Initial commit

2024-12-30 05:36:42 -07:00
commit 39cea7b77c
7 changed files with 480 additions and 0 deletions
--- a/rate_limit/rate_limit.go
+++ b/rate_limit/rate_limit.go
@@ -0,0 +1,124 @@
+package rate_limit
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"strconv"
+	"time"
+)
+
+type RateLimit struct {
+	client    *http.Client
+	used      int
+	remaining int
+	reset     time.Time
+}
+
+func getFutureTime(seconds int) time.Time {
+	return time.Now().Add(time.Duration(seconds) * time.Second)
+}
+
+func sleepUntil(when time.Time) {
+	now := time.Now()
+	if now.After(when) {
+		return
+	}
+	time.Sleep(when.Sub(now))
+}
+
+func NewRateLimit() *RateLimit {
+	return &RateLimit{
+		client:    &http.Client{},
+		remaining: 100,
+		reset:     time.Now(),
+	}
+}
+
+func (rl *RateLimit) UpdateUsed(used string) {
+	val, err := strconv.ParseFloat(used, 64)
+	if err == nil {
+		rl.used = int(val)
+		log.Println("used ->", rl.used)
+	}
+}
+
+func (rl *RateLimit) UpdateRemaining(used string) {
+	val, err := strconv.ParseFloat(used, 64)
+	if err == nil {
+		rl.remaining = int(val)
+		log.Println("remaining ->", rl.remaining)
+	}
+}
+
+func (rl *RateLimit) UpdateReset(used string) {
+	val, err := strconv.ParseFloat(used, 64)
+	if err == nil {
+		maybe := getFutureTime(int(val))
+		if rl.reset.Before(maybe) {
+			rl.reset = maybe
+			log.Println("reset ->", rl.reset)
+		}
+	}
+}
+
+// Get makes an HTTP GET request to the specified URL while respecting rate limits
+func (rl *RateLimit) Get(url string, accept string) ([]byte, error) {
+	if rl.remaining <= 0 {
+		log.Println("no requests remaining, sleep until", rl.reset)
+		sleepUntil(rl.reset)
+	}
+
+	// Create new request
+	log.Println("GET", url)
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to make request: %w", err)
+	}
+
+	// Add any required headers
+	req.Header.Add("User-Agent", "linux:reddit-images:0.1")
+	if accept != "" {
+		req.Header.Add("Accept", accept)
+	}
+
+	// Make the request
+	resp, err := rl.client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("failed to make request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	// parse rate limit
+	used := resp.Header.Get("X-Ratelimit-Used")
+	remaining := resp.Header.Get("X-Ratelimit-Remaining")
+	reset := resp.Header.Get("X-Ratelimit-Reset")
+	// fmt.Printf("User Limit: %s\n", used)
+	// fmt.Printf("Remaining: %s\n", remaining)
+	// fmt.Printf("Reset: %s\n", reset)
+	rl.UpdateUsed(used)
+	rl.UpdateRemaining(remaining)
+	rl.UpdateReset(reset)
+
+	if resp.StatusCode == http.StatusTooManyRequests {
+		rl.remaining = 0
+
+		// if the reset time is before now, just pick a while in the future for the next retry
+		if rl.reset.Before(time.Now()) {
+			rl.UpdateReset("450")
+		}
+		return nil, fmt.Errorf("request failed with 429")
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("request failed with status: %d", resp.StatusCode)
+	}
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response body: %w", err)
+	}
+
+	return body, nil
+}