From 93e42bd9f0ac6491ba79931e59677d3269ab40fd Mon Sep 17 00:00:00 2001
From: Ken Hibino <ken.hibino7@gmail.com>
Date: Sun, 27 Dec 2020 15:45:54 -0800
Subject: [PATCH] Add API endpoint to fetch historical stats

---
 conversion_helpers.go |  8 ++++++++
 main.go               |  3 +++
 queue_handlers.go     | 28 ++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+)

diff --git a/conversion_helpers.go b/conversion_helpers.go
index 54025c8..5cc999b 100644
--- a/conversion_helpers.go
+++ b/conversion_helpers.go
@@ -72,6 +72,14 @@ func toDailyStats(s *asynq.DailyStats) *DailyStats {
 	}
 }
 
+func toDailyStatsList(in []*asynq.DailyStats) []*DailyStats {
+	out := make([]*DailyStats, len(in))
+	for i, s := range in {
+		out[i] = toDailyStats(s)
+	}
+	return out
+}
+
 type BaseTask struct {
 	ID      string        `json:"id"`
 	Type    string        `json:"type"`
diff --git a/main.go b/main.go
index d03f9e1..09aaaeb 100644
--- a/main.go
+++ b/main.go
@@ -75,6 +75,9 @@ func main() {
 	api.HandleFunc("/queues/{qname}:pause", newPauseQueueHandlerFunc(inspector)).Methods("POST")
 	api.HandleFunc("/queues/{qname}:resume", newResumeQueueHandlerFunc(inspector)).Methods("POST")
 
+	// Queue Historical Stats endpoint.
+	api.HandleFunc("/queue_stats", newListQueueStatsHandlerFunc(inspector)).Methods("GET")
+
 	// Task endpoints.
 	api.HandleFunc("/queues/{qname}/active_tasks", newListActiveTasksHandlerFunc(inspector)).Methods("GET")
 	api.HandleFunc("/queues/{qname}/active_tasks/{task_id}:cancel", newCancelActiveTaskHandlerFunc(inspector)).Methods("POST")
diff --git a/queue_handlers.go b/queue_handlers.go
index e774a00..c3af31f 100644
--- a/queue_handlers.go
+++ b/queue_handlers.go
@@ -106,3 +106,31 @@ func newResumeQueueHandlerFunc(inspector *asynq.Inspector) http.HandlerFunc {
 		w.WriteHeader(http.StatusNoContent)
 	}
 }
+
+type ListQueueStatsResponse struct {
+	Stats map[string][]*DailyStats `json:"stats"`
+}
+
+func newListQueueStatsHandlerFunc(inspector *asynq.Inspector) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		qnames, err := inspector.Queues()
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		resp := ListQueueStatsResponse{Stats: make(map[string][]*DailyStats)}
+		const numdays = 90 // Get stats for the last 90 days.
+		for _, qname := range qnames {
+			stats, err := inspector.History(qname, numdays)
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+			resp.Stats[qname] = toDailyStatsList(stats)
+		}
+		if err := json.NewEncoder(w).Encode(resp); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+	}
+}