package dbus

import (
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"strings"

	"github.com/AvengeMedia/DankMaterialShell/core/internal/log"
	"github.com/AvengeMedia/DankMaterialShell/core/pkg/dbusutil"
	"github.com/godbus/dbus/v5"
)

func NewManager() (*Manager, error) {
	systemConn, err := dbus.ConnectSystemBus()
	if err != nil {
		return nil, fmt.Errorf("failed to connect to system bus: %w", err)
	}

	sessionConn, err := dbus.ConnectSessionBus()
	if err != nil {
		systemConn.Close()
		return nil, fmt.Errorf("failed to connect to session bus: %w", err)
	}

	m := &Manager{
		systemConn:  systemConn,
		sessionConn: sessionConn,
	}

	go m.processSystemSignals()
	go m.processSessionSignals()

	return m, nil
}

func (m *Manager) getConn(bus string) (*dbus.Conn, error) {
	switch bus {
	case "system":
		if m.systemConn == nil {
			return nil, fmt.Errorf("system bus not connected")
		}
		return m.systemConn, nil
	case "session":
		if m.sessionConn == nil {
			return nil, fmt.Errorf("session bus not connected")
		}
		return m.sessionConn, nil
	default:
		return nil, fmt.Errorf("invalid bus: %s (must be 'system' or 'session')", bus)
	}
}

func (m *Manager) Call(bus, dest, path, iface, method string, args []any) (*CallResult, error) {
	conn, err := m.getConn(bus)
	if err != nil {
		return nil, err
	}

	obj := conn.Object(dest, dbus.ObjectPath(path))
	fullMethod := iface + "." + method

	call := obj.Call(fullMethod, 0, args...)
	if call.Err != nil {
		return nil, fmt.Errorf("dbus call failed: %w", call.Err)
	}

	return &CallResult{Values: call.Body}, nil
}

func (m *Manager) GetProperty(bus, dest, path, iface, property string) (*PropertyResult, error) {
	conn, err := m.getConn(bus)
	if err != nil {
		return nil, err
	}

	obj := conn.Object(dest, dbus.ObjectPath(path))

	var variant dbus.Variant
	err = obj.Call("org.freedesktop.DBus.Properties.Get", 0, iface, property).Store(&variant)
	if err != nil {
		return nil, fmt.Errorf("failed to get property: %w", err)
	}

	return &PropertyResult{Value: dbusutil.Normalize(variant.Value())}, nil
}

func (m *Manager) SetProperty(bus, dest, path, iface, property string, value any) error {
	conn, err := m.getConn(bus)
	if err != nil {
		return err
	}

	obj := conn.Object(dest, dbus.ObjectPath(path))

	call := obj.Call("org.freedesktop.DBus.Properties.Set", 0, iface, property, dbus.MakeVariant(value))
	if call.Err != nil {
		return fmt.Errorf("failed to set property: %w", call.Err)
	}

	return nil
}

func (m *Manager) GetAllProperties(bus, dest, path, iface string) (map[string]any, error) {
	conn, err := m.getConn(bus)
	if err != nil {
		return nil, err
	}

	obj := conn.Object(dest, dbus.ObjectPath(path))

	var props map[string]dbus.Variant
	err = obj.Call("org.freedesktop.DBus.Properties.GetAll", 0, iface).Store(&props)
	if err != nil {
		return nil, fmt.Errorf("failed to get properties: %w", err)
	}

	result := make(map[string]any)
	for k, v := range props {
		result[k] = dbusutil.Normalize(v.Value())
	}

	return result, nil
}

func (m *Manager) Introspect(bus, dest, path string) (*IntrospectResult, error) {
	conn, err := m.getConn(bus)
	if err != nil {
		return nil, err
	}

	obj := conn.Object(dest, dbus.ObjectPath(path))

	var xml string
	err = obj.Call("org.freedesktop.DBus.Introspectable.Introspect", 0).Store(&xml)
	if err != nil {
		return nil, fmt.Errorf("failed to introspect: %w", err)
	}

	return &IntrospectResult{XML: xml}, nil
}

func (m *Manager) ListNames(bus string) (*ListNamesResult, error) {
	conn, err := m.getConn(bus)
	if err != nil {
		return nil, err
	}

	var names []string
	err = conn.BusObject().Call("org.freedesktop.DBus.ListNames", 0).Store(&names)
	if err != nil {
		return nil, fmt.Errorf("failed to list names: %w", err)
	}

	return &ListNamesResult{Names: names}, nil
}

func (m *Manager) Subscribe(clientID, bus, sender, path, iface, member string) (*SubscribeResult, error) {
	conn, err := m.getConn(bus)
	if err != nil {
		return nil, err
	}

	subID := generateSubscriptionID()

	parts := []string{"type='signal'"}
	if sender != "" {
		parts = append(parts, fmt.Sprintf("sender='%s'", sender))
	}
	if path != "" {
		parts = append(parts, fmt.Sprintf("path='%s'", path))
	}
	if iface != "" {
		parts = append(parts, fmt.Sprintf("interface='%s'", iface))
	}
	if member != "" {
		parts = append(parts, fmt.Sprintf("member='%s'", member))
	}
	matchRule := strings.Join(parts, ",")

