package gengateway

import (
	"bytes"
	"errors"
	"fmt"
	"net/http"
	"strings"
	"text/template"

	"github.com/grpc-ecosystem/grpc-gateway/v2/internal/casing"
	"github.com/grpc-ecosystem/grpc-gateway/v2/internal/descriptor"
	"github.com/grpc-ecosystem/grpc-gateway/v2/utilities"
	"google.golang.org/grpc/grpclog"
	"google.golang.org/protobuf/types/descriptorpb"
)

type param struct {
	*descriptor.File
	Imports            []descriptor.GoPackage
	UseRequestContext  bool
	RegisterFuncSuffix string
	AllowPatchFeature  bool
	OmitPackageDoc     bool
	UseOpaqueAPI       bool
}

type binding struct {
	*descriptor.Binding
	Registry          *descriptor.Registry
	AllowPatchFeature bool
	UseOpaqueAPI      bool
}

// GetBodyFieldPath returns the binding body's field path.
func (b binding) GetBodyFieldPath() string {
	if b.Body != nil && len(b.Body.FieldPath) != 0 {
		return b.Body.FieldPath.String()
	}
	return "*"
}

// GetBodyFieldStructName returns the binding body's struct field name.
func (b binding) GetBodyFieldStructName() (string, error) {
	if b.Body != nil && len(b.Body.FieldPath) != 0 {
		return casing.Camel(b.Body.FieldPath.String()), nil
	}
	return "", errors.New("no body field found")
}

// GetBodyFieldType returns the Go type of the body field.
func (b binding) GetBodyFieldType() (string, error) {
	if b.Body == nil || len(b.Body.FieldPath) == 0 {
		return "", errors.New("no body field found")
	}

	lastComponent := b.Body.FieldPath[len(b.Body.FieldPath)-1]
	fieldType := lastComponent.Target.GetType()

	// Handle message types
	if fieldType == descriptorpb.FieldDescriptorProto_TYPE_MESSAGE {
		// Get the parent message to provide proper lookup context
		parentMsg := lastComponent.Target.Message
		msg, err := b.Registry.LookupMsg(parentMsg.FQMN(), lastComponent.Target.GetTypeName())
		if err != nil {
			return "", fmt.Errorf("failed to lookup message type %s: %w", lastComponent.Target.GetTypeName(), err)
		}
		return msg.GoType(b.Method.Service.File.GoPkg.Path), nil
	}

	return "", errors.New("unsupported body field type")
}

// HasQueryParam determines if the binding needs parameters in query string.
//
// It sometimes returns true even though actually the binding does not need.
// But it is not serious because it just results in a small amount of extra codes generated.
func (b binding) HasQueryParam() bool {
	if b.Body != nil && len(b.Body.FieldPath) == 0 {
		return false
	}
	fields := make(map[string]bool)
	for _, f := range b.Method.RequestType.Fields {
		fields[f.GetName()] = true
	}
	if b.Body != nil {
		delete(fields, b.Body.FieldPath.String())
	}
	for _, p := range b.PathParams {
		delete(fields, p.FieldPath.String())
	}
	return len(fields) > 0
}

func (b binding) QueryParamFilter() queryParamFilter {
	var seqs [][]string
	if b.Body != nil {
		seqs = append(seqs, strings.Split(b.Body.FieldPath.String(), "."))
	}
	for _, p := range b.PathParams {
		seqs = append(seqs, strings.Split(p.FieldPath.String(), "."))
	}
	return queryParamFilter{utilities.NewDoubleArray(seqs)}
}

// HasEnumPathParam returns true if the path parameter slice contains a parameter
// that maps to an enum proto field that is not repeated, if not false is returned.
func (b binding) HasEnumPathParam() bool {
	return b.hasEnumPathParam(false)
}

// HasRepeatedEnumPathParam returns true if the path parameter slice contains a parameter
// that maps to a repeated enum proto field, if not false is returned.
func (b binding) HasRepeatedEnumPathParam() bool {
	return b.hasEnumPathParam(true)
}

// hasEnumPathParam returns true if the path parameter slice contains a parameter
// that maps to an enum proto field and that the enum proto field is or isn't repeated
// based on the provided 'repeated' parameter.
func (b binding) hasEnumPathParam(repeated bool) bool {
	for _, p := range b.PathParams {
		if p.IsEnum() && p.IsRepeated() == repeated {
			return true
		}
	}
	return false
}

// LookupEnum looks up an enum type by path parameter.
func (b binding) LookupEnum(p descriptor.Parameter) *descriptor.Enum {
	e, err := b.Registry.LookupEnum("", p.Target.GetTypeName())
	if err != nil {
		return nil
	}
	return e
}

// FieldMaskField returns the golang-style name of the variable for a FieldMask, if there is exactly one of that type in
// the message. Otherwise, it returns an empty string.
func (b binding) FieldMaskField() string {
	var fieldMaskField *descriptor.Field
	for _, f := range b.Method.RequestType.Fields {
		if f.GetTypeName() == ".google.protobuf.FieldMask" {
			// if there is more than 1 FieldMask for this request, then return none
			if fieldMaskField != nil {
				return ""
			}
			fieldMaskField = f
		}
	}
	if fieldMaskField != nil {
		return casing.Camel(fieldMaskField.GetName())
	}
	return ""
}

