config: add columns based index format

The index-format option comes from mutt and is neither user friendly,
nor intuitive. Introduce a new way of configuring the message list
contents. Replace index-format with multiple settings to make everything
more intuitive. Reuse the table widget added in the previous commit.

index-columns
	Comma-separated list of column names followed by optional
	alignment and width specifiers.

column-separator
	String separator between columns.

column-$name
	One setting for every name defined in index-columns. This
	supports golang text/template syntax and allows access to the
	same message information than before and much more.

When index-format is still defined in aerc.conf (which will most likely
happen when users will update after this patch), convert it to the new
index-columns + column-$name and column-separator system and a warning
is displayed on startup so that users are aware that they need to update
their config.

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

9 files changed, 474 insertions, 149 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 269846f0..913084c2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -34,6 +34,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   external command configured via `[compose].file-picker-cmd` in `aerc.conf`.
 - Sample stylesets are now installed in `$PREFIX/share/aerc/stylesets`.
 - The built-in `colorize` filter now has different themes.
+- New column-based message list format with `index-columns`.
 
 ### Changed
 
@@ -52,6 +53,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Deprecated
 
 - Removed broken `:set` command.
+- `[ui].index-format` setting has been replaced by `index-columns`.
 
 ## [0.13.0](https://git.sr.ht/~rjarry/aerc/refs/0.13.0) - 2022-10-20
 
diff --git a/config/aerc.conf b/config/aerc.conf
index 05ebbf41..1ce4810e 100644
--- a/config/aerc.conf
+++ b/config/aerc.conf
@@ -40,11 +40,38 @@
 
 [ui]
 #
-# Describes the format for each row in a mailbox view. This field is compatible
-# with mutt's printf-like syntax.
-#
-# Default: %-20.20D %-17.17n %Z %s
-#index-format=%-20.20D %-17.17n %Z %s
+# Describes the format for each row in a mailbox view. This is a comma
+# separated list of column names with an optional align and width suffix. After
+# the column name, one of the '<' (left), ':' (center) or '>' (right) alignment
+# characters can be added (by default, left) followed by an optional width
+# specifier. The width is either an integer representing a fixed number of
+# characters, or a percentage between 1% and 99% representing a fraction of the
+# terminal width. It can also be one of the '*' (auto) or '=' (fit) special
+# width specifiers. Auto width columns will be equally attributed the remaining
+# terminal width. Fit width columns take the width of their contents. If no
+# width specifier is set, '*' is used by default.
+#
+# Default: date<20,name<17,flags>4,subject<*
+#index-columns=date<20,name<17,flags>4,subject<*
+
+#
+# Each name in index-columns must have a corresponding column-$name setting.
+# All column-$name settings accept golang text/template syntax. See
+# aerc-templates(7) for available template attributes and functions.
+#
+# Default settings
+#column-date={{.DateAutoFormat .Date.Local}}
+#column-name={{index (.From | names) 0}}
+#column-flags={{.Flags | join ""}}
+#column-subject={{.Subject}}
+
+#
+# String separator inserted between columns. When the column width specifier is
+# an exact number of characters, the separator is added to it (i.e. the exact
+# width will be fully available for the column contents).
+#
+# Default: "  "
+#column-separator="  "
 
