From c816103a24757bd0e91f7d96b60073a3063bc85a Mon Sep 17 00:00:00 2001
From: Robin Jarry <robin@jarry.cc>
Date: Thu, 28 Jul 2022 23:10:30 +0200
Subject: [PATCH] pipe: fix ordering by message id for long patch series

Git send-email Message-Id headers have the following format:

   DATETIME.PID-NUM-COMMITTER

Unfortunately, when there are more than 9 patches, the patch number
(NUM) is not zero-padded which makes ascii sorting invalid, e.g.:

   1 10 11 12 2 3 4 5 6 7 8 9

Instead of:

   1 2 3 4 5 6 7 8 9 10 11 12

We need the patches to be ordered correctly to pipe them to git am.

Make sure to pad the patch number with zero characters to allow series
of up to 999 patches.

Only re-order messages before piping them if all the Message-Id headers
look like git-send-email headers.

Link: https://github.com/git/git/blob/v2.36.0/git-send-email.perl#L1197
Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: Koni Marti <koni.marti@gmail.com>
---
 commands/msg/pipe.go | 49 ++++++++++++++++++++++++++++++++++++--------
 1 file changed, 40 insertions(+), 9 deletions(-)

diff --git a/commands/msg/pipe.go b/commands/msg/pipe.go
index 35ee05b..71e402d 100644
--- a/commands/msg/pipe.go
+++ b/commands/msg/pipe.go
@@ -5,7 +5,9 @@ import (
 	"fmt"
 	"io"
 	"os/exec"
+	"regexp"
 	"sort"
+	"strconv"
 	"time"
 
 	"git.sr.ht/~rjarry/aerc/commands"
@@ -164,16 +166,28 @@ func (Pipe) Execute(aerc *widgets.Aerc, args []string) error {
 				}
 			}
 
-			// Sort all messages by increasing Message-Id header.
-			// This will ensure that patch series are applied in order.
-			sort.Slice(messages, func(i, j int) bool {
-				infoi := store.Messages[messages[i].Content.Uid]
-				infoj := store.Messages[messages[j].Content.Uid]
-				if infoi == nil || infoj == nil {
-					return false
+			is_git_patches := true
+			for _, msg := range messages {
+				info := store.Messages[msg.Content.Uid]
+				if info == nil || !gitMessageIdRe.MatchString(info.Envelope.MessageId) {
+					is_git_patches = false
+					break
 				}
-				return infoi.Envelope.MessageId < infoj.Envelope.MessageId
-			})
+			}
+			if is_git_patches {
+				// Sort all messages by increasing Message-Id header.
+				// This will ensure that patch series are applied in order.
+				sort.Slice(messages, func(i, j int) bool {
+					infoi := store.Messages[messages[i].Content.Uid]
+					infoj := store.Messages[messages[j].Content.Uid]
+					if infoi == nil || infoj == nil {
+						return false
+					}
+					msgidi := padGitMessageId(infoi.Envelope.MessageId)
+					msgidj := padGitMessageId(infoj.Envelope.MessageId)
+					return msgidi < msgidj
+				})
+			}
 
 			reader := newMessagesReader(messages, len(messages) > 1)
 			if background {
@@ -219,3 +233,20 @@ func newMessagesReader(messages []*types.FullMessage, useMbox bool) io.Reader {
 	}()
 	return pr
 }
+
+var gitMessageIdRe = regexp.MustCompile(`^(\d+\.\d+)-(\d+)-(.+)$`)
+
+// Git send-email Message-Id headers have the following format:
+//    DATETIME.PID-NUM-COMMITTER
+// Return a copy of the message id with NUM zero-padded to three characters.
+func padGitMessageId(msgId string) string {
+	matches := gitMessageIdRe.FindStringSubmatch(msgId)
+	if matches == nil {
+		return msgId
+	}
+	number, err := strconv.Atoi(matches[2])
+	if err != nil {
+		return msgId
+	}
+	return fmt.Sprintf("%s-%03d-%s", matches[1], number, matches[3])
+}