patch: add auto-switch option

Add an auto-switch option that changes the project of the patch manager
based on the subject line of a message if it contains a '[PATCH
<project>]' segment.

A subject line with '[PATCH aerc v2]' would switch to the 'aerc' project
if that project is available in the patch manager.

The auto switching can be activated per account by adding
'pama-auto-switch = true' to your account config.

Implements: https://todo.sr.ht/~rjarry/aerc/226
Changelog-added: Auto-switch projects based on the message subject
 for the :patch command.
Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

4 files changed, 133 insertions, 1 deletions

diff --git a/app/account.go b/app/account.go
index 7a2cf582..5577e461 100644
--- a/app/account.go
+++ b/app/account.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"strings"
 	"sync"
 	"time"
 
@@ -12,6 +13,7 @@ import (
 	"git.sr.ht/~rjarry/aerc/lib/hooks"
 	"git.sr.ht/~rjarry/aerc/lib/log"
 	"git.sr.ht/~rjarry/aerc/lib/marker"
+	"git.sr.ht/~rjarry/aerc/lib/pama"
 	"git.sr.ht/~rjarry/aerc/lib/sort"
 	"git.sr.ht/~rjarry/aerc/lib/state"
 	"git.sr.ht/~rjarry/aerc/lib/templates"
@@ -337,7 +339,27 @@ func (acct *AccountView) newStore(name string) *lib.MessageStore {
 				PushError(msg)
 			}
 		},
-		acct.updateSplitView,
+		func(msg *models.MessageInfo) {
+			acct.updateSplitView(msg)
+
+			auto := false
+			if c := acct.AccountConfig(); c != nil {
+				r, ok := c.Params["pama-auto-switch"]
+				if ok {
+					if strings.ToLower(r) == "true" {
+						auto = true
+					}
+				}
+			}
+			if !auto {
+				return
+			}
+			var name string
+			if msg != nil && msg.Envelope != nil {
+				name = pama.FromSubject(msg.Envelope.Subject)
+			}
+			pama.DebouncedSwitchProject(name)
+		},
 	)
 	store.Configure(acct.SortCriteria(uiConf))
 	store.SetMarker(marker.New(store))
diff --git a/doc/aerc-accounts.5.scd b/doc/aerc-accounts.5.scd
index 9f52ef8a..399da629 100644
--- a/doc/aerc-accounts.5.scd
+++ b/doc/aerc-accounts.5.scd
@@ -187,6 +187,13 @@ Note that many of these configuration options are written for you, such as
 
 	Default: _true_
 
+*pama-auto-switch* = _true_|_false_
+	If _true_, the patch manager will automatically switch to an existing
+	project for the *:patch* command if the subject contains a '[PATCH <project>]'
+	segment.
+
+	Default: _false_
+
 *pgp-auto-sign* = _true_|_false_
 	If _true_, all outgoing emails from this account will be signed (if a signing
 	key is available).
diff --git a/lib/pama/switch.go b/lib/pama/switch.go
index 4d6b25f7..8190f3c8 100644
--- a/lib/pama/switch.go
+++ b/lib/pama/switch.go
@@ -2,6 +2,10 @@ package pama
 
 import (
 	"fmt"
+	"regexp"
+	"time"
+
+	"git.sr.ht/~rjarry/aerc/lib/log"
 )
 
 func (m PatchManager) SwitchProject(name string) error {
@@ -27,3 +31,35 @@ func (m PatchManager) SwitchProject(name string) error {
 	}
 	return storeErr(m.store().SetCurrent(name))
 }
+
+var switchDebouncer *time.Timer
+
+func DebouncedSwitchProject(name string) {
+	if switchDebouncer != nil {
+		if switchDebouncer.Stop() {
+			log.Debugf("pama: switch debounced")
+		}
+	}
+	if name == "" {
+		return
+	}
+	switchDebouncer = time.AfterFunc(500*time.Millisecond, func() {
+		if err := New().SwitchProject(name); err != nil {
+			log.Debugf("could not switch to project %s: %v",
+				name, err)
+		} else {
+			log.Debugf("project switch to project %s", name)
+		}
+	})
+}
+
+var fromSubject = regexp.MustCompile(
+	`\[\s*(RFC|DRAFT|[Dd]raft)*\s*(PATCH|[Pp]atch)\s+([^\s\]]+)\s*[vV]*[0-9/]*\s*\] `)
+
+func FromSubject(s string) string {
+	matches := fromSubject.FindStringSubmatch(s)
+	if len(matches) >= 3 {
+		return matches[3]
+	}
+	return ""
+}
diff --git a/lib/pama/switch_test.go b/lib/pama/switch_test.go
new file mode 100644
index 00000000..04c72dfa
--- /dev/null
+++ b/lib/pama/switch_test.go
@@ -0,0 +1,67 @@
+package pama_test
+
+import (
+	"testing"
+
+	"git.sr.ht/~rjarry/aerc/lib/pama"
+)
+
+func TestFromSubject(t *testing.T) {
+	tests := []struct {
+		s    string
+		want string
+	}{
+		{
+			s:    "[PATCH aerc] pama: new patch",
+			want: "aerc",
+		},
+		{
+			s:    "[PATCH aerc v2] pama: new patch",
+			want: "aerc",
+		},
+		{
+			s:    "[PATCH aerc 1/2] pama: new patch",
+			want: "aerc",
+		},
+		{
+			s:    "[Patch aerc] pama: new patch",
+			want: "aerc",
+		},
+		{
+			s:    "[patch aerc] pama: new patch",
+			want: "aerc",
+		},
+		{
+			s:    "[RFC PATCH aerc] pama: new patch",
+			want: "aerc",
+		},
+		{
+			s:    "[DRAFT PATCH aerc] pama: new patch",
+			want: "aerc",
+		},
+		{
+			s:    "RE: [PATCH aerc v1] pama: new patch",
+			want: "aerc",
+		},
+		{
+			s:    "[PATCH] pama: new patch",
+			want: "",
+		},
+		{
+			s:    "just a subject line",
+			want: "",
+		},
+		{
+			s:    "just a subject line with unrelated [asdf aerc v1]",
+			want: "",
+		},
+	}
+
+	for _, test := range tests {
+		got := pama.FromSubject(test.s)
+		if got != test.want {
+			t.Errorf("failed to get name from '%s': "+
+				"got '%s', want '%s'", test.s, got, test.want)
+		}
+	}
+}