[v3] fix panic on publish methods (#167)

* move publish methods to a separate file
* reorder client methods
* fix panic for publish
* refactoring
* go mod tidy
* rename go.micro => micro
* add comment to README about Set-Cookie headers

client_publish.go

@@ -0,0 +1,84 @@
+package http
+
+import (
+	"context"
+	"os"
+
+	"go.unistack.org/micro/v3/broker"
+	"go.unistack.org/micro/v3/client"
+	"go.unistack.org/micro/v3/codec"
+	"go.unistack.org/micro/v3/errors"
+	"go.unistack.org/micro/v3/metadata"
+)
+
+func (c *Client) publish(ctx context.Context, ps []client.Message, opts ...client.PublishOption) error {
+	var body []byte
+
+	options := client.NewPublishOptions(opts...)
+
+	// get proxy
+	exchange := ""
+	if v, ok := os.LookupEnv("MICRO_PROXY"); ok {
+		exchange = v
+	}
+	// get the exchange
+	if len(options.Exchange) > 0 {
+		exchange = options.Exchange
+	}
+
+	msgs := make([]*broker.Message, 0, len(ps))
+
+	omd, ok := metadata.FromOutgoingContext(ctx)
+	if !ok {
+		omd = metadata.New(2)
+	}
+
+	for _, p := range ps {
+		md := metadata.Copy(omd)
+		topic := p.Topic()
+		if len(exchange) > 0 {
+			topic = exchange
+		}
+		md.Set(metadata.HeaderTopic, topic)
+		iter := p.Metadata().Iterator()
+		var k, v string
+		for iter.Next(&k, &v) {
+			md.Set(k, v)
+		}
+
+		md[metadata.HeaderContentType] = p.ContentType()
+
+		// passed in raw data
+		if d, ok := p.Payload().(*codec.Frame); ok {
+			body = d.Data
+		} else {
+			// use codec for payload
+			cf, err := c.newCodec(p.ContentType())
+			if err != nil {
+				return errors.InternalServerError("go.micro.client", "%+v", err)
+			}
+			// set the body
+			b, err := cf.Marshal(p.Payload())
+			if err != nil {
+				return errors.InternalServerError("go.micro.client", "%+v", err)
+			}
+			body = b
+		}
+		msgs = append(msgs, &broker.Message{Header: md, Body: body})
+	}
+
+	return c.opts.Broker.BatchPublish(
+		ctx,
+		msgs,
+		broker.PublishContext(options.Context),
+		broker.PublishBodyOnly(options.BodyOnly),
+	)
+}
+
+func (c *Client) fnPublish(ctx context.Context, p client.Message, opts ...client.PublishOption) error {
+	return c.publish(ctx, []client.Message{p}, opts...)
+}
+
+func (c *Client) fnBatchPublish(ctx context.Context, ps []client.Message, opts ...client.PublishOption) error {
+	return c.publish(ctx, ps, opts...)
+}