// queryParamFilter is a wrapper of utilities.DoubleArray which provides String() to output DoubleArray.Encoding in a stable and predictable format.
type queryParamFilter struct {
	*utilities.DoubleArray
}

func (f queryParamFilter) String() string {
	encodings := make([]string, len(f.Encoding))
	for str, enc := range f.Encoding {
		encodings[enc] = fmt.Sprintf("%q: %d", str, enc)
	}
	e := strings.Join(encodings, ", ")
	return fmt.Sprintf("&utilities.DoubleArray{Encoding: map[string]int{%s}, Base: %#v, Check: %#v}", e, f.Base, f.Check)
}

type trailerParams struct {
	Services           []*descriptor.Service
	UseRequestContext  bool
	RegisterFuncSuffix string
	UseOpaqueAPI       bool
}

func applyTemplate(p param, reg *descriptor.Registry) (string, error) {
	w := bytes.NewBuffer(nil)
	if err := headerTemplate.Execute(w, p); err != nil {
		return "", err
	}
	var targetServices []*descriptor.Service

	for _, msg := range p.Messages {
		msgName := casing.Camel(*msg.Name)
		msg.Name = &msgName
	}

	for _, svc := range p.Services {
		var methodWithBindingsSeen bool
		svcName := casing.Camel(*svc.Name)
		svc.Name = &svcName

		for _, meth := range svc.Methods {
			if grpclog.V(2) {
				grpclog.Infof("Processing %s.%s", svc.GetName(), meth.GetName())
			}
			methName := casing.Camel(*meth.Name)
			meth.Name = &methName
			for _, b := range meth.Bindings {
				if err := reg.CheckDuplicateAnnotation(b.HTTPMethod, b.PathTmpl.Template, svc); err != nil {
					return "", err
				}

				methodWithBindingsSeen = true
				if err := handlerTemplate.Execute(w, binding{
					Binding:           b,
					Registry:          reg,
					AllowPatchFeature: p.AllowPatchFeature,
					UseOpaqueAPI:      p.UseOpaqueAPI,
				}); err != nil {
					return "", err
				}

				// Local
				if err := localHandlerTemplate.Execute(w, binding{
					Binding:           b,
					Registry:          reg,
					AllowPatchFeature: p.AllowPatchFeature,
					UseOpaqueAPI:      p.UseOpaqueAPI,
				}); err != nil {
					return "", err
				}
			}
		}
		if methodWithBindingsSeen {
			targetServices = append(targetServices, svc)
		}
	}
	if len(targetServices) == 0 {
		return "", errNoTargetService
	}

	tp := trailerParams{
		Services:           targetServices,
		UseRequestContext:  p.UseRequestContext,
		RegisterFuncSuffix: p.RegisterFuncSuffix,
		UseOpaqueAPI:       p.UseOpaqueAPI,
	}
	// Local
	if err := localTrailerTemplate.Execute(w, tp); err != nil {
		return "", err
	}

	if err := trailerTemplate.Execute(w, tp); err != nil {
		return "", err
	}
	return w.String(), nil
}

var (
	httpMethods = map[string]string{
		http.MethodGet:     "http.MethodGet",
		http.MethodHead:    "http.MethodHead",
		http.MethodPost:    "http.MethodPost",
		http.MethodPut:     "http.MethodPut",
		http.MethodPatch:   "http.MethodPatch",
		http.MethodDelete:  "http.MethodDelete",
		http.MethodConnect: "http.MethodConnect",
		http.MethodOptions: "http.MethodOptions",
		http.MethodTrace:   "http.MethodTrace",
	}
	headerTemplate = template.Must(template.New("header").Parse(`
// Code generated by protoc-gen-grpc-gateway. DO NOT EDIT.
// source: {{ .GetName }}

{{ if not .OmitPackageDoc }}/*
Package {{ .GoPkg.Name }} is a reverse proxy.

It translates gRPC into RESTful JSON APIs.
*/{{ end }}
package {{ .GoPkg.Name }}
import (
	{{ range $i := .Imports }}{{ if $i.Standard }}{{ $i | printf "%s\n" }}{{ end }}{{ end }}

	{{ range $i := .Imports }}{{ if not $i.Standard }}{{ $i | printf "%s\n" }}{{ end }}{{ end }}
)

// Suppress "imported and not used" errors
var (
	_ codes.Code
	_ io.Reader
	_ status.Status
	_ = errors.New
	_ = runtime.String
	_ = utilities.NewDoubleArray
	_ = metadata.Join
)
`))

	handlerTemplate = template.Must(template.New("handler").Parse(`
{{ if and .Method.GetClientStreaming .Method.GetServerStreaming }}
{{ template "bidi-streaming-request-func" . }}
{{ else if .Method.GetClientStreaming }}
{{ template "client-streaming-request-func" . }}
{{ else }}
{{ template "client-rpc-request-func" . }}
{{ end }}
`))

	_ = template.Must(handlerTemplate.New("request-func-signature").Parse(strings.ReplaceAll(`
{{ if and .Method.GetClientStreaming .Method.GetServerStreaming }}
func request_{{ .Method.Service.GetName }}_{{ .Method.GetName }}_{{ .Index }}(ctx context.Context, marshaler runtime.Marshaler, client {{ .Method.Service.InstanceName }}Client, req *http.Request, pathParams map[string]string) ({{ .Method.Service.InstanceName }}_{{ .Method.GetName }}Client, runtime.ServerMetadata, error)
{{ else if .Method.GetServerStreaming }}
func request_{{ .Method.Service.GetName }}_{{ .Method.GetName }}_{{ .Index }}(ctx context.Context, marshaler runtime.Marshaler, client {{ .Method.Service.InstanceName }}Client, req *http.Request, pathParams map[string]string) ({{ .Method.Service.InstanceName }}_{{ .Method.GetName }}Client, runtime.ServerMetadata, error)
{{ else }}
func request_{{ .Method.Service.GetName }}_{{ .Method.GetName }}_{{ .Index }}(ctx context.Context, marshaler runtime.Marshaler, client {{ .Method.Service.InstanceName }}Client, req *http.Request, pathParams map[string]string) (proto.Message, runtime.ServerMetadata, error)
{{ end }}`, "\n", "")))

