completion: display descriptions next to choices

Use go-opt v2 new completion API which returns items descriptions along
with their text values.

Display the descriptions after the items separated by two spaces. Wrap
the descriptions in parentheses to better indicate that they are not
part of the completion choices. Limit the description length to 80
characters to avoid display issues.

Add a new style object completion_description in stylesets. By default,
the object will be rendered with a dimmed terminal attribute. Update all
stylesets and documentation accordingly.

Implements: https://todo.sr.ht/~rjarry/aerc/271
Link: https://git.sr.ht/~rjarry/go-opt/commit/ebeb82538395a
Changelog-added: Command completion now displays descriptions next
 to completion items.
Changelog-added: New `completion_description` style object in style
 sets used for rendering completion item descriptions.
Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: Bojan Gabric <bojan@bojangabric.com>
Tested-by: Jason Cox <me@jasoncarloscox.com>
Acked-by: Tim Culverhouse <tim@timculverhouse.com>

3 files changed, 46 insertions, 27 deletions

diff --git a/lib/open.go b/lib/open.go
index 5ca819e0..edbc7ff6 100644
--- a/lib/open.go
+++ b/lib/open.go
@@ -6,7 +6,7 @@ import (
 	"runtime"
 	"strings"
 
-	"git.sr.ht/~rjarry/go-opt"
+	"git.sr.ht/~rjarry/go-opt/v2"
 	"github.com/danwakefield/fnmatch"
 
 	"git.sr.ht/~rjarry/aerc/config"
diff --git a/lib/send/sendmail.go b/lib/send/sendmail.go
index b267721e..9d98cf8f 100644
--- a/lib/send/sendmail.go
+++ b/lib/send/sendmail.go
@@ -6,7 +6,7 @@ import (
 	"net/url"
 	"os/exec"
 
-	"git.sr.ht/~rjarry/go-opt"
+	"git.sr.ht/~rjarry/go-opt/v2"
 	"github.com/emersion/go-message/mail"
 	"github.com/pkg/errors"
 )
diff --git a/lib/ui/textinput.go b/lib/ui/textinput.go
index 6c4551b3..d52859b7 100644
--- a/lib/ui/textinput.go
+++ b/lib/ui/textinput.go
@@ -10,6 +10,7 @@ import (
 
 	"git.sr.ht/~rjarry/aerc/config"
 	"git.sr.ht/~rjarry/aerc/lib/log"
+	"git.sr.ht/~rjarry/go-opt/v2"
 	"git.sr.ht/~rockorager/vaxis"
 )
 
@@ -27,8 +28,8 @@ type TextInput struct {
 	text              []vaxis.Character
 	change            []func(ti *TextInput)
 	focusLost         []func(ti *TextInput)
-	tabcomplete       func(s string) ([]string, string)
-	completions       []string
+	tabcomplete       func(s string) ([]opt.Completion, string)
+	completions       []opt.Completion
 	prefix            string
 	completeIndex     int
 	completeDelay     time.Duration
@@ -62,7 +63,7 @@ func (ti *TextInput) Prompt(prompt string) *TextInput {
 }
 
 func (ti *TextInput) TabComplete(
-	tabcomplete func(s string) ([]string, string),
+	tabcomplete func(s string) ([]opt.Completion, string),
 	d time.Duration, minChars int, key *config.KeyStroke,
 ) *TextInput {
 	ti.tabcomplete = tabcomplete
@@ -142,8 +143,24 @@ func (ti *TextInput) drawPopover(ctx *Context) {
 	if len(ti.completions) == 0 {
 		return
 	}
-	cmp := &completions{ti: ti}
-	width := maxLen(ti.completions) + 3
+
+	valWidth := 0
+	descWidth := 0
+	for _, c := range ti.completions {
+		valWidth = max(valWidth, runewidth.StringWidth(unquote(c.Value)))
+		descWidth = max(descWidth, runewidth.StringWidth(c.Description))
+	}
+	descWidth = min(descWidth, 80)
+	// one space padding
+	width := 1 + valWidth
+	if descWidth != 0 {
+		// two spaces padding + parentheses
+		width += 2 + descWidth + 2
+	}
+	// one space padding + gutter
+	width += 2
+
+	cmp := &completions{ti: ti, valWidth: valWidth, descWidth: descWidth}
 	height := len(ti.completions)
 
