Simplify Go Endpoints + Add Tests (#120)

This MR represents a major refactor of the Go codebase, as well as introducing tests for the handlers. The MR also introduces an endpoint to shutdown or restart the Go server, which may be useful for clients who want to refresh the state of the plugin after checking out branches. Finally, this MR adds a contributing document for users who want to make feature changes.

cmd/pipeline.go

@@ -2,16 +2,14 @@ package main
 
 import (
 	"encoding/json"
-	"io"
+	"fmt"
 	"net/http"
+	"strconv"
+	"strings"
 
 	"github.com/xanzy/go-gitlab"
 )
 
-type PipelineRequest struct {
-	PipelineId int `json:"pipeline_id"`
-}
-
 type RetriggerPipelineResponse struct {
 	SuccessResponse
 	Pipeline *gitlab.Pipeline
@@ -22,80 +20,82 @@ type GetJobsResponse struct {
 	Jobs []*gitlab.Job
 }
 
-func PipelineHandler(w http.ResponseWriter, r *http.Request) {
+/*
+pipelineHandler fetches information about the current pipeline, and retriggers a pipeline run. For more detailed information
+about a given job in a pipeline, see the jobHandler function
+*/
+func (a *api) pipelineHandler(w http.ResponseWriter, r *http.Request) {
 	switch r.Method {
 	case http.MethodGet:
-		GetJobs(w, r)
+		a.GetJobs(w, r)
 	case http.MethodPost:
-		RetriggerPipeline(w, r)
+		a.RetriggerPipeline(w, r)
 	default:
-		w.WriteHeader(http.StatusMethodNotAllowed)
+		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Access-Control-Allow-Methods", fmt.Sprintf("%s, %s", http.MethodGet, http.MethodPost))
+		handleError(w, InvalidRequestError{}, "Expected GET or POST", http.StatusMethodNotAllowed)
 	}
 }
 
-func GetJobs(w http.ResponseWriter, r *http.Request) {
+func (a *api) GetJobs(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json")
-	c := r.Context().Value("client").(Client)
 
-	body, err := io.ReadAll(r.Body)
+	id := strings.TrimPrefix(r.URL.Path, "/pipeline/")
+	idInt, err := strconv.Atoi(id)
+
 	if err != nil {
-		c.handleError(w, err, "Could not read request body", http.StatusBadRequest)
+		handleError(w, err, "Could not convert pipeline ID to integer", http.StatusBadRequest)
 		return
 	}
 
-	defer r.Body.Close()
+	jobs, res, err := a.client.ListPipelineJobs(a.projectInfo.ProjectId, idInt, &gitlab.ListJobsOptions{})
 
-	var pipelineRequest PipelineRequest
-	err = json.Unmarshal(body, &pipelineRequest)
 	if err != nil {
-		c.handleError(w, err, "Could not read JSON", http.StatusBadRequest)
+		handleError(w, err, "Could not get pipeline jobs", http.StatusInternalServerError)
+		return
 	}
 
-	jobs, res, err := c.git.Jobs.ListPipelineJobs(c.projectId, pipelineRequest.PipelineId, &gitlab.ListJobsOptions{})
-
-	if err != nil {
-		c.handleError(w, err, "Could not get pipeline jobs", res.StatusCode)
+	if res.StatusCode >= 300 {
+		handleError(w, GenericError{endpoint: "/pipeline"}, "Could not get pipeline jobs", res.StatusCode)
+		return
 	}
 
 	w.WriteHeader(http.StatusOK)
-
 	response := GetJobsResponse{
 		SuccessResponse: SuccessResponse{
 			Status:  http.StatusOK,
-			Message: "Jobs fetched successfully",
+			Message: "Pipeline jobs retrieved",
 		},
 		Jobs: jobs,
 	}
 
 	err = json.NewEncoder(w).Encode(response)
 	if err != nil {
-		c.handleError(w, err, "Could not encode response", http.StatusInternalServerError)
+		handleError(w, err, "Could not encode response", http.StatusInternalServerError)
 	}
-
 }
 
-func RetriggerPipeline(w http.ResponseWriter, r *http.Request) {
+func (a *api) RetriggerPipeline(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json")
-	c := r.Context().Value("client").(Client)
 
-	body, err := io.ReadAll(r.Body)
+	id := strings.TrimPrefix(r.URL.Path, "/pipeline/")
+
+	idInt, err := strconv.Atoi(id)
 	if err != nil {
-		c.handleError(w, err, "Could not read request body", http.StatusBadRequest)
+		handleError(w, err, "Could not convert pipeline ID to integer", http.StatusBadRequest)
 		return
 	}
 
-	defer r.Body.Close()
+	pipeline, res, err := a.client.RetryPipelineBuild(a.projectInfo.ProjectId, idInt)
 
-	var pipelineRequest PipelineRequest
-	err = json.Unmarshal(body, &pipelineRequest)
 	if err != nil {
-		c.handleError(w, err, "Could not read JSON", http.StatusBadRequest)
+		handleError(w, err, "Could not retrigger pipeline", http.StatusInternalServerError)
+		return
 	}
 
-	pipeline, res, err := c.git.Pipelines.RetryPipelineBuild(c.projectId, pipelineRequest.PipelineId)
-
-	if err != nil {
-		c.handleError(w, err, "Could not retrigger pipeline", res.StatusCode)
+	if res.StatusCode >= 300 {
+		handleError(w, GenericError{endpoint: "/pipeline"}, "Could not retrigger pipeline", res.StatusCode)
+		return
 	}
 
 	w.WriteHeader(http.StatusOK)
@@ -109,6 +109,6 @@ func RetriggerPipeline(w http.ResponseWriter, r *http.Request) {
 
 	err = json.NewEncoder(w).Encode(response)
 	if err != nil {
-		c.handleError(w, err, "Could not encode response", http.StatusInternalServerError)
+		handleError(w, err, "Could not encode response", http.StatusInternalServerError)
 	}
 }