1 files changed, 204 insertions, 0 deletions
diff --git a/lib/textui/text.go b/lib/textui/text.go
new file mode 100644
index 0000000..d6a80b3
--- /dev/null
+++ b/lib/textui/text.go
@@ -0,0 +1,204 @@
+// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package textui
+
+import (
+	"fmt"
+	"io"
+	"math"
+
+	"golang.org/x/exp/constraints"
+	"golang.org/x/text/language"
+	"golang.org/x/text/message"
+	"golang.org/x/text/number"
+
+	"git.lukeshu.com/btrfs-progs-ng/lib/fmtutil"
+)
+
+var printer = message.NewPrinter(language.English)
+
+// Fprintf is like `fmt.Fprintf`, but (1) includes the extensions of
+// `golang.org/x/text/message.Printer`, and (2) is useful for marking
+// when a print call is part of the UI, rather than something
+// internal.
+func Fprintf(w io.Writer, key string, a ...any) (n int, err error) {
+	return printer.Fprintf(w, key, a...)
+}
+
+// Sprintf is like `fmt.Sprintf`, but (1) includes the extensions of
+// `golang.org/x/text/message.Printer`, and (2) is useful for marking
+// when a sprint call is part of the UI, rather than something
+// internal.
+func Sprintf(key string, a ...any) string {
+	return printer.Sprintf(key, a...)
+}
+
+// Humanized wraps a value such that formatting of it can make use of
+// the `golang.org/x/text/message.Printer` extensions even when used
+// with plain-old `fmt`.
+func Humanized(x any) any {
+	return humanized{val: x}
+}
+
+type humanized struct {
+	val any
+}
+
+var (
+	_ fmt.Formatter = humanized{}
+	_ fmt.Stringer  = humanized{}
+)
+
+// String implements fmt.Formatter.
+func (h humanized) Format(f fmt.State, verb rune) {
+	printer.Fprintf(f, fmtutil.FmtStateString(f, verb), h.val)
+}
+
+// String implements fmt.Stringer.
+func (h humanized) String() string {
+	return fmt.Sprint(h)
+}
+
+// Portion renders a fraction N/D as both a percentage and
+// parenthetically as the exact fractional value, rendered with
+// human-friendly commas.
+//
+// For example:
+//
+//	fmt.Sprint(Portion[int]{N: 1, D: 12345}) ⇒ "0% (1/12,345)"
+type Portion[T constraints.Integer] struct {
+	N, D T
+}
+
+var (
+	_ fmt.Stringer = Portion[int]{}
+)
+
+// String implements fmt.Stringer.
+func (p Portion[T]) String() string {
+	pct := float64(1)
+	if p.D > 0 {
+		pct = float64(p.N) / float64(p.D)
+	}
+	return printer.Sprintf("%v (%v/%v)", number.Percent(pct), uint64(p.N), uint64(p.D))
+}
+
+type metric[T constraints.Integer | constraints.Float] struct {
+	Val  T
+	Unit string
+}
+
+var (
+	_ fmt.Formatter = metric[int]{}
+	_ fmt.Stringer  = metric[int]{}
+)
+
+func Metric[T constraints.Integer | constraints.Float](x T, unit string) metric[T] {
+	return metric[T]{
+		Val:  x,
+		Unit: unit,
+	}
+}
+
+var metricSmallPrefixes = []string{
+	"m",
+	"μ",
+	"n",
+	"p",
+	"f",
+	"a",
+	"z",
+	"y",
+	"r",
+	"q",
+}
+
+var metricBigPrefixes = []string{
+	"k",
+	"M",
+	"G",
+	"T",
+	"P",
+	"E",
+	"Z",
+	"Y",
+	"R",
+	"Q",
+}
+
+// String implements fmt.Formatter.
+func (v metric[T]) Format(f fmt.State, verb rune) {
+	var prefix string
+	y := math.Abs(float64(v.Val))
+	if y < 1 {
+		for i := 0; y < 1 && i <= len(metricSmallPrefixes); i++ {
+			y *= 1000
+			prefix = metricSmallPrefixes[i]
+		}
+	} else {
+		for i := 0; y > 1000 && i <= len(metricBigPrefixes); i++ {
+			y /= 1000
+			prefix = metricBigPrefixes[i]
+		}
+	}
+	if v.Val < 0 {
+		y = -y
+	}
+	printer.Fprintf(f, fmtutil.FmtStateString(f, verb)+"%s%s",
+		y, prefix, v.Unit)
+}
+
+// String implements fmt.Stringer.
+func (v metric[T]) String() string {
+	return fmt.Sprint(v)
+}
+
+type iec[T constraints.Integer | constraints.Float] struct {
+	Val  T
+	Unit string
+}
+
+var (
+	_ fmt.Formatter = iec[int]{}
+	_ fmt.Stringer  = iec[int]{}
+)
+
+func IEC[T constraints.Integer | constraints.Float](x T, unit string) iec[T] {
+	return iec[T]{
+		Val:  x,
+		Unit: unit,
+	}
+}
+
+var iecPrefixes = []string{
+	"Ki",
+	"Mi",
+	"Gi",
+	"Ti",
+	"Pi",
+	"Ei",
+	"Zi",
+	"Yi",
+}
+
+// String implements fmt.Formatter.
+func (v iec[T]) Format(f fmt.State, verb rune) {
+	var prefix string
+	y := math.Abs(float64(v.Val))
+	for i := 0; y > 1024 && i <= len(iecPrefixes); i++ {
+		y /= 1024
+		prefix = iecPrefixes[i]
+	}
+	if v.Val < 0 {
+		y = -y
+	}
+	printer.Fprintf(f, fmtutil.FmtStateString(f, verb)+"%s%s",
+		number.Decimal(y), prefix, v.Unit)
+}
+
+// String implements fmt.Stringer.
+func (v iec[T]) String() string {
+	return fmt.Sprint(v)
+}