 #
 # See time.Time#Format at https://godoc.org/time#Time.Format
diff --git a/config/columns.go b/config/columns.go
index 659be2c3..b1c7191b 100644
--- a/config/columns.go
+++ b/config/columns.go
@@ -3,6 +3,7 @@ package config
 import (
 	"bytes"
 	"fmt"
+	"reflect"
 	"regexp"
 	"strconv"
 	"strings"
@@ -118,3 +119,42 @@ func ParseColumnDefs(key *ini.Key, section *ini.Section) ([]*ColumnDef, error) {
 	}
 	return columns, nil
 }
+
+func ColumnDefsToIni(defs []*ColumnDef, keyName string) string {
+	var s strings.Builder
+	var cols []string
+	templates := make(map[string]string)
+
+	for _, def := range defs {
+		col := def.Name
+		switch {
+		case def.Flags.Has(ALIGN_LEFT):
+			col += "<"
+		case def.Flags.Has(ALIGN_CENTER):
+			col += ":"
+		case def.Flags.Has(ALIGN_RIGHT):
+			col += ">"
+		}
+		switch {
+		case def.Flags.Has(WIDTH_FIT):
+			col += "="
+		case def.Flags.Has(WIDTH_AUTO):
+			col += "*"
+		case def.Flags.Has(WIDTH_FRACTION):
+			col += fmt.Sprintf("%.0f%%", def.Width*100)
+		default:
+			col += fmt.Sprintf("%.0f", def.Width)
+		}
+		cols = append(cols, col)
+		tree := reflect.ValueOf(def.Template.Tree)
+		text := tree.Elem().FieldByName("text").String()
+		templates[fmt.Sprintf("column-%s", def.Name)] = text
+	}
+
+	s.WriteString(fmt.Sprintf("%s = %s\n", keyName, strings.Join(cols, ",")))
+	for name, text := range templates {
+		s.WriteString(fmt.Sprintf("%s = %s\n", name, text))
+	}
+
+	return s.String()
+}
diff --git a/config/ui.go b/config/ui.go
index 18724af2..98b9f629 100644
--- a/config/ui.go
+++ b/config/ui.go
@@ -4,9 +4,11 @@ import (
 	"fmt"
 	"path"
 	"regexp"
+	"strconv"
 	"strings"
 	"time"
 
+	"git.sr.ht/~rjarry/aerc/lib/templates"
 	"git.sr.ht/~rjarry/aerc/log"
 	"github.com/gdamore/tcell/v2"
 	"github.com/go-ini/ini"
@@ -14,8 +16,12 @@ import (
 )
 
 type UIConfig struct {
+	IndexColumns    []*ColumnDef `ini:"-"`
+	ColumnSeparator string       `ini:"column-separator"`
+	// deprecated
+	IndexFormat string `ini:"index-format"`
+
 	AutoMarkRead                  bool          `ini:"auto-mark-read"`
-	IndexFormat                   string        `ini:"index-format"`
 	TimestampFormat               string        `ini:"timestamp-format"`
 	ThisDayTimeFormat             string        `ini:"this-day-time-format"`
 	ThisWeekTimeFormat            string        `ini:"this-week-time-format"`
@@ -92,9 +98,39 @@ type uiContextKey struct {
 }
 
 func defaultUiConfig() *UIConfig {
+	date, _ := templates.ParseTemplate("column-date", "{{.DateAutoFormat .Date.Local}}")
+	name, _ := templates.ParseTemplate("column-name", "{{index (.From | names) 0}}")
+	flags, _ := templates.ParseTemplate("column-flags", `{{.Flags | join ""}}`)
+	subject, _ := templates.ParseTemplate("column-subject", "{{.Subject}}")
 	return &UIConfig{
+		IndexFormat: "", // deprecated
+		IndexColumns: []*ColumnDef{
+			{
+				Name:     "date",
+				Width:    20,
+				Flags:    ALIGN_LEFT | WIDTH_EXACT,
+				Template: date,
+			},
+			{
+				Name:     "name",
+				Width:    17,
+				Flags:    ALIGN_LEFT | WIDTH_EXACT,
+				Template: name,
+			},
+			{
+				Name:     "flags",
+				Width:    4,
+				Flags:    ALIGN_RIGHT | WIDTH_EXACT,
+				Template: flags,
+			},
+			{
+				Name:     "subject",
+				Flags:    ALIGN_LEFT | WIDTH_AUTO,
+				Template: subject,
+			},
+		},
+		ColumnSeparator:    "  ",
 		AutoMarkRead:       true,
-		IndexFormat:        "%-20.20D %-17.17n %Z %s",
 		TimestampFormat:    "2006-01-02 03:04 PM",
 		ThisDayTimeFormat:  "",
 		ThisWeekTimeFormat: "",
@@ -283,9 +319,147 @@ func (config *UIConfig) parse(section *ini.Section) error {
 		config.MessageViewThisDayTimeFormat = config.TimestampFormat
 	}
 
