package stan

import (
	"context"
	"github.com/cloudevents/sdk-go/v2/binding"
	"github.com/cloudevents/sdk-go/v2/binding/format"
	"io"
)

// WriteMsg fills the provided writer with the bindings.Message m.
// Using context you can tweak the encoding processing (more details on binding.Write documentation).
func WriteMsg(ctx context.Context, m binding.Message, writer io.ReaderFrom, transformers ...binding.Transformer) error {
	structuredWriter := &stanMessageWriter{writer}

	_, err := binding.Write(
		ctx,
		m,
		structuredWriter,
		nil,
		transformers...,
	)
	return err
}

type stanMessageWriter struct {
	io.ReaderFrom
}

func (w *stanMessageWriter) SetStructuredEvent(_ context.Context, _ format.Format, event io.Reader) error {
	if _, err := w.ReadFrom(event); err != nil {
		return err
	}

	return nil
}

var _ binding.StructuredWriter = (*stanMessageWriter)(nil) // Test it conforms to the interface