package main

import (
	"bytes"
	"html/template"
	"strings"
)

var httpTemplate = `
type {{.ServiceType}}Handler interface {
{{range .MethodSets}}
	{{.Name}}(context.Context, *{{.Request}}) (*{{.Reply}}, error)
{{end}}
}

func New{{.ServiceType}}Handler(srv {{.ServiceType}}Handler, opts ...http1.HandleOption) http.Handler {
	h := http1.DefaultHandleOptions()
	for _, o := range opts {
		o(&h)
	}
	r := mux.NewRouter()
	{{range .Methods}}
	r.HandleFunc("{{.Path}}", func(w http.ResponseWriter, r *http.Request) {
		var in {{.Request}}
		{{if ne (len .Vars) 0}}
		if err := binding.MapProto(&in, mux.Vars(r)); err != nil {
			h.Error(w, r, err)
			return
		}
		{{end}}
		if err := h.Decode(r, &in{{.Body}}); err != nil {
			h.Error(w, r, err)
			return
		}
		next := func(ctx context.Context, req interface{}) (interface{}, error) {
			return srv.{{.Name}}(ctx, req.(*{{.Request}}))
		}
		if h.Middleware != nil {
			next = h.Middleware(next)
		}
		out, err := next(r.Context(), &in)
		if err != nil {
			h.Error(w, r, err)
			return
		}
		if err := h.Encode(w, r, out{{.ResponseBody}}); err != nil {
			h.Error(w, r, err)
		}
	}).Methods("{{.Method}}")
	{{end}}
	return r
}
`

type serviceDesc struct {
	ServiceType string // Greeter
	ServiceName string // helloworld.Greeter
	Metadata    string // api/helloworld/helloworld.proto
	Methods     []*methodDesc
	MethodSets  map[string]*methodDesc
}

type methodDesc struct {
	// method
	Name    string
	Num     int
	Vars    []string
	Forms   []string
	Request string
	Reply   string
	// http_rule
	Path         string
	Method       string
	Body         string
	ResponseBody string
}

func (s *serviceDesc) execute() string {
	s.MethodSets = make(map[string]*methodDesc)
	for _, m := range s.Methods {
		s.MethodSets[m.Name] = m
	}
	buf := new(bytes.Buffer)
	tmpl, err := template.New("http").Parse(strings.TrimSpace(httpTemplate))
	if err != nil {
		panic(err)
	}
	if err := tmpl.Execute(buf, s); err != nil {
		panic(err)
	}
	return string(buf.Bytes())
}