+	if config.IndexFormat != "" {
+		log.Warnf("%s %s",
+			"The index-format setting has been replaced by index-columns.",
+			"index-format will be removed in aerc 0.17.")
+	}
+	if key, err := section.GetKey("index-columns"); err == nil {
+		columns, err := ParseColumnDefs(key, section)
+		if err != nil {
+			return err
+		}
+		config.IndexColumns = columns
+		config.IndexFormat = "" // to silence popup at startup
+	} else if config.IndexFormat != "" {
+		columns, err := convertIndexFormat(config.IndexFormat)
+		if err != nil {
+			return err
+		}
+		config.IndexColumns = columns
+	}
+
 	return nil
 }
 
+var indexFmtRegexp = regexp.MustCompile(`%(-?\d+)?(\.\d+)?([A-Za-z%])`)
+
+func convertIndexFormat(indexFormat string) ([]*ColumnDef, error) {
+	matches := indexFmtRegexp.FindAllStringSubmatch(indexFormat, -1)
+	if matches == nil {
+		return nil, fmt.Errorf("invalid index-format")
+	}
+
+	var columns []*ColumnDef
+
+	for _, m := range matches {
+		alignWidth := m[1]
+		verb := m[3]
+
+		var f string
+		var width float64 = 0
+		var flags ColumnFlags = ALIGN_LEFT
+		name := ""
+
+		switch verb {
+		case "%":
+			f = verb
+		case "a":
+			f = `{{(index .From 0).Address}}`
+			name = "sender"
+		case "A":
+			f = `{{if eq (len .ReplyTo) 0}}{{(index .From 0).Address}}{{else}}{{(index .ReplyTo 0).Address}}{{end}}`
+			name = "reply-to"
+		case "C":
+			f = "{{.Number}}"
+			name = "num"
+		case "d", "D":
+			f = "{{.DateAutoFormat .Date.Local}}"
+			name = "date"
+		case "f":
+			f = `{{index (.From | persons) 0}}`
+			name = "from"
+		case "F":
+			f = `{{.Peer | names | join ", "}}`
+			name = "peers"
+		case "g":
+			f = `{{.Labels | join ", "}}`
+			name = "labels"
+		case "i":
+			f = "{{.MessageId}}"
+			name = "msg-id"
+		case "n":
+			f = `{{index (.From | names) 0}}`
+			name = "name"
+		case "r":
+			f = `{{.To | persons | join ", "}}`
+			name = "to"
+		case "R":
+			f = `{{.Cc | persons | join ", "}}`
+			name = "cc"
+		case "s":
+			f = "{{.Subject}}"
+			name = "subject"
+		case "t":
+			f = "{{(index .To 0).Address}}"
+			name = "to0"
+		case "T":
+			f = "{{.Account}}"
+			name = "account"
+		case "u":
+			f = "{{index (.From | mboxes) 0}}"
+			name = "mboxes"
+		case "v":
+			f = "{{index (.From | names) 0}}"
+			name = "name"
+		case "Z":
+			f = `{{.Flags | join ""}}`
+			name = "flags"
+			width = 4
+			flags = ALIGN_RIGHT
+		case "l":
+			f = "{{.Size}}"
+			name = "size"
+		default:
+			f = "%" + verb
+		}
+		if name == "" {
+			name = "wtf"
+		}
+