	_ = template.Must(handlerTemplate.New("client-streaming-request-func").Parse(`
{{ template "request-func-signature" . }} {
	var metadata runtime.ServerMetadata
	stream, err := client.{{ .Method.GetName }}(ctx)
	if err != nil {
		grpclog.Errorf("Failed to start streaming: %v", err)
		return nil, metadata, err
	}
	dec := marshaler.NewDecoder(req.Body)
	for {
		var protoReq {{ .Method.RequestType.GoType .Method.Service.File.GoPkg.Path }}
		err = dec.Decode(&protoReq)
		if errors.Is(err, io.EOF) {
			break
		}
		if err != nil {
			grpclog.Errorf("Failed to decode request: %v", err)
			return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
		}
		if err = stream.Send(&protoReq); err != nil {
			if errors.Is(err, io.EOF) {
				break
			}
			grpclog.Errorf("Failed to send request: %v", err)
			return nil, metadata, err
		}
	}
	if err := stream.CloseSend(); err != nil {
		grpclog.Errorf("Failed to terminate client stream: %v", err)
		return nil, metadata, err
	}
	header, err := stream.Header()
	if err != nil {
		grpclog.Errorf("Failed to get header from client: %v", err)
		return nil, metadata, err
	}
	metadata.HeaderMD = header
{{- if .Method.GetServerStreaming }}
	return stream, metadata, nil
{{- else }}
	msg, err := stream.CloseAndRecv()
	metadata.TrailerMD = stream.Trailer()
	return msg, metadata, err
{{- end }}
}
`))

	funcMap template.FuncMap = map[string]interface{}{
		"camelIdentifier": casing.CamelIdentifier,
		"opaqueSetter": func(p descriptor.FieldPath, msgExpr string) string {
			return p.OpaqueSetterExpr(msgExpr)
		},
		"toHTTPMethod": func(method string) string {
			return httpMethods[method]
		},
	}

