Server: Refactor internal server package to use new state file

This completely rewrites the internal server package. Some advantages:

- Caches less
- Uses a callback interface so that the client package does not get so
 convoluted
- Introduce a new API package that only deals with the server API and
 uses github.com/jwijenbergh/eduoauth-go

1 files changed, 70 insertions, 0 deletions

diff --git a/internal/server/time.go b/internal/server/time.go
new file mode 100644
index 0000000..4e54ef6
--- /dev/null
+++ b/internal/server/time.go
@@ -0,0 +1,70 @@
+package server
+
+import "time"
+
+// RenewButtonTime returns the time when the renew button should be shown for the server
+// Implemented according to: https://github.com/eduvpn/documentation/blob/cdf4d054f7652d74e4192494e8bb0e21040e46ac/API.md#session-expiry
+func RenewButtonTime(st time.Time, et time.Time) int64 {
+	d := et.Sub(st)
+
+	// If the time is less than 24 hours (a day left), show it when 30 minutes have passed or on expired if less than 30 minutes
+	dayl := time.Duration(24 * time.Hour)
+	if d < dayl {
+		// Get the minimum time to add, 30 minutes or on expired
+		m := time.Duration(30 * time.Minute)
+		// The total delta time is larger, return that we should show the button after 30 minutes
+		if d > m {
+			return st.Add(30 * time.Minute).Unix()
+		}
+		// Just show it on expired
+		return st.Add(d).Unix()
+	}
+
+	// Else just show it when 24 hours is left
+	// This is the delta minus 24 hours left as that's how long it takes for a day to be left in the expiry
+	// We thus add this to the start time
+	tillDay := d - dayl
+	t := st.Add(tillDay)
+	return t.Unix()
+}
+
+func CountdownTime(st time.Time, et time.Time) int64 {
+	d := et.Sub(st)
+
+	dayl := time.Duration(24 * time.Hour)
+
+	// This is just the last 24 hours
+	// if less than or equal to 24 hours, immediately
+	if d <= dayl {
+		return st.Unix()
+	}
+
+	tillDay := d - dayl
+	t := st.Add(tillDay)
+	return t.Unix()
+}
+
+func NotificationTimes(st time.Time, et time.Time) []int64 {
+	last := []time.Duration{
+		time.Duration(0),
+		time.Duration(1 * time.Hour),
+		time.Duration(2 * time.Hour),
+		time.Duration(4 * time.Hour),
+	}
+
+	var t []int64
+
+	d := et.Sub(st)
+	for _, l := range last {
+		// If the notification remaining time is more than the total delta, continue
+		if l > d {
+			continue
+		}
+		// calculating the time till a notification must happen
+		tillN := d - l
+		// Get absolute time when this notification must be shown by adding the delta
+		c := st.Add(tillN)
+		t = append(t, c.Unix())
+	}
+	return t
+}