+		t, err := templates.ParseTemplate(fmt.Sprintf("column-%s", name), f)
+		if err != nil {
+			return nil, err
+		}
+
+		if alignWidth != "" {
+			width, err = strconv.ParseFloat(alignWidth, 64)
+			if err != nil {
+				return nil, err
+			}
+			if width < 0 {
+				width = -width
+			} else {
+				flags = ALIGN_RIGHT
+			}
+		}
+		if width == 0 {
+			flags |= WIDTH_AUTO
+		} else {
+			flags |= WIDTH_EXACT
+		}
+
+		columns = append(columns, &ColumnDef{
+			Name:     name,
+			Width:    width,
+			Flags:    flags,
+			Template: t,
+		})
+	}
+
+	return columns, nil
+}
+
 func (ui *UIConfig) loadStyleSet(styleSetDirs []string) error {
 	ui.style = NewStyleSet()
 	err := ui.style.LoadStyleSet(ui.StyleSetName, styleSetDirs)
diff --git a/config/ui_test.go b/config/ui_test.go
new file mode 100644
index 00000000..c5eb6031
--- /dev/null
+++ b/config/ui_test.go
@@ -0,0 +1,46 @@
+package config
+
+import (
+	"bytes"
+	"testing"
+
+	"git.sr.ht/~rjarry/aerc/lib/templates"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestConvertIndexFormat(t *testing.T) {
+	columns, err := convertIndexFormat("%-20.20D %-17.17n %Z %s")
+	if err != nil {
+		t.Fatal(err)
+	}
+	assert.Len(t, columns, 4)
+
+	data := templates.DummyData()
+	var buf bytes.Buffer
+
+	assert.Equal(t, "date", columns[0].Name)
+	assert.Equal(t, 20.0, columns[0].Width)
+	assert.Equal(t, ALIGN_LEFT|WIDTH_EXACT, columns[0].Flags)
+	assert.Nil(t, columns[0].Template.Execute(&buf, data))
+
+	buf.Reset()
+	assert.Equal(t, "name", columns[1].Name)
+	assert.Equal(t, 17.0, columns[1].Width)
+	assert.Equal(t, ALIGN_LEFT|WIDTH_EXACT, columns[1].Flags)
+	assert.Nil(t, columns[1].Template.Execute(&buf, data))
+	assert.Equal(t, "John Doe", buf.String())
+
+	buf.Reset()
+	assert.Equal(t, "flags", columns[2].Name)
+	assert.Equal(t, 4.0, columns[2].Width)
+	assert.Equal(t, ALIGN_RIGHT|WIDTH_EXACT, columns[2].Flags)
+	assert.Nil(t, columns[2].Template.Execute(&buf, data))
+	assert.Equal(t, "O!*", buf.String())
+
+	buf.Reset()
+	assert.Equal(t, "subject", columns[3].Name)
+	assert.Equal(t, 0.0, columns[3].Width)
+	assert.Equal(t, ALIGN_LEFT|WIDTH_AUTO, columns[3].Flags)
+	assert.Nil(t, columns[3].Template.Execute(&buf, data))
+	assert.Equal(t, "[PATCH aerc 2/3] foo: baz bar buz", buf.String())
+}
diff --git a/doc/aerc-config.5.scd b/doc/aerc-config.5.scd
index dcaa3dd4..7e189a48 100644
--- a/doc/aerc-config.5.scd
+++ b/doc/aerc-config.5.scd
@@ -66,53 +66,43 @@ These options are configured in the *[general]* section of _aerc.conf_.
 
