Refactor app context setup and move API fetch logic to PostService

internal/services/postService.go

@@ -2,6 +2,12 @@ package services
 
 import (
 	"CatsOfMastodonBotGo/internal/models"
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"strings"
 
 	"gorm.io/gorm"
 	"gorm.io/gorm/clause"
@@ -16,6 +22,38 @@ func NewPostService(db *gorm.DB) *PostService {
 	return &PostService{db: db}
 }
 
+func (ps *PostService) GetPostsFromApi(ctx context.Context, tag string, instance string) (error, []models.Post) {
+	var requestUrl = instance + "/api/v1/timelines/tag/" + tag + "?limit=40"
+	req, err := http.NewRequestWithContext(ctx, "GET", requestUrl, nil)
+	if err != nil {
+		log.Fatal(err)
+		return err, nil
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		log.Fatal(err)
+		return err, nil
+	}
+	if resp.StatusCode != 200 || strings.Split(strings.ToLower(resp.Header.Get("Content-Type")), ";")[0] != "application/json" {
+		log.Fatal("Status code:", resp.StatusCode, " Content-Type:", resp.Header.Get("Content-Type"))
+		return err, nil
+	}
+
+	var posts []models.Post = nil
+	err = json.NewDecoder(resp.Body).Decode(&posts)
+	if err != nil {
+		log.Fatal(err)
+		return err, nil
+	}
+	// defer: it basically means "do this later when the function returns"
+	defer resp.Body.Close()
+	if posts == nil {
+		return fmt.Errorf("no posts found for tag %s on instance %s", tag, instance), nil
+	}
+	return nil, posts
+}
+
 func (ps *PostService) GetExistingPostIds() []string {
 	var existingPostIds []string
 	ps.db.Model(&models.Post{}).Pluck("id", &existingPostIds)