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router.go
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router.go
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package smartapi
import (
"errors"
"fmt"
"net/http"
"reflect"
"github.com/go-chi/chi"
)
type Router interface {
Use(middlewares ...func(http.Handler) http.Handler)
With(middlewares ...func(http.Handler) http.Handler) Router
AddEndpoint(method Method, pattern string, handler interface{}, args []EndpointParam)
Post(pattern string, handler interface{}, args ...EndpointParam)
Get(pattern string, handler interface{}, args ...EndpointParam)
Put(pattern string, handler interface{}, args ...EndpointParam)
Patch(pattern string, handler interface{}, args ...EndpointParam)
Delete(pattern string, handler interface{}, args ...EndpointParam)
Head(pattern string, handler interface{}, args ...EndpointParam)
Options(pattern string, handler interface{}, args ...EndpointParam)
Connect(pattern string, handler interface{}, args ...EndpointParam)
Trace(pattern string, handler interface{}, args ...EndpointParam)
Route(pattern string, handler RouteHandler, args ...EndpointParam)
Handle(pattern string, handler http.Handler)
Handler() (http.Handler, error)
MustHandler() http.Handler
}
type RouteHandler func(r Router)
type router struct {
chiRouter chi.Router
errors []error
logger Logger
params []EndpointParam
}
func NewRouter() *router {
return &router{
chiRouter: chi.NewRouter(),
logger: DefaultLogger,
}
}
func NewRouterLogger(logger Logger) *router {
return &router{
chiRouter: chi.NewRouter(),
logger: logger,
}
}
var errType = reflect.TypeOf((*error)(nil)).Elem()
var byteType = reflect.TypeOf([]byte(nil))
func checkHandler(handlerFunc interface{}, arguments []Argument, writesResponse bool) (endpointHandler, error) {
fnType := reflect.TypeOf(handlerFunc)
if fnType.Kind() != reflect.Func {
return nil, errors.New("handler must be a function")
}
if fnType.NumIn() != len(arguments) {
return nil, errors.New("number of arguments of a function doesn't match provided arguments")
}
for i := 0; i < len(arguments); i++ {
arg := fnType.In(i)
if err := arguments[i].checkArg(arg); err != nil {
return nil, fmt.Errorf("(argument %d) %w", i, err)
}
}
switch fnType.NumOut() {
case 0:
return noResponseHandler{handlerFunc: handlerFunc}, nil
case 1:
outValue := fnType.Out(0)
if outValue.Implements(errType) {
return errorOnlyHandler{handlerFunc: handlerFunc}, nil
}
value := fnType.Out(0)
switch value.Kind() {
case reflect.String:
return stringHandler{handlerFunc: handlerFunc}, nil
case reflect.Slice:
if value == byteType {
return byteSliceHandler{handlerFunc: handlerFunc}, nil
}
fallthrough
case reflect.Ptr, reflect.Interface:
return ptrHandler{handlerFunc: handlerFunc}, nil
case reflect.Struct, reflect.Int:
return structHandler{handlerFunc: handlerFunc}, nil
}
return nil, errors.New("unsupported return type")
case 2:
if writesResponse {
return nil, errors.New("cannot write response and return response")
}
errValue := fnType.Out(1)
if !errValue.Implements(errType) {
return nil, errors.New("expect an error type in return arguments")
}
value := fnType.Out(0)
switch value.Kind() {
case reflect.String:
return stringErrorHandler{handlerFunc: handlerFunc}, nil
case reflect.Slice:
if value == byteType {
return byteSliceErrorHandler{handlerFunc: handlerFunc}, nil
}
fallthrough
case reflect.Ptr, reflect.Interface:
return ptrErrorHandler{handlerFunc: handlerFunc}, nil
case reflect.Struct, reflect.Int:
return structErrorHandler{handlerFunc: handlerFunc}, nil
}
return nil, errors.New("unsupported return type")
}
return nil, errors.New("invalid number of return arguments")
}
func isLegacyHandler(returnStatus int, args []Argument, handler interface{}) (http.HandlerFunc, bool) {
switch len(args) {
case 2:
_, ok := args[0].(responseWriterArgument)
if !ok {
return nil, false
}
_, ok = args[1].(fullRequestArgument)
if !ok {
return nil, false
}
if returnStatus != 200 {
return nil, false
}
case 0:
if returnStatus != 0 {
return nil, false
}
default:
return nil, false
}
if h, ok := handler.(http.HandlerFunc); ok {
return h, ok
}
h, ok := handler.(func(w http.ResponseWriter, h *http.Request))
return h, ok
}
func (r *router) AddEndpoint(method Method, name string, handler interface{}, params []EndpointParam) {
if handler == nil {
r.errors = append(r.errors, fmt.Errorf("endpoint %s: nil handler", name))
return
}
returnStatus := 0
query := false
writesResponse := false
numReadsBody := 0
joinedParams := append(r.params, params...)
