package hardware

import (
	"context"
	"errors"
	"fmt"
	"sync"

	"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"
	// PeripheralStatus is triggered when a peripheral status has been updated (disconnected - connecting - connected)
	PeripheralStatus PeripheralEvent = "PERIPHERAL_STATUS"
	// debounceDuration                  = 500 * time.Millisecond
)

// HardwareManager is the class who manages the hardware
type HardwareManager struct {
	wg sync.WaitGroup

	finders                map[string]PeripheralFinder // The map of peripherals finders
	peripherals            []Peripheral                // The current list of peripherals
	peripheralsScanTrigger chan struct{}               // Trigger the peripherals scans
}

// 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 {
	// Initialize all the finders
	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
		}
	}

	// Periodically scan all the finders
	h.wg.Add(1)
	go func() {
		defer h.wg.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")
}

// Scan scans all the peripherals for the registered finders
func (h *HardwareManager) Scan() error {
	select {
	case h.peripheralsScanTrigger <- struct{}{}:
		return nil
	default:
		return fmt.Errorf("scan trigger not available (manager stopped?)")
	}
}

// emitPeripheralsChanges compares the old and new peripherals to determine which ones have been added or removed.
func emitPeripheralsChanges(ctx context.Context, oldPeripherals map[string]PeripheralInfo, newPeripherals map[string]PeripheralInfo) {
	log.Trace().Any("oldList", oldPeripherals).Any("newList", newPeripherals).Msg("emitting peripherals changes to the front")

	// Identify removed peripherals: present in the old list but not in the new list
	for oldPeriphName := range oldPeripherals {
		if _, exists := newPeripherals[oldPeriphName]; !exists {
			runtime.EventsEmit(ctx, string(PeripheralRemoval), oldPeripherals[oldPeriphName])
			log.Trace().Str("file", "hardware").Str("event", string(PeripheralRemoval)).Msg("emit peripheral removal event")
		}
	}

	// Identify added peripherals: present in the new list but not in the old list
	for newPeriphName := range newPeripherals {
		if _, exists := oldPeripherals[newPeriphName]; !exists {
			runtime.EventsEmit(ctx, string(PeripheralArrival), newPeripherals[newPeriphName])
			log.Trace().Str("file", "hardware").Str("event", string(PeripheralArrival)).Msg("emit peripheral arrival event")
		}
	}
}

// WaitStop stops the hardware manager
func (h *HardwareManager) WaitStop() error {
	log.Trace().Str("file", "hardware").Msg("closing the hardware manager")

	// Closing trigger channel
	close(h.peripheralsScanTrigger)

	// Stop each finder
	var errs []error
	for name, f := range h.finders {
		if err := f.WaitStop(); err != nil {
			errs = append(errs, fmt.Errorf("%s: %w", name, err))
		}
	}

	// Wait for goroutines to finish
	h.wg.Wait()

	// Returning errors
	if len(errs) > 0 {
		return errors.Join(errs...)
	}
	log.Info().Str("file", "hardware").Msg("hardware manager stopped")

	return nil
}