auto-completion: add option to require a min number of chars

When doing address completion via commands that take a while to run,
having the completion trigger even with a single character can be
non-optimal. Add an option to allow requiring a minimum number of
characters to actually run the completion command.

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

6 files changed, 52 insertions, 8 deletions

diff --git a/config/aerc.conf b/config/aerc.conf
index e290525c..688f2ca1 100644
--- a/config/aerc.conf
+++ b/config/aerc.conf
@@ -169,6 +169,12 @@ styleset-name=default
 # Default: 250ms
 completion-delay=250ms
 
+# The minimum required characters to allow auto-completion to be triggered after
+# completion-delay.
+#
+# Default: 1
+#completion-min-chars=1
+
 #
 # Global switch for completion popovers
 #
diff --git a/config/config.go b/config/config.go
index a15e1d51..5e5b49bc 100644
--- a/config/config.go
+++ b/config/config.go
@@ -71,6 +71,7 @@ type UIConfig struct {
 	Sort                          []string      `delim:" "`
 	NextMessageOnDelete           bool          `ini:"next-message-on-delete"`
 	CompletionDelay               time.Duration `ini:"completion-delay"`
+	CompletionMinChars            int           `ini:"completion-min-chars"`
 	CompletionPopovers            bool          `ini:"completion-popovers"`
 	StyleSetDirs                  []string      `ini:"stylesets-dirs" delim:":"`
 	StyleSetName                  string        `ini:"styleset-name"`
@@ -811,6 +812,7 @@ func LoadConfigFromFile(root *string, accts []string) (*AercConfig, error) {
 			DirListDelay:        200 * time.Millisecond,
 			NextMessageOnDelete: true,
 			CompletionDelay:     250 * time.Millisecond,
+			CompletionMinChars:  1,
 			CompletionPopovers:  true,
 			StyleSetDirs:        []string{},
 			StyleSetName:        "default",
diff --git a/doc/aerc-config.5.scd b/doc/aerc-config.5.scd
index 94dfb593..5483ee93 100644
--- a/doc/aerc-config.5.scd
+++ b/doc/aerc-config.5.scd
@@ -256,6 +256,12 @@ These options are configured in the *[ui]* section of aerc.conf.
 
 	Default: 250ms
 
+*completion-min-chars*
+	The minimum required characters to allow auto-completion to be triggered
+	after *completion-delay*.
+
+	Default: 1
+
 *border-char-vertical*
 *border-char-horizontal*
 	Set stylable characters (via the 'border' element) for vertical and
diff --git a/lib/ui/textinput.go b/lib/ui/textinput.go
index 2a8b7c73..c2acd546 100644
--- a/lib/ui/textinput.go
+++ b/lib/ui/textinput.go
@@ -34,6 +34,7 @@ type TextInput struct {
 	completeIndex     int
 	completeDelay     time.Duration
 	completeDebouncer *time.Timer
+	completeMinChars  int
 	uiConfig          *config.UIConfig
 }
 
@@ -60,10 +61,13 @@ func (ti *TextInput) Prompt(prompt string) *TextInput {
 }
 
 func (ti *TextInput) TabComplete(
-	tabcomplete func(s string) ([]string, string), d time.Duration,
+	tabcomplete func(s string) ([]string, string),
+	d time.Duration,
+	minChars int,
 ) *TextInput {
 	ti.tabcomplete = tabcomplete
 	ti.completeDelay = d
+	ti.completeMinChars = minChars
 	return ti
 }
 
