package testutil

import "net"
import "fmt"
import "strings"

var _ net.Conn = new(ConnRecorder)

// ConnRecorder records write/flush actions performed on a net.Conn.
type ConnRecorder struct {
	net.Conn
	// A []byte means data was written, and untyped nil
	// means data was flushed.
	Log []any
}

func RecordConn(underlying net.Conn) *ConnRecorder {
	return &ConnRecorder {
		Conn: underlying,
	}
}

func (this *ConnRecorder) Write(data []byte) (n int, err error) {
	this.Log = append(this.Log, data)
	return len(data), nil
}

func (this *ConnRecorder) Flush() error {
	this.Log = append(this.Log, nil)
	return nil
}

func (this *ConnRecorder) Dump() string {
	builder := strings.Builder { }
	for index, item := range this.Log {
		fmt.Fprintf(&builder, "%06d ", index)
		switch item := item.(type) {
		case nil:
			fmt.Fprintln(&builder, "FLUSH")
		case []byte:
			fmt.Fprintln(&builder, HexBytes(item))
		}
	}
	return builder.String()
}