webhook.go

package patreon

import (
	"crypto/hmac"
	"crypto/md5"
	"encoding/hex"
)

const (
	// EventCreatePledge specifies a create pledge event
	EventCreatePledge = "pledges:create"

	// EventUpdatePledge specifies an update pledge event
	EventUpdatePledge = "pledges:update"

	// EventDeletePledge specifies a delete pledge event
	EventDeletePledge = "pledges:delete"
)

const (
	// HeaderEventType specifies an event type HTTP header name
	HeaderEventType = "X-Patreon-Event"

	// HeaderEventSignature specifies message signature HTTP header name to verify message body
	HeaderSignature = "X-Patreon-Signature"
)

var (
	// WebhookDefaultIncludes specifies default includes for Webhook.
	WebhookDefaultIncludes = []string{"campaign", "client"}

	// WebhookFields is all fields in the Webhook Attributes struct
	WebhookFields = getObjectFields(Webhook{}.Attributes)
)

// VerifySignature verifies the sender of the message
func VerifySignature(message []byte, secret string, signature string) (bool, error) {
	hash := hmac.New(md5.New, []byte(secret))
	if _, err := hash.Write(message); err != nil {
		return false, err
	}

	sum := hash.Sum(nil)
	expectedSignature := hex.EncodeToString(sum)

	return expectedSignature == signature, nil
}

// Webhook is fired based on events happening on a particular campaign.
type Webhook struct {
	Type          string            `json:"type"`
	ID            string            `json:"id"`
	Attributes    WebhookAttributes `json:"attributes"`
	Relationships struct {
		Campaign    *CampaignRelationship    `json:"campaign,omitempty"`
		Memberships *MembershipsRelationship `json:"memberships,omitempty"`
	} `json:"relationships"`
}

// WebhookAttributes is the attributes struct for Webhook
type WebhookAttributes struct {
	LastAttemptedAt           NullTime    `json:"last_attempted_at"`
	NumConsecutiveTimesFailed int         `json:"num_consecutive_times_failed"`
	Paused                    bool        `json:"paused"`
	Secret                    string      `json:"secret"`
	Triggers                  interface{} `json:"triggers"`
	URI                       string      `json:"uri"`
}

// WebhookResponse wraps Patreon's fetch user API response
type WebhookResponse struct {
	Data     Webhook  `json:"data"`
	Included Includes `json:"included"`
	Links    struct {
		Self string `json:"self"`
	} `json:"links"`
}