application.twirp.go

// Code generated by protoc-gen-twirp v7.1.1, DO NOT EDIT.
// source: application.proto

/*
Package application is a generated twirp stub package.
This code was generated with github.com/twitchtv/twirp/protoc-gen-twirp v7.1.1.

It is generated from these files:
	application.proto
*/
package application

import bytes "bytes"
import strings "strings"
import context "context"
import fmt "fmt"
import ioutil "io/ioutil"
import http "net/http"
import strconv "strconv"

import jsonpb "github.com/golang/protobuf/jsonpb"
import proto "github.com/golang/protobuf/proto"
import twirp "github.com/twitchtv/twirp"
import ctxsetters "github.com/twitchtv/twirp/ctxsetters"

// Imports only used by utility functions:
import io "io"
import json "encoding/json"
import path "path"
import url "net/url"

// This is a compile-time assertion to ensure that this generated file
// is compatible with the twirp package used in your project.
// A compilation error at this line likely means your copy of the
// twirp package needs to be updated.
const _ = twirp.TwirpPackageIsVersion7

// =====================
// Application Interface
// =====================

type Application interface {
	// gets all applications currently found in each cluster and their status
	All(context.Context, *ReadApplications) (*ApplicationsRead, error)
}

// ===========================
// Application Protobuf Client
// ===========================

type applicationProtobufClient struct {
	client      HTTPClient
	urls        [1]string
	interceptor twirp.Interceptor
	opts        twirp.ClientOptions
}

// NewApplicationProtobufClient creates a Protobuf client that implements the Application interface.
// It communicates using Protobuf and can be configured with a custom HTTPClient.
func NewApplicationProtobufClient(baseURL string, client HTTPClient, opts ...twirp.ClientOption) Application {
	if c, ok := client.(*http.Client); ok {
		client = withoutRedirects(c)
	}

	clientOpts := twirp.ClientOptions{}
	for _, o := range opts {
		o(&clientOpts)
	}

	// Build method URLs: <baseURL>[<prefix>]/<package>.<Service>/<Method>
	serviceURL := sanitizeBaseURL(baseURL)
	serviceURL += baseServicePath(clientOpts.PathPrefix(), "redsail.bosn", "Application")
	urls := [1]string{
		serviceURL + "All",
	}

	return &applicationProtobufClient{
		client:      client,
		urls:        urls,
		interceptor: twirp.ChainInterceptors(clientOpts.Interceptors...),
		opts:        clientOpts,
	}
}

func (c *applicationProtobufClient) All(ctx context.Context, in *ReadApplications) (*ApplicationsRead, error) {
	ctx = ctxsetters.WithPackageName(ctx, "redsail.bosn")
	ctx = ctxsetters.WithServiceName(ctx, "Application")
	ctx = ctxsetters.WithMethodName(ctx, "All")
	caller := c.callAll
	if c.interceptor != nil {
		caller = func(ctx context.Context, req *ReadApplications) (*ApplicationsRead, error) {
			resp, err := c.interceptor(
				func(ctx context.Context, req interface{}) (interface{}, error) {
					typedReq, ok := req.(*ReadApplications)
					if !ok {
						return nil, twirp.InternalError("failed type assertion req.(*ReadApplications) when calling interceptor")
					}
					return c.callAll(ctx, typedReq)
				},
			)(ctx, req)
			if resp != nil {
				typedResp, ok := resp.(*ApplicationsRead)
				if !ok {
					return nil, twirp.InternalError("failed type assertion resp.(*ApplicationsRead) when calling interceptor")
				}
				return typedResp, err
			}
			return nil, err
		}
	}
	return caller(ctx, in)
}

func (c *applicationProtobufClient) callAll(ctx context.Context, in *ReadApplications) (*ApplicationsRead, error) {
	out := new(ApplicationsRead)
	ctx, err := doProtobufRequest(ctx, c.client, c.opts.Hooks, c.urls[0], in, out)
	if err != nil {
		twerr, ok := err.(twirp.Error)
		if !ok {
			twerr = twirp.InternalErrorWith(err)
		}
		callClientError(ctx, c.opts.Hooks, twerr)
		return nil, err
	}

	callClientResponseReceived(ctx, c.opts.Hooks)

	return out, nil
}

// =======================
// Application JSON Client
// =======================

type applicationJSONClient struct {
	client      HTTPClient
	urls        [1]string
	interceptor twirp.Interceptor
	opts        twirp.ClientOptions
}

// NewApplicationJSONClient creates a JSON client that implements the Application interface.
// It communicates using JSON and can be configured with a custom HTTPClient.
func NewApplicationJSONClient(baseURL string, client HTTPClient, opts ...twirp.ClientOption) Application {
	if c, ok := client.(*http.Client); ok {
		client = withoutRedirects(c)
	}

	clientOpts := twirp.ClientOptions{}
	for _, o := range opts {
		o(&clientOpts)
	}