 These options are configured in the *[ui]* section of _aerc.conf_.
 
-*index-format* = _<format>_
-	Describes the format for each row in a mailbox view. This field is
-	compatible with mutt's printf-like syntax.
+*index-columns* = _<column1,column2,column3...>_
+	Describes the format for each row in a mailbox view. This is a comma
+	separated list of column names with an optional align and width suffix.
+	After the column name, one of the _<_ (left), _:_ (center) or _>_
+	(right) alignment characters can be added (by default, left) followed by
+	an optional width specifier. The width is either an integer representing
+	a fixed number of characters, or a percentage between _1%_ and _99%_
+	representing a fraction of the terminal width. It can also be one of the
+	_\*_ (auto) or _=_ (fit) special width specifiers. Auto width columns
+	will be equally attributed the remaining terminal width. Fit width
+	columns take the width of their contents. If no width specifier is set,
+	_\*_ is used by default.
 
-	Default: _%D %-17.17n %s_
+	Default: _date<20,name<17,flags>4,subject<\*_
 
-[- *Format specifier*
-:[ *Description*
-|  _%%_
-:  literal %
-|  _%a_
-:  sender address
-|  _%A_
-:  reply-to address, or sender address if none
-|  _%C_
-:  message number
-|  _%d_
-:  formatted message timestamp
-|  _%D_
-:  formatted message timestamp converted to local timezone
-|  _%f_
-:  sender name and address
-|  _%F_
-:  author name, or recipient name if the message is from you.
-   The address is shown if no name part.
-|  _%g_
-:  message labels (for example notmuch tags)
-|  _%i_
-:  message id
-|  _%n_
-:  sender name, or sender address if none
-|  _%r_
-:  comma-separated list of formatted recipient names and addresses
-|  _%R_
-:  comma-separated list of formatted CC names and addresses
-|  _%s_
-:  subject
-|  _%t_
-:  the (first) address the new email was sent to
-|  _%T_
-:  the account name which received the email
-|  _%u_
-:  sender mailbox name (e.g. "smith" in "smith@example.net")
-|  _%v_
-:  sender first name (e.g. "Alex" in "Alex Smith <smith@example.net>")
-|  _%Z_
-:  flags (O=old, N=new, r=answered, D=deleted, !=flagged, \*=marked, a=attachment)
+*column-separator* = _"<separator>"_
+	String separator inserted between columns. When a column width specifier
+	is an exact number of characters, the separator is added to it (i.e. the
+	exact width will be fully available for that column contents).
+
+	Default: _"  "_
+
+*column-<name>* = _<go template>_
+	Each name in *index-columns* must have a corresponding *column-<name>*
+	setting. All *column-<name>* settings accept golang text/template
+	syntax.
+
+	By default, these columns are defined:
+
+	```
+	column-date = {{.DateAutoFormat .Date.Local}}
+	column-name = {{index (.From | names) 0}}
+	column-flags = {{.Flags | join ""}}
+	column-subject = {{.Subject}}
+	```
+
+	See *aerc-templates*(7) for all available symbols and functions.
 
 *timestamp-format* = _<timeformat>_
 	See time.Time#Format at https://godoc.org/time#Time.Format
diff --git a/lib/templates/data.go b/lib/templates/data.go
index dab698d5..cb69d8fe 100644
--- a/lib/templates/data.go
+++ b/lib/templates/data.go
@@ -20,6 +20,10 @@ type TemplateData struct {
 	marked bool
 	msgNum int
 
+	// message list threading
+	ThreadSameSubject bool
+	ThreadPrefix      string
+
 	// account config
 	myAddresses map[string]bool
 	account     string
@@ -215,7 +219,10 @@ func (d *TemplateData) Subject() string {
 	case d.headers != nil:
 		subject = d.Header("subject")
 	}
-	return subject
+	if d.ThreadSameSubject {
+		subject = ""
+	}
+	return d.ThreadPrefix + subject
 }
 
 func (d *TemplateData) SubjectBase() string {
diff --git a/widgets/aerc.go b/widgets/aerc.go
index eb904ea0..59944cc6 100644
--- a/widgets/aerc.go
+++ b/widgets/aerc.go
@@ -126,6 +126,30 @@ func NewAerc(
 		}
 	}
 
+	if config.Ui.IndexFormat != "" {
+		ini := config.ColumnDefsToIni(
+			config.Ui.IndexColumns, "index-columns")
+		title := "DEPRECATION WARNING"
+		text := `
+The index-format setting is deprecated. It has been replaced by index-columns.
+
+Your configuration in this instance was automatically converted to:
+
+[ui]
+` + ini + `
+Your configuration file was not changed. To make this change permanent and to
+dismiss this deprecation warning on launch, copy the above lines into aerc.conf
+and remove index-format from it. See aerc-config(5) for more details.
+
+index-format will be removed in aerc 0.17.
+`
+		aerc.AddDialog(NewSelectorDialog(
+			title, text, []string{"OK"}, 0,
+			aerc.SelectedAccountUiConfig(),
+			func(string, error) { aerc.CloseDialog() },
+		))
+	}
+
 	return aerc
 }
 
diff --git a/widgets/msglist.go b/widgets/msglist.go
index 839453f2..169fb310 100644
--- a/widgets/msglist.go
+++ b/widgets/msglist.go
@@ -1,18 +1,17 @@
 package widgets
 
 import (
+	"bytes"
 	"fmt"
 	"math"
 	"strings"
 
