add minification

app/utils.go

@@ -1,9 +1,18 @@
 package app
 
 import (
+	"embed"
 	"encoding/json"
+	"io"
+	"io/fs"
 	"log"
 	"os"
+	"strings"
+
+	"github.com/tdewolff/minify"
+	"github.com/tdewolff/minify/css"
+	"github.com/tdewolff/minify/html"
+	"github.com/tdewolff/minify/js"
 )
 
 type Config struct {
@@ -26,3 +35,92 @@ func GetConfig(configPath string) Config {
 	}
 	return config
 }
+
+type MimeType struct {
+	Type     string
+	Minifier func(m *minify.M, w io.Writer, r io.Reader, params map[string]string) error
+}
+
+var PlainTextMimeType = MimeType{
+	Type:     "text/plain",
+	Minifier: nil,
+}
+
+var MimeTypes = map[string]MimeType{
+	"css": {
+		Type:     "text/css",
+		Minifier: css.Minify,
+	},
+	"html": {
+		Type:     "text/html",
+		Minifier: html.Minify,
+	},
+	"svg": {
+		Type:     "image/svg+xml",
+		Minifier: nil,
+	},
+	"js": {
+		Type:     "application/javascript",
+		Minifier: js.Minify,
+	},
+	"wasm": {
+		Type:     "application/wasm",
+		Minifier: nil,
+	},
+}
+
+func InitMinify() *minify.M {
+	m := minify.New()
+	for _, v := range MimeTypes {
+		if v.Minifier != nil {
+			m.AddFunc(v.Type, v.Minifier)
+		}
+	}
+	return m
+}
+
+type StaticFile struct {
+	Data     string
+	MimeType MimeType
+}
+
+func MinifyStatic(m *minify.M, files embed.FS) map[string]StaticFile {
+	minified := make(map[string]StaticFile)
+	fs.WalkDir(files, ".", func(path string, entry fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if !entry.IsDir() {
+			v, err := files.ReadFile(path)
+			if err != nil {
+				log.Fatalf("error parsing template file %s: %s", path, err.Error())
+			}
+			x := strings.Split(entry.Name(), ".")
+			if len(x) >= 2 { // file has extension
+				mimetype, ok := MimeTypes[x[len(x)-1]]
+				if ok && mimetype.Minifier != nil { // if the extension is mapped in MimeTypes and has a minifier
+					min, err := m.String(mimetype.Type, string(v)) // try to minify
+					if err != nil {
+						log.Fatalf("error minifying file %s: %s", path, err.Error())
+					}
+					minified[path] = StaticFile{
+						Data:     min,
+						MimeType: mimetype,
+					}
+				} else { // if extension is not in MimeTypes and does not have minifier, skip minify
+					minified[path] = StaticFile{
+						Data:     string(v),
+						MimeType: mimetype,
+					}
+				}
+			} else { // if the file has no extension, skip minify
+				minified[path] = StaticFile{
+					Data:     string(v),
+					MimeType: PlainTextMimeType,
+				}
+			}
+		}
+		return nil
+	})
+	return minified
+}