package proxy

import (
	"crypto/tls"
	"errors"
	"net"
	"time"
)

type splitterShutdown interface {
	PendingCount() int
	Disconnect()
}

// New wires the proxy and returns a ready-to-start instance.
//
//	p, errorValue := proxy.New(config)
func New(config *Config) (*Proxy, error) {
	if config == nil {
		return nil, errors.New("config is nil")
	}
	if errorValue := config.Validate(); errorValue != nil {
		return nil, errorValue
	}

	eventBus := NewEventBus()
	statsValue := NewStats()
	customDifficultyFilter := NewCustomDiff(config.CustomDiff)
	eventBus.Subscribe(EventLogin, customDifficultyFilter.OnLogin)
	workersValue := NewWorkers(config.Workers, eventBus)
	workersValue.SetCustomDiffStats(config.CustomDiffStats)
	splitterValue := newSplitter(config, eventBus)

	proxyInstance := &Proxy{
		config:           config,
		customDifficulty: customDifficultyFilter,
		splitter:         splitterValue,
		stats:            statsValue,
		workers:          workersValue,
		events:           eventBus,
		miners:           make(map[int64]*Miner),
		rateLimiter:      NewRateLimiter(config.RateLimit),
		done:             make(chan struct{}),
	}

	proxyInstance.accessLogger = subscribeAccessLog(eventBus, config.AccessLogFile)
	proxyInstance.shareLogger = subscribeShareLog(eventBus, config.ShareLogFile)

	eventBus.Subscribe(EventLogin, func(event Event) {
		if event.Miner != nil {
			proxyInstance.minerMu.Lock()
			proxyInstance.miners[event.Miner.ID()] = event.Miner
			proxyInstance.minerMu.Unlock()
		}
		current := proxyInstance.currentMiners.Add(1)
		for {
			maximum := statsValue.maxMiners.Load()
			if current <= maximum || statsValue.maxMiners.CompareAndSwap(maximum, current) {
				break
			}
		}
	})
	eventBus.Subscribe(EventClose, func(event Event) {
		if event.Miner != nil {
			proxyInstance.minerMu.Lock()
			delete(proxyInstance.miners, event.Miner.ID())
			proxyInstance.minerMu.Unlock()
		}
		if proxyInstance.currentMiners.Load() > 0 {
			proxyInstance.currentMiners.Add(^uint64(0))
		}
	})
	eventBus.Subscribe(EventAccept, statsValue.OnAccept)
	eventBus.Subscribe(EventReject, statsValue.OnReject)
	if splitterValue != nil {
		eventBus.Subscribe(EventSubmit, func(event Event) {
			splitterValue.OnSubmit(&SubmitEvent{
				Miner:     event.Miner,
				JobID:     event.JobID,
				Nonce:     event.Nonce,
				Result:    event.Result,
				Algo:      event.Algo,
				RequestID: event.RequestID,
			})
		})
		eventBus.Subscribe(EventLogin, func(event Event) {
			splitterValue.OnLogin(&LoginEvent{Miner: event.Miner})
		})
		eventBus.Subscribe(EventClose, func(event Event) {
			splitterValue.OnClose(&CloseEvent{Miner: event.Miner})
		})
	}
	if config.Watch && config.sourcePath != "" {
		proxyInstance.watcher = newConfigWatcher(config.sourcePath, proxyInstance.Reload, config.Watch)
		proxyInstance.watcher.Start()
	}

	return proxyInstance, nil
}

// Start connects the pool, opens listeners, and blocks until `Stop()`.
//
//	p.Start()
func (p *Proxy) Start() {
	if p.splitter != nil {
		p.splitter.Connect()
	}
	p.ticker = time.NewTicker(time.Second)

	for _, bind := range p.config.Bind {
		var tlsConfig *tls.Config
		if bind.TLS && p.config.TLS.Enabled {
			certificate, errorValue := tls.LoadX509KeyPair(p.config.TLS.CertFile, p.config.TLS.KeyFile)
			if errorValue == nil {
				tlsConfig = buildTLSConfig(p.config.TLS)
				tlsConfig.Certificates = []tls.Certificate{certificate}
			} else {
				p.Stop()
				return
			}
		}
		server, errorValue := NewServer(bind, tlsConfig, p.rateLimiter, p.acceptConn)
		if errorValue != nil {
			p.Stop()
			return
		}
		p.servers = append(p.servers, server)
		server.Start()
	}

	if p.config != nil && p.config.HTTP.Enabled {
		startHTTPServer(p)
	}

	go func() {
		var ticks uint64
		for {
			select {
			case <-p.ticker.C:
				ticks++
				p.stats.Tick()
				p.workers.Tick()
				if p.rateLimiter != nil {
					p.rateLimiter.Tick()
				}
				if p.splitter != nil {
					p.splitter.Tick(ticks)
				}
			case <-p.done:
				return
			}
		}
	}()