	// Build method URLs: <baseURL>[<prefix>]/<package>.<Service>/<Method>
	serviceURL := sanitizeBaseURL(baseURL)
	serviceURL += baseServicePath(clientOpts.PathPrefix(), "redsail.bosn", "Application")
	urls := [1]string{
		serviceURL + "All",
	}

	return &applicationJSONClient{
		client:      client,
		urls:        urls,
		interceptor: twirp.ChainInterceptors(clientOpts.Interceptors...),
		opts:        clientOpts,
	}
}

func (c *applicationJSONClient) All(ctx context.Context, in *ReadApplications) (*ApplicationsRead, error) {
	ctx = ctxsetters.WithPackageName(ctx, "redsail.bosn")
	ctx = ctxsetters.WithServiceName(ctx, "Application")
	ctx = ctxsetters.WithMethodName(ctx, "All")
	caller := c.callAll
	if c.interceptor != nil {
		caller = func(ctx context.Context, req *ReadApplications) (*ApplicationsRead, error) {
			resp, err := c.interceptor(
				func(ctx context.Context, req interface{}) (interface{}, error) {
					typedReq, ok := req.(*ReadApplications)
					if !ok {
						return nil, twirp.InternalError("failed type assertion req.(*ReadApplications) when calling interceptor")
					}
					return c.callAll(ctx, typedReq)
				},
			)(ctx, req)
			if resp != nil {
				typedResp, ok := resp.(*ApplicationsRead)
				if !ok {
					return nil, twirp.InternalError("failed type assertion resp.(*ApplicationsRead) when calling interceptor")
				}
				return typedResp, err
			}
			return nil, err
		}
	}
	return caller(ctx, in)
}

func (c *applicationJSONClient) callAll(ctx context.Context, in *ReadApplications) (*ApplicationsRead, error) {
	out := new(ApplicationsRead)
	ctx, err := doJSONRequest(ctx, c.client, c.opts.Hooks, c.urls[0], in, out)
	if err != nil {
		twerr, ok := err.(twirp.Error)
		if !ok {
			twerr = twirp.InternalErrorWith(err)
		}
		callClientError(ctx, c.opts.Hooks, twerr)
		return nil, err
	}

	callClientResponseReceived(ctx, c.opts.Hooks)

	return out, nil
}

// ==========================
// Application Server Handler
// ==========================

type applicationServer struct {
	Application
	interceptor      twirp.Interceptor
	hooks            *twirp.ServerHooks
	pathPrefix       string // prefix for routing
	jsonSkipDefaults bool   // do not include unpopulated fields (default values) in the response
}

// NewApplicationServer builds a TwirpServer that can be used as an http.Handler to handle
// HTTP requests that are routed to the right method in the provided svc implementation.
// The opts are twirp.ServerOption modifiers, for example twirp.WithServerHooks(hooks).
func NewApplicationServer(svc Application, opts ...interface{}) TwirpServer {
	serverOpts := twirp.ServerOptions{}
	for _, opt := range opts {
		switch o := opt.(type) {
		case twirp.ServerOption:
			o(&serverOpts)
		case *twirp.ServerHooks: // backwards compatibility, allow to specify hooks as an argument
			twirp.WithServerHooks(o)(&serverOpts)
		case nil: // backwards compatibility, allow nil value for the argument
			continue
		default:
			panic(fmt.Sprintf("Invalid option type %T on NewApplicationServer", o))
		}
	}

	return &applicationServer{
		Application:      svc,
		pathPrefix:       serverOpts.PathPrefix(),
		interceptor:      twirp.ChainInterceptors(serverOpts.Interceptors...),
		hooks:            serverOpts.Hooks,
		jsonSkipDefaults: serverOpts.JSONSkipDefaults,
	}
}

// writeError writes an HTTP response with a valid Twirp error format, and triggers hooks.
// If err is not a twirp.Error, it will get wrapped with twirp.InternalErrorWith(err)
func (s *applicationServer) writeError(ctx context.Context, resp http.ResponseWriter, err error) {
	writeError(ctx, resp, err, s.hooks)
}

// ApplicationPathPrefix is a convenience constant that could used to identify URL paths.
// Should be used with caution, it only matches routes generated by Twirp Go clients,
// that add a "/twirp" prefix by default, and use CamelCase service and method names.
// More info: https://twitchtv.github.io/twirp/docs/routing.html
const ApplicationPathPrefix = "/twirp/redsail.bosn.Application/"

func (s *applicationServer) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
	ctx := req.Context()
	ctx = ctxsetters.WithPackageName(ctx, "redsail.bosn")
	ctx = ctxsetters.WithServiceName(ctx, "Application")
	ctx = ctxsetters.WithResponseWriter(ctx, resp)

	var err error
	ctx, err = callRequestReceived(ctx, s.hooks)
	if err != nil {
		s.writeError(ctx, resp, err)
		return
	}

	if req.Method != "POST" {
		msg := fmt.Sprintf("unsupported method %q (only POST is allowed)", req.Method)
		s.writeError(ctx, resp, badRouteError(msg, req.Method, req.URL.Path))
		return
	}

