msglist: allow configuring default split

Add a new setting to configure the default split layout for message list
tabs. The syntax is a bit different from the :split and :vsplit commands
since it needs to convey the direction in the value as well. I didn't
reuse split/vsplit since they are a bit confusing when used in
a configuration file.

The syntax is as follows:

	message-list-split = [<direction>] <size>

The direction is optional and defaults to horizontal. The size is the
number of terminal cells that will be used to display the message list.

All these examples are equivalent:

	message-list-split = horiz 12
	message-list-split = h 12
	message-list-split = 12

Same idea for vertical splits:

	message-list-split = vertical 120
	message-list-split = vert 120
	message-list-split = v 120

Both :split and :vsplit commands remain usable as before. The
configuration options only affect the initial layout at startup.

Add config.SPLIT_* constants and sanitize AccountView.{Split,Vsplit}
methods.

Changelog-added: Configure default message list `:split` or `:vsplit`
 on startup with `message-list-split` in `aerc.conf`.
Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: Tim Culverhouse <tim@timculverhouse.com>

2 files changed, 51 insertions, 0 deletions

diff --git a/config/aerc.conf b/config/aerc.conf
index 51c73a8f..17b9d216 100644
--- a/config/aerc.conf
+++ b/config/aerc.conf
@@ -163,6 +163,19 @@
 #sidebar-width=22
 
 #
+# Default split layout for message list tabs. The syntax is:
+#
+#       [<direction>] <size>
+#
+# <direction> is optional and defaults to horizontal. It can take one
+# of the following values: h, horiz, horizontal, v, vert, vertical.
+#
+# <size> is a positive integer representing the size (in terminal cells)
+# of the message list window.
+#
+#message-list-split=
+
+#
 # Message to display when viewing an empty folder.
 #
 # Default: (no messages)
diff --git a/config/ui.go b/config/ui.go
index 8b10c8a8..a6034d46 100644
--- a/config/ui.go
+++ b/config/ui.go
@@ -5,6 +5,7 @@ import (
 	"math"
 	"path"
 	"regexp"
+	"strconv"
 	"text/template"
 	"time"
 
@@ -32,6 +33,7 @@ type UIConfig struct {
 	MessageViewThisYearTimeFormat string        `ini:"message-view-this-year-time-format"`
 	PinnedTabMarker               string        "ini:\"pinned-tab-marker\" default:\"`\""
 	SidebarWidth                  int           `ini:"sidebar-width" default:"22"`
+	MessageListSplit              SplitParams   `ini:"message-list-split" parse:"ParseSplit"`
 	EmptyMessage                  string        `ini:"empty-message" default:"(no messages)"`
 	EmptyDirlist                  string        `ini:"empty-dirlist" default:"(no folders)"`
 	EmptySubject                  string        `ini:"empty-subject" default:"(no subject)"`
@@ -233,6 +235,42 @@ func (*UIConfig) ParseIndexColumns(section *ini.Section, key *ini.Key) ([]*Colum
 	return ParseColumnDefs(key, section)
 }
 
+type SplitDirection int
+
+const (
+	SPLIT_NONE SplitDirection = iota
+	SPLIT_HORIZONTAL
+	SPLIT_VERTICAL
+)
+
+type SplitParams struct {
+	Direction SplitDirection
+	Size      int
+}
+
+func (*UIConfig) ParseSplit(section *ini.Section, key *ini.Key) (p SplitParams, err error) {
+	re := regexp.MustCompile(`^\s*(v(?:ert(?:ical)?)?|h(?:oriz(?:ontal)?)?)?\s+(\d+)\s*$`)
+	match := re.FindStringSubmatch(key.String())
+	if len(match) != 3 {
+		err = fmt.Errorf("bad option value")
+		return
+	}
+	p.Direction = SPLIT_HORIZONTAL
+	switch match[1] {
+	case "v", "vert", "vertical":
+		p.Direction = SPLIT_VERTICAL
+	case "h", "horiz", "horizontal":
+		p.Direction = SPLIT_HORIZONTAL
+	}
+	size, e := strconv.ParseUint(match[2], 10, 32)
+	if e != nil {
+		err = e
+		return
+	}
+	p.Size = int(size)
+	return
+}
+
 const MANUAL_COMPLETE = math.MaxInt
 
 func (*UIConfig) ParseCompletionMinChars(section *ini.Section, key *ini.Key) (int, error) {