Add/Remove Reviewers and Assignees (#38)

Adds APIs for the ability to add or remove reviewers and assignees to a merge request. The eligible reviewers and assignees are pulled from the current members of a project.

cmd/reviewer.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+
+	"github.com/xanzy/go-gitlab"
+)
+
+type ReviewerUpdateRequest struct {
+	Ids []int `json:"ids"`
+}
+
+type ReviewerUpdateResponse struct {
+	SuccessResponse
+	Reviewers []*gitlab.BasicUser `json:"reviewers"`
+}
+
+type ReviewersRequestResponse struct {
+	SuccessResponse
+	Reviewers []int `json:"reviewers"`
+}
+
+func ReviewersHandler(w http.ResponseWriter, r *http.Request) {
+	c := r.Context().Value("client").(Client)
+	w.Header().Set("Content-Type", "application/json")
+
+	body, err := io.ReadAll(r.Body)
+	if err != nil {
+		c.handleError(w, err, "Could not read request body", http.StatusBadRequest)
+		return
+	}
+
+	defer r.Body.Close()
+	var reviewerUpdateRequest ReviewerUpdateRequest
+	err = json.Unmarshal(body, &reviewerUpdateRequest)
+
+	if err != nil {
+		c.handleError(w, err, "Could not read JSON from request", http.StatusBadRequest)
+		return
+	}
+
+	mr, res, err := c.git.MergeRequests.UpdateMergeRequest(c.projectId, c.mergeId, &gitlab.UpdateMergeRequestOptions{
+		ReviewerIDs: &reviewerUpdateRequest.Ids,
+	})
+
+	if err != nil {
+		c.handleError(w, err, "Could not modify merge request reviewers", http.StatusBadRequest)
+		return
+	}
+
+	if res.StatusCode != http.StatusOK {
+		c.handleError(w, err, "Could not modify merge request reviewers", http.StatusBadRequest)
+		return
+	}
+
+	w.WriteHeader(http.StatusOK)
+
+	response := ReviewerUpdateResponse{
+		SuccessResponse: SuccessResponse{
+			Message: "Reviewers updated",
+			Status:  http.StatusOK,
+		},
+		Reviewers: mr.Reviewers,
+	}
+
+	json.NewEncoder(w).Encode(response)
+
+}