-	sortthread "github.com/emersion/go-imap-sortthread"
 	"github.com/gdamore/tcell/v2"
-	"github.com/mattn/go-runewidth"
 
 	"git.sr.ht/~rjarry/aerc/config"
 	"git.sr.ht/~rjarry/aerc/lib"
-	"git.sr.ht/~rjarry/aerc/lib/format"
 	"git.sr.ht/~rjarry/aerc/lib/iterator"
+	"git.sr.ht/~rjarry/aerc/lib/templates"
 	"git.sr.ht/~rjarry/aerc/lib/ui"
 	"git.sr.ht/~rjarry/aerc/log"
 	"git.sr.ht/~rjarry/aerc/models"
@@ -45,6 +44,13 @@ func (ml *MessageList) Invalidate() {
 	ui.Invalidate()
 }
 
+type messageRowParams struct {
+	uid          uint32
+	needsHeaders bool
+	uiConfig     *config.UIConfig
+	styles       []config.StyleObject
+}
+
 func (ml *MessageList) Draw(ctx *ui.Context) {
 	ml.height = ctx.Height()
 	ml.width = ctx.Width()
@@ -54,25 +60,22 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 
 	acct := ml.aerc.SelectedAccount()
 	store := ml.Store()
-	if store == nil || acct == nil {
+	if store == nil || acct == nil || len(store.Uids()) == 0 {
 		if ml.isInitalizing {
 			ml.spinner.Draw(ctx)
-			return
 		} else {
 			ml.spinner.Stop()
 			ml.drawEmptyMessage(ctx)
-			return
 		}
+		return
 	}
 
 	ml.UpdateScroller(ml.height, len(store.Uids()))
-	if store := ml.Store(); store != nil && len(store.Uids()) > 0 {
-		iter := store.UidsIterator()
-		for i := 0; iter.Next(); i++ {
-			if store.SelectedUid() == iter.Value().(uint32) {
-				ml.EnsureScroll(i)
-				break
-			}
+	iter := store.UidsIterator()
+	for i := 0; iter.Next(); i++ {
+		if store.SelectedUid() == iter.Value().(uint32) {
+			ml.EnsureScroll(i)
+			break
 		}
 	}
 
@@ -80,25 +83,57 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 	if ml.NeedScrollbar() {
 		textWidth -= 1
 	}
-	if textWidth < 0 {
-		textWidth = 0
+	if textWidth <= 0 {
+		return
 	}
 
-	var (
-		needsHeaders []uint32
-		row          int = 0
+	data := templates.NewTemplateData(
+		acct.acct.From,
+		acct.acct.Aliases,
+		acct.Name(),
+		acct.Directories().Selected(),
+		uiConfig.TimestampFormat,
+		uiConfig.ThisDayTimeFormat,
+		uiConfig.ThisWeekTimeFormat,
+		uiConfig.ThisYearTimeFormat,
+		uiConfig.IconAttachment,
 	)
 