 	pos := len(ti.prefix) - ti.scroll
@@ -275,7 +292,7 @@ func (ti *TextInput) backspace() {
 
 func (ti *TextInput) executeCompletion() {
 	if len(ti.completions) > 0 {
-		ti.Set(ti.prefix + ti.completions[ti.completeIndex] + ti.StringRight())
+		ti.Set(ti.prefix + ti.completions[ti.completeIndex].Value + ti.StringRight())
 	}
 }
 
@@ -402,7 +419,9 @@ func (ti *TextInput) Event(event vaxis.Event) bool {
 }
 
 type completions struct {
-	ti *TextInput
+	ti        *TextInput
+	valWidth  int
+	descWidth int
 }
 
 func unquote(s string) string {
@@ -412,22 +431,13 @@ func unquote(s string) string {
 	return s
 }
 
-func maxLen(ss []string) int {
-	max := 0
-	for _, s := range ss {
-		l := runewidth.StringWidth(unquote(s))
-		if l > max {
-			max = l
-		}
-	}
-	return max
-}
-
 func (c *completions) Draw(ctx *Context) {
 	bg := c.ti.uiConfig.GetStyle(config.STYLE_COMPLETION_DEFAULT)
+	bgDesc := c.ti.uiConfig.GetStyle(config.STYLE_COMPLETION_DESCRIPTION)
 	gutter := c.ti.uiConfig.GetStyle(config.STYLE_COMPLETION_GUTTER)
 	pill := c.ti.uiConfig.GetStyle(config.STYLE_COMPLETION_PILL)
 	sel := c.ti.uiConfig.GetStyleSelected(config.STYLE_COMPLETION_DEFAULT)
+	selDesc := c.ti.uiConfig.GetStyleSelected(config.STYLE_COMPLETION_DESCRIPTION)
 
 	ctx.Fill(0, 0, ctx.Width(), ctx.Height(), ' ', bg)
 
@@ -445,11 +455,20 @@ func (c *completions) Draw(ctx *Context) {
 		if idx > endIdx {
 			continue
 		}
+		val := runewidth.FillRight(unquote(opt.Value), c.valWidth)
+		desc := opt.Description
+		if desc != "" {
+			if runewidth.StringWidth(desc) > c.descWidth {
+				desc = runewidth.Truncate(desc, c.descWidth, "…")
+			}
+			desc = "  " + runewidth.FillRight("("+desc+")", c.descWidth+2)
+		}
 		if c.index() == idx {
-			ctx.Fill(0, idx-startIdx, ctx.Width(), 1, ' ', sel)
-			ctx.Printf(0, idx-startIdx, sel, " %s ", unquote(opt))
+			n := ctx.Printf(0, idx-startIdx, sel, " %s", val)
+			ctx.Printf(n, idx-startIdx, selDesc, "%s ", desc)
 		} else {
-			ctx.Printf(0, idx-startIdx, bg, " %s ", unquote(opt))
+			n := ctx.Printf(0, idx-startIdx, bg, " %s", val)
+			ctx.Printf(n, idx-startIdx, bgDesc, "%s ", desc)
 		}
 	}
 
@@ -548,23 +567,23 @@ func (c *completions) stem(stem string) {
 	c.ti.index = len(vaxis.Characters(c.ti.prefix + stem))
 }
 
-func findStem(words []string) string {
+func findStem(words []opt.Completion) string {
 	if len(words) == 0 {
 		return ""
 	}
 	if len(words) == 1 {
-		return words[0]
+		return words[0].Value
 	}
 	var stem string
 	stemLen := 1
-	firstWord := []rune(words[0])
+	firstWord := []rune(words[0].Value)
 	for {
 		if len(firstWord) < stemLen {
 			return stem
 		}
 		var r rune = firstWord[stemLen-1]
 		for _, word := range words[1:] {
-			runes := []rune(word)
+			runes := []rune(word.Value)
 			if len(runes) < stemLen {
 				return stem
 			}