	// Verify path format: [<prefix>]/<package>.<Service>/<Method>
	prefix, pkgService, method := parseTwirpPath(req.URL.Path)
	if pkgService != "redsail.bosn.Application" {
		msg := fmt.Sprintf("no handler for path %q", req.URL.Path)
		s.writeError(ctx, resp, badRouteError(msg, req.Method, req.URL.Path))
		return
	}
	if prefix != s.pathPrefix {
		msg := fmt.Sprintf("invalid path prefix %q, expected %q, on path %q", prefix, s.pathPrefix, req.URL.Path)
		s.writeError(ctx, resp, badRouteError(msg, req.Method, req.URL.Path))
		return
	}

	switch method {
	case "All":
		s.serveAll(ctx, resp, req)
		return
	default:
		msg := fmt.Sprintf("no handler for path %q", req.URL.Path)
		s.writeError(ctx, resp, badRouteError(msg, req.Method, req.URL.Path))
		return
	}
}

func (s *applicationServer) serveAll(ctx context.Context, resp http.ResponseWriter, req *http.Request) {
	header := req.Header.Get("Content-Type")
	i := strings.Index(header, ";")
	if i == -1 {
		i = len(header)
	}
	switch strings.TrimSpace(strings.ToLower(header[:i])) {
	case "application/json":
		s.serveAllJSON(ctx, resp, req)
	case "application/protobuf":
		s.serveAllProtobuf(ctx, resp, req)
	default:
		msg := fmt.Sprintf("unexpected Content-Type: %q", req.Header.Get("Content-Type"))
		twerr := badRouteError(msg, req.Method, req.URL.Path)
		s.writeError(ctx, resp, twerr)
	}
}

func (s *applicationServer) serveAllJSON(ctx context.Context, resp http.ResponseWriter, req *http.Request) {
	var err error
	ctx = ctxsetters.WithMethodName(ctx, "All")
	ctx, err = callRequestRouted(ctx, s.hooks)
	if err != nil {
		s.writeError(ctx, resp, err)
		return
	}

	reqContent := new(ReadApplications)
	unmarshaler := jsonpb.Unmarshaler{AllowUnknownFields: true}
	if err = unmarshaler.Unmarshal(req.Body, reqContent); err != nil {
		s.writeError(ctx, resp, malformedRequestError("the json request could not be decoded"))
		return
	}

	handler := s.Application.All
	if s.interceptor != nil {
		handler = func(ctx context.Context, req *ReadApplications) (*ApplicationsRead, error) {
			resp, err := s.interceptor(
				func(ctx context.Context, req interface{}) (interface{}, error) {
					typedReq, ok := req.(*ReadApplications)
					if !ok {
						return nil, twirp.InternalError("failed type assertion req.(*ReadApplications) when calling interceptor")
					}
					return s.Application.All(ctx, typedReq)
				},
			)(ctx, req)
			if resp != nil {
				typedResp, ok := resp.(*ApplicationsRead)
				if !ok {
					return nil, twirp.InternalError("failed type assertion resp.(*ApplicationsRead) when calling interceptor")
				}
				return typedResp, err
			}
			return nil, err
		}
	}

	// Call service method
	var respContent *ApplicationsRead
	func() {
		defer ensurePanicResponses(ctx, resp, s.hooks)
		respContent, err = handler(ctx, reqContent)
	}()

	if err != nil {
		s.writeError(ctx, resp, err)
		return
	}
	if respContent == nil {
		s.writeError(ctx, resp, twirp.InternalError("received a nil *ApplicationsRead and nil error while calling All. nil responses are not supported"))
		return
	}

	ctx = callResponsePrepared(ctx, s.hooks)

	var buf bytes.Buffer
	marshaler := &jsonpb.Marshaler{OrigName: true, EmitDefaults: !s.jsonSkipDefaults}
	if err = marshaler.Marshal(&buf, respContent); err != nil {
		s.writeError(ctx, resp, wrapInternal(err, "failed to marshal json response"))
		return
	}

	ctx = ctxsetters.WithStatusCode(ctx, http.StatusOK)
	respBytes := buf.Bytes()
	resp.Header().Set("Content-Type", "application/json")
	resp.Header().Set("Content-Length", strconv.Itoa(len(respBytes)))
	resp.WriteHeader(http.StatusOK)

	if n, err := resp.Write(respBytes); err != nil {
		msg := fmt.Sprintf("failed to write response, %d of %d bytes written: %s", n, len(respBytes), err.Error())
		twerr := twirp.NewError(twirp.Unknown, msg)
		ctx = callError(ctx, s.hooks, twerr)
	}
	callResponseSent(ctx, s.hooks)
}

