Refactor - extract functionality into structs

internal/github/action.go

@@ -0,0 +1,40 @@
+package github
+
+import (
+	"encoding/json"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type action struct {
+}
+
+func (action action) repositoryOwner() string {
+	return strings.Split(os.Getenv("GITHUB_REPOSITORY"), "/")[0]
+}
+
+func (action action) repositoryName() string {
+	return strings.Split(os.Getenv("GITHUB_REPOSITORY"), "/")[1]
+}
+
+func (action action) pullRequestNumber() int {
+	s := strings.Split(os.Getenv("GITHUB_REF"), "/")[2]
+	pullRequestNumber, err := strconv.Atoi(s)
+	panicIfError((err))
+
+	return pullRequestNumber
+}
+
+func (action action) token() string {
+	return os.Getenv("GITHUB_TOKEN")
+}
+
+func (action action) specifiedLabels() []string {
+	var specifiedLabels []string
+
+	specifiedJSONLabels := os.Getenv("GITHUB_ACTION_INPUT_LABELS")
+	panicIfError(json.Unmarshal([]byte(specifiedJSONLabels), &specifiedLabels))
+
+	return specifiedLabels
+}

internal/github/label_checker.go

@@ -0,0 +1,43 @@
+/*
+Package github checks pull requests for specified GitHub labels
+*/
+package github
+
+import (
+	"fmt"
+	"strings"
+)
+
+// CheckLabels checks for the presence of the given GitHub labels
+func CheckLabels() {
+	var githubAction action
+	pullRequest := newPullRequest(githubAction)
+	checkLabels(githubAction.specifiedLabels(), pullRequest.labels(), 1)
+}
+
+func checkLabels(specifiedLabels []string, pullRequestLabels []string, allowedNumberOfLabels int) {
+	counter := 0
+
+	for i := 0; i < len(pullRequestLabels); i++ {
+		if contains(specifiedLabels, pullRequestLabels[i]) {
+			counter++
+		}
+	}
+
+	if counter != allowedNumberOfLabels {
+		panic(`Label check failed: required one of ` + strings.Join(specifiedLabels, ", "))
+	}
+
+	fmt.Println(`Label check successful: required one of ` +
+		strings.Join(specifiedLabels, ", ") + `, and found: ` + pullRequestLabels[0])
+}
+
+func contains(slice []string, val string) bool {
+	for _, item := range slice {
+		if item == val {
+			return true
+		}
+	}
+
+	return false
+}

internal/github/pull_request.go

@@ -0,0 +1,62 @@
+package github
+
+import (
+	"context"
+
+	"github.com/shurcooL/githubv4"
+	"golang.org/x/oauth2"
+)
+
+type pullRequest struct {
+	repositoryOwner string
+	repository      string
+	number          int
+	apiClient       *githubv4.Client
+}
+
+func newPullRequest(action action) *pullRequest {
+	return &pullRequest{action.repositoryOwner(),
+		action.repositoryName(),
+		action.pullRequestNumber(),
+		apiClient(action.token())}
+}
+
+func (pr pullRequest) labels() []string {
+	variables := map[string]interface{}{
+		"owner":             githubv4.String(pr.repositoryOwner),
+		"name":              githubv4.String(pr.repository),
+		"pullRequestNumber": githubv4.Int(pr.number),
+	}
+
+	var query struct {
+		Repository struct {
+			PullRequest struct {
+				Labels struct {
+					Nodes []struct {
+						Name string
+					}
+				} `graphql:"labels(first: 100)"`
+			} `graphql:"pullRequest(number: $pullRequestNumber)"`
+		} `graphql:"repository(owner: $owner, name: $name)"`
+	}
+
+	err := pr.apiClient.Query(context.Background(), &query, variables)
+	panicIfError(err)
+
+	labelNodes := query.Repository.PullRequest.Labels.Nodes
+
+	var labels []string
+
+	for i := 0; i < len(labelNodes); i++ {
+		labels = append(labels, labelNodes[i].Name)
+	}
+
+	return labels
+}
+
+func apiClient(token string) *githubv4.Client {
+	tokenSource := oauth2.StaticTokenSource(&oauth2.Token{AccessToken: token})
+	httpClient := oauth2.NewClient(context.Background(), tokenSource)
+
+	return githubv4.NewClient(httpClient)
+}

internal/github/util.go

@@ -0,0 +1,9 @@
+package github
+
+import "log"
+
+func panicIfError(err error) {
+	if err != nil {
+		log.Fatalf("Error that we cannot handle, %v", err)
+	}
+}