From 4dc62b1f1e24bb38a6944526ba58a7b442c90b09 Mon Sep 17 00:00:00 2001
From: Dipesh Dulal <nilkantha.dipesh@gmail.com>
Date: Sat, 16 Jan 2021 10:58:42 +0545
Subject: [PATCH] feat: added schedule implementation

---
 scheduler.go | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 scheduler.go

diff --git a/scheduler.go b/scheduler.go
new file mode 100644
index 0000000..5d0c987
--- /dev/null
+++ b/scheduler.go
@@ -0,0 +1,53 @@
+package main
+
+import (
+	"database/sql"
+	"log"
+	"time"
+)
+
+// Scheduler data structure
+type Scheduler struct {
+	db        *sql.DB
+	listeners Listeners
+}
+
+// Listeners has attached event listeners
+type Listeners map[string]ListenFunc
+
+// ListenFunc function that listens to events
+type ListenFunc func(string)
+
+// Event structure
+type Event struct {
+	ID      uint
+	Name    string
+	Payload string
+}
+
+// NewScheduler creates a new scheduler
+func NewScheduler(db *sql.DB, listeners Listeners) Scheduler {
+	return Scheduler{
+		db:        db,
+		listeners: listeners,
+	}
+}
+
+// AddListener adds the listener function to Listeners
+func (s Scheduler) AddListener(event string, listenFunc ListenFunc) {
+	s.listeners[event] = listenFunc
+}
+
+// CheckDueEvents checks and returns due events
+func (s Scheduler) CheckDueEvents() {
+	// var event Event
+	// s.db.Query(`SELECT id, name, payload FROM jobs WHERE locked = 0`)
+}
+
+// Schedule sechedules the provided events
+func (s Scheduler) Schedule(event string, payload string, runAt time.Time) {
+	_, err := s.db.Exec(`INSERT INTO "public"."jobs" ("name", "payload", "runAt") VALUES ($1, $2, $3)`, event, payload, runAt)
+	if err != nil {
+		log.Print("schedule insert error: ", err)
+	}
+}