func (s *applicationServer) serveAllProtobuf(ctx context.Context, resp http.ResponseWriter, req *http.Request) {
	var err error
	ctx = ctxsetters.WithMethodName(ctx, "All")
	ctx, err = callRequestRouted(ctx, s.hooks)
	if err != nil {
		s.writeError(ctx, resp, err)
		return
	}

	buf, err := ioutil.ReadAll(req.Body)
	if err != nil {
		s.writeError(ctx, resp, wrapInternal(err, "failed to read request body"))
		return
	}
	reqContent := new(ReadApplications)
	if err = proto.Unmarshal(buf, reqContent); err != nil {
		s.writeError(ctx, resp, malformedRequestError("the protobuf request could not be decoded"))
		return
	}

	handler := s.Application.All
	if s.interceptor != nil {
		handler = func(ctx context.Context, req *ReadApplications) (*ApplicationsRead, error) {
			resp, err := s.interceptor(
				func(ctx context.Context, req interface{}) (interface{}, error) {
					typedReq, ok := req.(*ReadApplications)
					if !ok {
						return nil, twirp.InternalError("failed type assertion req.(*ReadApplications) when calling interceptor")
					}
					return s.Application.All(ctx, typedReq)
				},
			)(ctx, req)
			if resp != nil {
				typedResp, ok := resp.(*ApplicationsRead)
				if !ok {
					return nil, twirp.InternalError("failed type assertion resp.(*ApplicationsRead) when calling interceptor")
				}
				return typedResp, err
			}
			return nil, err
		}
	}

	// Call service method
	var respContent *ApplicationsRead
	func() {
		defer ensurePanicResponses(ctx, resp, s.hooks)
		respContent, err = handler(ctx, reqContent)
	}()

	if err != nil {
		s.writeError(ctx, resp, err)
		return
	}
	if respContent == nil {
		s.writeError(ctx, resp, twirp.InternalError("received a nil *ApplicationsRead and nil error while calling All. nil responses are not supported"))
		return
	}

	ctx = callResponsePrepared(ctx, s.hooks)

	respBytes, err := proto.Marshal(respContent)
	if err != nil {
		s.writeError(ctx, resp, wrapInternal(err, "failed to marshal proto response"))
		return
	}

	ctx = ctxsetters.WithStatusCode(ctx, http.StatusOK)
	resp.Header().Set("Content-Type", "application/protobuf")
	resp.Header().Set("Content-Length", strconv.Itoa(len(respBytes)))
	resp.WriteHeader(http.StatusOK)
	if n, err := resp.Write(respBytes); err != nil {
		msg := fmt.Sprintf("failed to write response, %d of %d bytes written: %s", n, len(respBytes), err.Error())
		twerr := twirp.NewError(twirp.Unknown, msg)
		ctx = callError(ctx, s.hooks, twerr)
	}
	callResponseSent(ctx, s.hooks)
}

func (s *applicationServer) ServiceDescriptor() ([]byte, int) {
	return twirpFileDescriptor0, 0
}

func (s *applicationServer) ProtocGenTwirpVersion() string {
	return "v7.1.1"
}

// PathPrefix returns the base service path, in the form: "/<prefix>/<package>.<Service>/"
// that is everything in a Twirp route except for the <Method>. This can be used for routing,
// for example to identify the requests that are targeted to this service in a mux.
func (s *applicationServer) PathPrefix() string {
	return baseServicePath(s.pathPrefix, "redsail.bosn", "Application")
}

// =====
// Utils
// =====

// HTTPClient is the interface used by generated clients to send HTTP requests.
// It is fulfilled by *(net/http).Client, which is sufficient for most users.
// Users can provide their own implementation for special retry policies.
//
// HTTPClient implementations should not follow redirects. Redirects are
// automatically disabled if *(net/http).Client is passed to client
// constructors. See the withoutRedirects function in this file for more
// details.
type HTTPClient interface {
	Do(req *http.Request) (*http.Response, error)
}

// TwirpServer is the interface generated server structs will support: they're
// HTTP handlers with additional methods for accessing metadata about the
// service. Those accessors are a low-level API for building reflection tools.
// Most people can think of TwirpServers as just http.Handlers.
type TwirpServer interface {
	http.Handler

	// ServiceDescriptor returns gzipped bytes describing the .proto file that
	// this service was generated from. Once unzipped, the bytes can be
	// unmarshalled as a
	// github.com/golang/protobuf/protoc-gen-go/descriptor.FileDescriptorProto.
	//
	// The returned integer is the index of this particular service within that
	// FileDescriptorProto's 'Service' slice of ServiceDescriptorProtos. This is a
	// low-level field, expected to be used for reflection.
	ServiceDescriptor() ([]byte, int)

