doi: add new doi backend

Add a new backend to support mounting datasets published with a digital
object identifier (DOI).

backend/doi/dataverse.go

@@ -0,0 +1,112 @@
+// Implementation for Dataverse
+
+package doi
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/url"
+	"path"
+	"strings"
+	"time"
+
+	"github.com/rclone/rclone/backend/doi/api"
+	"github.com/rclone/rclone/fs"
+	"github.com/rclone/rclone/lib/rest"
+)
+
+// Returns true if resolvedURL is likely a DOI hosted on a Dataverse intallation
+func activateDataverse(resolvedURL *url.URL) (isActive bool) {
+	queryValues := resolvedURL.Query()
+	persistentID := queryValues.Get("persistentId")
+	return persistentID != ""
+}
+
+// Resolve the main API endpoint for a DOI hosted on a Dataverse installation
+func resolveDataverseEndpoint(resolvedURL *url.URL) (provider Provider, endpoint *url.URL, err error) {
+	queryValues := resolvedURL.Query()
+	persistentID := queryValues.Get("persistentId")
+
+	query := url.Values{}
+	query.Add("persistentId", persistentID)
+	endpointURL := resolvedURL.ResolveReference(&url.URL{Path: "/api/datasets/:persistentId/", RawQuery: query.Encode()})
+
+	return Dataverse, endpointURL, nil
+}
+
+// dataverseProvider implements the doiProvider interface for Dataverse installations
+type dataverseProvider struct {
+	f *Fs
+}
+
+// ListEntries returns the full list of entries found at the remote, regardless of root
+func (dp *dataverseProvider) ListEntries(ctx context.Context) (entries []*Object, err error) {
+	// Use the cache if populated
+	cachedEntries, found := dp.f.cache.GetMaybe("files")
+	if found {
+		parsedEntries, ok := cachedEntries.([]Object)
+		if ok {
+			for _, entry := range parsedEntries {
+				newEntry := entry
+				entries = append(entries, &newEntry)
+			}
+			return entries, nil
+		}
+	}
+
+	filesURL := dp.f.endpoint
+	var res *http.Response
+	var result api.DataverseDatasetResponse
+	opts := rest.Opts{
+		Method:     "GET",
+		Path:       strings.TrimLeft(filesURL.EscapedPath(), "/"),
+		Parameters: filesURL.Query(),
+	}
+	err = dp.f.pacer.Call(func() (bool, error) {
+		res, err = dp.f.srv.CallJSON(ctx, &opts, nil, &result)
+		return shouldRetry(ctx, res, err)
+	})
+	if err != nil {
+		return nil, fmt.Errorf("readDir failed: %w", err)
+	}
+	modTime, modTimeErr := time.Parse(time.RFC3339, result.Data.LatestVersion.LastUpdateTime)
+	if modTimeErr != nil {
+		fs.Logf(dp.f, "error: could not parse last update time %v", modTimeErr)
+		modTime = timeUnset
+	}
+	for _, file := range result.Data.LatestVersion.Files {
+		contentURLPath := fmt.Sprintf("/api/access/datafile/%d", file.DataFile.ID)
+		query := url.Values{}
+		query.Add("format", "original")
+		contentURL := dp.f.endpoint.ResolveReference(&url.URL{Path: contentURLPath, RawQuery: query.Encode()})
+		entry := &Object{
+			fs:          dp.f,
+			remote:      path.Join(file.DirectoryLabel, file.DataFile.Filename),
+			contentURL:  contentURL.String(),
+			size:        file.DataFile.FileSize,
+			modTime:     modTime,
+			md5:         file.DataFile.MD5,
+			contentType: file.DataFile.ContentType,
+		}
+		if file.DataFile.OriginalFileName != "" {
+			entry.remote = path.Join(file.DirectoryLabel, file.DataFile.OriginalFileName)
+			entry.size = file.DataFile.OriginalFileSize
+			entry.contentType = file.DataFile.OriginalFileFormat
+		}
+		entries = append(entries, entry)
+	}
+	// Populate the cache
+	cacheEntries := []Object{}
+	for _, entry := range entries {
+		cacheEntries = append(cacheEntries, *entry)
+	}
+	dp.f.cache.Put("files", cacheEntries)
+	return entries, nil
+}
+
+func newDataverseProvider(f *Fs) doiProvider {
+	return &dataverseProvider{
+		f: f,
+	}
+}