updated tmdb

tmdb/request.go

@@ -4,25 +4,113 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/url"
+	"strings"
+	"time"
 
 	"github.com/pkg/errors"
 )
 
-func tmdbGet(url string, token string) ([]byte, error) {
-	req, err := http.NewRequest("GET", url, nil)
-	if err != nil {
-		return nil, errors.Wrap(err, "http.NewRequest")
-	}
-	req.Header.Add("accept", "application/json")
-	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", token))
-	res, err := http.DefaultClient.Do(req)
-	if err != nil {
-		return nil, errors.Wrap(err, "http.DefaultClient.Do")
-	}
-	defer res.Body.Close()
-	body, err := io.ReadAll(res.Body)
-	if err != nil {
-		return nil, errors.Wrap(err, "io.ReadAll")
-	}
-	return body, nil
+const baseURL string = "https://api.themoviedb.org"
+const apiVer string = "3"
+
+const (
+	maxRetries     = 3                // Maximum number of retry attempts for 429 responses
+	initialBackoff = 1 * time.Second  // Initial backoff duration
+	maxBackoff     = 32 * time.Second // Maximum backoff duration
+)
+
+// requestURL builds a clean API URL from path segments.
+// Example: requestURL("movie", "550") -> "https://api.themoviedb.org/3/movie/550"
+// Example: requestURL("search", "movie") -> "https://api.themoviedb.org/3/search/movie"
+func requestURL(pathSegments ...string) string {
+	path := strings.Join(pathSegments, "/")
+	return fmt.Sprintf("%s/%s/%s", baseURL, apiVer, path)
+}
+
+// buildURL is a convenience function that builds a URL with query parameters.
+// Example: buildURL([]string{"search", "movie"}, map[string]string{"query": "Inception", "page": "1"})
+func buildURL(pathSegments []string, params map[string]string) string {
+	baseURL := requestURL(pathSegments...)
+	if params == nil {
+		params = map[string]string{}
+	}
+	params["language"] = "en-US"
+	values := url.Values{}
+	for key, val := range params {
+		values.Add(key, val)
+	}
+
+	return fmt.Sprintf("%s?%s", baseURL, values.Encode())
+}
+
+// get performs a GET request to the TMDB API with proper authentication headers
+// and automatic retry logic with exponential backoff for rate limiting (429 responses).
+//
+// The TMDB API has rate limits around 40 requests per second. This function
+// implements a courtesy backoff mechanism that:
+//   - Retries up to maxRetries times on 429 responses
+//   - Uses exponential backoff: 1s, 2s, 4s, 8s, etc. (up to maxBackoff)
+//   - Returns an error if max retries are exceeded
+//
+// The url parameter should be the full URL (can be built using requestURL or buildURL).
+func (api *API) get(url string) ([]byte, error) {
+	backoff := initialBackoff
+
+	for attempt := 0; attempt <= maxRetries; attempt++ {
+		req, err := http.NewRequest("GET", url, nil)
+		if err != nil {
+			return nil, errors.Wrap(err, "http.NewRequest")
+		}
+		req.Header.Add("accept", "application/json")
+		req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", api.token))
+
+		res, err := http.DefaultClient.Do(req)
+		if err != nil {
+			return nil, errors.Wrap(err, "http.DefaultClient.Do")
+		}
+
+		// Check for rate limiting (429 Too Many Requests)
+		if res.StatusCode == http.StatusTooManyRequests {
+			res.Body.Close()
+
+			// If we've exhausted retries, return an error
+			if attempt >= maxRetries {
+				return nil, errors.New("rate limit exceeded: maximum retries reached")
+			}
+
+			// Check for Retry-After header first (respect server's guidance)
+			if retryAfter := res.Header.Get("Retry-After"); retryAfter != "" {
+				if duration, err := time.ParseDuration(retryAfter + "s"); err == nil {
+					backoff = duration
+				}
+			}
+
+			// Apply exponential backoff: 1s, 2s, 4s, 8s, etc.
+			if backoff > maxBackoff {
+				backoff = maxBackoff
+			}
+
+			time.Sleep(backoff)
+
+			// Double the backoff for next iteration
+			backoff *= 2
+
+			continue
+		}
+
+		// For other error status codes, return an error
+		if res.StatusCode != http.StatusOK {
+			return nil, errors.Errorf("unexpected status code: %d", res.StatusCode)
+		}
+
+		// Success - read and return body
+		body, err := io.ReadAll(res.Body)
+		if err != nil {
+			return nil, errors.Wrap(err, "io.ReadAll")
+		}
+		return body, nil
+	}
+
+	return nil, errors.Errorf("max retries (%d) exceeded due to rate limiting (HTTP 429)", maxRetries)
 }