	_ = template.Must(handlerTemplate.New("client-rpc-request-func").Funcs(funcMap).Parse(`
{{ $AllowPatchFeature := .AllowPatchFeature }}
{{ $UseOpaqueAPI := .UseOpaqueAPI }}
{{ if .HasQueryParam }}
var filter_{{ .Method.Service.GetName }}_{{ .Method.GetName }}_{{ .Index }} = {{ .QueryParamFilter }}
{{ end }}
{{ template "request-func-signature" . }} {
	var (
		protoReq {{ .Method.RequestType.GoType .Method.Service.File.GoPkg.Path }}
		metadata runtime.ServerMetadata
{{- if .PathParams }}
{{- if .HasEnumPathParam }}
		e int32
{{- end }}
{{- if .HasRepeatedEnumPathParam }}
		es []int32
{{- end }}
		err error
{{- end }}
	)
{{- if .Body }}
	{{- $isFieldMask := and $AllowPatchFeature (eq (.HTTPMethod) "PATCH") (.FieldMaskField) (not (eq "*" .GetBodyFieldPath)) }}
	{{- if $isFieldMask }}
	newReader, berr := utilities.IOReaderFactory(req.Body)
	if berr != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", berr)
	}
	{{- end }}
	{{- $protoReq := .Body.AssignableExprPrep "protoReq" .Method.Service.File.GoPkg.Path -}}
	{{- if ne "" $protoReq }}
	{{printf "%s" $protoReq }}
	{{- end }}
	{{- if not $isFieldMask }}
	{{- if $UseOpaqueAPI }}
	{{- if eq "*" .GetBodyFieldPath }}
	var bodyData {{.Method.RequestType.GoType .Method.Service.File.GoPkg.Path}}
	if err := marshaler.NewDecoder(req.Body).Decode(&bodyData); err != nil && !errors.Is(err, io.EOF) {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	proto.Merge(&protoReq, &bodyData)
	{{- else }}
	bodyData := &{{ .GetBodyFieldType }}{}
	if err := marshaler.NewDecoder(req.Body).Decode(bodyData); err != nil && !errors.Is(err, io.EOF) {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	protoReq.Set{{ .GetBodyFieldStructName }}(bodyData)
	{{- end }}
	{{- else }}
	if err := marshaler.NewDecoder(req.Body).Decode(&{{.Body.AssignableExpr "protoReq" .Method.Service.File.GoPkg.Path}}); err != nil && !errors.Is(err, io.EOF) {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	{{- end }}
	if req.Body != nil {
		_, _  = io.Copy(io.Discard, req.Body)
	}
	{{- end }}
	{{- if $isFieldMask }}
	{{- if $UseOpaqueAPI }}
	{{- if eq "*" .GetBodyFieldPath }}
	var bodyData {{.Method.RequestType.GoType .Method.Service.File.GoPkg.Path}}
	if err := marshaler.NewDecoder(newReader()).Decode(&bodyData); err != nil && !errors.Is(err, io.EOF) {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	proto.Merge(&protoReq, &bodyData)
	{{- else }}
	bodyData := &{{ .GetBodyFieldType }}{}
	if err := marshaler.NewDecoder(newReader()).Decode(bodyData); err != nil && !errors.Is(err, io.EOF) {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	protoReq.Set{{ .GetBodyFieldStructName }}(bodyData)
	{{- end }}
	{{- else }}
	if err := marshaler.NewDecoder(newReader()).Decode(&{{ .Body.AssignableExpr "protoReq" .Method.Service.File.GoPkg.Path }}); err != nil && !errors.Is(err, io.EOF) {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	{{- end }}
	if req.Body != nil {
		_, _  = io.Copy(io.Discard, req.Body)
	}
	{{- if $UseOpaqueAPI }}
	if !protoReq.Has{{ .FieldMaskField }}() || len(protoReq.Get{{ .FieldMaskField }}().GetPaths()) == 0 {
			if fieldMask, err := runtime.FieldMaskFromRequestBody(newReader(), protoReq.Get{{ .GetBodyFieldStructName }}()); err != nil {
				return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
			} else {
				protoReq.Set{{ .FieldMaskField }}(fieldMask)
			}
	}
	{{- else }}
	if protoReq.{{ .FieldMaskField }} == nil || len(protoReq.{{ .FieldMaskField }}.GetPaths()) == 0 {
			if fieldMask, err := runtime.FieldMaskFromRequestBody(newReader(), protoReq.{{ .GetBodyFieldStructName }}); err != nil {
				return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
			} else {
				protoReq.{{ .FieldMaskField }} = fieldMask
			}
	}
	{{- end }}
	{{- end }}
{{- else }}
	if req.Body != nil {
		_, _  = io.Copy(io.Discard, req.Body)
	}
{{- end }}
{{- if .PathParams }}
	{{- $binding := . }}
	{{- range $index, $param := .PathParams }}
	{{- $enum := $binding.LookupEnum $param }}
	val, ok {{ if eq $index 0 }}:{{ end }}= pathParams[{{ $param | printf "%q" }}]
	if !ok {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "missing parameter %s", {{ $param | printf "%q"}})
	}
{{- if $param.IsNestedProto3 }}
	err = runtime.PopulateFieldFromPath(&protoReq, {{ $param | printf "%q" }}, val)
	if err != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "type mismatch, parameter: %s, error: %v", {{ $param | printf "%q" }}, err)
	}
	{{- if $enum }}
		e{{ if $param.IsRepeated }}s{{ end }}, err = {{ $param.ConvertFuncExpr }}(val{{ if $param.IsRepeated }}, {{ $binding.Registry.GetRepeatedPathParamSeparator | printf "%c" | printf "%q" }}{{ end }}, {{ $enum.GoType $param.Method.Service.File.GoPkg.Path | camelIdentifier }}_value)
		if err != nil {
			return nil, metadata, status.Errorf(codes.InvalidArgument, "could not parse path as enum value, parameter: %s, error: %v", {{ $param | printf "%q"}}, err)
		}
	{{- end }}
{{- else if $enum }}
	e{{ if $param.IsRepeated }}s{{ end }}, err = {{ $param.ConvertFuncExpr }}(val{{ if $param.IsRepeated }}, {{ $binding.Registry.GetRepeatedPathParamSeparator | printf "%c" | printf "%q" }}{{ end }}, {{ $enum.GoType $param.Method.Service.File.GoPkg.Path | camelIdentifier }}_value)
	if err != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "type mismatch, parameter: %s, error: %v", {{ $param | printf "%q"}}, err)
	}
{{- else -}}
	{{- $protoReq := $param.AssignableExprPrep "protoReq" $binding.Method.Service.File.GoPkg.Path -}}
	{{- if ne "" $protoReq }}
	{{ printf "%s" $protoReq }}
	{{- end}}
	{{- if $UseOpaqueAPI }}
	converted{{ $param.FieldPath.String | camelIdentifier }}, err := {{ $param.ConvertFuncExpr }}(val{{ if $param.IsRepeated }}, {{ $binding.Registry.GetRepeatedPathParamSeparator | printf "%c" | printf "%q" }}{{ end }})
	if err != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "type mismatch, parameter: %s, error: %v", {{ $param | printf "%q"}}, err)
	}
	{{ opaqueSetter $param.FieldPath "protoReq" }}(converted{{ $param.FieldPath.String | camelIdentifier }})
	{{- else }}
	{{ $param.AssignableExpr "protoReq" $binding.Method.Service.File.GoPkg.Path }}, err = {{ $param.ConvertFuncExpr }}(val{{ if $param.IsRepeated }}, {{ $binding.Registry.GetRepeatedPathParamSeparator | printf "%c" | printf "%q" }}{{ end }})
	if err != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "type mismatch, parameter: %s, error: %v", {{ $param | printf "%q"}}, err)
	}
	{{- end }}
{{- end}}
{{- if and $enum $param.IsRepeated }}
	s := make([]{{ $enum.GoType $param.Method.Service.File.GoPkg.Path }}, len(es))
	for i, v := range es {
		s[i] = {{ $enum.GoType $param.Method.Service.File.GoPkg.Path}}(v)
	}
	{{- if $UseOpaqueAPI }}
	{{ opaqueSetter $param.FieldPath "protoReq" }}(s)
	{{- else }}
	{{ $param.AssignableExpr "protoReq" $binding.Method.Service.File.GoPkg.Path }} = s
	{{- end }}
{{- else if $enum}}
	{{- if $UseOpaqueAPI }}
	{{ opaqueSetter $param.FieldPath "protoReq" }}({{ $enum.GoType $param.Method.Service.File.GoPkg.Path | camelIdentifier }}(e))
	{{- else }}
	{{ $param.AssignableExpr "protoReq" $binding.Method.Service.File.GoPkg.Path }} = {{ $enum.GoType $param.Method.Service.File.GoPkg.Path | camelIdentifier }}(e)
	{{- end }}
{{- end}}
	{{- end }}
{{- end }}
{{- if .HasQueryParam }}
	if err := req.ParseForm(); err != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	if err := runtime.PopulateQueryParameters(&protoReq, req.Form, filter_{{ .Method.Service.GetName }}_{{ .Method.GetName }}_{{ .Index }}); err != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
{{- end }}
{{- if .Method.GetServerStreaming }}
	stream, err := client.{{ .Method.GetName }}(ctx, &protoReq)
	if err != nil {
		return nil, metadata, err
	}
	header, err := stream.Header()
	if err != nil {
		return nil, metadata, err
	}
	metadata.HeaderMD = header
	return stream, metadata, nil
{{- else }}
	msg, err := client.{{ .Method.GetName }}(ctx, &protoReq, grpc.Header(&metadata.HeaderMD), grpc.Trailer(&metadata.TrailerMD))
	return msg, metadata, err
{{- end }}
}`))

