ruler.go

package main

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"text/template"

	_ "embed"
)

//go:embed etc/ruler.default
var gDefaultRuler string

type statData struct {
	Path        string
	Name        string
	Extension   string
	Size        int64
	DirSize     int64
	DirCount    int
	Permissions string
	ModTime     string
	AccessTime  string
	BirthTime   string
	ChangeTime  string
	LinkCount   string
	User        string
	Group       string
	Target      string
	CustomInfo  string
}

type rulerData struct {
	SPACER           string
	Message          string
	Keys             string
	Progress         []string
	Copy             []string
	Cut              []string
	Select           []string
	Visual           []string
	Index            int
	Total            int
	Hidden           int
	All              int
	LinePercentage   string
	ScrollPercentage string
	Filter           []string
	Mode             string
	Options          map[string]string
	UserOptions      map[string]string
	Stat             *statData
}

func parseRuler(path string) (*template.Template, error) {
	funcs := template.FuncMap{
		"df":       func() string { return diskFree(".") },
		"env":      os.Getenv,
		"humanize": humanize,
		"join":     strings.Join,
		"lower":    strings.ToLower,
		"substr":   func(s string, start, length int) string { return string([]rune(s)[start : start+length]) },
		"upper":    strings.ToUpper,
	}

	if path == "" {
		return template.New("ruler").Funcs(funcs).Parse(gDefaultRuler)
	}

	return template.New(filepath.Base(path)).Funcs(funcs).ParseFiles(path)
}

func renderRuler(ruler *template.Template, data rulerData, width int) (string, string, error) {
	var b strings.Builder
	if err := ruler.Execute(&b, data); err != nil {
		return "", "", err
	}

	s := strings.NewReplacer("\r", "", "\n", "").Replace(b.String())
	sections := strings.Split(s, "\x1f")

	if len(sections) == 1 {
		return s, "", nil
	}

	wtot := 0
	for _, section := range sections {
		wtot += printLength(section)
	}

	if wtot > width {
		return sections[0], strings.Join(sections[1:], ""), nil
	}

	wspacer := max(width-wtot, 0) / (len(sections) - 1)
	wspacerLast := max(width-wtot-wspacer*(len(sections)-2), 0)

	b.Reset()
	for i, section := range sections {
		switch i {
		case 0:
			b.WriteString(section)
		case len(sections) - 1:
			fmt.Fprintf(&b, "%*s%s", wspacerLast, "", section)
		default:
			fmt.Fprintf(&b, "%*s%s", wspacer, "", section)
		}
	}

	return b.String(), "", nil
}