package service

import (
	"context"
	"strings"

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

	statsv1 "github.com/bergabruh/stats-gateway/gen/stats/v1"
	"github.com/bergabruh/stats-gateway/internal/storage"
)

// RecordSpeedTest ingests a single client-side speedtest sample from an edge
// node. Authenticates via Bearer JWT (same scheme as Tunnel), validates the
// request, and persists via the storage layer.
func (s *Service) RecordSpeedTest(ctx context.Context, req *statsv1.RecordSpeedTestRequest) (*statsv1.RecordSpeedTestResponse, error) {
	// 1. JWT auth — mirrors the Tunnel handler.
	md, ok := metadata.FromIncomingContext(ctx)
	if !ok {
		return nil, status.Error(codes.Unauthenticated, "no metadata")
	}
	authH := md.Get("authorization")
	if len(authH) == 0 {
		return nil, status.Error(codes.Unauthenticated, "no auth")
	}
	tok := strings.TrimPrefix(authH[0], "Bearer ")
	if tok == authH[0] {
		return nil, status.Error(codes.Unauthenticated, "expected Bearer")
	}
	if _, err := s.verifier.Verify(tok); err != nil {
		return nil, status.Errorf(codes.Unauthenticated, "auth: %v", err)
	}

	// 2. Input validation.
	if req.Node != "fl" && req.Node != "pl1" {
		return nil, status.Errorf(codes.InvalidArgument, "node: must be 'fl' or 'pl1', got %q", req.Node)
	}
	if !validCountry(req.Country) {
		return nil, status.Errorf(codes.InvalidArgument, "country: must match ^[A-Z]{2}$ or 'XX', got %q", req.Country)
	}
	if req.DlMbps < 0 {
		return nil, status.Errorf(codes.InvalidArgument, "dl_mbps: must be >= 0, got %v", req.DlMbps)
	}
	if req.UlMbps < 0 {
		return nil, status.Errorf(codes.InvalidArgument, "ul_mbps: must be >= 0, got %v", req.UlMbps)
	}
	if req.PingMs < 0 {
		return nil, status.Errorf(codes.InvalidArgument, "ping_ms: must be >= 0, got %v", req.PingMs)
	}
	if req.JitterMs < 0 {
		return nil, status.Errorf(codes.InvalidArgument, "jitter_ms: must be >= 0, got %v", req.JitterMs)
	}
	if req.Timestamp <= 0 {
		return nil, status.Errorf(codes.InvalidArgument, "timestamp: must be > 0, got %d", req.Timestamp)
	}

	// 3. Persist.
	id, err := s.store.SaveSpeedTest(ctx, storage.SpeedTest{
		Timestamp: req.Timestamp,
		Node:      req.Node,
		Country:   req.Country,
		DlMbps:    req.DlMbps,
		UlMbps:    req.UlMbps,
		PingMs:    req.PingMs,
		JitterMs:  req.JitterMs,
	})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "save: %v", err)
	}
	return &statsv1.RecordSpeedTestResponse{Id: id}, nil
}

// validCountry returns true when c is two uppercase ASCII letters (ISO-3166-1
// alpha-2 shape) or the literal "XX" sentinel for unknown.
func validCountry(c string) bool {
	if len(c) != 2 {
		return false
	}
	if c == "XX" {
		return true
	}
	for i := 0; i < 2; i++ {
		if c[i] < 'A' || c[i] > 'Z' {
			return false
		}
	}
	return true
}