// Copyright (c) 2026 Storm Dragon
// Authors: Storm Dragon, Angus Kola
// SPDX-License-Identifier: GPL-3.0-or-later

package notification

import (
	"context"
	"fmt"
	"html"
	"regexp"
	"strings"
	"sync"

	"github.com/godbus/dbus/v5"
)

const (
	MakoSource     = "mako"
	makoBusName    = "org.freedesktop.Notifications"
	makoObjectPath = "/fr/emersion/Mako"
	makoInterface  = "fr.emersion.Mako"
)

type MakoConnection interface {
	Signal(chan<- *dbus.Signal)
	RemoveSignal(subscription chan<- *dbus.Signal)
	Object(dest string, path dbus.ObjectPath) dbus.BusObject
	AddMatchSignal(match ...dbus.MatchOption) error
	RemoveMatchSignal(match ...dbus.MatchOption) error
	Close() error
}

type MakoAnnouncer interface {
	Announce(entry Entry)
}

type MakoMonitor struct {
	connection MakoConnection
	presenter  *Presenter
	announcer  MakoAnnouncer

	mutex        sync.Mutex
	generation   int
	available    bool
	known        map[int]struct{}
	running      bool
	stop         chan struct{}
	stopped      chan struct{}
	subscription <-chan *dbus.Signal
}

type MakoController interface {
	IsCurrent(entry Entry) bool
	Dismiss(notificationID int) bool
	InvokeAction(notificationID int, actionKey string) bool
}

func NewMakoMonitor(connection MakoConnection, presenter *Presenter, announcer MakoAnnouncer) *MakoMonitor {
	return &MakoMonitor{
		connection: connection,
		presenter:  presenter,
		announcer:  announcer,
		known:      make(map[int]struct{}),
		stop:       make(chan struct{}),
		stopped:    make(chan struct{}),
	}
}

func (monitor *MakoMonitor) Start(ctx context.Context) error {
	monitor.mutex.Lock()
	if monitor.running {
		monitor.mutex.Unlock()
		return nil
	}
	monitor.running = true
	monitor.stop = make(chan struct{})
	monitor.stopped = make(chan struct{})
	monitor.mutex.Unlock()

	go monitor.watch(ctx)
	return nil
}

func (monitor *MakoMonitor) Stop(ctx context.Context) error {
	monitor.mutex.Lock()
	if !monitor.running {
		monitor.mutex.Unlock()
		return nil
	}
	monitor.running = false
	close(monitor.stop)
	monitor.mutex.Unlock()

	select {
	case <-monitor.stopped:
	case <-ctx.Done():
		return ctx.Err()
	}

	monitor.mutex.Lock()
	defer monitor.mutex.Unlock()
	monitor.unsubscribe()
	monitor.presenter.MarkSourceUnavailable(MakoSource)
	clear(monitor.known)
	monitor.available = false
	return monitor.connection.Close()
}

func (monitor *MakoMonitor) Refresh(announceNew bool) bool {
	monitor.mutex.Lock()
	available := monitor.available
	monitor.mutex.Unlock()
	if !available {
		return false
	}

	notifications, err := monitor.list()
	if err != nil {
		monitor.markUnavailable()
		return false
	}
	monitor.sync(notifications, announceNew)
	return true
}

func (monitor *MakoMonitor) activate(announceNew bool) bool {
	notifications, err := monitor.list()
	if err != nil {
		monitor.markUnavailable()
		return false
	}
	monitor.mutex.Lock()
	monitor.generation++
	monitor.available = true
	clear(monitor.known)
	monitor.mutex.Unlock()
	monitor.sync(notifications, announceNew)
	return true
}

func (monitor *MakoMonitor) Dismiss(notificationID int) bool {
	options := map[string]dbus.Variant{
		"id":      dbus.MakeVariant(uint32(notificationID)),
		"group":   dbus.MakeVariant(false),
		"history": dbus.MakeVariant(true),
		"all":     dbus.MakeVariant(false),
	}
	if err := monitor.object().Call("fr.emersion.Mako.DismissNotifications", 0, options).Err; err != nil {
		return false
	}
	monitor.Refresh(false)
	return true
}

