Add cmd code, it was accidentally ignored

.gitignore

@@ -6,4 +6,5 @@ data/*.tmp-wal
 simplify*
 tgpkg*
 docgen*
+!cmd/**
 .tup

cmd/docgen/docgen.go

@@ -0,0 +1,225 @@
+package main
+
+import (
+	"compress/gzip"
+	_ "embed"
+	"flag"
+	"fmt"
+	"html/template"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+type CompressOpts struct {
+	Name              string
+	Simplify          []float64
+	SimplifyMinPoints int
+	MinPrecXY         int
+}
+
+type RenderOpts struct {
+	Places []Place
+}
+
+type Place struct {
+	Name string
+}
+
+type Readme struct {
+	Parameters  []CompressOpts
+	LargePlaces []string
+	SmallPlaces []string
+	Datasets    []Dataset
+}
+
+type Dataset struct {
+	Name         string
+	Variants     []Variant
+	PreviewNames []string
+	Render       RenderOpts
+}
+
+type Variant struct {
+	Name     string
+	Fullname string
+	Path     string
+	Size     string
+	Previews []Preview
+}
+
+type Preview struct {
+	Name string
+	Path string
+}
+
+type Featured struct {
+	Name   string
+	Source string
+	Desc   string
+}
+
+type WriteCounter struct {
+	Total int64
+}
+
+func (wc *WriteCounter) Write(p []byte) (int, error) {
+	n := len(p)
+	wc.Total += int64(n)
+	return n, nil
+}
+
+func main() {
+
+	var templatePath string
+	var rootDir string
+	var dataDir string
+	var dataUri string
+	var output string
+
+	flag.StringVar(&templatePath, "template", "", "path to the template file")
+	flag.StringVar(&rootDir, "root", "./", "root directory")
+	flag.StringVar(&dataDir, "data", rootDir+"data/", "data directory")
+	flag.StringVar(&dataUri, "download", rootDir+"data/", "download uri prefix")
+	flag.StringVar(&output, "output", rootDir+"README.md", "output file")
+	flag.Parse()
+
+	if templatePath == "" {
+		panic("template path not set")
+	}
+
+	templateStr, err := os.ReadFile(templatePath)
+	if err != nil {
+		panic(err)
+	}
+
+	gzipCache := map[string]int64{}
+
+	t, err := template.
+		New("readme").
+		Funcs(template.FuncMap{
+			"filesize": func(path string) int64 {
+				stat, err := os.Stat(rootDir + path)
+				if err != nil {
+					return 0
+					// return "❓"
+				}
+				return stat.Size()
+			},
+			"gzipfilesize": func(path string) int64 {
+				if size, ok := gzipCache[path]; ok {
+					return size
+				}
+
+				f, err := os.Open(rootDir + path)
+				if err != nil {
+					return 0
+				}
+				defer f.Close()
+
+				wc := &WriteCounter{}
+				gw := gzip.NewWriter(wc)
+				if _, err = io.Copy(gw, f); err != nil {
+					return 0
+				}
+				gw.Close()
+				gzipCache[path] = wc.Total
+				return wc.Total
+			},
+			"kb": func(b int64) string {
+				return fmt.Sprintf("%d\u202FKB", b/1000)
+			},
+			"variants": func(name, glob string, previews []string, suffix string) []Variant {
+				return getVariants(name, dataDir+name+glob+".gpkg", previews, suffix)
+			},
+			"gpkg": func(name string) string {
+				return name + ".gpkg"
+			},
+			"download": func(name string) string {
+				return dataUri + name
+			},
+			"local": func(name string) string {
+				return dataDir + name
+			},
+			"percent": func(a, b int64) string {
+				frac := float64(a) / float64(b)
+				return fmt.Sprintf("%.1f%%", frac*100)
+			},
+			"featured": func(name, source, desc string) Featured {
+				return Featured{
+					Name:   name,
+					Source: source,
+					Desc:   desc,
+				}
+			},
+		}).
+		Parse(string(templateStr))
+
+	if err != nil {
+		panic(err)
+	}
+
+	f, err := os.Create(output)
+	if err != nil {
+		panic(err)
+	}
+	defer f.Close()
+
+	f.WriteString("<!-- Generated from " + templatePath + " DO NOT EDIT -->\n\n")
+
+	readme := Readme{
+		LargePlaces: []string{
+			"world",
+			"europe",
+			"africa",
+			"usa",
+			"japan",
+		},
+		SmallPlaces: []string{
+			"world",
+			"berlin",
+			"nyc",
+			"tokyo",
+			"ljubljana",
+		},
+	}
+
+	err = t.Execute(f, readme)
+	if err != nil {
+		panic(err)
+	}
+}
+
+func getVariants(name, glob string, previewNames []string, previewSuffix string) []Variant {
+	files, err := filepath.Glob(glob)
+	if err != nil {
+		panic(err)
+	}
+	var variants []Variant
+	for _, file := range files {
+		base := filepath.Base(file)
+		noext := strings.TrimSuffix(base, filepath.Ext(file))
+		suffix := strings.TrimPrefix(noext, name+"_")
+		dir := filepath.Dir(file)
+		pbase := name + "_" + previewSuffix + suffix
+		previews := []Preview{}
+		for _, place := range previewNames {
+			pfile := filepath.Join(dir, pbase+"_"+place+".png")
+			if _, err := os.Stat(pfile); os.IsNotExist(err) {
+				continue
+			}
+			previews = append(previews, Preview{
+				Name: place,
+				Path: filepath.ToSlash(pfile),
+			})
+		}
+		variant := Variant{
+			Name:     suffix,
+			Fullname: noext,
+			Previews: previews,
+		}
+		variants = append(variants, variant)
+	}
+	return variants
+}