@@ -0,0 +1,179 @@
+package gitea
+
+import (
+"crypto/hmac"
+"crypto/sha256"
+"encoding/hex"
+"encoding/json"
+"errors"
+"fmt"
+"io"
+"io/ioutil"
+"net/http"
+)
+
+// parse errors
+var (
+ErrEventNotSpecifiedToParse = errors.New("no Event specified to parse")
+ErrInvalidHTTPMethod = errors.New("invalid HTTP Method")
+ErrMissingGiteaEventHeader = errors.New("missing X-Gitea-Event Header")
+ErrMissingGiteaSignatureHeader = errors.New("missing X-Gitea-Signature Header")
+ErrEventNotFound = errors.New("event not defined to be parsed")
+ErrParsingPayload = errors.New("error parsing payload")
+ErrHMACVerificationFailed = errors.New("HMAC verification failed")
+)
+
+// Gitea hook types
+// https://.com/go-gitea/gitea/blob/bf7b083cfe47cc922090ce7922b89f7a5030a44d/models/webhook/hooktask.go#L31
+const (
+CreateEvent Event = "create"
+DeleteEvent Event = "delete"
+ForkEvent Event = "fork"
+IssuesEvent Event = "issues"
+IssueAssignEvent Event = "issue_assign"
+IssueLabelEvent Event = "issue_label"
+IssueMilestoneEvent Event = "issue_milestone"
+IssueCommentEvent Event = "issue_comment"
+PushEvent Event = "push"
+PullRequestEvent Event = "pull_request"
+PullRequestAssignEvent Event = "pull_request_assign"
+PullRequestLabelEvent Event = "pull_request_label"
+PullRequestMilestoneEvent Event = "pull_request_milestone"
+PullRequestCommentEvent Event = "pull_request_comment"
+PullRequestReviewEvent Event = "pull_request_review"
+PullRequestSyncEvent Event = "pull_request_sync"
+RepositoryEvent Event = "repository"
+ReleaseEvent Event = "release"
+)
+
+// Option is a configuration option for the webhook
+type Option func(*Webhook) error
+
+// Options is a namespace var for configuration options
+var Options = WebhookOptions{}
+
+// WebhookOptions is a namespace for configuration option methods
+type WebhookOptions struct{}
+
+// Secret registers the GitLab secret
+func (WebhookOptions) Secret(secret string) Option {
+return func(hook *Webhook) error {
+hook.secret = secret
+return nil
+}
+}
+
+// Webhook instance contains all methods needed to process events
+type Webhook struct {
+secret string
+}
+
+// Event defines a GitLab hook event type by the X-Gitlab-Event Header
+type Event string
+
+// New creates and returns a WebHook instance denoted by the Provider type
+func New(options ...Option) (*Webhook, error) {
+hook := new(Webhook)
+for _, opt := range options {
+if err := opt(hook); err != nil {
+return nil, errors.New("Error applying Option")
+}
+}
+return hook, nil
+}
+
+// Parse verifies and parses the events specified and returns the payload object or an error
+func (hook Webhook) Parse(r *http.Request, events ...Event) (interface{}, error) {
+defer func() {
+_, _ = io.Copy(ioutil.Discard, r.Body)
+_ = r.Body.Close()
+}()
+
+if len(events) == 0 {
+return nil, ErrEventNotSpecifiedToParse
+}
+if r.Method != http.MethodPost {
+return nil, ErrInvalidHTTPMethod
+}
+
+event := r.Header.Get("X-Gitea-Event")
+if len(event) == 0 {
+return nil, ErrMissingGiteaEventHeader
+}
+
+giteaEvent := Event(event)
+
+var found bool
+for _, evt := range events {
+if evt == giteaEvent {
+found = true
+break
+}
+}
+// event not defined to be parsed
+if !found {
+return nil, ErrEventNotFound
+}
+
+payload, err := ioutil.ReadAll(r.Body)
+if err != nil || len(payload) == 0 {
+return nil, ErrParsingPayload
+}
+
+// If we have a Secret set, we should check the MAC
+if len(hook.secret) > 0 {
+signature := r.Header.Get("X-Gitea-Signature")
+if len(signature) == 0 {
+return nil, ErrMissingGiteaSignatureHeader
+}
+sig256 := hmac.New(sha256.New, []byte(hook.secret))
+_, _ = io.Writer(sig256).Write([]byte(payload))
+expectedMAC := hex.EncodeToString(sig256.Sum(nil))
+
+if !hmac.Equal([]byte(signature), []byte(expectedMAC)) {
+return nil, ErrHMACVerificationFailed
+}
+}
+
+// https://.com/go-gitea/gitea/blob/33fca2b537d36cf998dd27425b2bb8ed5b0965f3/services/webhook/payloader.go#L27
+switch giteaEvent {
+case CreateEvent:
+var pl CreatePayload
+err = json.Unmarshal([]byte(payload), &pl)
+return pl, err
+case DeleteEvent:
+var pl DeletePayload
+err = json.Unmarshal([]byte(payload), &pl)
+return pl, err
+case ForkEvent:
+var pl ForkPayload
+err = json.Unmarshal([]byte(payload), &pl)
+return pl, err
+case PushEvent:
+var pl PushPayload
+err = json.Unmarshal([]byte(payload), &pl)
+return pl, err
+case IssuesEvent, IssueAssignEvent, IssueLabelEvent, IssueMilestoneEvent:
+var pl IssuePayload
+err = json.Unmarshal([]byte(payload), &pl)
+return pl, err
+case IssueCommentEvent, PullRequestCommentEvent:
+var pl IssueCommentPayload
+err = json.Unmarshal([]byte(payload), &pl)
+return pl, err
+case PullRequestEvent, PullRequestAssignEvent, PullRequestLabelEvent, PullRequestMilestoneEvent, PullRequestReviewEvent, PullRequestSyncEvent:
+var pl PullRequestPayload
+err = json.Unmarshal([]byte(payload), &pl)
+return pl, err
+case RepositoryEvent:
+var pl RepositoryPayload
+err = json.Unmarshal([]byte(payload), &pl)
+return pl, err
+case ReleaseEvent:
+var pl ReleasePayload
+err = json.Unmarshal([]byte(payload), &pl)
+return pl, err
+default:
+return nil, fmt.Errorf("unknown event %s", giteaEvent)
+}
+}