package collector

import (
	"fmt"
	"io"
	"log"
	"sync"
	"time"

	"gitea.d3m0k1d.ru/d3m0k1d/HellreigN/backend/internal/repository"
	"gitea.d3m0k1d.ru/d3m0k1d/HellreigN/backend/internal/storage"
	"gitea.d3m0k1d.ru/d3m0k1d/HellreigN/proto/proto"
	"google.golang.org/grpc/metadata"
)

type Collector struct {
	proto.UnimplementedCollectorServer
	logRepo       *repository.LogRepository
	agents        map[string]*Agent
	mu            sync.RWMutex
	batchSize     int
	flushInterval time.Duration
}

type Agent struct {
	ID          string
	Label       string
	Services    []string
	ConnectedAt time.Time
}

func New(logRepo *repository.LogRepository) *Collector {
	return &Collector{
		logRepo:       logRepo,
		agents:        make(map[string]*Agent),
		batchSize:     100,
		flushInterval: 2 * time.Second,
	}
}

func (c *Collector) Stream(stream proto.Collector_StreamServer) error {
	md, ok := metadata.FromIncomingContext(stream.Context())
	if !ok {
		return fmt.Errorf("no metadata in context")
	}

	whoamiVals := md["whoami"]
	if len(whoamiVals) == 0 {
		return fmt.Errorf("whoami metadata missing")
	}
	agentName := whoamiVals[0]

	serviceVals := md["service"]
	if len(serviceVals) == 0 {
		return fmt.Errorf("service metadata missing")
	}
	service := serviceVals[0]

	servicesVals := md["services"]
	var services []string
	if len(servicesVals) > 0 {
		services = servicesVals
	}

	// Register agent
	c.mu.Lock()
	c.agents[agentName] = &Agent{
		ID:          agentName,
		Label:       agentName,
		Services:    services,
		ConnectedAt: time.Now(),
	}
	c.mu.Unlock()

	defer func() {
		c.mu.Lock()
		delete(c.agents, agentName)
		c.mu.Unlock()
	}()

	log.Printf("Agent %s connected, streaming logs for service: %s", agentName, service)

	// If no ClickHouse, just consume the stream without storing
	if !c.logRepo.IsConnected() {
		log.Printf(
			"Warning: ClickHouse not connected yet, consuming logs without storing for agent %s",
			agentName,
		)
		for {
			_, err := stream.Recv()
			if err == io.EOF {
				return nil
			}
			if err != nil {
				return fmt.Errorf("failed to receive: %w", err)
			}
		}
	}

	// Channels for communication with recv goroutine
	recvCh := make(chan *proto.CollectorRequest, 1)
	errCh := make(chan error, 1)

	// Goroutine that blocks on Recv
	go func() {
		for {
			req, err := stream.Recv()
			if err != nil {
				errCh <- err
				return
			}
			recvCh <- req
		}
	}()

	// Buffer for batch inserts
	var batch []storage.LogEntry
	ticker := time.NewTicker(c.flushInterval)
	defer ticker.Stop()

	flush := func() error {
		if len(batch) == 0 {
			return nil
		}
		if err := c.logRepo.InsertBatch(stream.Context(), batch); err != nil {
			log.Printf(
				"Failed to insert batch for agent %s, service %s: %v",
				agentName,
				service,
				err,
			)
			return err
		}
		log.Printf("Flushed %d logs for agent %s, service %s", len(batch), agentName, service)
		batch = batch[:0]
		return nil
	}

	for {
		select {
		case <-stream.Context().Done():
			// Context cancelled, flush remaining
			_ = flush()
			return stream.Context().Err()
		case <-ticker.C:
			if err := flush(); err != nil {
				return err
			}
		case req := <-recvCh:
			batch = append(batch, storage.LogEntry{
				Timestamp: time.Now(),
				Level:     "info",
				Service:   service,
				Agent:     agentName,
				Message:   req.Message,
			})

			if len(batch) >= c.batchSize {
				if err := flush(); err != nil {
					return err
				}
			}
		case err := <-errCh:
			if err == io.EOF {
				// Client closed stream
				return flush()
			}
			return fmt.Errorf("failed to receive: %w", err)
		}
	}
}

func (c *Collector) GetAgent(name string) (*Agent, bool) {
	c.mu.RLock()
	defer c.mu.RUnlock()
	a, ok := c.agents[name]
	return a, ok
}

func (c *Collector) Agents() []*Agent {
	c.mu.RLock()
	defer c.mu.RUnlock()
	result := make([]*Agent, 0, len(c.agents))
	for _, a := range c.agents {
		result = append(result, a)
	}
	return result
}

// ServicesStream handles the ServicesUpdate client-streaming RPC.
// Agents send service status updates which are stored in the collector.
// Returns a single response when the agent closes the stream.
func (c *Collector) ServicesStream(stream proto.Collector_ServicesStreamServer) error {
	md, ok := metadata.FromIncomingContext(stream.Context())
	if !ok {
		return fmt.Errorf("no metadata in context")
	}

	whoamiVals := md["whoami"]
	if len(whoamiVals) == 0 {
		return fmt.Errorf("whoami metadata missing")
	}
	agentName := whoamiVals[0]

	log.Printf("Agent %s started services update stream", agentName)

	for {
		update, err := stream.Recv()
		if err == io.EOF {
			log.Printf("Agent %s finished services update stream", agentName)
			return stream.SendAndClose(&proto.ServicesUpdateResp{})
		}
		if err != nil {
			return fmt.Errorf("failed to receive services update: %w", err)
		}

		c.mu.Lock()
		if agent, ok := c.agents[agentName]; ok {
			services := make([]string, 0, len(update.Services))
			for _, s := range update.Services {
				services = append(services, fmt.Sprintf("%s:%s", s.Name, s.Status))
			}
			agent.Services = services
			log.Printf("Updated services for agent %s: %v", agentName, agent.Services)
		} else {
			log.Printf("Warning: received services update for unknown agent %s", agentName)
		}
		c.mu.Unlock()
	}
}