Fix MR Selection, Go Code Refactor (#358)

refactor: Refactors the Go codebase into a more modular and idiomatic approach
fix: require selection of specific MR when there are multiple targets for a given source branch
feat: Allows for the passing of Gitlab's filter options when choosing an MR, improves MR selection
feat: API to choose an MR from a list based on the provided username's involvement as an assignee/reviewer/author

This is a #MINOR release

cmd/app/draft_note_publisher.go

@@ -0,0 +1,76 @@
+package app
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+
+	"github.com/xanzy/go-gitlab"
+)
+
+type DraftNotePublisher interface {
+	PublishAllDraftNotes(pid interface{}, mergeRequest int, options ...gitlab.RequestOptionFunc) (*gitlab.Response, error)
+	PublishDraftNote(pid interface{}, mergeRequest int, note int, options ...gitlab.RequestOptionFunc) (*gitlab.Response, error)
+}
+
+type draftNotePublisherService struct {
+	data
+	client DraftNotePublisher
+}
+
+func (a draftNotePublisherService) handler(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	if r.Method != http.MethodPost {
+		w.Header().Set("Access-Control-Allow-Methods", http.MethodPost)
+		handleError(w, InvalidRequestError{}, "Expected POST", http.StatusMethodNotAllowed)
+		return
+	}
+
+	body, err := io.ReadAll(r.Body)
+	if err != nil {
+		handleError(w, err, "Could not read request body", http.StatusBadRequest)
+		return
+	}
+
+	defer r.Body.Close()
+	var draftNotePublishRequest DraftNotePublishRequest
+	err = json.Unmarshal(body, &draftNotePublishRequest)
+
+	if err != nil {
+		handleError(w, err, "Could not read JSON from request", http.StatusBadRequest)
+		return
+	}
+
+	var res *gitlab.Response
+	if draftNotePublishRequest.PublishAll {
+		res, err = a.client.PublishAllDraftNotes(a.projectInfo.ProjectId, a.projectInfo.MergeId)
+	} else {
+		if draftNotePublishRequest.Note == 0 {
+			handleError(w, errors.New("No ID provided"), "Must provide Note ID", http.StatusBadRequest)
+			return
+		}
+		res, err = a.client.PublishDraftNote(a.projectInfo.ProjectId, a.projectInfo.MergeId, draftNotePublishRequest.Note)
+	}
+
+	if err != nil {
+		handleError(w, err, "Could not publish draft note(s)", http.StatusInternalServerError)
+		return
+	}
+
+	if res.StatusCode >= 300 {
+		handleError(w, GenericError{endpoint: "/mr/draft_notes/publish"}, "Could not publish dfaft note", res.StatusCode)
+		return
+	}
+
+	w.WriteHeader(http.StatusOK)
+	response := SuccessResponse{
+		Message: "Draft note(s) published",
+		Status:  http.StatusOK,
+	}
+
+	err = json.NewEncoder(w).Encode(response)
+	if err != nil {
+		handleError(w, err, "Could not encode response", http.StatusInternalServerError)
+	}
+}