dirstore: list the folders in arrival order

List the folders in arrival order when dirstore.List() is called instead
of returning it in an arbitrary order.

If enable-folders-sort=false and dirlist-tree=false, the directory list
will arbitrarly reshuffle when changing directories because the
dirlist.dirs are generated from keys in a map in the dirstore.

Fixes: https://todo.sr.ht/~rjarry/aerc/178
Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

3 files changed, 45 insertions, 1 deletions

diff --git a/lib/dirstore.go b/lib/dirstore.go
index bbf4e20b..8749fb09 100644
--- a/lib/dirstore.go
+++ b/lib/dirstore.go
@@ -1,10 +1,14 @@
 package lib
 
-import "git.sr.ht/~rjarry/aerc/models"
+import (
+	"git.sr.ht/~rjarry/aerc/lib/sort"
+	"git.sr.ht/~rjarry/aerc/models"
+)
 
 type DirStore struct {
 	dirs      map[string]*models.Directory
 	msgStores map[string]*MessageStore
+	order     []string
 }
 
 func NewDirStore() *DirStore {
@@ -19,6 +23,7 @@ func (store *DirStore) List() []string {
 	for dir := range store.msgStores {
 		dirs = append(dirs, dir)
 	}
+	sort.SortStringBy(dirs, store.order)
 	return dirs
 }
 
@@ -28,6 +33,10 @@ func (store *DirStore) MessageStore(dirname string) (*MessageStore, bool) {
 }
 
 func (store *DirStore) SetMessageStore(dir *models.Directory, msgStore *MessageStore) {
+	s := dir.Name
+	if _, ok := store.dirs[s]; !ok {
+		store.order = append(store.order, s)
+	}
 	store.dirs[dir.Name] = dir
 	store.msgStores[dir.Name] = msgStore
 }
diff --git a/lib/dirstore_test.go b/lib/dirstore_test.go
new file mode 100644
index 00000000..b1ba4eb9
--- /dev/null
+++ b/lib/dirstore_test.go
@@ -0,0 +1,23 @@
+package lib_test
+
+import (
+	"reflect"
+	"testing"
+
+	"git.sr.ht/~rjarry/aerc/lib"
+	"git.sr.ht/~rjarry/aerc/models"
+)
+
+func TestDirStore_List(t *testing.T) {
+	dirs := []string{"a/c", "x", "a/b", "d"}
+	dirstore := lib.NewDirStore()
+	for _, d := range dirs {
+		dirstore.SetMessageStore(&models.Directory{Name: d}, nil)
+	}
+	for i := 0; i < 10; i++ {
+		if !reflect.DeepEqual(dirstore.List(), dirs) {
+			t.Errorf("order does not match")
+			return
+		}
+	}
+}
diff --git a/lib/sort/sort.go b/lib/sort/sort.go
index c7e2b8ce..287f986c 100644
--- a/lib/sort/sort.go
+++ b/lib/sort/sort.go
@@ -70,3 +70,15 @@ func SortBy(toSort []uint32, sortBy []uint32) {
 		return uidMap[toSort[i]] < uidMap[toSort[j]]
 	})
 }
+
+// SortStringBy sorts the string slice s according to the order given in the
+// order string slice.
+func SortStringBy(s []string, order []string) {
+	m := make(map[string]int)
+	for i, d := range order {
+		m[d] = i
+	}
+	sort.Slice(s, func(i, j int) bool {
+		return m[s[i]] < m[s[j]]
+	})
+}