change from rust to go as I could not figure out the image loading problem in rust

cmd/ecload/main.go

@@ -0,0 +1,60 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+package main
+
+import (
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+
+	"github.com/jawher/mow.cli"
+
+	"ecload/pkg/ecload"
+)
+
+// Initialize logger formats.
+func initLogger(
+	traceHandle io.Writer,
+	infoHandle io.Writer,
+	warningHandle io.Writer,
+	errorHandle io.Writer) ecload.Logger {
+
+	return ecload.Logger{
+		Trace:   log.New(traceHandle, "TRACE: ", log.Ldate|log.Ltime),
+		Info:    log.New(infoHandle, "INFO: ", log.Ldate|log.Ltime),
+		Warning: log.New(warningHandle, "WARNING: ", log.Ldate|log.Ltime),
+		Error:   log.New(errorHandle, "ERROR: ", log.Ldate|log.Ltime),
+	}
+}
+
+func main() {
+	logger := initLogger(ioutil.Discard, os.Stdout, os.Stdout, os.Stderr)
+
+	app := cli.App("ecload", "Download books from https://www.e-codices.unifr.ch")
+	app.Version("v version", "0.1.0")
+
+	app.Spec = "[-o=<PATH>] [-s=<SIZE>] ID"
+
+	var (
+		outDir = app.StringOpt("o out-dir", ".", "save pdf in PATH")
+		size   = app.StringOpt("s size", "medium", "Size of the downloaded images. One of small, medium, large, max.")
+		id     = app.StringArg("ID", "", "ID of the book to download. Copy the last two url parts on the overview page to get it (for example bbb/0003).")
+	)
+
+	app.Action = func() {
+		if *size != "small" && *size != "medium" && *size != "large" && *size != "max" {
+			logger.Error.Println("SIZE must be one of: small, medium, large, max")
+			cli.Exit(1)
+		}
+
+		err := ecload.DownloadBook(*outDir, *size, *id, logger)
+		if err != nil {
+			logger.Error.Println(err)
+		}
+	}
+
+	app.Run(os.Args)
+}