package jsonrpc

import (

"context"

"fmt"

"reflect"

"github.com/sourcegraph/jsonrpc2"

)

var (

defaultHandler = NewHandler()

)

// HandlerFunc is a function adapter to Handler.

type HandlerFunc func(context.Context, *jsonrpc2.Conn, *jsonrpc2.Request) (interface{}, error)

// RegisterMethod register a method to the default handler.

func RegisterMethod(method string, handlerFunc HandlerFunc, paramsType interface{}) {

defaultHandler.RegisterMethod(method, handlerFunc, paramsType)

}

// Handler is a handler handling JSON-RPC protocol.

type Handler struct {

methods map[string]HandlerFunc

}

// NewHandler creates a new JSONRPCHandler.

func NewHandler() *Handler {

return &Handler{

methods: make(map[string]HandlerFunc),

}

}

// RegisterMethod register a method.

func (h *Handler) RegisterMethod(method string, handlerFunc HandlerFunc, paramsType interface{}) {

if _, ok := h.methods[method]; ok {

panic(fmt.Sprintf("method %q already registered", method))

}

if paramsType == nil {

h.methods[method] = handlerFunc

return

}

// Pre-process rpc parameters with a middleware

typ := reflect.TypeOf(paramsType)

if typ.Kind() == reflect.Ptr {

typ = typ.Elem()

}

h.methods[method] = processParams(handlerFunc, typ)

}

// Handle implements jsonrpc2.Handler.

func (h *Handler) Handle(ctx context.Context, conn *jsonrpc2.Conn, req *jsonrpc2.Request) {

jsonrpc2.HandlerWithError(h.handle).Handle(ctx, conn, req)

}

// handle is a function to be used by jsonrpc2.Handler.

func (h *Handler) handle(ctx context.Context, conn *jsonrpc2.Conn, req *jsonrpc2.Request) (

result interface{}, err error,

) {

defer func() {

if p := recover(); p != nil {

switch p := p.(type) {

case error:

err = p

default:

err = fmt.Errorf("%v", p)

}

}

}()

fn := h.methods[req.Method]

if fn == nil {

return nil, &jsonrpc2.Error{Code: jsonrpc2.CodeMethodNotFound}

} else if req.Params == nil {

// pre-check req.Params not be nil

return nil, &jsonrpc2.Error{Code: jsonrpc2.CodeInvalidParams}

}

return fn(ctx, conn, req)

}