-	createBaseCtx := func(uid uint32, row int) format.Ctx {
-		return format.Ctx{
-			FromAddress: format.AddressForHumans(acct.acct.From),
-			AccountName: acct.Name(),
-			MsgInfo:     store.Messages[uid],
-			MsgNum:      row,
-			MsgIsMarked: store.Marker().IsMarked(uid),
+	var needsHeaders []uint32
+
+	customDraw := func(t *ui.Table, r int, c *ui.Context) bool {
+		row := &t.Rows[r]
+		params, _ := row.Priv.(messageRowParams)
+		if params.needsHeaders {
+			needsHeaders = append(needsHeaders, params.uid)
+			ml.spinner.Draw(ctx.Subcontext(0, r, t.Width, 1))
+			return true
+		}
+		return false
+	}
+
+	getRowStyle := func(t *ui.Table, r int) tcell.Style {
+		var style tcell.Style
+		row := &t.Rows[r]
+		params, _ := row.Priv.(messageRowParams)
+		if params.uid == store.SelectedUid() {
+			style = params.uiConfig.GetComposedStyleSelected(
+				config.STYLE_MSGLIST_DEFAULT, params.styles)
+		} else {
+			style = params.uiConfig.GetComposedStyle(
+				config.STYLE_MSGLIST_DEFAULT, params.styles)
 		}
+		return style
 	}
 
+	table := ui.NewTable(
+		textWidth, ml.height,
+		uiConfig.IndexColumns,
+		uiConfig.ColumnSeparator,
+		customDraw,
+		getRowStyle,
+	)
+
 	if store.ThreadedView() {
 		var (
 			lastSubject string
@@ -126,23 +161,22 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 					i++
 					continue
 				}
-				if thread := curIter.Value().(*types.Thread); thread != nil {
-					fmtCtx := createBaseCtx(thread.Uid, row)
-					fmtCtx.ThreadPrefix = threadPrefix(thread,
-						store.ReverseThreadOrder())
-					if fmtCtx.MsgInfo != nil && fmtCtx.MsgInfo.Envelope != nil {
-						baseSubject, _ := sortthread.GetBaseSubject(
-							fmtCtx.MsgInfo.Envelope.Subject)
-						fmtCtx.ThreadSameSubject = baseSubject == lastSubject &&
-							sameParent(thread, prevThread) &&
-							!isParent(thread)
-						lastSubject = baseSubject
-						prevThread = thread
-					}
-					if ml.drawRow(textWidth, ctx, thread.Uid, row, &needsHeaders, fmtCtx) {
-						break threadLoop
-					}
-					row += 1
+				thread := curIter.Value().(*types.Thread)
+				if thread == nil {
+					continue
+				}
+
+				baseSubject := data.SubjectBase()
+				data.ThreadSameSubject = baseSubject == lastSubject &&
+					sameParent(thread, prevThread) &&
+					!isParent(thread)
+				data.ThreadPrefix = threadPrefix(thread,
+					store.ReverseThreadOrder())
+				lastSubject = baseSubject
+				prevThread = thread
+
+				if addMessage(store, thread.Uid, &table, data, uiConfig) {
+					break threadLoop
 				}
 			}
 		}
@@ -153,14 +187,14 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 				continue
 			}
 			uid := iter.Value().(uint32)
-			fmtCtx := createBaseCtx(uid, row)
-			if ml.drawRow(textWidth, ctx, uid, row, &needsHeaders, fmtCtx) {
+			if addMessage(store, uid, &table, data, uiConfig) {
 				break
 			}
-			row += 1
 		}
 	}
 
+	table.Draw(ctx)
+
 	if ml.NeedScrollbar() {
 		scrollbarCtx := ctx.Subcontext(ctx.Width()-1, 0, 1, ctx.Height())
 		ml.drawScrollbar(scrollbarCtx)
@@ -184,79 +218,60 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 	}
 }
 
-func (ml *MessageList) drawRow(textWidth int, ctx *ui.Context, uid uint32, row int, needsHeaders *[]uint32, fmtCtx format.Ctx) bool {
-	store := ml.store
+func addMessage(
+	store *lib.MessageStore, uid uint32,
+	table *ui.Table, data *templates.TemplateData,
+	uiConfig *config.UIConfig,
+) bool {
 	msg := store.Messages[uid]
-	acct := ml.aerc.SelectedAccount()
 
-	if row >= ctx.Height() || acct == nil {
-		return true
-	}
-
-	if msg == nil {
-		*needsHeaders = append(*needsHeaders, uid)
-		ml.spinner.Draw(ctx.Subcontext(0, row, textWidth, 1))
-		return false
-	}
+	cells := make([]string, len(table.Columns))
+	params := messageRowParams{uid: uid}
 
