add rss service (#117)

* add rss service

* git ignore rss

* update readme

* go fmt

* maintain map by url

* make rss service multi-tenant

rss/handler/rss.go

@@ -0,0 +1,174 @@
+package handler
+
+import (
+	"context"
+	"fmt"
+	"hash/fnv"
+	"strings"
+	"time"
+
+	"github.com/micro/micro/v3/service/errors"
+	log "github.com/micro/micro/v3/service/logger"
+	"github.com/micro/micro/v3/service/model"
+	"github.com/micro/services/pkg/tenant"
+	pb "github.com/micro/services/rss/proto"
+)
+
+type Rss struct {
+	feeds            model.Model
+	entries          model.Model
+	feedsIdIndex     model.Index
+	feedsNameIndex   model.Index
+	entriesDateIndex model.Index
+	entriesURLIndex  model.Index
+}
+
+func idFromName(name string) string {
+	hash := fnv.New64a()
+	hash.Write([]byte(name))
+	return fmt.Sprintf("%d", hash.Sum64())
+}
+
+func NewRss() *Rss {
+	idIndex := model.ByEquality("id")
+	idIndex.Order.Type = model.OrderTypeUnordered
+
+	nameIndex := model.ByEquality("name")
+	nameIndex.Order.Type = model.OrderTypeUnordered
+
+	dateIndex := model.ByEquality("date")
+	dateIndex.Order.Type = model.OrderTypeDesc
+
+	entriesURLIndex := model.ByEquality("url")
+	entriesURLIndex.Order.Type = model.OrderTypeDesc
+	entriesURLIndex.Order.FieldName = "date"
+
+	f := &Rss{
+		feeds: model.NewModel(
+			model.WithNamespace("feeds"),
+			model.WithIndexes(idIndex, nameIndex),
+		),
+		entries: model.NewModel(
+			model.WithNamespace("entries"),
+			model.WithIndexes(dateIndex, entriesURLIndex),
+		),
+		feedsIdIndex:     idIndex,
+		feedsNameIndex:   nameIndex,
+		entriesDateIndex: dateIndex,
+		entriesURLIndex:  entriesURLIndex,
+	}
+
+	// register model instances
+	f.feeds.Register(new(pb.Feed))
+	f.entries.Register(new(pb.Entry))
+
+	go f.crawl()
+	return f
+}
+
+func (e *Rss) crawl() {
+	e.fetchAll()
+	tick := time.NewTicker(1 * time.Minute)
+	for _ = range tick.C {
+		e.fetchAll()
+	}
+}
+
+func (e *Rss) Add(ctx context.Context, req *pb.AddRequest, rsp *pb.AddResponse) error {
+	log.Info("Received Rss.Add request")
+
+	if len(req.Name) == 0 {
+		return errors.BadRequest("rss.add", "require name")
+	}
+
+	// get the tenantID
+	tenantID, ok := tenant.FromContext(ctx)
+	if !ok {
+		tenantID = "micro"
+	}
+
+	f := pb.Feed{
+		Id:       tenantID + "/" + idFromName(req.Name),
+		Name:     req.Name,
+		Url:      req.Url,
+		Category: req.Category,
+	}
+
+	// create the feed
+	e.feeds.Create(f)
+
+	// schedule immediate fetch
+	go e.fetch(&f)
+
+	return nil
+}
+
+func (e *Rss) Feed(ctx context.Context, req *pb.FeedRequest, rsp *pb.FeedResponse) error {
+	log.Info("Received Rss.Entries request")
+	if len(req.Name) == 0 {
+		return errors.BadRequest("rss.feed", "missing feed name")
+	}
+
+	// get the tenantID
+	tenantID, ok := tenant.FromContext(ctx)
+	if !ok {
+		tenantID = "micro"
+	}
+
+	feed := new(pb.Feed)
+	id := tenantID + "/" + idFromName(req.Name)
+	q := model.QueryEquals("ID", id)
+
+	// get the feed
+	if err := e.feeds.Read(q, feed); err != nil {
+		return errors.InternalServerError("rss.feeds", "could not read feed")
+	}
+
+	// get the entries for each
+	return e.entries.Read(e.entriesURLIndex.ToQuery(feed.Url), &rsp.Entries)
+}
+
+func (e *Rss) List(ctx context.Context, req *pb.ListRequest, rsp *pb.ListResponse) error {
+	var feeds []*pb.Feed
+	q := model.QueryAll()
+
+	// TODO: find a way to query only by tenant
+	err := e.feeds.Read(q, &feeds)
+	if err != nil {
+		return errors.InternalServerError("rss.list", "failed to read list of feeds: %v", err)
+	}
+
+	// get the tenantID
+	tenantID, ok := tenant.FromContext(ctx)
+	if !ok {
+		tenantID = "micro"
+	}
+
+	for _, feed := range feeds {
+		// filter for the tenant
+		if !strings.HasPrefix(feed.Id, tenantID+"/") {
+			continue
+		}
+
+		rsp.Feeds = append(rsp.Feeds, feed)
+	}
+
+	return nil
+}
+
+func (e *Rss) Remove(ctx context.Context, req *pb.RemoveRequest, rsp *pb.RemoveResponse) error {
+	if len(req.Name) == 0 {
+		return errors.BadRequest("rss.remove", "blank name provided")
+	}
+
+	// get the tenantID
+	tenantID, ok := tenant.FromContext(ctx)
+	if !ok {
+		tenantID = "micro"
+	}
+
+	id := tenantID + "/" + idFromName(req.Name)
+
+	e.feeds.Delete(model.QueryEquals("ID", id))
+	return nil
+}