papero/fs/maildir.go

package fs

import (
	"fmt"
	"os"
	"strings"
	"time"
)

type Flag string

func cat(f []Flag) string {
	var list []string
	for _, el := range f {
		list = append(list, string(el))
	}
	return strings.Join(list, "")
}

const (
	Seen     Flag = "S"
	Answered      = "R"
	Flagged       = "F"
	Deleted       = "T"
	Draft         = "D"
)

// MailFile holds the information needed to format the name of the file
// containing a single email. The format is:
// `<%d_%d.%d.%s>,U=<%d>,FMD5=<%s>:2,<FLAGS>`
// (logical groups being enclosed by angle brackets) where:
//   - `<%d_%d.%d.%s>` is the concatenation of:
//     * system unix timestamp of arrival time of the message
//     * a progressive number to distinguish messages arrived at once
//     * pid of the current process
//     * hostname of the local machine
//   - `,U=<%d>` holds the UID of the message as decided by the server
//   - `,FMD5=<%s>:2` holds the md5sum of the name of the current mailbox
//   - `,<FLAGS>` carries the flags active on the message
type MailFile struct {
	timestamp   time.Time
	progressive int
	pid         int
	hostname    string
	uid         int
	md5         string
	flags       []Flag
}

func (m *MailFile) SetUid(uid int) {
	m.uid = uid
}

func (m *MailFile) SetMd5(md5 string) {
	m.md5 = md5
}

func (m *MailFile) SetFlags(flags []Flag) {
	m.flags = flags
}

func (m *MailFile) String() string {
	return fmt.Sprintf(
		"%d_%d.%d.%s,U=%d,FMD5=%s:2,%s",
		m.timestamp.Unix(),
		m.progressive,
		m.pid,
		m.hostname,
		m.uid,
		m.md5,
		cat(m.flags),
	)
}

type MailFileRequest struct {
	respCh chan MailFile
}

func NewMailFileRequest() MailFileRequest {
	ch := make(chan MailFile)
	return MailFileRequest{respCh: ch}
}

func (r MailFileRequest) Response() MailFile {
	return <-r.respCh
}

func NewOracle() chan MailFileRequest {
	r := realClock{}
	return newOracle(r)
}

func newOracle(c clock) chan MailFileRequest {
	reqCh := make(chan MailFileRequest, 10)
	go spawnOracle(reqCh, c)
	return reqCh
}

func spawnOracle(reqCh <-chan MailFileRequest, c clock) {
	count := 0
	C := c.Ticker().getC()
	pid := os.Getpid()
	hostname, err := os.Hostname()
	if err != nil {
		hostname = "MISSING"
	}
	for {
		select {
		case <-C:
			count = 0
		case req := <-reqCh:
			req.respCh <- MailFile{
				timestamp:   c.Now(),
				progressive: count,
				pid:         pid,
				hostname:    hostname,
			}
			count += 1
		}
	}
}

type MailDir struct {
	basePath string
}