From 68f179021d304d6edf939ecf5fc7d0d073b16152 Mon Sep 17 00:00:00 2001
From: Jeffas <dev@jeffas.io>
Date: Mon, 2 Mar 2020 19:54:42 +0000
Subject: [PATCH] Add move-tab command

---
 commands/move-tab.go | 51 ++++++++++++++++++++++++++++++++++++++++++++
 doc/aerc.1.scd       |  4 ++++
 lib/ui/tab.go        | 41 +++++++++++++++++++++++++++++++++++
 widgets/aerc.go      | 12 +++++++++++
 4 files changed, 108 insertions(+)
 create mode 100644 commands/move-tab.go

diff --git a/commands/move-tab.go b/commands/move-tab.go
new file mode 100644
index 0000000..9f0293c
--- /dev/null
+++ b/commands/move-tab.go
@@ -0,0 +1,51 @@
+package commands
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"git.sr.ht/~sircmpwn/aerc/widgets"
+)
+
+type MoveTab struct{}
+
+func init() {
+	register(MoveTab{})
+}
+
+func (MoveTab) Aliases() []string {
+	return []string{"move-tab"}
+}
+
+func (MoveTab) Complete(aerc *widgets.Aerc, args []string) []string {
+	return nil
+}
+
+func (MoveTab) Execute(aerc *widgets.Aerc, args []string) error {
+	if len(args) == 1 {
+		return fmt.Errorf("Usage: %s [+|-]<index>", args[0])
+	}
+
+	joinedArgs := strings.Join(args[1:], "")
+
+	n, err := strconv.Atoi(joinedArgs)
+	if err != nil {
+		return fmt.Errorf("failed to parse index argument: %v", err)
+	}
+
+	i := aerc.SelectedTabIndex()
+	l := aerc.NumTabs()
+
+	if strings.HasPrefix(joinedArgs, "+") {
+		i = (i + n) % l
+	} else if strings.HasPrefix(joinedArgs, "-") {
+		i = (((i + n) % l) + l) % l
+	} else {
+		i = n
+	}
+
+	aerc.MoveTab(i)
+
+	return nil
+}
diff --git a/doc/aerc.1.scd b/doc/aerc.1.scd
index 38c0bd4..0294784 100644
--- a/doc/aerc.1.scd
+++ b/doc/aerc.1.scd
@@ -63,6 +63,10 @@ These commands work in any context.
 	Opens a new terminal tab with a shell running in the current working
 	directory, or the specified command.
 
+*move-tab* [+|-]<index>
+	Moves the selected tab to the given index. If + or - is specified, the
+	number is interpreted as a delta from the selected tab.
+
 *prev-tab* [n], *next-tab* [n]
 	Cycles to the previous or next tab in the list, repeating n times
 	(default: 1).
diff --git a/lib/ui/tab.go b/lib/ui/tab.go
index 27fb604..e1c53ea 100644
--- a/lib/ui/tab.go
+++ b/lib/ui/tab.go
@@ -132,6 +132,47 @@ func (tabs *Tabs) SelectPrevious() bool {
 	return true
 }
 
+func (tabs *Tabs) MoveTab(to int) {
+	from := tabs.Selected
+
+	if to < 0 {
+		to = 0
+	}
+
+	if to >= len(tabs.Tabs) {
+		to = len(tabs.Tabs) - 1
+	}
+
+	tab := tabs.Tabs[from]
+	if to > from {
+		copy(tabs.Tabs[from:to], tabs.Tabs[from+1:to+1])
+		for i, h := range tabs.history {
+			if h == from {
+				tabs.history[i] = to
+			}
+			if h > from && h <= to {
+				tabs.history[i] -= 1
+			}
+		}
+	} else if from > to {
+		copy(tabs.Tabs[to+1:from+1], tabs.Tabs[to:from])
+		for i, h := range tabs.history {
+			if h == from {
+				tabs.history[i] = to
+			}
+			if h >= to && h < from {
+				tabs.history[i] += 1
+			}
+		}
+	} else {
+		return
+	}
+
+	tabs.Tabs[to] = tab
+	tabs.Selected = to
+	tabs.TabStrip.Invalidate()
+}
+
 func (tabs *Tabs) NextTab() {
 	next := tabs.Selected + 1
 	if next >= len(tabs.Tabs) {
diff --git a/widgets/aerc.go b/widgets/aerc.go
index a0e356a..a9be47e 100644
--- a/widgets/aerc.go
+++ b/widgets/aerc.go
@@ -283,6 +283,14 @@ func (aerc *Aerc) SelectedTab() ui.Drawable {
 	return aerc.tabs.Tabs[aerc.tabs.Selected].Content
 }
 
+func (aerc *Aerc) SelectedTabIndex() int {
+	return aerc.tabs.Selected
+}
+
+func (aerc *Aerc) NumTabs() int {
+	return len(aerc.tabs.Tabs)
+}
+
 func (aerc *Aerc) NewTab(clickable ui.Drawable, name string) *ui.Tab {
 	tab := aerc.tabs.Add(clickable, name)
 	aerc.tabs.Select(len(aerc.tabs.Tabs) - 1)
@@ -297,6 +305,10 @@ func (aerc *Aerc) ReplaceTab(tabSrc ui.Drawable, tabTarget ui.Drawable, name str
 	aerc.tabs.Replace(tabSrc, tabTarget, name)
 }
 
+func (aerc *Aerc) MoveTab(i int) {
+	aerc.tabs.MoveTab(i)
+}
+
 func (aerc *Aerc) NextTab() {
 	aerc.tabs.NextTab()
 }