var args []Argument
for i, a := range joinedParams {
flags := a.options()
if flags.has(flagArgument) {
args = append(args, a.(Argument))
}
if flags.has(flagParsesQuery) {
query = true
}
if flags.has(flagResponseStatus) {
returnStatus = a.(responseStatusArgument).status
}
if flags.has(flagReadsRequestBody) {
numReadsBody++
}
if flags.has(flagWritesResponse) {
writesResponse = true
if returnStatus == 0 {
returnStatus = http.StatusOK
}
}
if flags.has(flagError) {
r.errors = append(r.errors, fmt.Errorf("endpoint %s: (argument %d) %w", name, i, a.(errorEndpointParam).err))
return
}
}
if h, ok := isLegacyHandler(returnStatus, args, handler); ok {
r.chiRouter.MethodFunc(method.String(), name, h)
return
}
if returnStatus == 0 {
returnStatus = http.StatusNoContent
}
if numReadsBody > 1 {
r.errors = append(r.errors, fmt.Errorf("endpoint %s: only one argument can read request's body", name))
}
endpointHandler, err := checkHandler(handler, args, writesResponse)
if err != nil {
r.errors = append(r.errors, fmt.Errorf("endpoint %s: %w", name, err))
}
if len(r.errors) > 0 {
return
}
data := endpointData{
arguments: args,
returnStatus: returnStatus,
query: query,
}
f := func(w http.ResponseWriter, rq *http.Request) {
endpointHandler.handleRequest(w, rq, r.logger, data)
}
r.chiRouter.MethodFunc(method.String(), name, f)
}
// Use adds chi middlewares
func (r *router) Use(middlewares ...func(http.Handler) http.Handler) {
r.chiRouter.Use(middlewares...)
}
// With returns a version of a handler with a middleware
func (r *router) With(middlewares ...func(http.Handler) http.Handler) Router {
return &router{
chiRouter: r.chiRouter.With(middlewares...),
errors: r.errors,
logger: r.logger,
params: r.params,
}
}
// Post adds an endpoint with a POST Method
func (r *router) Post(pattern string, handler interface{}, args ...EndpointParam) {
r.AddEndpoint(MethodPost, pattern, handler, args)
}
// Get adds an endpoint with a GET Method
func (r *router) Get(pattern string, handler interface{}, args ...EndpointParam) {
r.AddEndpoint(MethodGet, pattern, handler, args)
}
// Put adds an endpoint with a PUT Method
func (r *router) Put(pattern string, handler interface{}, args ...EndpointParam) {
r.AddEndpoint(MethodPut, pattern, handler, args)
}
// Patch adds an endpoint with a PATCH Method
func (r *router) Patch(pattern string, handler interface{}, args ...EndpointParam) {
r.AddEndpoint(MethodPatch, pattern, handler, args)
}
// Delete adds an endpoint with a DELETE Method
func (r *router) Delete(pattern string, handler interface{}, args ...EndpointParam) {
r.AddEndpoint(MethodDelete, pattern, handler, args)
}
// Head adds an endpoint with a HEAD Method
func (r *router) Head(pattern string, handler interface{}, args ...EndpointParam) {
r.AddEndpoint(MethodHead, pattern, handler, args)
}
// Options adds an endpoint with a OPTIONS Method
func (r *router) Options(pattern string, handler interface{}, args ...EndpointParam) {
r.AddEndpoint(MethodOptions, pattern, handler, args)
}
// Connect adds an endpoint with a CONNECT Method
func (r *router) Connect(pattern string, handler interface{}, args ...EndpointParam) {
r.AddEndpoint(MethodConnect, pattern, handler, args)
}
// Trace adds an endpoint with a TRACE Method
func (r *router) Trace(pattern string, handler interface{}, args ...EndpointParam) {
r.AddEndpoint(MethodTrace, pattern, handler, args)
}
// Route routs endpoints to a specific path
func (r *router) Route(pattern string, handler RouteHandler, params ...EndpointParam) {
if handler == nil {
r.errors = append(r.errors, fmt.Errorf("route %s: nil handler", pattern))
return
}
r.chiRouter.Route(pattern, func(rt chi.Router) {
node := &router{
logger: r.logger,
chiRouter: rt,
params: append(r.params, params...),
}
handler(node)
for _, err := range node.errors {
r.errors = append(r.errors, fmt.Errorf("route %s: %w", pattern, err))
}
})
}
// Handle handles request with specified http handler
func (r *router) Handle(pattern string, handler http.Handler) {
r.chiRouter.Handle(pattern, handler)
}
// Handler returns an http.Handler of the API
func (r *router) Handler() (http.Handler, error) {
if len(r.errors) != 0 {
errMsg := r.errors[0].Error()
for _, e := range r.errors[1:] {
errMsg += ", " + e.Error()
}
return nil, errors.New(errMsg)
}
return r.chiRouter, nil
}
// MustHandler returns a handler but panics if handler cannot be obtained
func (r *router) MustHandler() http.Handler {
h, err := r.Handler()
if err != nil {
panic(err)
}
return h
}