goreportcard/handlers/home.go

package handlers

import (
	"encoding/json"
	"log"
	"net/http"
	"sync"

	"github.com/dgraph-io/badger/v2"
)

var cache struct {
	items []string
	mux   sync.Mutex
	count int
}

// HomeHandler handles the homepage
func (gh *GRCHandler) HomeHandler(w http.ResponseWriter, r *http.Request, db *badger.DB) {
	if r.URL.Path[1:] == "" {
		var recentRepos []string

		cache.mux.Lock()
		cache.count++
		defer cache.mux.Unlock()

		if cache.count < 100 && len(cache.items) == 5 {
			recentRepos = cache.items
			log.Println("Fetching recent repos from cache...")
		} else {
			log.Println("Updating recent repos cache...")
			recent := &[]recentItem{}
			err := db.View(func(txn *badger.Txn) error {
				item, err := txn.Get([]byte("recent"))
				if err != nil && err != badger.ErrKeyNotFound {
					return err
				}

				if item != nil {
					err = item.Value(func(val []byte) error {
						return json.Unmarshal(val, recent)
					})

					return err
				}

				return nil
			})

			if err != nil {
				log.Println("ERROR: ", err)
			}

			recentRepos = make([]string, len(*recent))
			var j = len(*recent) - 1
			for _, r := range *recent {
				recentRepos[j] = r.Repo
				j--
			}

			cache.items = recentRepos
			cache.count = 0
		}

		t, err := gh.loadTemplate("templates/home.html")
		if err != nil {
			log.Println("ERROR: could not get home template: ", err)
			http.Error(w, err.Error(), 500)
			return
		}

		if err := t.ExecuteTemplate(w, "base", map[string]interface{}{
			"Recent":               recentRepos,
			"google_analytics_key": googleAnalyticsKey,
		}); err != nil {
			log.Println(err)
		}

		return
	}

	gh.errorHandler(w, r, http.StatusNotFound)
}