From 25e151f9580add2ff8e77facbda85dd70de29709 Mon Sep 17 00:00:00 2001
From: Robert Sesek <rsesek@bluestatic.org>
Date: Tue, 13 Dec 2016 14:26:02 -0500
Subject: [PATCH] Go back to using pop3.Message rather than IDs for most
 pop3.Mailbox methods.

But also add a Mailbox.GetMessage method to make it easier to convert.
---
 pop3.go        | 20 ++++++++++----------
 pop3/conn.go   | 33 ++++++++++++++++++++++-----------
 pop3/server.go |  5 +++--
 3 files changed, 35 insertions(+), 23 deletions(-)

diff --git a/pop3.go b/pop3.go
index ad4d1a4..6d8dfd2 100644
--- a/pop3.go
+++ b/pop3.go
@@ -123,20 +123,20 @@ func (mb *mailbox) ListMessages() ([]pop3.Message, error) {
 	return msgs, nil
 }
 
-func (mb *mailbox) Retrieve(idx int) (io.ReadCloser, error) {
-	if idx > len(mb.messages) {
-		return nil, errors.New("no such message")
+func (mb *mailbox) GetMessage(id int) pop3.Message {
+	if id > len(mb.messages) {
+		return nil
 	}
-	filename := mb.messages[idx-1].filename
+	return &mb.messages[id-1]
+}
+
+func (mb *mailbox) Retrieve(msg pop3.Message) (io.ReadCloser, error) {
+	filename := msg.(*message).filename
 	return os.Open(filename)
 }
 
-func (mb *mailbox) Delete(idx int) error {
-	message := &mb.messages[idx-1]
-	if message.deleted {
-		return errors.New("already deleted")
-	}
-	message.deleted = true
+func (mb *mailbox) Delete(msg pop3.Message) error {
+	msg.(*message).deleted = true
 	return nil
 }
 
diff --git a/pop3/conn.go b/pop3/conn.go
index 5341bcb..91a2543 100644
--- a/pop3/conn.go
+++ b/pop3/conn.go
@@ -196,12 +196,12 @@ func (conn *connection) doRETR() {
 		return
 	}
 
-	idx, ok := conn.intParam()
-	if !ok {
+	msg := conn.getRequestedMessage()
+	if msg == nil {
 		return
 	}
 
-	rc, err := conn.mb.Retrieve(idx)
+	rc, err := conn.mb.Retrieve(msg)
 	if err != nil {
 		conn.err(err.Error())
 		return
@@ -218,12 +218,12 @@ func (conn *connection) doDELE() {
 		return
 	}
 
-	idx, ok := conn.intParam()
-	if !ok {
+	msg := conn.getRequestedMessage()
+	if msg == nil {
 		return
 	}
 
-	if err := conn.mb.Delete(idx); err != nil {
+	if err := conn.mb.Delete(msg); err != nil {
 		conn.err(err.Error())
 	} else {
 		conn.ok("")
@@ -239,12 +239,23 @@ func (conn *connection) doRSET() {
 	conn.ok("")
 }
 
-func (conn *connection) intParam() (int, bool) {
+func (conn *connection) getRequestedMessage() Message {
 	var cmd string
-	var param int
-	if _, err := fmt.Sscanf(conn.line, "%s %d", &cmd, &param); err != nil {
+	var idx int
+	if _, err := fmt.Sscanf(conn.line, "%s %d", &cmd, &idx); err != nil {
 		conn.err(errSyntax)
-		return 0, false
+		return nil
 	}
-	return param, true
+
+	if idx < 1 {
+		conn.err("invalid message-number")
+		return nil
+	}
+
+	msg := conn.mb.GetMessage(idx)
+	if msg == nil {
+		conn.err("no such message")
+		return nil
+	}
+	return msg
 }
diff --git a/pop3/server.go b/pop3/server.go
index f0377b5..6e5dc36 100644
--- a/pop3/server.go
+++ b/pop3/server.go
@@ -12,8 +12,9 @@ type Message interface {
 
 type Mailbox interface {
 	ListMessages() ([]Message, error)
-	Retrieve(int) (io.ReadCloser, error)
-	Delete(int) error
+	GetMessage(int) Message
+	Retrieve(Message) (io.ReadCloser, error)
+	Delete(Message) error
 	Close() error
 	Reset()
 }
-- 
2.22.5