From c8a2799267b8877a36fe67b9904b580129786ecd Mon Sep 17 00:00:00 2001
From: Sherif Abdel-Naby <sherifabdlnaby@gmail.com>
Date: Sun, 4 Apr 2021 01:25:48 +0200
Subject: [PATCH] Add Schedule Interface + Fixed Intervals scheduler

Signed-off-by: Sherif Abdel-Naby <sherifabdlnaby@gmail.com>
---
 fixed.go    | 29 +++++++++++++++++++++++++++++
 schedule.go |  7 +++++++
 2 files changed, 36 insertions(+)
 create mode 100644 fixed.go
 create mode 100644 schedule.go

diff --git a/fixed.go b/fixed.go
new file mode 100644
index 0000000..09b62d1
--- /dev/null
+++ b/fixed.go
@@ -0,0 +1,29 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+type Fixed struct {
+	duration time.Duration
+	next     time.Time
+}
+
+func NewFixed(duration time.Duration) (*Fixed, error) {
+	if duration < 0 {
+		return nil, fmt.Errorf("invalid duration, must be >= 0")
+	}
+	return &Fixed{
+		duration: duration,
+		next:     time.Now().Add(duration),
+	}, nil
+}
+
+func (f *Fixed) Next() time.Time {
+	now := time.Now()
+	if now.After(f.next) {
+		f.next = f.next.Add(f.duration)
+	}
+	return f.next
+}
diff --git a/schedule.go b/schedule.go
new file mode 100644
index 0000000..964d9e8
--- /dev/null
+++ b/schedule.go
@@ -0,0 +1,7 @@
+package main
+
+import "time"
+
+type Schedule interface {
+	Next() time.Time
+}