	// ProtocGenTwirpVersion is the semantic version string of the version of
	// twirp used to generate this file.
	ProtocGenTwirpVersion() string

	// PathPrefix returns the HTTP URL path prefix for all methods handled by this
	// service. This can be used with an HTTP mux to route Twirp requests.
	// The path prefix is in the form: "/<prefix>/<package>.<Service>/"
	// that is, everything in a Twirp route except for the <Method> at the end.
	PathPrefix() string
}

// WriteError writes an HTTP response with a valid Twirp error format (code, msg, meta).
// Useful outside of the Twirp server (e.g. http middleware), but does not trigger hooks.
// If err is not a twirp.Error, it will get wrapped with twirp.InternalErrorWith(err)
func WriteError(resp http.ResponseWriter, err error) {
	writeError(context.Background(), resp, err, nil)
}

// writeError writes Twirp errors in the response and triggers hooks.
func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks *twirp.ServerHooks) {
	// Non-twirp errors are wrapped as Internal (default)
	twerr, ok := err.(twirp.Error)
	if !ok {
		twerr = twirp.InternalErrorWith(err)
	}

	statusCode := twirp.ServerHTTPStatusFromErrorCode(twerr.Code())
	ctx = ctxsetters.WithStatusCode(ctx, statusCode)
	ctx = callError(ctx, hooks, twerr)

	respBody := marshalErrorToJSON(twerr)

	resp.Header().Set("Content-Type", "application/json") // Error responses are always JSON
	resp.Header().Set("Content-Length", strconv.Itoa(len(respBody)))
	resp.WriteHeader(statusCode) // set HTTP status code and send response

	_, writeErr := resp.Write(respBody)
	if writeErr != nil {
		// We have three options here. We could log the error, call the Error
		// hook, or just silently ignore the error.
		//
		// Logging is unacceptable because we don't have a user-controlled
		// logger; writing out to stderr without permission is too rude.
		//
		// Calling the Error hook would confuse users: it would mean the Error
		// hook got called twice for one request, which is likely to lead to
		// duplicated log messages and metrics, no matter how well we document
		// the behavior.
		//
		// Silently ignoring the error is our least-bad option. It's highly
		// likely that the connection is broken and the original 'err' says
		// so anyway.
		_ = writeErr
	}

	callResponseSent(ctx, hooks)
}

// sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
// If the URL is unparsable, the baseURL is returned unchaged.
func sanitizeBaseURL(baseURL string) string {
	u, err := url.Parse(baseURL)
	if err != nil {
		return baseURL // invalid URL will fail later when making requests
	}
	if u.Scheme == "" {
		u.Scheme = "http"
	}
	return u.String()
}

// baseServicePath composes the path prefix for the service (without <Method>).
// e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
//       returns => "/twirp/my.pkg.MyService/"
// e.g.: baseServicePath("", "", "MyService")
//       returns => "/MyService/"
func baseServicePath(prefix, pkg, service string) string {
	fullServiceName := service
	if pkg != "" {
		fullServiceName = pkg + "." + service
	}
	return path.Join("/", prefix, fullServiceName) + "/"
}

// parseTwirpPath extracts path components form a valid Twirp route.
// Expected format: "[<prefix>]/<package>.<Service>/<Method>"
// e.g.: prefix, pkgService, method := parseTwirpPath("/twirp/pkg.Svc/MakeHat")
func parseTwirpPath(path string) (string, string, string) {
	parts := strings.Split(path, "/")
	if len(parts) < 2 {
		return "", "", ""
	}
	method := parts[len(parts)-1]
	pkgService := parts[len(parts)-2]
	prefix := strings.Join(parts[0:len(parts)-2], "/")
	return prefix, pkgService, method
}

// getCustomHTTPReqHeaders retrieves a copy of any headers that are set in
// a context through the twirp.WithHTTPRequestHeaders function.
// If there are no headers set, or if they have the wrong type, nil is returned.
func getCustomHTTPReqHeaders(ctx context.Context) http.Header {
	header, ok := twirp.HTTPRequestHeaders(ctx)
	if !ok || header == nil {
		return nil
	}
	copied := make(http.Header)
	for k, vv := range header {
		if vv == nil {
			copied[k] = nil
			continue
		}
		copied[k] = make([]string, len(vv))
		copy(copied[k], vv)
	}
	return copied
}

// newRequest makes an http.Request from a client, adding common headers.
func newRequest(ctx context.Context, url string, reqBody io.Reader, contentType string) (*http.Request, error) {
	req, err := http.NewRequest("POST", url, reqBody)
	if err != nil {
		return nil, err
	}
	req = req.WithContext(ctx)
	if customHeader := getCustomHTTPReqHeaders(ctx); customHeader != nil {
		req.Header = customHeader
	}
	req.Header.Set("Accept", contentType)
	req.Header.Set("Content-Type", contentType)
	req.Header.Set("Twirp-Version", "v7.1.1")
	return req, nil
}

