package server

import (
	"context"
	"errors"
	"strings"
	"sync"
	"time"

	"github.com/Neur0toxine/sshpoke/internal/config"
	"github.com/Neur0toxine/sshpoke/internal/docker"
	"github.com/Neur0toxine/sshpoke/internal/logger"
	"github.com/Neur0toxine/sshpoke/internal/server/driver"
	"github.com/Neur0toxine/sshpoke/internal/server/driver/base"
	"github.com/Neur0toxine/sshpoke/internal/server/driver/plugin"
	"github.com/Neur0toxine/sshpoke/pkg/dto"
)

type Manager struct {
	rw            sync.RWMutex
	forwardsLock  sync.Mutex
	servers       map[string]base.Driver
	plugins       map[string]plugin.Plugin
	statusMap     map[string]ServerStatus
	forwards      map[string]bool
	statusLock    sync.RWMutex
	ctx           context.Context
	defaultServer string
}

type ServerStatus struct {
	Name        string      `json:"name"`
	Connections Connections `json:"connections"`
}

var DefaultManager *Manager
var (
	ErrNoServer     = errors.New("server is not specified")
	ErrNoSuchServer = errors.New("server does not exist")
)

func NewManager(ctx context.Context, servers []config.Server, defaultServer string) *Manager {
	m := &Manager{
		ctx:           ctx,
		servers:       make(map[string]base.Driver),
		plugins:       make(map[string]plugin.Plugin),
		statusMap:     make(map[string]ServerStatus),
		forwards:      make(map[string]bool),
		defaultServer: defaultServer,
	}
	for _, serverConfig := range servers {
		server, err := driver.New(ctx, serverConfig.Name, serverConfig.Driver, serverConfig.Params)
		if err != nil {
			logger.Sugar.Errorf("cannot initialize server '%s': %s", serverConfig.Name, err)
			continue
		}
		server.SetEventStatusCallback(m.eventStatusCallback(server.Name()))
		if server.Driver() == config.DriverPlugin {
			pl := server.(plugin.Plugin)
			if pl.Token() == "" {
				logger.Sugar.Warnf("server '%s' will not work because it doesn't have a token", pl.Name())
				continue
			}
			existing, found := m.plugins[pl.Token()]
			if found {
				logger.Sugar.Fatalw("two plugins cannot have the same token",
					"plugin1", existing.Name(), "plugin2", pl.Name(), "token", pl.Token())
			}
			m.plugins[pl.Token()] = pl
		}
		m.servers[serverConfig.Name] = server
		m.statusMap[serverConfig.Name] = ServerStatus{Name: serverConfig.Name, Connections: make(Connections)}
	}
	go m.runMarkAndSweepForwards()
	return m
}

func (m *Manager) ProcessEvent(event dto.Event) error {
	serverName := event.Container.Server
	if serverName == "" {
		serverName = m.defaultServer
	}
	if serverName == "" {
		return ErrNoServer
	}
	defer m.rw.RUnlock()
	m.rw.RLock()
	srv, ok := m.servers[event.Container.Server]
	if !ok {
		return ErrNoSuchServer
	}
	if err := srv.Handle(event); err != nil {
		return err
	}
	defer m.forwardsLock.Unlock()
	m.forwardsLock.Lock()
	switch event.Type {
	case dto.EventStart:
		m.forwards[m.forwardID(serverName, event.Container.ID)] = false
	case dto.EventStop, dto.EventError, dto.EventShutdown:
		delete(m.forwards, m.forwardID(serverName, event.Container.ID))
	}
	return nil
}

func (m *Manager) forwardID(serverName, containerID string) string {
	return serverName + ":" + containerID
}

func (m *Manager) eventStatusCallback(serverName string) base.EventStatusCallback {
	return func(status dto.EventStatus) {
		m.processEventStatus(serverName, status)
	}
}

func (m *Manager) processEventStatus(serverName string, event dto.EventStatus) {
	logger.Sugar.Debugw("received EventStatus from server",
		"serverName", serverName, "eventStatus", event)
	item, found := docker.Default.GetContainer(event.ID, true)
	if !found {
		return
	}
	defer m.forwardsLock.Unlock()
	m.forwardsLock.Lock()
	switch event.Type {
	case dto.EventStart:
		defer m.statusLock.Unlock()
		m.statusLock.Lock()
		item.Domain = event.Domain
		m.forwards[m.forwardID(serverName, item.ID)] = false
		m.statusMap[serverName].Connections[item.ID] = item
	case dto.EventStop, dto.EventShutdown, dto.EventError:
		defer m.statusLock.Unlock()
		m.statusLock.Lock()
		item.Domain = ""
		delete(m.forwards, m.forwardID(serverName, item.ID))
		delete(m.statusMap[serverName].Connections, item.ID)
	default:
		return
	}
}

func (m *Manager) StatusMap() map[string]ServerStatus {
	defer m.statusLock.RUnlock()
	m.statusLock.RLock()
	return m.statusMap
}

// runMarkAndSweepForwards runs mark-and-sweep on the started forwards every 10 seconds.
// This job is necessary because Docker sometimes forgets to notify us that containers
// were stopped (usually happens when spamming Ctrl+C after `docker compose run`).
func (m *Manager) runMarkAndSweepForwards() {
	ticker := time.NewTicker(time.Second * 10)
	for {
		select {
		case <-m.ctx.Done():
			return
		case <-ticker.C:
			m.markAndSweepForwards()
		}
	}
}

// markAndSweepForwards marks stopped containers for removal on the first run and removes them from forwards later.
// This job will remove containers from forwards if Docker didn't notify us about stopping containers for some reason.
func (m *Manager) markAndSweepForwards() {
	defer m.forwardsLock.Unlock()
	m.forwardsLock.Lock()

	for id, state := range m.forwards {
		forwardIDs := strings.Split(id, ":")
		serverName, containerID := forwardIDs[0], forwardIDs[1]
		_, found := docker.Default.GetContainer(containerID, false)
		if found {
			m.forwards[id] = false // unmark
		} else {
			if state {
				m.processEventStatus(serverName, dto.EventStatus{
					Type: dto.EventStop,
					ID:   containerID,
				})
				continue
			}
			m.forwards[id] = true // mark
		}
	}
}

func (m *Manager) PluginByToken(token string) plugin.Plugin {
	server, ok := m.plugins[token]
	if !ok {
		return nil
	}
	return server
}

func (m *Manager) WaitForShutdown() {
	defer m.rw.RUnlock()
	m.rw.RLock()
	for _, srv := range m.servers {
		srv.WaitForShutdown()
	}
	return
}