Use Runner

This revamps code quite a bit. Series handling has been moved into the
gerrit client, it also handles caching.

The Runner logic itself has been greatly simplified.

The runner logic has been moved into the runner.go, submitqueue.go is
gone.

The "per-run result object" concept has been dropped - we instead just
use annotated logs.

Also, we switched to apex/log

frontend/frontend.go

@@ -13,9 +13,9 @@ import (
 	"github.com/tweag/gerrit-queue/gerrit"
 	_ "github.com/tweag/gerrit-queue/statik" // register static assets
 	"github.com/tweag/gerrit-queue/submitqueue"
-)
 
-//TODO: log last update
+	"github.com/apex/log/handlers/memory"
+)
 
 //loadTemplate loads a list of templates, relative to the statikFS root, and a FuncMap, and returns a template object
 func loadTemplate(templateNames []string, funcMap template.FuncMap) (*template.Template, error) {
@@ -47,46 +47,48 @@ func loadTemplate(templateNames []string, funcMap template.FuncMap) (*template.T
 	return tmpl, nil
 }
 
-// MakeFrontend configures the router and returns a new Frontend struct
-func MakeFrontend(runner *submitqueue.Runner) http.Handler {
+// MakeFrontend returns a http.Handler
+func MakeFrontend(memoryHandler *memory.Handler, gerritClient *gerrit.Client, runner *submitqueue.Runner) http.Handler {
 	router := gin.Default()
 
-	router.GET("/submit-queue.json", func(c *gin.Context) {
-		submitQueue, _, _ := runner.GetState()
-		c.JSON(http.StatusOK, submitQueue)
-	})
+	projectName := gerritClient.GetProjectName()
+	branchName := gerritClient.GetBranchName()
 
 	router.GET("/", func(c *gin.Context) {
-		submitQueue, currentlyRunning, results := runner.GetState()
+		var wipSerie *gerrit.Serie = nil
+		HEAD := ""
+		currentlyRunning := runner.IsCurrentlyRunning()
+
+		// don't trigger operations requiring a lock
+		if !currentlyRunning {
+			wipSerie = runner.GetWIPSerie()
+			HEAD = gerritClient.GetHEAD()
+		}
 
 		funcMap := template.FuncMap{
-			"isAutoSubmittable": func(serie *submitqueue.Serie) bool {
-				return submitQueue.IsAutoSubmittable(serie)
-			},
 			"changesetURL": func(changeset *gerrit.Changeset) string {
-				return submitQueue.GetChangesetURL(changeset)
+				return gerritClient.GetChangesetURL(changeset)
 			},
 		}
 
 		tmpl := template.Must(loadTemplate([]string{
 			"submit-queue.tmpl.html",
-			"series.tmpl.html",
 			"serie.tmpl.html",
 			"changeset.tmpl.html",
 		}, funcMap))
 
 		tmpl.ExecuteTemplate(c.Writer, "submit-queue.tmpl.html", gin.H{
 			// Config
-			"projectName": submitQueue.ProjectName,
-			"branchName":  submitQueue.BranchName,
+			"projectName": projectName,
+			"branchName":  branchName,
 
 			// State
 			"currentlyRunning": currentlyRunning,
-			"series":           submitQueue.Series,
-			"HEAD":             submitQueue.HEAD,
+			"wipSerie":         wipSerie,
+			"HEAD":             HEAD,
 
 			// History
-			"results": results,
+			"memory": memoryHandler,
 		})
 	})
 	return router