api,db: add comments count endpoint

Closes https://gitlab.com/commento/commento-ce/issues/27

api/comment_count.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"net/http"
+)
+
+func commentCount(domain string, path string) (int, error) {
+	// path can be empty
+	if domain == "" {
+		return 0, errorMissingField
+	}
+
+	p, err := pageGet(domain, path)
+	if err != nil {
+		return 0, errorInternal
+	}
+
+	return p.CommentCount, nil
+}
+
+func commentCountHandler(w http.ResponseWriter, r *http.Request) {
+	type request struct {
+		Domain         *string `json:"domain"`
+		Path           *string `json:"path"`
+	}
+
+	var x request
+	if err := bodyUnmarshal(r, &x); err != nil {
+		bodyMarshal(w, response{"success": false, "message": err.Error()})
+		return
+	}
+
+	domain := domainStrip(*x.Domain)
+	path := *x.Path
+
+	count, err := commentCount(domain, path)
+	if err != nil {
+		bodyMarshal(w, response{"success": false, "message": err.Error()})
+		return
+	}
+
+	bodyMarshal(w, response{"success": true, "count": count})
+}