func (monitor *MakoMonitor) InvokeAction(notificationID int, actionKey string) bool {
	if err := monitor.object().Call("fr.emersion.Mako.InvokeAction", 0, uint32(notificationID), actionKey).Err; err != nil {
		return false
	}
	monitor.Refresh(false)
	return true
}

func (monitor *MakoMonitor) IsCurrent(entry Entry) bool {
	monitor.mutex.Lock()
	defer monitor.mutex.Unlock()
	return monitor.available && entry.Source == MakoSource &&
		entry.SourceGeneration == monitor.generation && entry.Live
}

func (monitor *MakoMonitor) Generation() int {
	monitor.mutex.Lock()
	defer monitor.mutex.Unlock()
	return monitor.generation
}

func (monitor *MakoMonitor) watch(ctx context.Context) {
	defer close(monitor.stopped)
	signals := make(chan *dbus.Signal, 16)
	monitor.subscription = signals
	monitor.connection.Signal(signals)
	defer monitor.connection.RemoveSignal(signals)

	if err := monitor.connection.AddMatchSignal(
		dbus.WithMatchObjectPath(makoObjectPath),
		dbus.WithMatchInterface("org.freedesktop.DBus.Properties"),
	); err != nil {
		monitor.markUnavailable()
		return
	}
	if err := monitor.connection.AddMatchSignal(
		dbus.WithMatchSender("org.freedesktop.DBus"),
		dbus.WithMatchObjectPath("/org/freedesktop/DBus"),
		dbus.WithMatchInterface("org.freedesktop.DBus"),
		dbus.WithMatchMember("NameOwnerChanged"),
	); err != nil {
		monitor.markUnavailable()
		return
	}
	monitor.activate(false)

	for {
		select {
		case <-ctx.Done():
			return
		case <-monitor.stop:
			return
		case signal := <-signals:
			monitor.handleSignal(signal)
		}
	}
}

func (monitor *MakoMonitor) handleSignal(signal *dbus.Signal) {
	if signal == nil {
		return
	}
	switch signal.Name {
	case "org.freedesktop.DBus.Properties.PropertiesChanged":
		if signal.Path == makoObjectPath {
			monitor.Refresh(true)
		}
	case "org.freedesktop.DBus.NameOwnerChanged":
		if signal.Path != "/org/freedesktop/DBus" || len(signal.Body) < 3 {
			return
		}
		name, _ := signal.Body[0].(string)
		newOwner, _ := signal.Body[2].(string)
		if name != makoBusName {
			return
		}
		if newOwner == "" {
			monitor.markUnavailable()
		} else {
			monitor.activate(false)
		}
	}
}

func (monitor *MakoMonitor) sync(notifications []map[string]dbus.Variant, announceNew bool) {
	parsed := make([]LiveMetadata, 0, len(notifications))
	ids := make([]int, 0, len(notifications))
	live := make(map[int]LiveMetadata)
	for _, notification := range notifications {
		metadata, id := parseMako(notification)
		if id == nil {
			continue
		}
		parsed = append(parsed, metadata)
		ids = append(ids, *id)
		live[*id] = metadata
	}
	monitor.presenter.SyncLive(MakoSource, monitor.Generation(), live)
	if announceNew {
		for index, id := range ids {
			if monitor.knownID(id) {
				continue
			}
			notificationID := id
			monitor.announcer.Announce(Entry{
				Message:          parsed[index].Message,
				Source:           MakoSource,
				SourceGeneration: monitor.Generation(),
				NotificationID:   &notificationID,
				Live:             true,
				Actions:          parsed[index].Actions,
				AppName:          parsed[index].AppName,
				Summary:          parsed[index].Summary,
				Body:             parsed[index].Body,
				Urgency:          parsed[index].Urgency,
				DesktopEntry:     parsed[index].DesktopEntry,
			})
		}
	}
	monitor.replaceKnown(live)
}

