// Package server exposes the scoreboard Store over gRPC and HTTP/JSON.
package server

import (
	"context"

	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"

	pb "git.mkz.me/mycroft/root-me-api/gen/scoreboard/v1"
	"git.mkz.me/mycroft/root-me-api/internal/scoreboard"
)

// GRPCServer implements pb.ScoreboardServiceServer over a Store.
type GRPCServer struct {
	pb.UnimplementedScoreboardServiceServer
	Store *scoreboard.Store
}

// NewGRPC returns a gRPC server backed by the given store.
func NewGRPC(store *scoreboard.Store) *GRPCServer { return &GRPCServer{Store: store} }

func (s *GRPCServer) ListScoreboard(_ context.Context, req *pb.ListScoreboardRequest) (*pb.ListScoreboardResponse, error) {
	if !s.Store.Ready() {
		return nil, status.Error(codes.Unavailable, "scoreboard not loaded yet")
	}
	entries, fetchedAt := s.Store.List(int(req.GetOffset()), int(req.GetLimit()))
	resp := &pb.ListScoreboardResponse{
		Total:     int32(s.Store.Len()),
		FetchedAt: fetchedAt.Unix(),
	}
	resp.Entries = make([]*pb.Entry, len(entries))
	for i, e := range entries {
		resp.Entries[i] = toProto(e)
	}
	return resp, nil
}

func (s *GRPCServer) GetByRank(_ context.Context, req *pb.GetByRankRequest) (*pb.Entry, error) {
	if !s.Store.Ready() {
		return nil, status.Error(codes.Unavailable, "scoreboard not loaded yet")
	}
	e, ok := s.Store.ByRank(int(req.GetRank()))
	if !ok {
		return nil, status.Errorf(codes.NotFound, "no entry at rank %d", req.GetRank())
	}
	return toProto(e), nil
}

func (s *GRPCServer) GetByUsername(_ context.Context, req *pb.GetByUsernameRequest) (*pb.Entry, error) {
	if !s.Store.Ready() {
		return nil, status.Error(codes.Unavailable, "scoreboard not loaded yet")
	}
	if req.GetUsername() == "" {
		return nil, status.Error(codes.InvalidArgument, "username is required")
	}
	e, ok := s.Store.ByUsername(req.GetUsername())
	if !ok {
		return nil, status.Errorf(codes.NotFound, "no entry for user %q", req.GetUsername())
	}
	return toProto(e), nil
}

func toProto(e scoreboard.Entry) *pb.Entry {
	return &pb.Entry{
		Rank:        int32(e.Rank),
		Username:    e.Username,
		ProfilePath: e.ProfilePath,
		Country:     e.Country,
		Grade:       e.Grade,
		Score:       int32(e.Score),
	}
}