package hardware

import (
	"context"
	"fmt"
	"sync"
	"time"

	"github.com/rs/zerolog/log"

	"github.com/wailsapp/wails/v2/pkg/runtime"
)

// PeripheralEvent is trigger by the finders when the scan is complete
type PeripheralEvent string

const (
	// PeripheralArrival is triggerd when a peripheral has been connected to the system
	PeripheralArrival PeripheralEvent = "PERIPHERAL_ARRIVAL"
	// PeripheralRemoval is triggered when a peripheral has been disconnected from the system
	PeripheralRemoval PeripheralEvent = "PERIPHERAL_REMOVAL"
	// debounceDuration                  = 500 * time.Millisecond
)

var (
	debounceTimer *time.Timer
)

// HardwareManager is the class who manages the hardware
type HardwareManager struct {
	finders                map[string]PeripheralFinder // The map of peripherals finders
	peripherals            []Peripheral                // The current list of peripherals
	peripheralsScanTrigger chan struct{}               // Trigger the peripherals scans
	goWait                 sync.WaitGroup              // Wait for goroutines to terminate
}

// NewHardwareManager creates a new HardwareManager
func NewHardwareManager() *HardwareManager {
	log.Trace().Str("package", "hardware").Msg("Hardware instance created")
	return &HardwareManager{
		finders:                make(map[string]PeripheralFinder),
		peripherals:            make([]Peripheral, 0),
		peripheralsScanTrigger: make(chan struct{}),
	}
}

// Start starts to find new peripheral events
func (h *HardwareManager) Start(ctx context.Context) error {
	for finderName, finder := range h.finders {
		err := finder.Initialize()
		if err != nil {
			log.Err(err).Str("file", "hardware").Str("finderName", finderName).Msg("unable to initialize finder")
			return err
		}
		err = finder.Start(ctx)
		if err != nil {
			log.Err(err).Str("file", "hardware").Str("finderName", finderName).Msg("unable to start finder")
			return err
		}
	}
	h.goWait.Add(1)
	go func() {
		defer h.goWait.Done()
		for {
			select {
			case <-ctx.Done():
				return
			case <-h.peripheralsScanTrigger:
				for finderName, finder := range h.finders {
					log.Trace().Str("file", "hardware").Str("finderName", finderName).Msg("force a finder to scan peripherals")
					finder.ForceScan()
				}
			}
		}
	}()
	return nil
}

// GetFinder returns a register finder
func (h *HardwareManager) GetFinder(finderName string) (PeripheralFinder, error) {
	finder, exists := h.finders[finderName]
	if !exists {
		log.Error().Str("file", "hardware").Str("finderName", finderName).Msg("unable to get the finder")
		return nil, fmt.Errorf("unable to locate the '%s' finder", finderName)
	}
	log.Debug().Str("file", "hardware").Str("finderName", finderName).Msg("got finder")
	return finder, nil
}

// RegisterFinder registers a new peripherals finder
func (h *HardwareManager) RegisterFinder(finder PeripheralFinder) {
	h.finders[finder.GetName()] = finder
	log.Info().Str("file", "hardware").Str("finderName", finder.GetName()).Msg("finder registered")
}

// GetPeripheral gets the peripheral object from the parent finder
func (h *HardwareManager) GetPeripheral(finderName string, peripheralID string) (Peripheral, bool) {
	// Get the finder
	parentFinder, found := h.finders[finderName]
	// If no finder found, return false
	if !found {
		log.Error().Str("file", "hardware").Str("finderName", finderName).Msg("unable to get the finder")
		return nil, false
	}
	log.Trace().Str("file", "hardware").Str("finderName", parentFinder.GetName()).Msg("finder got")
	// Contact the finder to get the peripheral
	return parentFinder.GetPeripheral(peripheralID)
}

// Scan scans all the peripherals for the registered finders
func (h *HardwareManager) Scan() error {
	h.peripheralsScanTrigger <- struct{}{}
	return nil
}

// Stop stops the hardware manager
func (h *HardwareManager) Stop() error {
	log.Trace().Str("file", "hardware").Msg("closing the hardware manager")
	// Stop each finder
	for finderName, finder := range h.finders {
		err := finder.Stop()
		if err != nil {
			log.Err(err).Str("file", "hardware").Str("finderName", finderName).Msg("unable to stop the finder")
		}
	}
	// Wait for goroutines to finish
	h.goWait.Wait()
	log.Info().Str("file", "hardware").Msg("hardware manager stopped")
	return nil
}

// peripheralsList emits a peripheral event
func emitPeripheralsEvents(ctx context.Context, peripheralsList map[string]Peripheral, peripheralEvent PeripheralEvent) {
	for _, peripheral := range peripheralsList {
		runtime.EventsEmit(ctx, string(peripheralEvent), peripheral.GetInfo())
		log.Trace().Str("file", "hardware").Str("event", string(peripheralEvent)).Msg("emit peripheral event")
	}
}

// comparePeripherals compares the peripherals to determine which has been inserted or removed
func comparePeripherals(oldPeripherals map[string]Peripheral, newPeripherals map[string]Peripheral) (map[string]Peripheral, map[string]Peripheral) {
	// Duplicate the lists
	oldList := make(map[string]Peripheral)
	newList := make(map[string]Peripheral)

	for key, value := range oldPeripherals {
		oldList[key] = value
	}
	log.Trace().Str("file", "hardware").Any("oldList", oldList).Msg("peripheral oldList comparison")
	for key, value := range newPeripherals {
		newList[key] = value
	}
	log.Trace().Str("file", "hardware").Any("newList", newList).Msg("peripheral newList comparison")
	// Remove in these lists all the commons peripherals
	for key := range newList {
		if _, exists := oldList[key]; exists {
			delete(oldList, key)
			delete(newList, key)
		}
	}
	// Now the old list contains the removed peripherals, and the new list contains the added peripherals
	log.Trace().Str("file", "hardware").Any("oldList", oldList).Msg("peripheral oldList computed")
	log.Trace().Str("file", "hardware").Any("newList", newList).Msg("peripheral newList computed")
	return oldList, newList
}