package pop3

import (
    "bytes"
    "fmt"
)

// Command only writes; it does not read a reply.
func (framed *Framed) Command(keyword Keyword, arguments ...string) error {
    buf := bytes.NewBuffer(make([]byte, 0, MaximumPhysicalLineLength))
    buf.WriteString(string(keyword))
    for _, argument := range arguments {
        // Cf. RFC 1939 3.
        if framed.Strict && (len(argument) > 40 || !IsASCIIWord(argument)) {
            return fmt.Errorf("%w: invalid command argument: %q", ErrSyntax, argument)
        }
        buf.WriteByte(SP)
        buf.WriteString(argument)
    }
    buf.WriteString(CRLF)

    if framed.Strict && buf.Len() > MaximumPhysicalLineLength {
        // TODO is this restriction there?
        return fmt.Errorf("%w: command line too long (> %d octets)", ErrProtocol, MaximumPhysicalLineLength)
    }

    _, err := framed.transport.Write(buf.Bytes())
    return err
}