-	// TODO deprecate subject contextual UIs? Only related setting is styleset,
-	// should implement a better per-message styling method
-	// Check if we have any applicable ContextualUIConfigs
-	uiConfig := acct.Directories().UiConfig(store.DirInfo.Name)
-	if msg.Envelope != nil {
-		uiConfig = uiConfig.ForSubject(msg.Envelope.Subject)
+	if msg == nil || msg.Envelope == nil {
+		params.needsHeaders = true
+		return table.AddRow(cells, params)
 	}
 
-	msg_styles := []config.StyleObject{}
 	if msg.Flags.Has(models.SeenFlag) {
-		msg_styles = append(msg_styles, config.STYLE_MSGLIST_READ)
+		params.styles = append(params.styles, config.STYLE_MSGLIST_READ)
 	} else {
-		msg_styles = append(msg_styles, config.STYLE_MSGLIST_UNREAD)
+		params.styles = append(params.styles, config.STYLE_MSGLIST_UNREAD)
 	}
-
 	if msg.Flags.Has(models.FlaggedFlag) {
-		msg_styles = append(msg_styles, config.STYLE_MSGLIST_FLAGGED)
+		params.styles = append(params.styles, config.STYLE_MSGLIST_FLAGGED)
 	}
-
 	// deleted message
 	if _, ok := store.Deleted[msg.Uid]; ok {
-		msg_styles = append(msg_styles, config.STYLE_MSGLIST_DELETED)
+		params.styles = append(params.styles, config.STYLE_MSGLIST_DELETED)
 	}
 	// search result
 	if store.IsResult(msg.Uid) {
-		msg_styles = append(msg_styles, config.STYLE_MSGLIST_RESULT)
+		params.styles = append(params.styles, config.STYLE_MSGLIST_RESULT)
 	}
-
 	// marked message
-	if store.Marker().IsMarked(msg.Uid) {
-		msg_styles = append(msg_styles, config.STYLE_MSGLIST_MARKED)
+	marked := store.Marker().IsMarked(msg.Uid)
+	if marked {
+		params.styles = append(params.styles, config.STYLE_MSGLIST_MARKED)
 	}
 
-	var style tcell.Style
-	// current row
-	if msg.Uid == ml.store.SelectedUid() {
-		style = uiConfig.GetComposedStyleSelected(config.STYLE_MSGLIST_DEFAULT, msg_styles)
-	} else {
-		style = uiConfig.GetComposedStyle(config.STYLE_MSGLIST_DEFAULT, msg_styles)
-	}
+	data.SetInfo(msg, len(table.Rows), marked)
 
-	ctx.Fill(0, row, ctx.Width(), 1, ' ', style)
-	fmtStr, args, err := format.ParseMessageFormat(
-		uiConfig.IndexFormat, uiConfig.TimestampFormat,
-		uiConfig.ThisDayTimeFormat,
-		uiConfig.ThisWeekTimeFormat,
-		uiConfig.ThisYearTimeFormat,
-		uiConfig.IconAttachment,
-		fmtCtx)
-	if err != nil {
-		ctx.Printf(0, row, style, "%v", err)
-	} else {
-		line := fmt.Sprintf(fmtStr, args...)
-		line = runewidth.Truncate(line, textWidth, "…")
-		ctx.Printf(0, row, style, "%s", line)
+	for c, col := range table.Columns {
+		var buf bytes.Buffer
+		err := col.Def.Template.Execute(&buf, data)
+		if err != nil {
+			cells[c] = err.Error()
+		} else {
+			cells[c] = buf.String()
+		}
 	}
 
-	return false
+	// TODO deprecate subject contextual UIs? Only related setting is
+	// styleset, should implement a better per-message styling method
+	params.uiConfig = uiConfig.ForSubject(msg.Envelope.Subject)
+
+	return table.AddRow(cells, params)
 }
 
 func (ml *MessageList) drawScrollbar(ctx *ui.Context) {