Implement sliding window

Author: Pavan-Rana

internal/algorithm/sliding_window.go

@@ -1 +1,46 @@
-// internal/algorithm/sliding_window.go
+package algorithm
+
+import (
+	"sync"
+	"time"
+)
+
+type SlidingWindow struct {
+	mu	   	 sync.Mutex
+	requests []time.Time
+	limit	 int
+	window 	 time.Duration
+}
+
+func NewSlidingWindoe(limit int, window time.Duration) *SlidingWindow {
+	return &SlidingWindow{limit: limit, window: window}
+}
+
+func (sw: *SlidingWindow) Allow() bool {
+	sw.mu.Lock()
+	defer sw.mu.Unlock()
+
+	now := time.Now()
+	cutoff := now.Add(-sw.window)
+
+	valid := sw.requests[:0]
+	for _, t := range sw.requests {
+		if t.After(cutoff) {
+			valid = append(valid, t)
+		}
+	}
+	sw.requests = valid
+
+	if len(sw.requests) >= sw.limit {
+		return false
+	}
+
+	sw.requests = append(sw.requests, now)
+	return true
+}
+
+func (sw *SlidingWindow) Count() int {
+	sw.mu.Lock()
+	defer sw.mu.Unlock()
+	return len(sw.requests)
+}