	_ = template.Must(handlerTemplate.New("bidi-streaming-request-func").Parse(`
{{ template "request-func-signature" . }} {
	var metadata runtime.ServerMetadata
	stream, err := client.{{ .Method.GetName }}(ctx)
	if err != nil {
		grpclog.Errorf("Failed to start streaming: %v", err)
		return nil, metadata, err
	}
	dec := marshaler.NewDecoder(req.Body)
	handleSend := func() error {
		var protoReq {{.Method.RequestType.GoType .Method.Service.File.GoPkg.Path}}
		err := dec.Decode(&protoReq)
		if errors.Is(err, io.EOF) {
			return err
		}
		if err != nil {
			grpclog.Errorf("Failed to decode request: %v", err)
			return status.Errorf(codes.InvalidArgument, "Failed to decode request: %v", err)
		}
		if err := stream.Send(&protoReq); err != nil {
			grpclog.Errorf("Failed to send request: %v", err)
			return err
		}
		return nil
	}
	go func() {
		for {
			if err := handleSend(); err != nil {
				break
			}
		}
		if err := stream.CloseSend(); err != nil {
			grpclog.Errorf("Failed to terminate client stream: %v", err)
		}
	}()
	header, err := stream.Header()
	if err != nil {
		grpclog.Errorf("Failed to get header from client: %v", err)
		return nil, metadata, err
	}
	metadata.HeaderMD = header
	return stream, metadata, nil
}
`))

	localHandlerTemplate = template.Must(template.New("local-handler").Parse(`
{{ if and .Method.GetClientStreaming .Method.GetServerStreaming }}
{{ else if .Method.GetClientStreaming }}
{{ else if .Method.GetServerStreaming }}
{{ else}}
{{ template "local-client-rpc-request-func" . }}
{{ end }}
`))

	_ = template.Must(localHandlerTemplate.New("local-request-func-signature").Parse(strings.ReplaceAll(`
{{ if .Method.GetServerStreaming }}
{{ else }}
func local_request_{{ .Method.Service.GetName }}_{{ .Method.GetName }}_{{ .Index }}(ctx context.Context, marshaler runtime.Marshaler, server {{ .Method.Service.InstanceName }}Server, req *http.Request, pathParams map[string]string) (proto.Message, runtime.ServerMetadata, error)
{{ end }}`, "\n", "")))