// JSON serialization for errors
type twerrJSON struct {
	Code string            `json:"code"`
	Msg  string            `json:"msg"`
	Meta map[string]string `json:"meta,omitempty"`
}

// marshalErrorToJSON returns JSON from a twirp.Error, that can be used as HTTP error response body.
// If serialization fails, it will use a descriptive Internal error instead.
func marshalErrorToJSON(twerr twirp.Error) []byte {
	// make sure that msg is not too large
	msg := twerr.Msg()
	if len(msg) > 1e6 {
		msg = msg[:1e6]
	}

	tj := twerrJSON{
		Code: string(twerr.Code()),
		Msg:  msg,
		Meta: twerr.MetaMap(),
	}

	buf, err := json.Marshal(&tj)
	if err != nil {
		buf = []byte("{\"type\": \"" + twirp.Internal + "\", \"msg\": \"There was an error but it could not be serialized into JSON\"}") // fallback
	}

	return buf
}

// errorFromResponse builds a twirp.Error from a non-200 HTTP response.
// If the response has a valid serialized Twirp error, then it's returned.
// If not, the response status code is used to generate a similar twirp
// error. See twirpErrorFromIntermediary for more info on intermediary errors.
func errorFromResponse(resp *http.Response) twirp.Error {
	statusCode := resp.StatusCode
	statusText := http.StatusText(statusCode)

	if isHTTPRedirect(statusCode) {
		// Unexpected redirect: it must be an error from an intermediary.
		// Twirp clients don't follow redirects automatically, Twirp only handles
		// POST requests, redirects should only happen on GET and HEAD requests.
		location := resp.Header.Get("Location")
		msg := fmt.Sprintf("unexpected HTTP status code %d %q received, Location=%q", statusCode, statusText, location)
		return twirpErrorFromIntermediary(statusCode, msg, location)
	}

	respBodyBytes, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return wrapInternal(err, "failed to read server error response body")
	}

	var tj twerrJSON
	dec := json.NewDecoder(bytes.NewReader(respBodyBytes))
	dec.DisallowUnknownFields()
	if err := dec.Decode(&tj); err != nil || tj.Code == "" {
		// Invalid JSON response; it must be an error from an intermediary.
		msg := fmt.Sprintf("Error from intermediary with HTTP status code %d %q", statusCode, statusText)
		return twirpErrorFromIntermediary(statusCode, msg, string(respBodyBytes))
	}

	errorCode := twirp.ErrorCode(tj.Code)
	if !twirp.IsValidErrorCode(errorCode) {
		msg := "invalid type returned from server error response: " + tj.Code
		return twirp.InternalError(msg).WithMeta("body", string(respBodyBytes))
	}

	twerr := twirp.NewError(errorCode, tj.Msg)
	for k, v := range tj.Meta {
		twerr = twerr.WithMeta(k, v)
	}
	return twerr
}

// twirpErrorFromIntermediary maps HTTP errors from non-twirp sources to twirp errors.
// The mapping is similar to gRPC: https://github.com/grpc/grpc/blob/master/doc/http-grpc-status-mapping.md.
// Returned twirp Errors have some additional metadata for inspection.
func twirpErrorFromIntermediary(status int, msg string, bodyOrLocation string) twirp.Error {
	var code twirp.ErrorCode
	if isHTTPRedirect(status) { // 3xx
		code = twirp.Internal
	} else {
		switch status {
		case 400: // Bad Request
			code = twirp.Internal
		case 401: // Unauthorized
			code = twirp.Unauthenticated
		case 403: // Forbidden
			code = twirp.PermissionDenied
		case 404: // Not Found
			code = twirp.BadRoute
		case 429: // Too Many Requests
			code = twirp.ResourceExhausted
		case 502, 503, 504: // Bad Gateway, Service Unavailable, Gateway Timeout
			code = twirp.Unavailable
		default: // All other codes
			code = twirp.Unknown
		}
	}

	twerr := twirp.NewError(code, msg)
	twerr = twerr.WithMeta("http_error_from_intermediary", "true") // to easily know if this error was from intermediary
	twerr = twerr.WithMeta("status_code", strconv.Itoa(status))
	if isHTTPRedirect(status) {
		twerr = twerr.WithMeta("location", bodyOrLocation)
	} else {
		twerr = twerr.WithMeta("body", bodyOrLocation)
	}
	return twerr
}

func isHTTPRedirect(status int) bool {
	return status >= 300 && status <= 399
}

// wrapInternal wraps an error with a prefix as an Internal error.
// The original error cause is accessible by github.com/pkg/errors.Cause.
func wrapInternal(err error, prefix string) twirp.Error {
	return twirp.InternalErrorWith(&wrappedError{prefix: prefix, cause: err})
}

type wrappedError struct {
	prefix string
	cause  error
}

func (e *wrappedError) Error() string { return e.prefix + ": " + e.cause.Error() }
func (e *wrappedError) Unwrap() error { return e.cause } // for go1.13 + errors.Is/As
func (e *wrappedError) Cause() error  { return e.cause } // for github.com/pkg/errors

