api: import from commento export format

JSON data can be imported to restore previously exported data
or to migrate data from another self-hosted commento instance.

Closes https://gitlab.com/commento/commento/issues/239

api/domain_import_commento.go

@@ -0,0 +1,168 @@
+package main
+
+import (
+	"bytes"
+	"compress/gzip"
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+)
+
+type dataImport struct {
+	Version    int         `json:"version"`
+	Comments   []comment   `json:"comments"`
+	Commenters []commenter `json:"commenters"`
+}
+
+func domainImportCommento(domain string, url string) (int, error) {
+	if domain == "" || url == "" {
+		return 0, errorMissingField
+	}
+
+	resp, err := http.Get(url)
+	if err != nil {
+		logger.Errorf("cannot get url: %v", err)
+		return 0, errorCannotDownloadCommento
+	}
+
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		logger.Errorf("cannot read body: %v", err)
+		return 0, errorCannotDownloadCommento
+	}
+
+	zr, err := gzip.NewReader(bytes.NewBuffer(body))
+	if err != nil {
+		logger.Errorf("cannot create gzip reader: %v", err)
+		return 0, errorInternal
+	}
+
+	contents, err := ioutil.ReadAll(zr)
+	if err != nil {
+		logger.Errorf("cannot read gzip contents uncompressed: %v", err)
+		return 0, errorInternal
+	}
+
+	var data dataImport
+	if err := json.Unmarshal(contents, &data); err != nil {
+		logger.Errorf("cannot unmarshal JSON at %s: %v", url, err)
+		return 0, errorInternal
+	}
+
+	if data.Version != 1 {
+		logger.Errorf("invalid data version (got %d, want 1): %v", data.Version, err)
+		return 0, errorUnsupportedCommentoImportVersion
+	}
+
+	// Check if imported commentedHex or email exists, creating a map of
+	// commenterHex (old hex, new hex)
+	commenterHex := map[string]string{"anonymous": "anonymous"}
+	for _, commenter := range data.Commenters {
+		c, err := commenterGetByEmail("commento", commenter.Email)
+		if err != nil && err != errorNoSuchCommenter {
+			logger.Errorf("cannot get commenter by email: %v", err)
+			return 0, errorInternal
+		}
+
+		if err == nil {
+			commenterHex[commenter.CommenterHex] = c.CommenterHex
+			continue
+		}
+
+		randomPassword, err := randomHex(32)
+		if err != nil {
+			logger.Errorf("cannot generate random password for new commenter: %v", err)
+			return 0, errorInternal
+		}
+
+		commenterHex[commenter.CommenterHex], err = commenterNew(commenter.Email,
+			commenter.Name, commenter.Link, commenter.Photo, "commento", randomPassword)
+		if err != nil {
+			return 0, err
+		}
+	}
+
+	// Create a map of (parent hex, comments)
+	comments := make(map[string][]comment)
+	for _, comment := range data.Comments {
+		parentHex := comment.ParentHex
+		comments[parentHex] = append(comments[parentHex], comment)
+	}
+
+	// Import comments, creating a map of comment hex (old hex, new hex)
+	commentHex := map[string]string{"root": "root"}
+	numImported := 0
+	keys := []string{"root"}
+	for i := 0; i < len(keys); i++ {
+		for _, comment := range comments[keys[i]] {
+			cHex, ok := commenterHex[comment.CommenterHex]
+			if !ok {
+				logger.Errorf("cannot get commenter: %v", err)
+				return numImported, errorInternal
+			}
+			parentHex, ok := commentHex[comment.ParentHex]
+			if !ok {
+				logger.Errorf("cannot get parent comment: %v", err)
+				return numImported, errorInternal
+			}
+
+			hex, err := commentNew(
+				cHex,
+				domain,
+				comment.Path,
+				parentHex,
+				comment.Markdown,
+				comment.State,
+				comment.CreationDate)
+			if err != nil {
+				return numImported, err
+			}
+			commentHex[comment.CommentHex] = hex
+			numImported++
+			keys = append(keys, comment.CommentHex)
+		}
+	}
+
+	return numImported, nil
+}
+
+func domainImportCommentoHandler(w http.ResponseWriter, r *http.Request) {
+	type request struct {
+		OwnerToken *string `json:"ownerToken"`
+		Domain     *string `json:"domain"`
+		URL        *string `json:"url"`
+	}
+
+	var x request
+	if err := bodyUnmarshal(r, &x); err != nil {
+		bodyMarshal(w, response{"success": false, "message": err.Error()})
+		return
+	}
+
+	o, err := ownerGetByOwnerToken(*x.OwnerToken)
+	if err != nil {
+		bodyMarshal(w, response{"success": false, "message": err.Error()})
+		return
+	}
+
+	domain := domainStrip(*x.Domain)
+	isOwner, err := domainOwnershipVerify(o.OwnerHex, domain)
+	if err != nil {
+		bodyMarshal(w, response{"success": false, "message": err.Error()})
+		return
+	}
+
+	if !isOwner {
+		bodyMarshal(w, response{"success": false, "message": errorNotAuthorised.Error()})
+		return
+	}
+
+	numImported, err := domainImportCommento(domain, *x.URL)
+	if err != nil {
+		bodyMarshal(w, response{"success": false, "message": err.Error()})
+		return
+	}
+
+	bodyMarshal(w, response{"success": true, "numImported": numImported})
+}