package servlet

import (
	"encoding/json"
	"fmt"
	"reflect"

	cdr "git.loafle.net/commons/di-go/registry"
	crr "git.loafle.net/commons/rest-go/registry"
	"git.loafle.net/commons/server-go"
	csw "git.loafle.net/commons/server-go/web"
	cswf "git.loafle.net/commons/server-go/web/fasthttp"
	oca "git.loafle.net/overflow/commons-go/annotation"
	"github.com/valyala/fasthttp"
)

type MethodMapping struct {
	Method    string
	ParamKeys []string
}

type RESTServlet interface {
	cswf.Servlet

	RegisterRESTServices(services []interface{}) error
}

type RESTServlets struct {
	cswf.Servlets

	restRegistry crr.RESTRegistry

	methodMapping map[string]map[string]*MethodMapping
}

func (s *RESTServlets) Init(serverCtx server.ServerCtx) error {
	if err := s.Servlets.Init(serverCtx); nil != err {
		return err
	}
	if nil == s.methodMapping {
		s.methodMapping = make(map[string]map[string]*MethodMapping)
	}

	return nil
}

func (s *RESTServlets) Handle(servletCtx server.ServletCtx, ctx *fasthttp.RequestCtx) *csw.Error {
	method := string(ctx.Method())
	path := string(ctx.Path())

	requestPath := s.RequestPath(ctx)

	es, ok := s.methodMapping[method]
	if !ok {
		return csw.NewError(fasthttp.StatusNotFound, fmt.Errorf("Not Found for [%s]%s", method, path))
	}
	mapping, ok := es[requestPath]
	if !ok {
		return csw.NewError(fasthttp.StatusNotFound, fmt.Errorf("Not Found for [%s]%s", method, path))
	}

	switch method {
	case "GET":
		return s.HandleGet(servletCtx, ctx, mapping)
	case "POST":
		return s.HandlePost(servletCtx, ctx, mapping)
	}

	return nil
}

func (s *RESTServlets) HandleGet(servletCtx server.ServletCtx, ctx *fasthttp.RequestCtx, mapping *MethodMapping) *csw.Error {
	params := make([]string, 0)
	if nil != mapping.ParamKeys {
		qargs := ctx.QueryArgs()
		if nil == qargs {
			return csw.NewError(fasthttp.StatusBadRequest, fmt.Errorf("Parameter is not valied"))
		}

		for _, k := range mapping.ParamKeys {
			buf := qargs.Peek(k)
			if nil == buf {
				return csw.NewError(fasthttp.StatusBadRequest, fmt.Errorf("Parameter for %s is not valied", k))
			}
			params = append(params, string(buf))
		}
	}

	_, err := s.restRegistry.Invoke(mapping.Method, params, servletCtx, ctx)

	if nil != err {
		return csw.NewError(fasthttp.StatusInternalServerError, err)
	}

	return nil
}

func (s *RESTServlets) HandlePost(servletCtx server.ServletCtx, ctx *fasthttp.RequestCtx, mapping *MethodMapping) *csw.Error {
	params := make([]string, 0)
	if nil != mapping.ParamKeys {
		buf := ctx.PostBody()
		if nil == buf || 0 == len(buf) {
			return csw.NewError(fasthttp.StatusBadRequest, fmt.Errorf("Parameter is not valied"))
		}

		var jsonMap map[string]string
		if err := json.Unmarshal(buf, jsonMap); nil != err {
			return csw.NewError(fasthttp.StatusBadRequest, fmt.Errorf("Parameter is not valied %v", err))
		}

		for _, k := range mapping.ParamKeys {
			v, ok := jsonMap[k]
			if !ok {
				return csw.NewError(fasthttp.StatusBadRequest, fmt.Errorf("Parameter for %s is not valied", k))
			}
			params = append(params, v)
		}
	}

	_, err := s.restRegistry.Invoke(mapping.Method, params, servletCtx, ctx)

	if nil != err {
		return csw.NewError(fasthttp.StatusInternalServerError, err)
	}

	return nil
}

func (s *RESTServlets) RegisterRESTServices(services []interface{}) error {
	if nil == services || 0 == len(services) {
		return nil
	}

	s.methodMapping = make(map[string]map[string]*MethodMapping)
	s.restRegistry = crr.NewRESTRegistry()

LOOP:
	for _, service := range services {
		t := reflect.TypeOf(service)
		ta := cdr.GetTypeAnnotation(t, oca.RESTServiceAnnotationType)
		if nil == ta {
			return fmt.Errorf("Service[%s] is not RESTService, use @RESTService", t.Elem().Name())
		}
		s.restRegistry.RegisterService(service, "")

		mas := cdr.GetMethodAnnotations(t, oca.RequestMappingAnnotationType)
		if nil == mas || 0 == len(mas) {
			continue LOOP
		}

		for methodName, v := range mas {
			ma := v.(*oca.RequestMappingAnnotation)
			mm, ok := s.methodMapping[ma.Method]
			if !ok {
				mm = make(map[string]*MethodMapping)
				s.methodMapping[ma.Method] = mm
			}

			_, ok = mm[ma.Entry]
			if ok {
				return fmt.Errorf("Mapping of method[%s], entry[%s] is exist already", ma.Method, ma.Entry)
			}

			mm[ma.Entry] = &MethodMapping{
				Method:    fmt.Sprintf("%s.%s", t.Elem().Name(), methodName),
				ParamKeys: ma.Params,
			}
		}
	}
	return nil
}