ui: add :split and :vsplit view options

Add :split and :vsplit commands, which split the message list view to
include a message viewer. Each command takes an int, or a delta value
("+1", "-1"). The int value is the resulting size of the message list,
and a new message viewer will be displayed below / to the right of the
message list. This viewer *does not* set seen flags.

Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>
Acked-by: Robin Jarry <robin@jarry.cc>

CHANGELOG.md

@@ -24,6 +24,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   defined in their environment.
 - Warn before sending emails that may need an attachment with
   `no-attachment-warning` in `aerc.conf`.
+- 3 panel view via `:split` and `:vsplit`
 
 ### Changed
 

commands/account/split.go

@@ -0,0 +1,63 @@
+package account
+
+import (
+	"errors"
+	"strconv"
+	"strings"
+
+	"git.sr.ht/~rjarry/aerc/widgets"
+)
+
+type Split struct{}
+
+func init() {
+	register(Split{})
+}
+
+func (Split) Aliases() []string {
+	return []string{"split", "vsplit"}
+}
+
+func (Split) Complete(aerc *widgets.Aerc, args []string) []string {
+	return nil
+}
+
+func (Split) Execute(aerc *widgets.Aerc, args []string) error {
+	if len(args) > 2 {
+		return errors.New("Usage: [v]split n")
+	}
+	acct := aerc.SelectedAccount()
+	if acct == nil {
+		return errors.New("No account selected")
+	}
+	n := 0
+	var err error
+	if len(args) > 1 {
+		delta := false
+		if strings.HasPrefix(args[1], "+") || strings.HasPrefix(args[1], "-") {
+			delta = true
+		}
+		n, err = strconv.Atoi(args[1])
+		if err != nil {
+			return errors.New("Usage: [v]split n")
+		}
+		if delta {
+			n = acct.SplitSize() + n
+			// Maintain split direction when using deltas
+			if acct.SplitSize() > 0 {
+				args[0] = acct.SplitDirection()
+			}
+		}
+	}
+	if n == acct.SplitSize() {
+		// Repeated commands of the same size have the effect of
+		// toggling the split
+		n = 0
+	}
+	if args[0] == "split" {
+		acct.Split(n)
+		return nil
+	}
+	acct.Vsplit(n)
+	return nil
+}

doc/aerc.1.scd

@@ -355,6 +355,14 @@ message list, the message in the message viewer, etc).
 	Selects the nth message in the message list (and scrolls it into view if
 	necessary).
 
+*split* [+|-] [<n>]
+	Creates a horizontal split, showing a <n> messages and a message view
+	below the message list. If a + or - is prepended, the message list size
+	will grow or shrink accordingly. The split can be cleared by calling
+	:split 0, or just :split. The split can be toggled by calling split with
+	the same size repeatedly. For example, :split 10 will create a split.
+	Calling :split 10 again will remove the split. Also see *vsplit*
+
 *sort* [[-r] <criterion>]...
 	Sorts the message list by the given criteria. *-r* sorts the
 	immediately following criterion in reverse order.
@@ -389,6 +397,15 @@ message list, the message in the message viewer, etc).
 	flag -p is set, the message will not be marked as "seen" and ignores the
 	"auto-mark-read" config.
 
+*vsplit* [+|-] [<n>]
+	Creates a vertical split of the message list. The message list will be
+	<n> columns wide, and a vertical message view will be shown to the right
+	of the message list. If a + or - is prepended, the message list size
+	will grow or shrink accordingly. The split can be cleared by calling
+	:vsplit 0, or just :vsplit. The split can be toggled by calling split
+	with the same size repeatedly. For example, :vsplit 10 will create a
+	split. Calling :vsplit 10 again will remove the split. Also see *split*
+
 ## MESSAGE VIEW COMMANDS
 
 *close*

lib/ui/grid.go

@@ -234,6 +234,24 @@ func (grid *Grid) RemoveChild(content Drawable) {
 	grid.Invalidate()
 }
 
+func (grid *Grid) ReplaceChild(old Drawable, new Drawable) {
+	grid.mutex.Lock()
+	for i, cell := range grid.cells {
+		if cell.Content == old {
+			grid.cells[i] = &GridCell{
+				RowSpan: cell.RowSpan,
+				ColSpan: cell.ColSpan,
+				Row:     cell.Row,
+				Column:  cell.Column,
+				Content: new,
+			}
+			break
+		}
+	}
+	grid.mutex.Unlock()
+	grid.Invalidate()
+}
+
 func Const(i int) func() int {
 	return func() int { return i }
 }

widgets/account.go

@@ -37,6 +37,12 @@ type AccountView struct {
 	newConn bool // True if this is a first run after a new connection/reconnection
 	uiConf  *config.UIConfig
 
+	split         *MessageViewer
+	splitSize     int
+	splitDebounce *time.Timer
+	splitMsg      *models.MessageInfo
+	splitDir      string
+
 	// Check-mail ticker
 	ticker       *time.Ticker
 	checkingMail bool
@@ -151,6 +157,9 @@ func (acct *AccountView) Draw(ctx *ui.Context) {
 	if acct.state.SetWidth(ctx.Width()) {
 		acct.UpdateStatus()
 	}
+	if acct.SplitSize() > 0 {
+		acct.UpdateSplitView()
+	}
 	acct.grid.Draw(ctx)
 }
 
