ui: add reusable table widget

This will be used by the message list index and by the status line.
A table is constructed from rows/width dimensions, a list of column
definitions and a column separator.

Provide functions to parse column definitions from ini config files.

This will be used in the next commit.

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

1 files changed, 120 insertions, 0 deletions

diff --git a/config/columns.go b/config/columns.go
new file mode 100644
index 00000000..659be2c3
--- /dev/null
+++ b/config/columns.go
@@ -0,0 +1,120 @@
+package config
+
+import (
+	"bytes"
+	"fmt"
+	"regexp"
+	"strconv"
+	"strings"
+	"text/template"
+
+	"git.sr.ht/~rjarry/aerc/lib/templates"
+	"github.com/go-ini/ini"
+)
+
+type ColumnFlags uint32
+
+func (f ColumnFlags) Has(o ColumnFlags) bool { return f&o == o }
+
+const (
+	ALIGN_LEFT ColumnFlags = 1 << iota
+	ALIGN_CENTER
+	ALIGN_RIGHT
+	WIDTH_AUTO     // whatever is left
+	WIDTH_FRACTION // ratio of total width
+	WIDTH_EXACT    // exact number of characters
+	WIDTH_FIT      // fit to column content width
+)
+
+type ColumnDef struct {
+	Name     string
+	Flags    ColumnFlags
+	Width    float64
+	Template *template.Template
+}
+
+var columnRe = regexp.MustCompile(`^([\w-]+)(?:([<:>])(=|\*|\d+%?)?)?$`)
+
+func parseColumnDef(col string, section *ini.Section) (*ColumnDef, error) {
+	col = strings.TrimSpace(col)
+	match := columnRe.FindStringSubmatch(col)
+	if match == nil {
+		return nil, fmt.Errorf("invalid column def: %v", col)
+	}
+	name := match[1]
+	keyName := fmt.Sprintf("column-%s", name)
+
+	var flags ColumnFlags
+	switch match[2] {
+	case "<", "":
+		flags |= ALIGN_LEFT
+	case ":":
+		flags |= ALIGN_CENTER
+	case ">":
+		flags |= ALIGN_RIGHT
+	}
+
+	var width float64 = 0
+	switch match[3] {
+	case "=":
+		flags |= WIDTH_FIT
+	case "*", "":
+		flags |= WIDTH_AUTO
+	default:
+		s := match[3]
+		var divider float64 = 1
+		if strings.HasSuffix(s, "%") {
+			divider = 100
+			s = strings.TrimSuffix(s, "%")
+			flags |= WIDTH_FRACTION
+		} else {
+			flags |= WIDTH_EXACT
+		}
+		w, err := strconv.ParseFloat(s, 64)
+		if err != nil {
+			return nil, fmt.Errorf("%s: %w", keyName, err)
+		}
+		if divider == 100 && w > 100 {
+			return nil, fmt.Errorf("%s: invalid width %.0f%%", keyName, w)
+		}
+		width = w / divider
+	}
+	key, err := section.GetKey(keyName)
+	if err != nil {
+		return nil, err
+	}
+
+	t, err := templates.ParseTemplate(keyName, key.String())
+	if err != nil {
+		return nil, err
+	}
+
+	data := templates.DummyData()
+	var buf bytes.Buffer
+	err = t.Execute(&buf, data)
+	if err != nil {
+		return nil, err
+	}
+
+	return &ColumnDef{
+		Name:     name,
+		Flags:    flags,
+		Width:    width,
+		Template: t,
+	}, nil
+}
+
+func ParseColumnDefs(key *ini.Key, section *ini.Section) ([]*ColumnDef, error) {
+	var columns []*ColumnDef
+	for _, col := range key.Strings(",") {
+		c, err := parseColumnDef(col, section)
+		if err != nil {
+			return nil, err
+		}
+		columns = append(columns, c)
+	}
+	if len(columns) == 0 {
+		return nil, fmt.Errorf("%s cannot be empty", key.Name())
+	}
+	return columns, nil
+}