package grpc

import (
	"context"
	"fmt"
	"log"
	"net"

	pb "github.com/go-skynet/LocalAI/pkg/grpc/proto"
	"google.golang.org/grpc"
)

// A GRPC Server that allows to run LLM inference.
// It is used by the LLMServices to expose the LLM functionalities that are called by the client.
// The GRPC Service is general, trying to encompass all the possible LLM options models.
// It depends on the real implementer then what can be done or not.
//
// The server is implemented as a GRPC service, with the following methods:
// - Predict: to run the inference with options
// - PredictStream: to run the inference with options and stream the results

// server is used to implement helloworld.GreeterServer.
type server struct {
	pb.UnimplementedLLMServer
	llm LLM
}

func (s *server) Health(ctx context.Context, in *pb.HealthMessage) (*pb.Reply, error) {
	return &pb.Reply{Message: "OK"}, nil
}

func (s *server) Embedding(ctx context.Context, in *pb.PredictOptions) (*pb.EmbeddingResult, error) {
	embeds, err := s.llm.Embeddings(in)
	if err != nil {
		return nil, err
	}

	return &pb.EmbeddingResult{Embeddings: embeds}, nil
}

func (s *server) LoadModel(ctx context.Context, in *pb.ModelOptions) (*pb.Result, error) {
	err := s.llm.Load(in)
	if err != nil {
		return &pb.Result{Message: fmt.Sprintf("Error loading model: %s", err.Error()), Success: false}, err
	}
	return &pb.Result{Message: "Loading succeeded", Success: true}, nil
}

func (s *server) Predict(ctx context.Context, in *pb.PredictOptions) (*pb.Reply, error) {
	result, err := s.llm.Predict(in)
	return &pb.Reply{Message: result}, err
}

func (s *server) PredictStream(in *pb.PredictOptions, stream pb.LLM_PredictStreamServer) error {

	resultChan := make(chan string)

	done := make(chan bool)
	go func() {
		for result := range resultChan {
			stream.Send(&pb.Reply{Message: result})
		}
		done <- true
	}()

	s.llm.PredictStream(in, resultChan)
	<-done

	return nil
}

func StartServer(address string, model LLM) error {
	lis, err := net.Listen("tcp", address)
	if err != nil {
		return err
	}
	s := grpc.NewServer()
	pb.RegisterLLMServer(s, &server{llm: model})
	log.Printf("gRPC Server listening at %v", lis.Addr())
	if err := s.Serve(lis); err != nil {
		return err
	}

	return nil
}