First working version

- Move from separate dirs for upload to a unified one (identify
  media/metadata files by file extension)
- Prevent uploading when an import is already scheduled
- Allow setting custom, parser-specific settings
- Add CLI
- Implement WebDAV upload
- Implement checking of upload folders for uploadable contents

Close #6, close #7, close #9, close #3, close #1, close #4

src/webdavupload/Upload.go

@@ -0,0 +1,84 @@
+package webdavupload
+
+import (
+    "fmt"
+    "path/filepath"
+    "os"
+    "runtime"
+    "sync"
+    "sync/atomic"
+    "github.com/studio-b12/gowebdav"
+    "gitea.armuli.eu/museum-digital/museum-digital-webdav-uploader/src/configloader"
+    "gitea.armuli.eu/museum-digital/museum-digital-webdav-uploader/src/importconfiggen"
+)
+
+// Writes an import config to the remote
+func SetImportConfigToTheRemote(c *gowebdav.Client, config configloader.MDWebDavUploaderConfig) error {
+
+    importConf := importconfiggen.GenerateImportConfig(config)
+    return c.Write("import_config.txt", []byte(importConf), 0660)
+
+}
+
+// Uploads a list of files to the target folder.
+func uploadFiles(c *gowebdav.Client, files []string, remoteTarget string, outputContext string) {
+
+    total := len(files)
+    var counter atomic.Uint64
+
+    // Determine the number of upload tasks to be processed concurrently.
+    // 10 will be a hard maximum to not spam the server.
+    maxConcTasks := min(10, runtime.NumCPU())
+
+    // Set a semaphore to restrict the number of concurrent upload tasks.
+    semaphore := make(chan struct{}, maxConcTasks)
+    wg := &sync.WaitGroup{}
+
+    fmt.Printf("Will upload %v files. Processing %v tasks at a time.\n", total, maxConcTasks)
+
+    for _, f := range(files) {
+
+        semaphore <- struct{}{} // acquire
+        wg.Add(1)
+
+        go func() {
+
+            defer wg.Done()
+
+            basename := filepath.Base(f)
+
+            file, fOpenErr := os.Open(f)
+            if fOpenErr != nil {
+                panic("Failed to read file: " + f)
+            }
+            defer file.Close()
+
+            c.WriteStream("./" + remoteTarget + "/" + basename, file, 0644)
+
+            counter.Add(1)
+            fmt.Printf(outputContext + ". File %v of %v. Done. (File: %v)\n", counter, total, basename)
+
+            <-semaphore // release
+
+        }()
+
+    }
+
+    wg.Wait()
+    fmt.Println("Done")
+
+}
+
+// Uploads the selected metadata files.
+func UploadMetadataFiles(c *gowebdav.Client, files []string) {
+
+    uploadFiles(c, files, "IMPORT_XML", "Uploading metadata files")
+
+}
+
+// Uploads the selected media files.
+func UploadMediaFiles(c *gowebdav.Client, files []string) {
+
+    uploadFiles(c, files, "IMPORT_IMG", "Uploading media files")
+
+}