top-wallpaper/reddit/fetcher.go

package reddit

import (
	"context"
	"io"
	"net/http"
	"net/url"
	"os"
	"strconv"
	"strings"
	"time"

	"github.com/labstack/echo/v4"
	"github.com/siteworxpro/top-wallpaper/redis"
	"github.com/siteworxpro/top-wallpaper/resize"
)

func Fetch(ctx context.Context) {
	const defaultImageSize = 1600
	const minImageSize = 100

	rc, err := redis.FromContext(ctx)
	if err != nil {
		panic("Redis client not found in context: " + err.Error())
	}

	l := ctx.Value("logger").(echo.Logger)

	var size int
	if sizeS, ok := os.LookupEnv("MAX_SIZE"); ok {
		size, err = strconv.Atoi(sizeS)
		if err != nil {
			size = defaultImageSize
		}
	} else {
		size = defaultImageSize
	}

	if size < minImageSize {
		size = defaultImageSize
	}

	for {
		select {
		case <-ctx.Done():

			l.Info("Stopping Reddit fetcher...")
			_ = rc.Close()

			return
		default:

			val, err := rc.Get(redis.CacheKey)
			if err != nil {
				l.Error("Error fetching from Redis: ", err)
				break
			}

			if val != "" {
				l.Info("Reddit image fetched from cache...")

				break
			}

			l.Info("Fetching latest image from Reddit...")

			latestImageVal, err := GetLatestImage(func(u string) (*http.Response, error) {

				request := &http.Request{
					Method: http.MethodGet,
					Header: http.Header{
						"User-Agent": []string{"Mozilla/5.0 (compatible; RedditBot/1.0; +https://www.reddit.com/wiki/redditauth)"},
					},
					URL: &url.URL{
						Scheme: "https",
						Host:   "www.reddit.com",
						Path:   strings.TrimPrefix(u, "https://www.reddit.com"),
					},
				}

				httpClient := &http.Client{
					Timeout: 10 * time.Second,
				}

				response, e := httpClient.Do(request)

				if e != nil {
					l.Error("Error fetching image from Reddit: ", e)
					return nil, e
				}

				if response.StatusCode != http.StatusOK {
					l.Error("Error fetching image from Reddit: ", response.Status)
					return nil, &echo.HTTPError{
						Code:    response.StatusCode,
						Message: "Error fetching image from Reddit",
					}
				}

				return response, nil
			})

			if err != nil {
				l.Error("Error getting latest image URL: ", err)
				break
			}

			response, err := http.Get(latestImageVal)
			if err != nil {
				l.Error("Error fetching image from Reddit: ", err)

				break
			}

			if response.StatusCode != http.StatusOK {
				l.Error("Error fetching image from Reddit: ", response.Status)

				break
			}

			imageDataBytes, err := io.ReadAll(response.Body)
			if err != nil {
				l.Error("Error reading image data: ", err)
				_ = response.Body.Close()
				break
			}

			_ = response.Body.Close()

			imageData := string(imageDataBytes)
			resized, err := resize.Shrink(imageData, uint(size), 70)

			if err != nil {
				l.Error("Error resizing image: ", err)
				break
			}

			err = rc.Set(redis.CacheKey, resized, 10*time.Minute)
			if err != nil {
				l.Warn("could not cache image")
			}

			l.Info("Reddit image fetched and resized successfully, cached for 10 minutes.")
		}

		time.Sleep(10 * time.Minute)
	}
}