func (monitor *MakoMonitor) list() ([]map[string]dbus.Variant, error) {
	var reply []map[string]dbus.Variant
	object := monitor.object()
	if err := object.Call(makoInterface+".ListNotifications", 0).Store(&reply); err != nil {
		return nil, fmt.Errorf("list mako notifications: %w", err)
	}
	return reply, nil
}

func (monitor *MakoMonitor) object() dbus.BusObject {
	return monitor.connection.Object(makoBusName, makoObjectPath)
}

func (monitor *MakoMonitor) knownID(id int) bool {
	monitor.mutex.Lock()
	defer monitor.mutex.Unlock()
	_, known := monitor.known[id]
	return known
}

func (monitor *MakoMonitor) replaceKnown(live map[int]LiveMetadata) {
	monitor.mutex.Lock()
	defer monitor.mutex.Unlock()
	monitor.known = make(map[int]struct{}, len(live))
	for id := range live {
		monitor.known[id] = struct{}{}
	}
}

func (monitor *MakoMonitor) markUnavailable() {
	monitor.mutex.Lock()
	defer monitor.mutex.Unlock()
	monitor.available = false
	clear(monitor.known)
	monitor.presenter.MarkSourceUnavailable(MakoSource)
}

func (monitor *MakoMonitor) unsubscribe() {
	if monitor.subscription != nil {
		_ = monitor.connection.RemoveMatchSignal(
			dbus.WithMatchObjectPath(makoObjectPath),
			dbus.WithMatchInterface("org.freedesktop.DBus.Properties"),
		)
		_ = monitor.connection.RemoveMatchSignal(
			dbus.WithMatchSender("org.freedesktop.DBus"),
			dbus.WithMatchObjectPath("/org/freedesktop/DBus"),
			dbus.WithMatchInterface("org.freedesktop.DBus"),
			dbus.WithMatchMember("NameOwnerChanged"),
		)
	}
}

var (
	makoTagPattern        = regexp.MustCompile(`<[^>]+>`)
	makoWhitespacePattern = regexp.MustCompile(`\s+`)
)

func parseMako(notification map[string]dbus.Variant) (LiveMetadata, *int) {
	id, idValid := notification["id"].Value().(uint32)
	if !idValid {
		return LiveMetadata{}, nil
	}
	metadata := LiveMetadata{
		AppName:      normalizeMakoText(notification["app-name"]),
		Summary:      normalizeMakoText(notification["summary"]),
		Body:         normalizeMakoText(notification["body"]),
		DesktopEntry: normalizeMakoText(notification["desktop-entry"]),
	}
	if value, valid := notification["urgency"].Value().(int32); valid {
		metadata.Urgency = int(value)
	} else {
		metadata.Urgency = -1
	}
	if actions, valid := notification["actions"].Value().(map[string]dbus.Variant); valid {
		metadata.Actions = make(map[string]string, len(actions))
		for key, action := range actions {
			value := normalizeMakoText(action)
			if value == "" {
				value = key
			}
			metadata.Actions[key] = value
		}
	}
	notificationID := int(id)
	metadata.Message = buildMakoMessage(metadata)
	return metadata, &notificationID
}

func normalizeMakoText(variant dbus.Variant) string {
	text, valid := variant.Value().(string)
	if !valid {
		return ""
	}
	text = html.UnescapeString(text)
	text = makoTagPattern.ReplaceAllString(text, " ")
	text = makoWhitespacePattern.ReplaceAllString(text, " ")
	return strings.TrimSpace(text)
}

func buildMakoMessage(metadata LiveMetadata) string {
	parts := []string{MessageNotification}
	if metadata.Summary != "" {
		parts = append(parts, metadata.Summary)
	}
	if metadata.Body != "" && metadata.Body != metadata.Summary {
		parts = append(parts, metadata.Body)
	}
	if len(parts) == 1 {
		fallback := metadata.AppName
		if fallback == "" {
			fallback = metadata.DesktopEntry
		}
		if fallback != "" {
			parts = append(parts, fallback)
		}
	}
	return strings.Join(parts, " ")
}