	<-p.done
}

type noopSplitter struct{}

func (noopSplitter) Connect()                    {}
func (noopSplitter) OnLogin(event *LoginEvent)   {}
func (noopSplitter) OnSubmit(event *SubmitEvent) {}
func (noopSplitter) OnClose(event *CloseEvent)   {}
func (noopSplitter) Tick(ticks uint64)           {}
func (noopSplitter) GC()                         {}
func (noopSplitter) Upstreams() UpstreamStats    { return UpstreamStats{} }
func (noopSplitter) PendingCount() int           { return 0 }
func (noopSplitter) Disconnect()                 {}

func noopSplitterFactory(cfg *Config, events *EventBus) Splitter {
	return noopSplitter{}
}

// Stop closes listeners, log files, watcher, miners, and pool connections.
//
//	p.Stop()
func (p *Proxy) Stop() {
	if p.ticker != nil {
		p.ticker.Stop()
	}
	for _, server := range p.servers {
		server.Stop()
	}
	stopHTTPServer(p)
	if p.accessLogger != nil {
		p.accessLogger.close()
	}
	if p.shareLogger != nil {
		p.shareLogger.close()
	}
	if p.watcher != nil {
		p.watcher.Stop()
	}

	if shutdown, ok := p.splitter.(splitterShutdown); ok {
		deadline := time.Now().Add(5 * time.Second)
		for shutdown.PendingCount() > 0 && time.Now().Before(deadline) {
			time.Sleep(50 * time.Millisecond)
		}
	}

	p.minerMu.RLock()
	miners := make([]*Miner, 0, len(p.miners))
	for _, miner := range p.miners {
		miners = append(miners, miner)
	}
	p.minerMu.RUnlock()
	for _, miner := range miners {
		if miner != nil {
			miner.Close()
		}
	}

	if shutdown, ok := p.splitter.(splitterShutdown); ok {
		shutdown.Disconnect()
	}

	select {
	case <-p.done:
	default:
		close(p.done)
	}
}

// Reload replaces the live config.
//
//	p.Reload(newCfg)
func (p *Proxy) Reload(config *Config) {
	if config != nil {
		if p.config == nil {
			p.config = config
		} else {
			sourcePath := p.config.sourcePath
			bind := append([]BindAddr(nil), p.config.Bind...)
			*p.config = *config
			p.config.sourcePath = sourcePath
			p.config.Bind = bind
		}
		if p.customDifficulty != nil {
			p.customDifficulty.SetGlobalDiff(p.config.CustomDiff)
		}
		if p.workers != nil {
			p.workers.SetCustomDiffStats(p.config.CustomDiffStats)
		}
		if p.rateLimiter != nil {
			p.rateLimiter.SetConfig(p.config.RateLimit)
		}
		if p.accessLogger != nil {
			p.accessLogger.setPath(p.config.AccessLogFile)
		}
		if p.shareLogger != nil {
			p.shareLogger.setPath(p.config.ShareLogFile)
		}
	}
}

func (p *Proxy) Summary() StatsSummary {
	if p == nil || p.stats == nil {
		return StatsSummary{}
	}
	return p.stats.Summary()
}

func (p *Proxy) Workers() []WorkerRecord {
	if p == nil || p.workers == nil {
		return nil
	}
	return p.workers.List()
}

func (p *Proxy) Miners() []*Miner {
	if p == nil {
		return nil
	}

	p.minerMu.RLock()
	defer p.minerMu.RUnlock()

	miners := make([]*Miner, 0, len(p.miners))
	for _, miner := range p.miners {
		miners = append(miners, miner)
	}
	return miners
}

func (p *Proxy) CurrentMiners() uint64 {
	if p == nil {
		return 0
	}
	return p.currentMiners.Load()
}

func (p *Proxy) MaxMiners() uint64 {
	if p == nil || p.stats == nil {
		return 0
	}
	return p.stats.maxMiners.Load()
}

func (p *Proxy) Mode() string {
	if p == nil || p.config == nil {
		return ""
	}
	return p.config.Mode
}

func (p *Proxy) HTTPConfig() HTTPConfig {
	if p == nil || p.config == nil {
		return HTTPConfig{}
	}
	return p.config.HTTP
}

func (p *Proxy) WorkersMode() string {
	if p == nil || p.config == nil {
		return ""
	}
	return string(p.config.Workers)
}

func (p *Proxy) Upstreams() UpstreamStats {
	if p == nil || p.splitter == nil {
		return UpstreamStats{}
	}
	return p.splitter.Upstreams()
}

func (p *Proxy) acceptConn(conn net.Conn, localPort uint16) {
	if p != nil && p.stats != nil {
		p.stats.connections.Add(1)
	}

	var tlsConfig *tls.Config
	if _, ok := conn.(*tls.Conn); ok {
		tlsConfig = &tls.Config{}
	}
	miner := NewMiner(conn, localPort, tlsConfig)
	miner.events = p.events
	miner.splitter = p.splitter
	if p.config != nil {
		miner.accessPassword = p.config.AccessPassword
		miner.algoExtension = p.config.AlgoExtension
	}
	miner.Start()
}