// ensurePanicResponses makes sure that rpc methods causing a panic still result in a Twirp Internal
// error response (status 500), and error hooks are properly called with the panic wrapped as an error.
// The panic is re-raised so it can be handled normally with middleware.
func ensurePanicResponses(ctx context.Context, resp http.ResponseWriter, hooks *twirp.ServerHooks) {
	if r := recover(); r != nil {
		// Wrap the panic as an error so it can be passed to error hooks.
		// The original error is accessible from error hooks, but not visible in the response.
		err := errFromPanic(r)
		twerr := &internalWithCause{msg: "Internal service panic", cause: err}
		// Actually write the error
		writeError(ctx, resp, twerr, hooks)
		// If possible, flush the error to the wire.
		f, ok := resp.(http.Flusher)
		if ok {
			f.Flush()
		}

		panic(r)
	}
}

// errFromPanic returns the typed error if the recovered panic is an error, otherwise formats as error.
func errFromPanic(p interface{}) error {
	if err, ok := p.(error); ok {
		return err
	}
	return fmt.Errorf("panic: %v", p)
}

// internalWithCause is a Twirp Internal error wrapping an original error cause,
// but the original error message is not exposed on Msg(). The original error
// can be checked with go1.13+ errors.Is/As, and also by (github.com/pkg/errors).Unwrap
type internalWithCause struct {
	msg   string
	cause error
}

func (e *internalWithCause) Unwrap() error                               { return e.cause } // for go1.13 + errors.Is/As
func (e *internalWithCause) Cause() error                                { return e.cause } // for github.com/pkg/errors
func (e *internalWithCause) Error() string                               { return e.msg + ": " + e.cause.Error() }
func (e *internalWithCause) Code() twirp.ErrorCode                       { return twirp.Internal }
func (e *internalWithCause) Msg() string                                 { return e.msg }
func (e *internalWithCause) Meta(key string) string                      { return "" }
func (e *internalWithCause) MetaMap() map[string]string                  { return nil }
func (e *internalWithCause) WithMeta(key string, val string) twirp.Error { return e }

// malformedRequestError is used when the twirp server cannot unmarshal a request
func malformedRequestError(msg string) twirp.Error {
	return twirp.NewError(twirp.Malformed, msg)
}

// badRouteError is used when the twirp server cannot route a request
func badRouteError(msg string, method, url string) twirp.Error {
	err := twirp.NewError(twirp.BadRoute, msg)
	err = err.WithMeta("twirp_invalid_route", method+" "+url)
	return err
}

// withoutRedirects makes sure that the POST request can not be redirected.
// The standard library will, by default, redirect requests (including POSTs) if it gets a 302 or
// 303 response, and also 301s in go1.8. It redirects by making a second request, changing the
// method to GET and removing the body. This produces very confusing error messages, so instead we
// set a redirect policy that always errors. This stops Go from executing the redirect.
//
// We have to be a little careful in case the user-provided http.Client has its own CheckRedirect
// policy - if so, we'll run through that policy first.
//
// Because this requires modifying the http.Client, we make a new copy of the client and return it.
func withoutRedirects(in *http.Client) *http.Client {
	copy := *in
	copy.CheckRedirect = func(req *http.Request, via []*http.Request) error {
		if in.CheckRedirect != nil {
			// Run the input's redirect if it exists, in case it has side effects, but ignore any error it
			// returns, since we want to use ErrUseLastResponse.
			err := in.CheckRedirect(req, via)
			_ = err // Silly, but this makes sure generated code passes errcheck -blank, which some people use.
		}
		return http.ErrUseLastResponse
	}
	return &copy
}

// doProtobufRequest makes a Protobuf request to the remote Twirp service.
func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.ClientHooks, url string, in, out proto.Message) (_ context.Context, err error) {
	reqBodyBytes, err := proto.Marshal(in)
	if err != nil {
		return ctx, wrapInternal(err, "failed to marshal proto request")
	}
	reqBody := bytes.NewBuffer(reqBodyBytes)
	if err = ctx.Err(); err != nil {
		return ctx, wrapInternal(err, "aborted because context was done")
	}

	req, err := newRequest(ctx, url, reqBody, "application/protobuf")
	if err != nil {
		return ctx, wrapInternal(err, "could not build request")
	}
	ctx, err = callClientRequestPrepared(ctx, hooks, req)
	if err != nil {
		return ctx, err
	}

	req = req.WithContext(ctx)
	resp, err := client.Do(req)
	if err != nil {
		return ctx, wrapInternal(err, "failed to do request")
	}