	_ = template.Must(localHandlerTemplate.New("local-client-rpc-request-func").Funcs(funcMap).Parse(`
{{ $AllowPatchFeature := .AllowPatchFeature }}
{{ $UseOpaqueAPI := .UseOpaqueAPI }}
{{ template "local-request-func-signature" . }} {
	var (
		protoReq {{.Method.RequestType.GoType .Method.Service.File.GoPkg.Path}}
		metadata runtime.ServerMetadata
{{- if .PathParams }}
{{- if .HasEnumPathParam }}
		e int32
{{- end }}
{{- if .HasRepeatedEnumPathParam }}
		es []int32
{{- end }}
		err error
{{- end }}
	)
{{- if .Body }}
	{{- $isFieldMask := and $AllowPatchFeature (eq (.HTTPMethod) "PATCH") (.FieldMaskField) (not (eq "*" .GetBodyFieldPath)) }}
	{{- if $isFieldMask }}
	newReader, berr := utilities.IOReaderFactory(req.Body)
	if berr != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", berr)
	}
	{{- end }}
	{{- $protoReq := .Body.AssignableExprPrep "protoReq" .Method.Service.File.GoPkg.Path -}}
	{{- if ne "" $protoReq }}
	{{ printf "%s" $protoReq }}
	{{- end }}
	{{- if not $isFieldMask }}
	{{- if $UseOpaqueAPI }}
	{{- if eq "*" .GetBodyFieldPath }}
	var bodyData {{.Method.RequestType.GoType .Method.Service.File.GoPkg.Path}}
	if err := marshaler.NewDecoder(req.Body).Decode(&bodyData); err != nil && !errors.Is(err, io.EOF) {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	proto.Merge(&protoReq, &bodyData)
	{{- else }}
	bodyData := &{{ .GetBodyFieldType }}{}
	if err := marshaler.NewDecoder(req.Body).Decode(bodyData); err != nil && !errors.Is(err, io.EOF) {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	protoReq.Set{{ .GetBodyFieldStructName }}(bodyData)
	{{- end }}
	{{- else }}
	if err := marshaler.NewDecoder(req.Body).Decode(&{{ .Body.AssignableExpr "protoReq" .Method.Service.File.GoPkg.Path }}); err != nil && !errors.Is(err, io.EOF)  {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	{{- end }}
	{{- end }}
	{{- if $isFieldMask }}
	{{- if $UseOpaqueAPI }}
	{{- if eq "*" .GetBodyFieldPath }}
	var bodyData {{.Method.RequestType.GoType .Method.Service.File.GoPkg.Path}}
	if err := marshaler.NewDecoder(newReader()).Decode(&bodyData); err != nil && !errors.Is(err, io.EOF) {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	proto.Merge(&protoReq, &bodyData)
	{{- else }}
	bodyData := &{{ .GetBodyFieldType }}{}
	if err := marshaler.NewDecoder(newReader()).Decode(bodyData); err != nil && !errors.Is(err, io.EOF) {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	protoReq.Set{{ .GetBodyFieldStructName }}(bodyData)
	{{- end }}
	{{- else }}
	if err := marshaler.NewDecoder(newReader()).Decode(&{{ .Body.AssignableExpr "protoReq" .Method.Service.File.GoPkg.Path }}); err != nil && !errors.Is(err, io.EOF)  {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	{{- end }}
	{{- if $UseOpaqueAPI }}
	if !protoReq.Has{{ .FieldMaskField }}() || len(protoReq.Get{{ .FieldMaskField }}().GetPaths()) == 0 {
			if fieldMask, err := runtime.FieldMaskFromRequestBody(newReader(), protoReq.Get{{ .GetBodyFieldStructName }}()); err != nil {
				return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
			} else {
				protoReq.Set{{ .FieldMaskField }}(fieldMask)
			}
	}
	{{- else }}
	if protoReq.{{ .FieldMaskField }} == nil || len(protoReq.{{ .FieldMaskField }}.GetPaths()) == 0 {
			if fieldMask, err := runtime.FieldMaskFromRequestBody(newReader(), protoReq.{{ .GetBodyFieldStructName }}); err != nil {
				return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
			} else {
				protoReq.{{.FieldMaskField}} = fieldMask
			}
	}
	{{- end }}
	{{- end }}
{{- end }}
{{- if .PathParams}}
	{{- $binding := .}}
	{{- range $index, $param := .PathParams}}
	{{- $enum := $binding.LookupEnum $param}}
	val, ok {{if eq $index 0}}:{{ end }}= pathParams[{{ $param | printf "%q"}}]
	if !ok {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "missing parameter %s", {{ $param | printf "%q" }})
	}
{{- if $param.IsNestedProto3 }}
	err = runtime.PopulateFieldFromPath(&protoReq, {{ $param | printf "%q"}}, val)
	if err != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "type mismatch, parameter: %s, error: %v", {{ $param | printf "%q"}}, err)
	}
	{{- if $enum }}
		e{{ if $param.IsRepeated }}s{{ end }}, err = {{ $param.ConvertFuncExpr }}(val{{ if $param.IsRepeated }}, {{ $binding.Registry.GetRepeatedPathParamSeparator | printf "%c" | printf "%q" }}{{ end }}, {{ $enum.GoType $param.Method.Service.File.GoPkg.Path | camelIdentifier }}_value)
		if err != nil {
			return nil, metadata, status.Errorf(codes.InvalidArgument, "could not parse path as enum value, parameter: %s, error: %v", {{ $param | printf "%q"}}, err)
		}
	{{- end }}
{{- else if $enum}}
	e{{ if $param.IsRepeated }}s{{ end }}, err = {{ $param.ConvertFuncExpr }}(val{{ if $param.IsRepeated }}, {{ $binding.Registry.GetRepeatedPathParamSeparator | printf "%c" | printf "%q" }}{{ end }}, {{ $enum.GoType  $param.Method.Service.File.GoPkg.Path | camelIdentifier }}_value)
	if err != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "type mismatch, parameter: %s, error: %v", {{ $param | printf "%q"}}, err)
	}
{{- else}}
	{{- $protoReq := $param.AssignableExprPrep "protoReq" $binding.Method.Service.File.GoPkg.Path -}}
	{{- if ne "" $protoReq }}
	{{ printf "%s" $protoReq }}
	{{- end}}
	{{- if $UseOpaqueAPI }}
	converted{{ $param.FieldPath.String | camelIdentifier }}, err := {{ $param.ConvertFuncExpr }}(val{{ if $param.IsRepeated }}, {{ $binding.Registry.GetRepeatedPathParamSeparator | printf "%c" | printf "%q" }}{{ end }})
	if err != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "type mismatch, parameter: %s, error: %v", {{ $param | printf "%q"}}, err)
	}
	{{ opaqueSetter $param.FieldPath "protoReq" }}(converted{{ $param.FieldPath.String | camelIdentifier }})
	{{- else }}
	{{ $param.AssignableExpr "protoReq" $binding.Method.Service.File.GoPkg.Path }}, err = {{ $param.ConvertFuncExpr }}(val{{ if $param.IsRepeated }}, {{ $binding.Registry.GetRepeatedPathParamSeparator | printf "%c" | printf "%q" }}{{ end }})
	if err != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "type mismatch, parameter: %s, error: %v", {{ $param | printf "%q" }}, err)
	}
	{{- end }}
{{- end}}
{{- if and $enum $param.IsRepeated }}
	s := make([]{{ $enum.GoType $param.Method.Service.File.GoPkg.Path }}, len(es))
	for i, v := range es {
		s[i] = {{ $enum.GoType $param.Method.Service.File.GoPkg.Path }}(v)
	}
	{{- if $UseOpaqueAPI }}
	{{ opaqueSetter $param.FieldPath "protoReq" }}(s)
	{{- else }}
	{{ $param.AssignableExpr "protoReq" $binding.Method.Service.File.GoPkg.Path }} = s
	{{- end }}
{{- else if $enum }}
	{{- if $UseOpaqueAPI }}
	{{ opaqueSetter $param.FieldPath "protoReq" }}({{ $enum.GoType $param.Method.Service.File.GoPkg.Path | camelIdentifier }}(e))
	{{- else }}
	{{ $param.AssignableExpr "protoReq" $binding.Method.Service.File.GoPkg.Path }} = {{ $enum.GoType $param.Method.Service.File.GoPkg.Path | camelIdentifier }}(e)
	{{- end }}
{{- end }}
	{{- end }}
{{- end }}
{{- if .HasQueryParam }}
	if err := req.ParseForm(); err != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
	if err := runtime.PopulateQueryParameters(&protoReq, req.Form, filter_{{ .Method.Service.GetName }}_{{ .Method.GetName }}_{{ .Index }}); err != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
	}
{{- end}}
{{- if .Method.GetServerStreaming }}
	// TODO
{{- else}}
	msg, err := server.{{ .Method.GetName }}(ctx, &protoReq)
	return msg, metadata, err
{{- end}}
}`))

