package lambdarouter import ( "encoding/json" "log" "net/http" "strings" radix "github.com/armon/go-radix" "github.com/aws/aws-lambda-go/events" ) const ( post = http.MethodPost get = http.MethodGet put = http.MethodPut patch = http.MethodPatch delete = http.MethodDelete ) // APIGContext is used as the input and output of handler functions. // The Body, Claims, Path, and QryStr will be populated by the the APIGatewayProxyRequest. // The Request itself is also passed through if you need further access. // Fill the Status and Body, or Status and Error to respond. type APIGContext struct { Claims map[string]interface{} Path map[string]string QryStr map[string]string Request *events.APIGatewayProxyRequest Status int Body []byte Err error } // APIGHandler is the interface a handler function must implement to be used // with Get, Post, Put, Patch, and Delete. type APIGHandler func(ctx *APIGContext) // APIGRouter is the object that handlers build upon and is used in the end to respond. type APIGRouter struct { request *events.APIGatewayProxyRequest endpoints map[string]*radix.Tree params map[string]string prefix string headers map[string]string } // APIGRouterConfig is used as the input to NewAPIGRouter, request is your incoming // apig request and prefix will be stripped of all incoming request paths. Headers // will be sent with all responses. type APIGRouterConfig struct { Request *events.APIGatewayProxyRequest Prefix string Headers map[string]string } // NOTE: Begin router methods. // NewAPIGRouter creates a new router using the given router config. func NewAPIGRouter(cfg *APIGRouterConfig) *APIGRouter { return &APIGRouter{ request: cfg.Request, endpoints: map[string]*radix.Tree{ post: radix.New(), get: radix.New(), put: radix.New(), patch: radix.New(), delete: radix.New(), }, params: map[string]string{}, prefix: cfg.Prefix, headers: cfg.Headers, } } // Get creates a new get endpoint. func (r *APIGRouter) Get(route string, handlers ...APIGHandler) { r.addEndpoint(get, route, handlers) } // Post creates a new post endpoint. func (r *APIGRouter) Post(route string, handlers ...APIGHandler) { r.addEndpoint(post, route, handlers) } // Put creates a new put endpoint. func (r *APIGRouter) Put(route string, handlers ...APIGHandler) { r.addEndpoint(put, route, handlers) } // Patch creates a new patch endpoint func (r *APIGRouter) Patch(route string, handlers ...APIGHandler) { r.addEndpoint(patch, route, handlers) } // Delete creates a new delete endpoint. func (r *APIGRouter) Delete(route string, handlers ...APIGHandler) { r.addEndpoint(delete, route, handlers) } // Respond returns an APIGatewayProxyResponse to respond to the lambda request. func (r *APIGRouter) Respond() events.APIGatewayProxyResponse { var ( handlersInterface interface{} ok bool status int respbody []byte err error endpointTree = r.endpoints[r.request.HTTPMethod] path = strings.TrimPrefix(r.request.Path, r.prefix) response = events.APIGatewayProxyResponse{} splitPath = stripSlashesAndSplit(path) ) for k := range r.params { pname := strings.TrimPrefix(k, "{") pname = strings.TrimSuffix(pname, "}") if r.request.PathParameters[pname] != "" { pval := r.request.PathParameters[pname] for i, v := range splitPath { if v == pval { splitPath[i] = k } } } } path = "/" + strings.Join(splitPath, "/") if handlersInterface, ok = endpointTree.Get(path); !ok { respbody, _ := json.Marshal(map[string]string{"error": "no route matching path found"}) response.StatusCode = http.StatusNotFound response.Body = string(respbody) return response } handlers := handlersInterface.([]APIGHandler) for _, handler := range handlers { ctx := &APIGContext{ Body: []byte(r.request.Body), Path: r.request.PathParameters, QryStr: r.request.QueryStringParameters, Request: r.request, } if r.request.RequestContext.Authorizer["claims"] != nil { ctx.Claims = r.request.RequestContext.Authorizer["claims"].(map[string]interface{}) } handler(ctx) status, respbody, err = ctx.respDeconstruct() if err != nil { respbody, _ := json.Marshal(map[string]string{"error": err.Error()}) if strings.Contains(err.Error(), "record not found") { status = 204 } else if status < 400 { status = 400 } log.Printf("%v error: %v", status, err.Error()) response.StatusCode = status response.Body = string(respbody) return response } } response.StatusCode = status response.Body = string(respbody) response.Headers = r.headers return response } // NOTE: Begin helper functions. func stripSlashesAndSplit(s string) []string { s = strings.TrimPrefix(s, "/") s = strings.TrimSuffix(s, "/") return strings.Split(s, "/") } func (ctx *APIGContext) respDeconstruct() (int, []byte, error) { return ctx.Status, ctx.Body, ctx.Err } func (r *APIGRouter) addEndpoint(method string, route string, handlers []APIGHandler) { if _, overwrite := r.endpoints[method].Insert(route, handlers); overwrite { panic("endpoint already existent") } rtearr := stripSlashesAndSplit(route) for _, v := range rtearr { if strings.HasPrefix(v, "{") { r.params[v] = "" // adding params as keys with {brackets} } } }