feat: add change detection module

internal/feed/changedetection.go

@@ -0,0 +1,79 @@
+package feed
+
+import (
+	"fmt"
+	"log/slog"
+	"net/http"
+	"time"
+)
+
+type changeDetectionResponseJson struct {
+	Name        string `json:"title"`
+	Url         string `json:"url"`
+	LastChanged int    `json:"last_changed"`
+}
+
+	
+func parseLastChangeTime(t int) time.Time {
+	parsedTime := time.Unix(int64(t), 0)
+	return parsedTime
+}
+
+
+func FetchLatestDetectedChanges(watches []string, token string) (ChangeWatches, error) {
+	changeWatches := make(ChangeWatches, 0, len(watches))
+
+	if len(watches) == 0 {
+		return changeWatches, nil
+	}
+
+	requests := make([]*http.Request, len(watches))
+
+	for i, repository := range watches {
+		request, _ := http.NewRequest("GET", fmt.Sprintf("https://changedetection.knhash.in/api/v1/watch/%s", repository), nil)
+
+		if token != "" {
+			request.Header.Add("x-api-key", token)
+		}
+
+		requests[i] = request
+	}
+
+	task := decodeJsonFromRequestTask[changeDetectionResponseJson](defaultClient)
+	job := newJob(task, requests).withWorkers(15)
+	responses, errs, err := workerPoolDo(job)
+
+	if err != nil {
+		return nil, err
+	}
+
+	var failed int
+
+	for i := range responses {
+		if errs[i] != nil {
+			failed++
+			slog.Error("Failed to fetch or parse change detections", "error", errs[i], "url", requests[i].URL)
+			continue
+		}
+
+		watch := responses[i]
+
+		changeWatches = append(changeWatches, ChangeWatch{
+			Name:        watch.Name,
+			Url:         watch.Url,
+			LastChanged: parseLastChangeTime(watch.LastChanged),
+		})
+	}
+
+	if len(changeWatches) == 0 {
+		return nil, ErrNoContent
+	}
+
+	changeWatches.SortByNewest()
+
+	if failed > 0 {
+		return changeWatches, fmt.Errorf("%w: could not get %d watches", ErrPartialContent, failed)
+	}
+
+	return changeWatches, nil
+}

internal/feed/primitives.go

@@ -48,6 +48,14 @@ type AppRelease struct {
 
 type AppReleases []AppRelease
 
+type ChangeWatch struct {
+	Name        string
+	Url         string
+	LastChanged time.Time
+}
+
+type ChangeWatches []ChangeWatch
+
 type Video struct {
 	ThumbnailUrl string
 	Title        string
@@ -200,6 +208,14 @@ func (r AppReleases) SortByNewest() AppReleases {
 	return r
 }
 
+func (r ChangeWatches) SortByNewest() ChangeWatches {
+	sort.Slice(r, func(i, j int) bool {
+		return r[i].LastChanged.After(r[j].LastChanged)
+	})
+
+	return r
+}
+
 func (v Videos) SortByNewest() Videos {
 	sort.Slice(v, func(i, j int) bool {
 		return v[i].TimePosted.After(v[j].TimePosted)