	localTrailerTemplate = template.Must(template.New("local-trailer").Funcs(funcMap).Parse(`
{{ $UseRequestContext := .UseRequestContext }}
{{ range $svc := .Services }}
// Register{{ $svc.GetName }}{{ $.RegisterFuncSuffix }}Server registers the http handlers for service {{ $svc.GetName }} to "mux".
// UnaryRPC     :call {{ $svc.GetName }}Server directly.
// StreamingRPC :currently unsupported pending https://github.com/grpc/grpc-go/issues/906.
// Note that using this registration option will cause many gRPC library features to stop working. Consider using Register{{ $svc.GetName }}{{ $.RegisterFuncSuffix }}FromEndpoint instead.
// GRPC interceptors will not work for this type of registration. To use interceptors, you must use the "runtime.WithMiddlewares" option in the "runtime.NewServeMux" call.
func Register{{ $svc.GetName }}{{ $.RegisterFuncSuffix }}Server(ctx context.Context, mux *runtime.ServeMux, server {{ $svc.InstanceName }}Server) error {
	{{- range $m := $svc.Methods }}
	{{- range $b := $m.Bindings }}
	{{- if or $m.GetClientStreaming $m.GetServerStreaming }}
	mux.Handle({{ $b.HTTPMethod | toHTTPMethod }}, pattern_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
		err := status.Error(codes.Unimplemented, "streaming calls are not yet supported in the in-process transport")
		_, outboundMarshaler := runtime.MarshalerForRequest(mux, req)
		runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
		return
	})
	{{- else -}}
	mux.Handle({{ $b.HTTPMethod | toHTTPMethod}}, pattern_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
	{{- if $UseRequestContext }}
		ctx, cancel := context.WithCancel(req.Context())
	{{- else -}}
		ctx, cancel := context.WithCancel(ctx)
	{{- end }}
		defer cancel()
		var stream runtime.ServerTransportStream
		ctx = grpc.NewContextWithServerTransportStream(ctx, &stream)
		inboundMarshaler, outboundMarshaler := runtime.MarshalerForRequest(mux, req)
		{{- if $b.PathTmpl }}
		annotatedContext, err := runtime.AnnotateIncomingContext(ctx, mux, req, "/{{ $svc.File.GetPackage }}.{{ $svc.GetName }}/{{ $m.GetName }}", runtime.WithHTTPPathPattern("{{ $b.PathTmpl.Template }}"))
		{{- else -}}
		annotatedContext, err := runtime.AnnotateIncomingContext(ctx, mux, req, "/{{ $svc.File.GetPackage }}.{{ $svc.GetName }}/{{ $m.GetName }}")
		{{- end }}
		if err != nil {
			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
			return
		}
		resp, md, err := local_request_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}(annotatedContext, inboundMarshaler, server, req, pathParams)
		md.HeaderMD, md.TrailerMD = metadata.Join(md.HeaderMD, stream.Header()), metadata.Join(md.TrailerMD, stream.Trailer())
		annotatedContext = runtime.NewServerMetadataContext(annotatedContext, md)
		if err != nil {
			runtime.HTTPError(annotatedContext, mux, outboundMarshaler, w, req, err)
			return
		}
		{{- if $b.ResponseBody }}
		forward_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}(annotatedContext, mux, outboundMarshaler, w, req, response_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}{resp.(*{{ $m.ResponseType.GoType $m.Service.File.GoPkg.Path }})}, mux.GetForwardResponseOptions()...)
		{{- else }}
		forward_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}(annotatedContext, mux, outboundMarshaler, w, req, resp, mux.GetForwardResponseOptions()...)
		{{- end }}
	})
	{{- end }}
	{{ end }}
	{{- end }}
	return nil
}
{{ end }}`))

	trailerTemplate = template.Must(template.New("trailer").Funcs(funcMap).Parse(`
{{ $UseRequestContext := .UseRequestContext }}
{{ $UseOpaqueAPI := .UseOpaqueAPI }}
{{range $svc := .Services}}
// Register{{ $svc.GetName }}{{ $.RegisterFuncSuffix }}FromEndpoint is same as Register{{ $svc.GetName }}{{ $.RegisterFuncSuffix }} but
// automatically dials to "endpoint" and closes the connection when "ctx" gets done.
func Register{{ $svc.GetName }}{{ $.RegisterFuncSuffix }}FromEndpoint(ctx context.Context, mux *runtime.ServeMux, endpoint string, opts []grpc.DialOption) (err error) {
	conn, err := grpc.NewClient(endpoint, opts...)
	if err != nil {
		return err
	}
	defer func() {
		if err != nil {
			if cerr := conn.Close(); cerr != nil {
				grpclog.Errorf("Failed to close conn to %s: %v", endpoint, cerr)
			}
			return
		}
		go func() {
			<-ctx.Done()
			if cerr := conn.Close(); cerr != nil {
				grpclog.Errorf("Failed to close conn to %s: %v", endpoint, cerr)
			}
		}()
	}()
	return Register{{ $svc.GetName }}{{ $.RegisterFuncSuffix }}(ctx, mux, conn)
}

