// Package econetgrpc implements the EconetService gRPC API over a shared
// econetclient.Client, exposing read-only device state.
package econetgrpc

import (
	"context"

	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/codes"
	"go.opentelemetry.io/otel/trace"
	grpccodes "google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"

	"gitea.libretechconsulting.com/rmcguire/go-app/pkg/otel"

	pb "gitea.libretechconsulting.com/rmcguire/econet-exporter/api/econet/v1alpha1"
	"gitea.libretechconsulting.com/rmcguire/econet-exporter/pkg/config"
	"gitea.libretechconsulting.com/rmcguire/econet-exporter/pkg/econet/econetclient"
)

type EconetGRPCServer struct {
	tracer trace.Tracer
	ctx    context.Context
	cfg    *config.ServiceConfig
	client *econetclient.Client
	pb.UnimplementedEconetServiceServer
}

func NewEconetGRPCServer(ctx context.Context, cfg *config.ServiceConfig, client *econetclient.Client) *EconetGRPCServer {
	return &EconetGRPCServer{
		ctx:    ctx,
		cfg:    cfg,
		client: client,
		tracer: otel.GetTracer(ctx, "econetGRPCServer"),
	}
}

func (s *EconetGRPCServer) ListDevices(ctx context.Context, _ *pb.ListDevicesRequest) (
	*pb.ListDevicesResponse, error,
) {
	_, span := s.tracer.Start(ctx, "listDevices")
	defer span.End()

	devices := s.client.Devices()
	resp := &pb.ListDevicesResponse{Devices: make([]*pb.Device, 0, len(devices))}
	for _, d := range devices {
		resp.Devices = append(resp.Devices, deviceToProto(d))
	}

	span.SetAttributes(attribute.Int("devices", len(resp.Devices)))
	span.SetStatus(codes.Ok, "")
	return resp, nil
}

func (s *EconetGRPCServer) GetDevice(ctx context.Context, req *pb.GetDeviceRequest) (
	*pb.GetDeviceResponse, error,
) {
	_, span := s.tracer.Start(ctx, "getDevice", trace.WithAttributes(
		attribute.String("serialNumber", req.GetSerialNumber()),
	))
	defer span.End()

	d := s.client.Device(req.GetSerialNumber())
	if d == nil {
		err := status.Errorf(grpccodes.NotFound, "no device with serial %q", req.GetSerialNumber())
		span.SetStatus(codes.Error, err.Error())
		return nil, err
	}

	span.SetStatus(codes.Ok, "")
	return &pb.GetDeviceResponse{Device: deviceToProto(d)}, nil
}

// DeviceRawJSON returns the undecoded EcoNet equipment payload for a device,
// used by the web UI's debug view. ok is false if the serial is unknown or no
// raw payload was captured. It is a debug accessor, not part of the RPC surface.
func (s *EconetGRPCServer) DeviceRawJSON(serial string) ([]byte, bool) {
	d := s.client.Device(serial)
	if d == nil || len(d.Raw) == 0 {
		return nil, false
	}
	return d.Raw, true
}

// modeSlugs maps the settable proto Mode enum to the normalized slugs the
// client (and Device.mode) use. MODE_UNSPECIFIED is intentionally absent;
// protovalidate rejects it before we get here.
var modeSlugs = map[pb.Mode]string{
	pb.Mode_MODE_OFF:           "off",
	pb.Mode_MODE_ELECTRIC:      "electric",
	pb.Mode_MODE_ENERGY_SAVING: "energy-saving",
	pb.Mode_MODE_HEAT_PUMP:     "heat-pump",
	pb.Mode_MODE_HIGH_DEMAND:   "high-demand",
	pb.Mode_MODE_GAS:           "gas",
	pb.Mode_MODE_PERFORMANCE:   "performance",
	pb.Mode_MODE_VACATION:      "vacation",
	pb.Mode_MODE_ELECTRIC_GAS:  "electric-gas",
}

// ModeSlug returns the normalized slug for a settable Mode, or "" if unknown.
func ModeSlug(m pb.Mode) string { return modeSlugs[m] }

// modeFromSlug is the reverse of modeSlugs; ok is false for slugs with no
// settable enum (e.g. "unknown").
func modeFromSlug(slug string) (pb.Mode, bool) {
	for m, s := range modeSlugs {
		if s == slug {
			return m, true
		}
	}
	return pb.Mode_MODE_UNSPECIFIED, false
}

func (s *EconetGRPCServer) SetMode(ctx context.Context, req *pb.SetModeRequest) (
	*pb.SetModeResponse, error,
) {
	ctx, span := s.tracer.Start(ctx, "setMode", trace.WithAttributes(
		attribute.String("serialNumber", req.GetSerialNumber()),
		attribute.String("mode", req.GetMode().String()),
	))
	defer span.End()

	slug, ok := modeSlugs[req.GetMode()]
	if !ok {
		err := status.Errorf(grpccodes.InvalidArgument, "unsupported mode %q", req.GetMode())
		span.SetStatus(codes.Error, err.Error())
		return nil, err
	}

	if err := s.client.SetMode(ctx, req.GetSerialNumber(), slug); err != nil {
		err := status.Error(grpccodes.FailedPrecondition, err.Error())
		span.SetStatus(codes.Error, err.Error())
		return nil, err
	}

	span.SetStatus(codes.Ok, "")
	// State applies asynchronously; return the last-known snapshot. Guard against
	// a concurrent refresh evicting the device between publish and lookup.
	resp := &pb.SetModeResponse{}
	if d := s.client.Device(req.GetSerialNumber()); d != nil {
		resp.Device = deviceToProto(d)
	}
	return resp, nil
}