Refactor controller and handlers

controller/handler/chart.go

@@ -0,0 +1,121 @@
+package handler
+
+import (
+	"log"
+	"math"
+	"net/http"
+	"sort"
+	"time"
+
+	"github.com/TwinProduction/gatus/storage"
+	"github.com/TwinProduction/gatus/storage/store/common"
+	"github.com/gorilla/mux"
+	"github.com/wcharczuk/go-chart/v2"
+	"github.com/wcharczuk/go-chart/v2/drawing"
+)
+
+const timeFormat = "3:04PM"
+
+var (
+	gridStyle = chart.Style{
+		StrokeColor: drawing.Color{R: 119, G: 119, B: 119, A: 40},
+		StrokeWidth: 1.0,
+	}
+	axisStyle = chart.Style{
+		FontColor: drawing.Color{R: 119, G: 119, B: 119, A: 255},
+	}
+	transparentStyle = chart.Style{
+		FillColor: drawing.Color{R: 255, G: 255, B: 255, A: 0},
+	}
+)
+
+func ResponseTimeChart(writer http.ResponseWriter, r *http.Request) {
+	vars := mux.Vars(r)
+	duration := vars["duration"]
+	var from time.Time
+	switch duration {
+	case "7d":
+		from = time.Now().Truncate(time.Hour).Add(-24 * 7 * time.Hour)
+	case "24h":
+		from = time.Now().Truncate(time.Hour).Add(-24 * time.Hour)
+	default:
+		http.Error(writer, "Durations supported: 7d, 24h", http.StatusBadRequest)
+		return
+	}
+	hourlyAverageResponseTime, err := storage.Get().GetHourlyAverageResponseTimeByKey(vars["key"], from, time.Now())
+	if err != nil {
+		if err == common.ErrServiceNotFound {
+			writer.WriteHeader(http.StatusNotFound)
+		} else if err == common.ErrInvalidTimeRange {
+			writer.WriteHeader(http.StatusBadRequest)
+		} else {
+			writer.WriteHeader(http.StatusInternalServerError)
+		}
+		_, _ = writer.Write([]byte(err.Error()))
+		return
+	}
+	if len(hourlyAverageResponseTime) == 0 {
+		writer.WriteHeader(http.StatusNoContent)
+		_, _ = writer.Write(nil)
+		return
+	}
+	series := chart.TimeSeries{
+		Name: "Average response time per hour",
+		Style: chart.Style{
+			StrokeWidth: 1.5,
+			DotWidth:    2.0,
+		},
+	}
+	keys := make([]int, 0, len(hourlyAverageResponseTime))
+	earliestTimestamp := int64(0)
+	for hourlyTimestamp := range hourlyAverageResponseTime {
+		keys = append(keys, int(hourlyTimestamp))
+		if earliestTimestamp == 0 || hourlyTimestamp < earliestTimestamp {
+			earliestTimestamp = hourlyTimestamp
+		}
+	}
+	for earliestTimestamp > from.Unix() {
+		earliestTimestamp -= int64(time.Hour.Seconds())
+		keys = append(keys, int(earliestTimestamp))
+	}
+	sort.Ints(keys)
+	var maxAverageResponseTime float64
+	for _, key := range keys {
+		averageResponseTime := float64(hourlyAverageResponseTime[int64(key)])
+		if maxAverageResponseTime < averageResponseTime {
+			maxAverageResponseTime = averageResponseTime
+		}
+		series.XValues = append(series.XValues, time.Unix(int64(key), 0))
+		series.YValues = append(series.YValues, averageResponseTime)
+	}
+	graph := chart.Chart{
+		Canvas:     transparentStyle,
+		Background: transparentStyle,
+		Width:      1280,
+		Height:     300,
+		XAxis: chart.XAxis{
+			ValueFormatter: chart.TimeValueFormatterWithFormat(timeFormat),
+			GridMajorStyle: gridStyle,
+			GridMinorStyle: gridStyle,
+			Style:          axisStyle,
+			NameStyle:      axisStyle,
+		},
+		YAxis: chart.YAxis{
+			Name:           "Average response time",
+			GridMajorStyle: gridStyle,
+			GridMinorStyle: gridStyle,
+			Style:          axisStyle,
+			NameStyle:      axisStyle,
+			Range: &chart.ContinuousRange{
+				Min: 0,
+				Max: math.Ceil(maxAverageResponseTime * 1.25),
+			},
+		},
+		Series: []chart.Series{series},
+	}
+	writer.Header().Set("Content-Type", "image/svg+xml")
+	if err := graph.Render(chart.SVG, writer); err != nil {
+		log.Println("[handler][ResponseTimeChart] Failed to render response time chart:", err.Error())
+		return
+	}
+}