	call := conn.BusObject().Call("org.freedesktop.DBus.AddMatch", 0, matchRule)
	if call.Err != nil {
		return nil, fmt.Errorf("failed to add match rule: %w", call.Err)
	}

	sub := &signalSubscription{
		Bus:       bus,
		Sender:    sender,
		Path:      path,
		Interface: iface,
		Member:    member,
		ClientID:  clientID,
	}
	m.subscriptions.Store(subID, sub)

	log.Debugf("dbus: subscribed %s to %s", subID, matchRule)

	return &SubscribeResult{SubscriptionID: subID}, nil
}

func (m *Manager) Unsubscribe(subID string) error {
	sub, ok := m.subscriptions.LoadAndDelete(subID)
	if !ok {
		return fmt.Errorf("subscription not found: %s", subID)
	}

	conn, err := m.getConn(sub.Bus)
	if err != nil {
		return err
	}

	parts := []string{"type='signal'"}
	if sub.Sender != "" {
		parts = append(parts, fmt.Sprintf("sender='%s'", sub.Sender))
	}
	if sub.Path != "" {
		parts = append(parts, fmt.Sprintf("path='%s'", sub.Path))
	}
	if sub.Interface != "" {
		parts = append(parts, fmt.Sprintf("interface='%s'", sub.Interface))
	}
	if sub.Member != "" {
		parts = append(parts, fmt.Sprintf("member='%s'", sub.Member))
	}
	matchRule := strings.Join(parts, ",")

	call := conn.BusObject().Call("org.freedesktop.DBus.RemoveMatch", 0, matchRule)
	if call.Err != nil {
		log.Warnf("dbus: failed to remove match rule: %v", call.Err)
	}

	log.Debugf("dbus: unsubscribed %s", subID)

	return nil
}

func (m *Manager) UnsubscribeClient(clientID string) {
	var toDelete []string
	m.subscriptions.Range(func(subID string, sub *signalSubscription) bool {
		if sub.ClientID == clientID {
			toDelete = append(toDelete, subID)
		}
		return true
	})

	for _, subID := range toDelete {
		if err := m.Unsubscribe(subID); err != nil {
			log.Warnf("dbus: failed to unsubscribe %s: %v", subID, err)
		}
	}
}

func (m *Manager) SubscribeSignals(clientID string) chan SignalEvent {
	ch := make(chan SignalEvent, 64)
	existing, loaded := m.signalSubscribers.LoadOrStore(clientID, ch)
	if loaded {
		return existing
	}
	return ch
}

func (m *Manager) UnsubscribeSignals(clientID string) {
	if ch, ok := m.signalSubscribers.LoadAndDelete(clientID); ok {
		close(ch)
	}
	m.UnsubscribeClient(clientID)
}

func (m *Manager) processSystemSignals() {
	if m.systemConn == nil {
		return
	}
	ch := make(chan *dbus.Signal, 256)
	m.systemConn.Signal(ch)

	for sig := range ch {
		m.dispatchSignal("system", sig)
	}
}

func (m *Manager) processSessionSignals() {
	if m.sessionConn == nil {
		return
	}
	ch := make(chan *dbus.Signal, 256)
	m.sessionConn.Signal(ch)

	for sig := range ch {
		m.dispatchSignal("session", sig)
	}
}

func (m *Manager) dispatchSignal(bus string, sig *dbus.Signal) {
	path := string(sig.Path)
	iface := ""
	member := sig.Name

	if idx := strings.LastIndex(sig.Name, "."); idx != -1 {
		iface = sig.Name[:idx]
		member = sig.Name[idx+1:]
	}

	m.subscriptions.Range(func(subID string, sub *signalSubscription) bool {
		if sub.Bus != bus {
			return true
		}
		if sub.Path != "" && sub.Path != path && !strings.HasPrefix(path, sub.Path) {
			return true
		}
		if sub.Interface != "" && sub.Interface != iface {
			return true
		}
		if sub.Member != "" && sub.Member != member {
			return true
		}

		event := SignalEvent{
			SubscriptionID: subID,
			Sender:         sig.Sender,
			Path:           path,
			Interface:      iface,
			Member:         member,
			Body:           dbusutil.NormalizeSlice(sig.Body),
		}

		ch, ok := m.signalSubscribers.Load(sub.ClientID)
		if !ok {
			return true
		}

		select {
		case ch <- event:
		default:
			log.Warnf("dbus: channel full for %s, dropping signal", subID)
		}

		return true
	})
}

func (m *Manager) Close() {
	m.signalSubscribers.Range(func(clientID string, ch chan SignalEvent) bool {
		close(ch)
		m.signalSubscribers.Delete(clientID)
		return true
	})

	if m.systemConn != nil {
		m.systemConn.Close()
	}
	if m.sessionConn != nil {
		m.sessionConn.Close()
	}
}

func generateSubscriptionID() string {
	b := make([]byte, 8)
	if _, err := rand.Read(b); err != nil {
		log.Warnf("dbus: failed to generate random subscription ID: %v", err)
	}
	return hex.EncodeToString(b)
}