package tenantctx

import (
	"context"

	"google.golang.org/grpc"
	"google.golang.org/grpc/metadata"
)

const headerKey = "x-tenant-id"

func InjectTenantId(ctx context.Context, tenantId string) context.Context {
	return metadata.AppendToOutgoingContext(ctx, headerKey, tenantId)
}

func ExtractTenantId(ctx context.Context) string {
	md, ok := metadata.FromIncomingContext(ctx)
	if !ok {
		return ""
	}
	vals := md.Get(headerKey)
	if len(vals) == 0 {
		return ""
	}
	return vals[0]
}

func UnaryClientInterceptor() grpc.UnaryClientInterceptor {
	return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
		if tid, ok := ctx.Value("tenantId").(string); ok && tid != "" {
			ctx = metadata.AppendToOutgoingContext(ctx, headerKey, tid)
		}
		return invoker(ctx, method, req, reply, cc, opts...)
	}
}