From 69f8bbaed6334c2d42180bf86ee43c9182bcb847 Mon Sep 17 00:00:00 2001
From: Robert Worgul <robert.worgul@scitotec.de>
Date: Wed, 18 Aug 2021 21:50:47 +0200
Subject: [PATCH] add computed bcc to Message

---
 message.go      | 71 ++++++++++++++++++++++++++++++++++++++++++++++-
 message_test.go | 73 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 143 insertions(+), 1 deletion(-)

diff --git a/message.go b/message.go
index 58e464b..015a716 100644
--- a/message.go
+++ b/message.go
@@ -7,6 +7,7 @@ import (
 	"io"
 	"log"
 	"mime"
+	"net/mail"
 	"strings"
 	"time"
 )
@@ -51,6 +52,7 @@ type Message struct {
 	ID      MessageID
 	From    *Path
 	To      []*Path
+	Bcc     []*Path
 	Content *Content
 	Created time.Time
 	MIME    *MIMEBody // FIXME refactor to use Content.MIME
@@ -94,11 +96,13 @@ func (m *SMTPMessage) Parse(hostname string) *Message {
 	}
 
 	id, _ := NewMessageID(hostname)
+	content := ContentFromString(m.Data)
 	msg := &Message{
 		ID:      id,
 		From:    PathFromString(m.From),
 		To:      arr,
-		Content: ContentFromString(m.Data),
+		Bcc:     extractBcc(arr, content),
+		Content: content,
 		Created: time.Now(),
 		Raw:     m,
 	}
@@ -328,3 +332,68 @@ func extractBoundary(contentType string) string {
 	}
 	return ""
 }
+
+func (self *Path) equals(other *Path) bool {
+	if self == other {
+		return true
+	}
+	if other == nil {
+		return false
+	}
+	if self.Domain != other.Domain || self.Mailbox != other.Mailbox || self.Params != other.Params || len(self.Relays) != len(other.Relays) {
+		return false
+	}
+	for i := range self.Relays {
+		if self.Relays[i] != other.Relays[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func toPathes(xs []string) []*Path {
+	var arr []*Path
+	for _, x := range xs {
+		as, err := mail.ParseAddressList(x)
+		if err != nil {
+			continue
+		}
+		for _, a := range as {
+			arr = append(arr, PathFromString(a.Address))
+		}
+	}
+	return arr
+}
+
+func remove(s []*Path, i int) []*Path {
+	s[i] = s[len(s)-1]
+	return s[:len(s)-1]
+}
+
+func indexOf(xs []*Path, y *Path) int {
+	for i, x := range xs {
+		if x.equals(y) {
+			return i
+		}
+	}
+	return -1
+}
+
+func extractBcc(allTos []*Path, content *Content) []*Path {
+	var tos = toPathes(content.Headers["To"])
+	var ccs = toPathes(content.Headers["Cc"])
+	var arr []*Path
+	for _, path := range allTos {
+		if i := indexOf(tos, path); i != -1 {
+			tos = remove(tos, i)
+			continue
+		}
+		if i := indexOf(ccs, path); i != -1 {
+			tos = remove(ccs, i)
+			continue
+		}
+
+		arr = append(arr, path)
+	}
+	return arr
+}
diff --git a/message_test.go b/message_test.go
index 32794a7..ba26954 100644
--- a/message_test.go
+++ b/message_test.go
@@ -25,3 +25,76 @@ func TestExtractBoundary(t *testing.T) {
 		}
 	}
 }
+
+func TestPathEquals(t *testing.T) {
+	a := Path{
+		Relays:  []string{"rel"},
+		Mailbox: "foo",
+		Domain:  "bar",
+		Params:  "",
+	}
+
+	if a.equals(nil) {
+		t.Errorf("Path should never be equal to nil")
+	}
+
+	if !a.equals(&a) {
+		t.Errorf("references should be equal")
+	}
+	b := a
+	if !a.equals(&b) {
+		t.Errorf("%s should be equal to %s.", a, b)
+	}
+	mailboxChanged := a
+	mailboxChanged.Mailbox = "!"
+	if a.equals(&mailboxChanged) {
+		t.Errorf("%s should NOT be equal to %s.", a, mailboxChanged)
+	}
+	domainChanged := a
+	domainChanged.Domain = "!"
+	if a.equals(&domainChanged) {
+		t.Errorf("%s should NOT be equal to %s.", a, domainChanged)
+	}
+	paramsChanged := a
+	paramsChanged.Params = "!"
+	if a.equals(&paramsChanged) {
+		t.Errorf("%s should NOT be equal to %s.", a, paramsChanged)
+	}
+	relaysChanged := a
+	relaysChanged.Relays = []string{"baz"}
+	if a.equals(&relaysChanged) {
+		t.Errorf("%s should NOT be equal to %s.", a, relaysChanged)
+	}
+	relaysChanged.Relays = []string{"baz", "rel"}
+	if a.equals(&relaysChanged) {
+		t.Errorf("%s should NOT be equal to %s.", a, relaysChanged)
+	}
+}
+
+func TestExtractBcc(t *testing.T) {
+	content := Content{
+		Size:    42,
+		Headers: map[string][]string{},
+		Body:    "body",
+	}
+	emptyTo := extractBcc(toPathes([]string{}), &content)
+	if l := len(emptyTo); l != 0 {
+		t.Errorf("result should be empty but had %d entries.", l)
+	}
+
+	content.Headers["Cc"] = []string{"admin@localhost, Alice <cjoao0@tinyurl.com>, aalesipo@example.com"}
+	content.Headers["To"] = []string{"circulars@localhost, Bob <mdenslow2@taobao.com>"}
+	allTos := []string{
+		"circulars@localhost", "admin@localhost", "cjoao0@tinyurl.com",
+		"aalesipo@example.com", "admin@localhost", "mdenslow2@taobao.com"}
+	bcc := extractBcc(toPathes(allTos), &content)
+	if l := len(bcc); l != 2 {
+		t.Errorf("%v should have 2 entries but had %d entries.", bcc, l)
+	}
+	for _, x := range []string{"admin@localhost", "mdenslow2@taobao.com"} {
+		if indexOf(bcc, PathFromString(x)) == -1 {
+			t.Errorf("%v should contain %s.", bcc, x)
+		}
+	}
+
+}