@@ -296,7 +300,9 @@ func (ti *TextInput) updateCompletions() {
 		ti.completeDebouncer = time.AfterFunc(ti.completeDelay, func() {
 			defer logging.PanicHandler()
 			ti.Lock()
-			ti.showCompletions()
+			if len(ti.StringLeft()) >= ti.completeMinChars {
+				ti.showCompletions()
+			}
 			ti.Unlock()
 		})
 	} else {
diff --git a/widgets/compose.go b/widgets/compose.go
index 6e34365a..14a75bb6 100644
--- a/widgets/compose.go
+++ b/widgets/compose.go
@@ -214,7 +214,11 @@ func (c *Composer) buildComposeHeader(aerc *Aerc, cmpl *completer.Completer) {
 			c.layout[i][j] = h // normalize to lowercase
 			e := newHeaderEditor(h, c.header, uiConfig)
 			if aerc.conf.Ui.CompletionPopovers {
-				e.input.TabComplete(cmpl.ForHeader(h), uiConfig.CompletionDelay)
+				e.input.TabComplete(
+					cmpl.ForHeader(h),
+					uiConfig.CompletionDelay,
+					uiConfig.CompletionMinChars,
+				)
 			}
 			c.editors[h] = e
 			switch h {
@@ -233,7 +237,11 @@ func (c *Composer) buildComposeHeader(aerc *Aerc, cmpl *completer.Completer) {
 			if _, ok := c.editors[h]; !ok {
 				e := newHeaderEditor(h, c.header, uiConfig)
 				if aerc.conf.Ui.CompletionPopovers {
-					e.input.TabComplete(cmpl.ForHeader(h), uiConfig.CompletionDelay)
+					e.input.TabComplete(
+						cmpl.ForHeader(h),
+						uiConfig.CompletionDelay,
+						uiConfig.CompletionMinChars,
+					)
 				}
 				c.editors[h] = e
 				c.focusable = append(c.focusable, e)
@@ -1005,7 +1013,11 @@ func (c *Composer) AddEditor(header string, value string, appendHeader bool) {
 		uiConfig := c.acct.UiConfig()
 		e := newHeaderEditor(header, c.header, uiConfig)
 		if uiConfig.CompletionPopovers {
-			e.input.TabComplete(c.completer.ForHeader(header), uiConfig.CompletionDelay)
+			e.input.TabComplete(
+				c.completer.ForHeader(header),
+				uiConfig.CompletionDelay,
+				uiConfig.CompletionMinChars,
+			)
 		}
 		c.editors[header] = e
 		c.layout = append(c.layout, []string{header})
diff --git a/widgets/exline.go b/widgets/exline.go
index 789ccde8..5cf4338d 100644
--- a/widgets/exline.go
+++ b/widgets/exline.go
@@ -23,7 +23,11 @@ func NewExLine(conf *config.AercConfig, cmd string, commit func(cmd string), fin
 ) *ExLine {
 	input := ui.NewTextInput("", &conf.Ui).Prompt(":").Set(cmd)
 	if conf.Ui.CompletionPopovers {
-		input.TabComplete(tabcomplete, conf.Ui.CompletionDelay)
+		input.TabComplete(
+			tabcomplete,
+			conf.Ui.CompletionDelay,
+			conf.Ui.CompletionMinChars,
+		)
 	}
 	exline := &ExLine{
 		commit:      commit,
@@ -37,7 +41,11 @@ func NewExLine(conf *config.AercConfig, cmd string, commit func(cmd string), fin
 }
 
 func (x *ExLine) TabComplete(tabComplete func(string) ([]string, string)) {
-	x.input.TabComplete(tabComplete, x.conf.Ui.CompletionDelay)
+	x.input.TabComplete(
+		tabComplete,
+		x.conf.Ui.CompletionDelay,
+		x.conf.Ui.CompletionMinChars,
+	)
 }
 
 func NewPrompt(conf *config.AercConfig, prompt string, commit func(text string),
@@ -45,7 +53,11 @@ func NewPrompt(conf *config.AercConfig, prompt string, commit func(text string),
 ) *ExLine {
 	input := ui.NewTextInput("", &conf.Ui).Prompt(prompt)
 	if conf.Ui.CompletionPopovers {
-		input.TabComplete(tabcomplete, conf.Ui.CompletionDelay)
+		input.TabComplete(
+			tabcomplete,
+			conf.Ui.CompletionDelay,
+			conf.Ui.CompletionMinChars,
+		)
 	}
 	exline := &ExLine{
 		commit:      commit,