package hardware

import (
	"context"
	"fmt"
	"syscall"
	"time"
	"unsafe"

	"github.com/rs/zerolog/log"

	"github.com/lxn/win"
	"github.com/wailsapp/wails/v2/pkg/runtime"
	"golang.org/x/sys/windows"
)

// 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 {
	drivers            map[string]PeripheralDriver // The map of peripherals finders
	peripherals        []Peripheral                // The current list of peripherals
	deviceChangedEvent chan struct{}               // The event when the devices list changed
	ctx                context.Context
}

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

// Start starts to find new peripheral events
func (h *HardwareManager) Start(ctx context.Context) error {
	cb := windows.NewCallback(h.wndProc)
	log.Trace().Str("file", "hardware").Msg("wndProc callback set")

	inst := win.GetModuleHandle(nil)
	log.Trace().Str("file", "hardware").Msg("got windows API instance")

	cn, err := syscall.UTF16PtrFromString("DMXConnect peripheral watcher")
	if err != nil {
		log.Err(err).Str("file", "hardware").Msg("failed to convert window class name to UTF16")
		return fmt.Errorf("failed to convert window class name to UTF16: %w", err)
	}
	wc := win.WNDCLASSEX{
		HInstance:     inst,
		LpfnWndProc:   cb,
		LpszClassName: cn,
	}
	log.Trace().Str("file", "hardware").Msg("windows API class created")

	wc.CbSize = uint32(unsafe.Sizeof(wc))
	if win.RegisterClassEx(&wc) == 0 {
		log.Err(syscall.GetLastError()).Str("file", "hardware").Msg("failed to register window class")
		return fmt.Errorf("failed to register window class: %w", syscall.GetLastError())
	}
	log.Trace().Str("file", "hardware").Msg("window class registered")

	wName, err := syscall.UTF16PtrFromString("usbevent.exe")
	if err != nil {
		log.Err(err).Str("file", "hardware").Msg("failed to convert window class name to UTF16")
		return fmt.Errorf("failed to convert window name to UTF16: %w", err)
	}
	wdw := win.CreateWindowEx(
		0,
		wc.LpszClassName,
		wName,
		win.WS_MINIMIZE|win.WS_OVERLAPPEDWINDOW,
		win.CW_USEDEFAULT,
		win.CW_USEDEFAULT,
		100,
		100,
		0,
		0,
		wc.HInstance,
		nil)
	if wdw == 0 {
		log.Err(syscall.GetLastError()).Str("file", "hardware").Msg("failed to create window")
		return fmt.Errorf("failed to create window: %w", syscall.GetLastError())
	}
	log.Trace().Str("file", "hardware").Msg("window created successfully")

	_ = win.ShowWindow(wdw, win.SW_HIDE)
	win.UpdateWindow(wdw)
	log.Trace().Str("file", "hardware").Msg("window shown and updated")

	// To continuously get the devices events from Windows
	go func() {
		defer log.Debug().Str("file", "hardware").Msg("peripheral watcher goroutine exited")
		for {
			select {
			case <-ctx.Done():
				return
			default:
				var msg win.MSG
				got := win.GetMessage(&msg, win.HWND(windows.HWND(wdw)), 0, 0)
				if got == 0 {
					win.TranslateMessage(&msg)
					win.DispatchMessage(&msg)
				}
			}
		}
	}()

	// To handle the peripheral changed
	go func() {
		defer log.Debug().Str("file", "hardware").Msg("peripheral getter goroutine exited")
		for {
			select {
			case <-ctx.Done():
				return
			case <-h.deviceChangedEvent:
				log.Debug().Str("file", "hardware").Msg("peripheral change event, triggering scan...")
				err := h.Scan(ctx)
				if err != nil {
					log.Err(err).Str("file", "hardware").Msg("unable to scan peripherals")
				}
			}
		}
	}()
	return nil
}

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

// RegisterDriver registers a new peripherals driver
func (h *HardwareManager) RegisterDriver(driver PeripheralDriver) {
	h.drivers[driver.GetName()] = driver
	log.Info().Str("file", "hardware").Str("driverName", driver.GetName()).Msg("driver registered")
}

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

// Scan scans all the peripherals for the registered finders
func (h *HardwareManager) Scan(ctx context.Context) error {
	if len(h.drivers) == 0 {
		log.Warn().Str("file", "hardware").Msg("no driver registered")
		return fmt.Errorf("no driver registered")
	}
	for _, driver := range h.drivers {
		driverCopy := driver
		go func() {
			err := driverCopy.Scan(ctx)
			if err != nil {
				log.Err(err).Str("file", "hardware").Str("driverName", driverCopy.GetName()).Msg("unable to scan peripheral")
				return
			}
		}()
	}
	return nil
}

func (h *HardwareManager) wndProc(hwnd windows.HWND, msg uint32, wParam, lParam uintptr) uintptr {
	switch msg {
	case win.WM_DEVICECHANGE:
		// Trigger the devices scan when the last DEVICE_CHANGE event is received
		if debounceTimer != nil {
			debounceTimer.Stop()
			log.Trace().Str("file", "hardware").Msg("scan debounce timer stopped")
		}
		debounceTimer = time.AfterFunc(debounceDuration, func() {
			log.Debug().Str("file", "hardware").Msg("peripheral changed")
			h.deviceChangedEvent <- struct{}{}
		})
	}
	return win.DefWindowProc(win.HWND(hwnd), msg, wParam, lParam)
}

// 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
}