.Context, light models.Light) error {
	bridge, err := s.bridges.FindByID(ctx, light.BridgeID)
	if err != nil {
		return httperr.NotFound("Bridge")
	}
	d, ok := drivers[bridge.Driver]
	if !ok {
		return ErrUnknownDriver
	}

	err = s.lights.Update(ctx, light)
	if err != nil {
		return err
	}

	return d.Apply(ctx, bridge, light)
}

// SyncLoop runs synclight on all bridges twice every second until the context is
// done.
func (s *Service) SyncLoop(ctx context.Context) {
	interval := time.NewTicker(time.Millisecond * 2500)

	for {
		select {
		case <-interval.C:
			{
				bridges, err := s.Bridges(context.Background())
				if err != nil {
					log.Println("Could not get bridges:", err)
				}

				for _, bridge := range bridges {
					err = s.SyncLights(ctx, bridge)
					if err != nil {
						log.Printf("Light sync failed for bridge %s (%d): %s", bridge.Name, bridge.ID, err)
						break
					}

					err = s.SyncButtons(ctx, bridge)
					if err != nil {
						log.Printf("Button sync failed for bridge %s (%d): %s", bridge.Name, bridge.ID, err)
						break
					}
				}
			}
		case <-ctx.Done():
			{
				log.Println("Sync loop stopped.")
				return
			}
		}
	}
}

// Bridge gets a bridge by ID.
func (s *Service) Bridge(ctx context.Context, id int) (models.Bridge, error) {
	return s.bridges.FindByID(ctx, id)
}

// Bridges gets all known bridges.
func (s *Service) Bridges(ctx context.Context) ([]models.Bridge, error) {
	return s.bridges.List(ctx)
}

// Light gets all known bridges.
func (s *Service) Light(ctx context.Context, id int) (models.Light, error) {
	return s.lights.FindByID(ctx, id)
}

// DeleteBridge deletes the bridge.
func (s *Service) DeleteBridge(ctx context.Context, bridge models.Bridge) error {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	err := s.bridges.Remove(ctx, bridge)
	if err != nil {
		return err
	}

	lights, err := s.lights.ListByBridge(ctx, bridge)
	if err != nil {
		return err
	}

	for _, light := range lights {
		err := s.lights.Remove(ctx, light)
		if err != nil {
			return err
		}
	}

	return nil
}

// DeleteBridgeLight deletes the light in a bridge.
func (s *Service) DeleteBridgeLight(ctx context.Context, bridge models.Bridge, light models.Light) error {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	d, ok := drivers[bridge.Driver]
	if !ok {
		return ErrUnknownDriver
	}

	err := d.ForgetLight(ctx, bridge, light)
	if err != nil {
		return err
	}

	err = s.lights.Remove(ctx, light)
	if err != nil {
		return err
	}

	return nil
}

// UpdateBridge updates a bridge.
func (s *Service) UpdateBridge(ctx context.Context, bridge models.Bridge) error {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	err := s.bridges.Update(ctx, bridge)
	if err != nil {
		return err
	}

	return nil
}

// DiscoverLights discovers new lights.
func (s *Service) DiscoverLights(ctx context.Context, bridge models.Bridge) error {
	d, ok := drivers[bridge.Driver]
	if !ok {
		return ErrUnknownDriver
	}

	return d.DiscoverLights(ctx, bridge)
}

// DiscoverBridges discovers new lights.
func (s *Service) DiscoverBridges(ctx context.Context, driver string) ([]models.Bridge, error) {
	d, ok := drivers[driver]
	if !ok {
		return nil, ErrUnknownDriver
	}

	existingBridges, err := s.Bridges(ctx)
	if err != nil {
		return nil, err
	}

	newBridges, err := d.Bridges(ctx)
	if err != nil {
		return nil, err
	}

	for _, existingBridge := range existingBridges {
		for j, newBridge := range newBridges {
			if newBridge.InternalID == existingBridge.InternalID {
				newBridges = append(newBridges[:j], newBridges[j+1:]...)
				break
			}
		}
	}

	return newBridges, nil
}

func (s *Service) pollButton(ctx context.Context, bridge models.Bridge, button models.Button) {
	defer func() {
		s.mutex.Lock()
		s.buttonActive[button.ID] = false
		s.mutex.Unlock()
	}()

	d, ok := drivers[bridge.Driver]
	if !ok {
		log.Printf("Could not listen on button %s (%d) because the driver %s is unknwon", button.Name, button.ID, bridge.Driver)
		return
	}

	events, err := d.PollButton(ctx, bridge, button)
	if err != nil {
		log.Printf("Could not listen on button %s (%d) because the driver %s is unknwon", button.Name, button.ID, bridge.Driver)
		return
	}

	for event := range events {
		s.mutex.Lock()
		targetGroupID := s.buttonTargets[button.ID]
		s.mutex.Unlock()

		if targetGroupID < 0 {
			continue
		}

		if event.Kind != models.ButtonEventKindPress && event.Kind != models.ButtonEventKindRepeat {
			continue
		}

		group, err := s.groups.FindByID(ctx, targetGroupID)
		if err != nil {
			if err != sql.ErrNoRows {
				log.Println("Group not found:", err, targetGroupID)
			}

			continue
		}

		lights, err := s.lights.ListByGroup(ctx, group)

		log.Printf("Got button input for group %s (%d) (id: %d, idx: %d, kind: %s)", group.Name, group.ID, button.ID, event.Index, event.Kind)

		eg, _ := errgroup.WithContext(ctx)

		for i := range lights {
			light := &lights[i]

			switch event.Index {
			case 1:
				{
					if !light.On {
						light.On = true

						eg.Go(func() error {
							return s.UpdateLight(ctx, *light)
						})
					}
				}
			case 2:
				{
					if light.Brightness < 254 {
						if light.Brightness >= (254 - 64) {
							light.Brightness = 254
						} else {
							light.Brightness += 64
						}

						eg.Go(func() error {
							return s.UpdateLight(ctx, *light)
						})
					}
				}
			case 3:
				{
					if light.Brightness > 0 {
						if light.Brightness < 64 {
							light.Brightness = 0
						} else {
							light.Brightness -= 64
						}

						eg.Go(func() error {
							return s.UpdateLight(ctx, *light)
						})
					}
				}
			case 4:
				{
					if light.On {
						light.On = false
						eg.Go(func() error {
							return s.UpdateLight(ctx, *light)
						})
					}
				}
			}
		}

		err = eg.Wait()
		if err != nil {
			log.Println("Failed to update one or more lights:", err)
		}
	}
}

// NewService creates a new light.Service.
func NewService(bridges models.BridgeRepository, lights models.LightRepository, groups models.GroupRepository, buttons models.ButtonRepository) *Service {
	return &Service{
		bridges: bridges,
		lights:  lights,
		buttons: buttons,
		groups:  groups,

		buttonActive:  make(map[int]bool, 64),
		buttonTargets: make(map[int]int, 64),
	}
}