@@ -466,3 +475,147 @@ func (acct *AccountView) CheckMailTimer(d time.Duration) {
 		}
 	}()
 }
+
+func (acct *AccountView) clearSplit() {
+	if acct.split != nil {
+		acct.split.Close()
+	}
+	acct.splitSize = 0
+	acct.splitDir = ""
+	acct.split = nil
+	acct.grid = ui.NewGrid().Rows([]ui.GridSpec{
+		{Strategy: ui.SIZE_WEIGHT, Size: ui.Const(1)},
+	}).Columns([]ui.GridSpec{
+		{Strategy: ui.SIZE_EXACT, Size: func() int {
+			return acct.UiConfig().SidebarWidth
+		}},
+		{Strategy: ui.SIZE_WEIGHT, Size: ui.Const(1)},
+	})
+
+	if acct.uiConf.SidebarWidth > 0 {
+		acct.grid.AddChild(ui.NewBordered(acct.dirlist, ui.BORDER_RIGHT, acct.uiConf))
+	}
+	acct.grid.AddChild(acct.msglist).At(0, 1)
+	ui.Invalidate()
+}
+
+func (acct *AccountView) UpdateSplitView() {
+	if acct.Store() == nil {
+		return
+	}
+	if acct.splitMsg == acct.msglist.Selected() {
+		return
+	}
+	if acct.splitDebounce != nil {
+		acct.splitDebounce.Stop()
+	}
+	fn := func() {
+		if acct.split != nil {
+			acct.split.Close()
+		}
+		msg, err := acct.SelectedMessage()
+		if err != nil {
+			return
+		}
+		lib.NewMessageStoreView(msg, false, acct.Store(), acct.aerc.Crypto, acct.aerc.DecryptKeys,
+			func(view lib.MessageView, err error) {
+				if err != nil {
+					acct.aerc.PushError(err.Error())
+					return
+				}
+				orig := acct.split
+				acct.split = NewMessageViewer(acct, acct.conf, view)
+				acct.grid.ReplaceChild(orig, acct.split)
+			})
+		acct.splitMsg = msg
+		ui.Invalidate()
+	}
+	acct.splitDebounce = time.AfterFunc(100*time.Millisecond, func() {
+		ui.QueueFunc(fn)
+	})
+}
+
+func (acct *AccountView) SplitSize() int {
+	return acct.splitSize
+}
+
+func (acct *AccountView) SplitDirection() string {
+	return acct.splitDir
+}
+
+// Split splits the message list view horizontally. The message list will be n
+// rows high. If n is 0, any existing split is removed
+func (acct *AccountView) Split(n int) {
+	if n == 0 {
+		acct.clearSplit()
+		return
+	}
+	acct.splitSize = n
+	acct.splitDir = "split"
+	if acct.split != nil {
+		acct.split.Close()
+	}
+	acct.grid = ui.NewGrid().Rows([]ui.GridSpec{
+		// Add 1 so that the splitSize is the number of visible messages
+		{Strategy: ui.SIZE_EXACT, Size: ui.Const(acct.splitSize + 1)},
+		{Strategy: ui.SIZE_WEIGHT, Size: ui.Const(1)},
+	}).Columns([]ui.GridSpec{
+		{Strategy: ui.SIZE_EXACT, Size: func() int {
+			return acct.UiConfig().SidebarWidth
+		}},
+		{Strategy: ui.SIZE_WEIGHT, Size: ui.Const(1)},
+	})
+
+	if acct.uiConf.SidebarWidth > 0 {
+		acct.grid.AddChild(ui.NewBordered(acct.dirlist, ui.BORDER_RIGHT, acct.uiConf)).Span(2, 1)
+	}
+	acct.grid.AddChild(ui.NewBordered(acct.msglist, ui.BORDER_BOTTOM, acct.uiConf)).At(0, 1)
+	lib.NewMessageStoreView(acct.msglist.Selected(), false, acct.Store(), acct.aerc.Crypto, acct.aerc.DecryptKeys,
+		func(view lib.MessageView, err error) {
+			if err != nil {
+				acct.aerc.PushError(err.Error())
+				return
+			}
+			acct.split = NewMessageViewer(acct, acct.conf, view)
+			acct.grid.AddChild(acct.split).At(1, 1)
+		})
+	ui.Invalidate()
+}
+
+// Vsplit splits the message list view vertically. The message list will be n
+// rows wide. If n is 0, any existing split is removed
+func (acct *AccountView) Vsplit(n int) {
+	if n == 0 {
+		acct.clearSplit()
+		return
+	}
+	acct.splitSize = n
+	acct.splitDir = "vsplit"
+	if acct.split != nil {
+		acct.split.Close()
+	}
+	acct.grid = ui.NewGrid().Rows([]ui.GridSpec{
+		{Strategy: ui.SIZE_WEIGHT, Size: ui.Const(1)},
+	}).Columns([]ui.GridSpec{
+		{Strategy: ui.SIZE_EXACT, Size: func() int {
+			return acct.UiConfig().SidebarWidth
+		}},
+		{Strategy: ui.SIZE_EXACT, Size: ui.Const(acct.splitSize)},
+		{Strategy: ui.SIZE_WEIGHT, Size: ui.Const(1)},
+	})
+
+	if acct.uiConf.SidebarWidth > 0 {
+		acct.grid.AddChild(ui.NewBordered(acct.dirlist, ui.BORDER_RIGHT, acct.uiConf)).At(0, 0)
+	}
+	acct.grid.AddChild(ui.NewBordered(acct.msglist, ui.BORDER_RIGHT, acct.uiConf)).At(0, 1)
+	lib.NewMessageStoreView(acct.msglist.Selected(), false, acct.Store(), acct.aerc.Crypto, acct.aerc.DecryptKeys,
+		func(view lib.MessageView, err error) {
+			if err != nil {
+				acct.aerc.PushError(err.Error())
+				return
+			}
+			acct.split = NewMessageViewer(acct, acct.conf, view)
+			acct.grid.AddChild(acct.split).At(0, 2)
+		})
+	ui.Invalidate()
+}