	defer func() {
		cerr := resp.Body.Close()
		if err == nil && cerr != nil {
			err = wrapInternal(cerr, "failed to close response body")
		}
	}()

	if err = ctx.Err(); err != nil {
		return ctx, wrapInternal(err, "aborted because context was done")
	}

	if resp.StatusCode != 200 {
		return ctx, errorFromResponse(resp)
	}

	respBodyBytes, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return ctx, wrapInternal(err, "failed to read response body")
	}
	if err = ctx.Err(); err != nil {
		return ctx, wrapInternal(err, "aborted because context was done")
	}

	if err = proto.Unmarshal(respBodyBytes, out); err != nil {
		return ctx, wrapInternal(err, "failed to unmarshal proto response")
	}
	return ctx, nil
}

// doJSONRequest makes a JSON request to the remote Twirp service.
func doJSONRequest(ctx context.Context, client HTTPClient, hooks *twirp.ClientHooks, url string, in, out proto.Message) (_ context.Context, err error) {
	reqBody := bytes.NewBuffer(nil)
	marshaler := &jsonpb.Marshaler{OrigName: true}
	if err = marshaler.Marshal(reqBody, in); err != nil {
		return ctx, wrapInternal(err, "failed to marshal json request")
	}
	if err = ctx.Err(); err != nil {
		return ctx, wrapInternal(err, "aborted because context was done")
	}

	req, err := newRequest(ctx, url, reqBody, "application/json")
	if err != nil {
		return ctx, wrapInternal(err, "could not build request")
	}
	ctx, err = callClientRequestPrepared(ctx, hooks, req)
	if err != nil {
		return ctx, err
	}

	req = req.WithContext(ctx)
	resp, err := client.Do(req)
	if err != nil {
		return ctx, wrapInternal(err, "failed to do request")
	}

	defer func() {
		cerr := resp.Body.Close()
		if err == nil && cerr != nil {
			err = wrapInternal(cerr, "failed to close response body")
		}
	}()

	if err = ctx.Err(); err != nil {
		return ctx, wrapInternal(err, "aborted because context was done")
	}

	if resp.StatusCode != 200 {
		return ctx, errorFromResponse(resp)
	}

	unmarshaler := jsonpb.Unmarshaler{AllowUnknownFields: true}
	if err = unmarshaler.Unmarshal(resp.Body, out); err != nil {
		return ctx, wrapInternal(err, "failed to unmarshal json response")
	}
	if err = ctx.Err(); err != nil {
		return ctx, wrapInternal(err, "aborted because context was done")
	}
	return ctx, nil
}

// Call twirp.ServerHooks.RequestReceived if the hook is available
func callRequestReceived(ctx context.Context, h *twirp.ServerHooks) (context.Context, error) {
	if h == nil || h.RequestReceived == nil {
		return ctx, nil
	}
	return h.RequestReceived(ctx)
}

// Call twirp.ServerHooks.RequestRouted if the hook is available
func callRequestRouted(ctx context.Context, h *twirp.ServerHooks) (context.Context, error) {
	if h == nil || h.RequestRouted == nil {
		return ctx, nil
	}
	return h.RequestRouted(ctx)
}

// Call twirp.ServerHooks.ResponsePrepared if the hook is available
func callResponsePrepared(ctx context.Context, h *twirp.ServerHooks) context.Context {
	if h == nil || h.ResponsePrepared == nil {
		return ctx
	}
	return h.ResponsePrepared(ctx)
}

// Call twirp.ServerHooks.ResponseSent if the hook is available
func callResponseSent(ctx context.Context, h *twirp.ServerHooks) {
	if h == nil || h.ResponseSent == nil {
		return
	}
	h.ResponseSent(ctx)
}

// Call twirp.ServerHooks.Error if the hook is available
func callError(ctx context.Context, h *twirp.ServerHooks, err twirp.Error) context.Context {
	if h == nil || h.Error == nil {
		return ctx
	}
	return h.Error(ctx, err)
}

func callClientResponseReceived(ctx context.Context, h *twirp.ClientHooks) {
	if h == nil || h.ResponseReceived == nil {
		return
	}
	h.ResponseReceived(ctx)
}

func callClientRequestPrepared(ctx context.Context, h *twirp.ClientHooks, req *http.Request) (context.Context, error) {
	if h == nil || h.RequestPrepared == nil {
		return ctx, nil
	}
	return h.RequestPrepared(ctx, req)
}

func callClientError(ctx context.Context, h *twirp.ClientHooks, err twirp.Error) {
	if h == nil || h.Error == nil {
		return
	}
	h.Error(ctx, err)
}

var twirpFileDescriptor0 = []byte{
	// 306 bytes of a gzipped FileDescriptorProto
	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x74, 0x92, 0x3f, 0x4f, 0xc3, 0x30,
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	0x00, 0x00,
}