server: Implement `interval` on /api/history/day

The default value is 5 for interval.

server/api.go

@@ -3,6 +3,7 @@ package server
 import (
 	"encoding/json"
 	"net/http"
+	"strconv"
 	"time"
 
 	"status/db"
@@ -36,39 +37,46 @@ func dayHistory(w http.ResponseWriter, req *http.Request) {
 		http.Error(w, "Only one `service_name` allowed", http.StatusBadRequest)
 		return
 	}
-	entries := db.GetFromDB(keys[0], time.Now().Add(time.Duration(-24)*time.Hour), time.Now())
-	writeJSON(w, entries)
-}
-
-func weekHistory(w http.ResponseWriter, req *http.Request) {
-	keys, ok := req.URL.Query()["service_name"]
-	if !ok || len(keys) == 0 || len(keys[0]) < 1 {
-		http.Error(w, "`service_name` not provided", http.StatusBadRequest)
+	service_name := keys[0]
+	keys, ok = req.URL.Query()["interval"]
+	var interval = 5
+	if len(keys) >= 2 {
+		http.Error(w, "Only one `interval` allowed", http.StatusBadRequest)
 		return
 	}
-	if len(keys) >= 2 {
-		http.Error(w, "Only one `service_name` allowed", http.StatusBadRequest)
+	if ok && len(keys) == 1 && len(keys[0]) >= 1 {
+		var err error
+		interval, err = strconv.Atoi(keys[0])
+		if err != nil || interval < 1 || interval > 1440 {
+			http.Error(w, "Invalid `interval` provided. Must be integer in [1, 1440]", http.StatusBadRequest)
 			return
 		}
-	entries := getHistoryDay(keys[0], 7)
-	writeJSON(w, entries)
 	}
-
-func monthHistory(w http.ResponseWriter, req *http.Request) {
-	keys, ok := req.URL.Query()["service_name"]
-	if !ok || len(keys) == 0 || len(keys[0]) < 1 {
-		http.Error(w, "`service_name` not provided", http.StatusBadRequest)
+	entries := db.GetFromDB(service_name, time.Now().Add(time.Duration(-24)*time.Hour), time.Now())
+	if interval == 1 {
+		writeJSON(w, entries)
 		return
 	}
-	if len(keys) >= 2 {
-		http.Error(w, "Only one `service_name` allowed", http.StatusBadRequest)
-		return
+	filteredEntries := make([]db.PingEntry, 0, len(entries)/interval)
+	for i := 0; i < len(entries); i += interval {
+		filteredEntries = append(filteredEntries, entries[i])
 	}
-	entries := getHistoryDay(keys[0], 31)
-	writeJSON(w, entries)
+	writeJSON(w, filteredEntries)
+}
+
+func weekHistory(w http.ResponseWriter, req *http.Request) {
+	history(w, req, 7)
+}
+
+func monthHistory(w http.ResponseWriter, req *http.Request) {
+	history(w, req, 31)
 }
 
 func yearHistory(w http.ResponseWriter, req *http.Request) {
+	history(w, req, 366)
+}
+
+func history(w http.ResponseWriter, req *http.Request, dayCount int) {
 	keys, ok := req.URL.Query()["service_name"]
 	if !ok || len(keys) == 0 || len(keys[0]) < 1 {
 		http.Error(w, "`service_name` not provided", http.StatusBadRequest)
@@ -78,6 +86,6 @@ func yearHistory(w http.ResponseWriter, req *http.Request) {
 		http.Error(w, "Only one `service_name` allowed", http.StatusBadRequest)
 		return
 	}
-	entries := getHistoryDay(keys[0], 366)
+	entries := getHistoryDay(keys[0], dayCount)
 	writeJSON(w, entries)
 }