Extract processing handler and imageType functions from server.go

image_type.go

@@ -0,0 +1,96 @@
+package main
+
+/*
+#cgo LDFLAGS: -s -w
+#include "vips.h"
+*/
+import "C"
+
+import (
+	"path/filepath"
+	"fmt"
+	"net/url"
+	"strings"
+)
+
+type imageType int
+
+const (
+	imageTypeUnknown = imageType(C.UNKNOWN)
+	imageTypeJPEG    = imageType(C.JPEG)
+	imageTypePNG     = imageType(C.PNG)
+	imageTypeWEBP    = imageType(C.WEBP)
+	imageTypeGIF     = imageType(C.GIF)
+	imageTypeICO     = imageType(C.ICO)
+	imageTypeSVG     = imageType(C.SVG)
+	imageTypeHEIC    = imageType(C.HEIC)
+
+	contentDispositionFilenameFallback = "image"
+)
+
+var (
+	imageTypes = map[string]imageType{
+		"jpeg": imageTypeJPEG,
+		"jpg":  imageTypeJPEG,
+		"png":  imageTypePNG,
+		"webp": imageTypeWEBP,
+		"gif":  imageTypeGIF,
+		"ico":  imageTypeICO,
+		"svg":  imageTypeSVG,
+		"heic": imageTypeHEIC,
+	}
+
+	mimes = map[imageType]string{
+		imageTypeJPEG: "image/jpeg",
+		imageTypePNG:  "image/png",
+		imageTypeWEBP: "image/webp",
+		imageTypeGIF:  "image/gif",
+		imageTypeICO:  "image/x-icon",
+		imageTypeHEIC: "image/heif",
+	}
+
+	contentDispositionsFmt = map[imageType]string{
+		imageTypeJPEG: "inline; filename=\"%s.jpg\"",
+		imageTypePNG:  "inline; filename=\"%s.png\"",
+		imageTypeWEBP: "inline; filename=\"%s.webp\"",
+		imageTypeGIF:  "inline; filename=\"%s.gif\"",
+		imageTypeICO:  "inline; filename=\"%s.ico\"",
+		imageTypeHEIC: "inline; filename=\"%s.heic\"",
+	}
+)
+
+func (it imageType) String() string {
+	for k, v := range imageTypes {
+		if v == it {
+			return k
+		}
+	}
+	return ""
+}
+
+func (it imageType) Mime() string {
+	if mime, ok := mimes[it]; ok {
+		return mime
+	} else {
+		return "application/octet-stream"
+	}
+}
+
+func (it imageType) ContentDisposition(imageURL string) string {
+	format, ok := contentDispositionsFmt[it]
+	if !ok {
+		return "inline"
+	}
+
+	url, err := url.Parse(imageURL)
+	if err != nil {
+		return fmt.Sprintf(format, contentDispositionFilenameFallback)
+	}
+
+	_, filename := filepath.Split(url.Path)
+	if len(filename) == 0 {
+		return fmt.Sprintf(format, contentDispositionFilenameFallback)
+	}
+
+	return fmt.Sprintf(format, strings.TrimSuffix(filename, filepath.Ext(filename)))
+}