package bus

import (
	"fmt"

	"github.com/novox/mesh-tools/node-tools/internal/wire"
)

// An answer larger than the bus carries in one message (novox/hq issue 314).
//
// The bus carries one message of at most its max_payload, and the client library refuses a larger one
// before it leaves the process that sent it. A module's answer too large is refused here, loudly, in a
// message that fits, so its caller reads why instead of waiting out RequestTimeout.

// fits is an answer the bus can carry: the answer itself, or — when it is larger than one message —
// an error that says so, which is.
func (c *Conn) fits(subject string, body []byte) []byte {
	limit := c.nc.MaxPayload()
	if limit <= 0 || int64(len(body)) <= limit {
		return body
	}
	c.Logf("[mesh-tools] the answer on %s is %d bytes, more than the bus carries in one message (%d): its caller "+
		"is told so instead", subject, len(body), limit)
	said, _ := wire.Marshal(reply{Node: c.node, Error: fmt.Sprintf("the answer is %d bytes, more than the bus "+
		"carries in one message (%d), so it was not sent: ask for less — a narrower question, a shorter window, "+
		"fewer lines", len(body), limit)})
	return said
}