// Register{{ $svc.GetName}}{{ $.RegisterFuncSuffix}} registers the http handlers for service {{ $svc.GetName }} to "mux".
// The handlers forward requests to the grpc endpoint over "conn".
func Register{{ $svc.GetName }}{{ $.RegisterFuncSuffix }}(ctx context.Context, mux *runtime.ServeMux, conn *grpc.ClientConn) error {
	return Register{{ $svc.GetName }}{{ $.RegisterFuncSuffix }}Client(ctx, mux, {{ $svc.ClientConstructorName }}(conn))
}

// Register{{ $svc.GetName }}{{ $.RegisterFuncSuffix }}Client registers the http handlers for service {{ $svc.GetName }}
// to "mux". The handlers forward requests to the grpc endpoint over the given implementation of "{{ $svc.InstanceName }}Client".
// Note: the gRPC framework executes interceptors within the gRPC handler. If the passed in "{{ $svc.InstanceName }}Client"
// doesn't go through the normal gRPC flow (creating a gRPC client etc.) then it will be up to the passed in
// "{{ $svc.InstanceName }}Client" to call the correct interceptors. This client ignores the HTTP middlewares.
func Register{{ $svc.GetName }}{{ $.RegisterFuncSuffix }}Client(ctx context.Context, mux *runtime.ServeMux, client {{ $svc.InstanceName }}Client) error {
	{{- range $m := $svc.Methods }}
	{{- range $b := $m.Bindings }}
	mux.Handle({{ $b.HTTPMethod | toHTTPMethod }}, pattern_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
	{{- if $UseRequestContext }}
		ctx, cancel := context.WithCancel(req.Context())
	{{- else -}}
		ctx, cancel := context.WithCancel(ctx)
	{{- end }}
		defer cancel()
		inboundMarshaler, outboundMarshaler := runtime.MarshalerForRequest(mux, req)
		{{- if $b.PathTmpl }}
		annotatedContext, err := runtime.AnnotateContext(ctx, mux, req, "/{{ $svc.File.GetPackage }}.{{ $svc.GetName }}/{{ $m.GetName }}", runtime.WithHTTPPathPattern("{{ $b.PathTmpl.Template}}"))
		{{- else -}}
		annotatedContext, err := runtime.AnnotateContext(ctx, mux, req, "/{{ $svc.File.GetPackage }}.{{ $svc.GetName }}/{{ $m.GetName }}")
		{{- end }}
		if err != nil {
			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
			return
		}
		resp, md, err := request_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}(annotatedContext, inboundMarshaler, client, req, pathParams)
		annotatedContext = runtime.NewServerMetadataContext(annotatedContext, md)
		if err != nil {
			runtime.HTTPError(annotatedContext, mux, outboundMarshaler, w, req, err)
			return
		}
		{{- if $m.GetServerStreaming }}
		{{- if $b.ResponseBody }}
		forward_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}(annotatedContext, mux, outboundMarshaler, w, req, func() (proto.Message, error) {
			res, err := resp.Recv()
			return response_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}{res}, err
		}, mux.GetForwardResponseOptions()...)
		{{- else }}
		forward_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}(annotatedContext, mux, outboundMarshaler, w, req, func() (proto.Message, error) { return resp.Recv() }, mux.GetForwardResponseOptions()...)
		{{- end }}
		{{- else }}
		{{- if $b.ResponseBody }}
		forward_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}(annotatedContext, mux, outboundMarshaler, w, req, response_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}{resp.(*{{ $m.ResponseType.GoType $m.Service.File.GoPkg.Path }})}, mux.GetForwardResponseOptions()...)
		{{- else }}
		forward_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}(annotatedContext, mux, outboundMarshaler, w, req, resp, mux.GetForwardResponseOptions()...)
		{{- end }}
		{{- end }}
	})
	{{- end }}
	{{- end }}
	return nil
}

{{range $m := $svc.Methods}}
{{range $b := $m.Bindings}}
{{if $b.ResponseBody}}
type response_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }} struct {
	*{{ $m.ResponseType.GoType $m.Service.File.GoPkg.Path }}
}

func (m response_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }}) XXX_ResponseBody() interface{} {
	response := m.{{ $m.ResponseType.GetName }}
	{{- if $UseOpaqueAPI }}
	{{- if eq "*" $b.ResponseBody.FieldPath.String }}
	return response
	{{- else }}
	return response.Get{{ $b.ResponseBody.FieldPath.String | camelIdentifier }}()
	{{- end }}
	{{- else }}
	return {{ $b.ResponseBody.AssignableExpr "response" $m.Service.File.GoPkg.Path }}
	{{- end }}
}
{{ end }}
{{ end }}
{{ end }}

var (
	{{- range $m := $svc.Methods }}
	{{- range $b := $m.Bindings }}
	pattern_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }} = runtime.MustPattern(runtime.NewPattern({{ $b.PathTmpl.Version }}, {{ $b.PathTmpl.OpCodes | printf "%#v" }}, {{ $b.PathTmpl.Pool | printf "%#v" }}, {{ $b.PathTmpl.Verb | printf "%q" }}))
	{{- end }}
	{{- end }}
)

var (
	{{- range $m := $svc.Methods }}
	{{- range $b := $m.Bindings }}
	forward_{{ $svc.GetName }}_{{ $m.GetName }}_{{ $b.Index }} = {{ if $m.GetServerStreaming }}runtime.ForwardResponseStream{{ else }}runtime.ForwardResponseMessage{{ end }}
	{{- end }}
	{{- end }}
)
{{ end }}`))
)
