all: implement server and client for dictionary API

Currently the server and client can onyl handle API for looking up
definitions of the words through "/api/definisi" URL.

1 files changed, 167 insertions, 0 deletions

diff --git a/server.go b/server.go
new file mode 100644
index 0000000..a241f05
--- /dev/null
+++ b/server.go
@@ -0,0 +1,167 @@
+// Copyright 2020, Shulhan <m.shulhan@gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package kbbi
+
+import (
+	"fmt"
+	"log"
+	stdhttp "net/http"
+	"strings"
+	"time"
+
+	"github.com/shuLhan/share/lib/http"
+)
+
+const (
+	defListen     = ":3394"
+	emptyResponse = "{}"
+)
+
+//
+// Server for KBBI with caching and spell checking functionalities.
+//
+type Server struct {
+	http  *http.Server
+	kamus *kamusCache
+
+	// The client that forward request to official KBBI server.
+	forwardc *directClient
+
+	// If offline is true and the word definition is not found on cache,
+	// the server will not forward request to official KBBI server.
+	offline bool
+}
+
+//
+// NewServer create and initialize the server.
+//
+func NewServer() (server *Server, err error) {
+	opts := &http.ServerOptions{
+		Address: defListen,
+	}
+
+	server = &Server{}
+
+	server.kamus, err = newKamusCache("")
+	if err != nil {
+		return nil, fmt.Errorf("http.NewServer: %w", err)
+	}
+
+	server.http, err = http.NewServer(opts)
+	if err != nil {
+		return nil, fmt.Errorf("http.NewServer: %w", err)
+	}
+
+	server.forwardc, err = newDirectClient(nil)
+	if err != nil {
+		return nil, fmt.Errorf("http.NewServer: %w", err)
+	}
+
+	err = server.registerEndpoints()
+	if err != nil {
+		return nil, fmt.Errorf("http.NewServer: %w", err)
+	}
+
+	return server, nil
+}
+
+//
+// Start the HTTP server.
+//
+func (server *Server) Start() (err error) {
+	go server.dumpCache()
+
+	return server.http.Start()
+}
+
+//
+// dumpCache periodically dump the cache to file to be loaded later.
+//
+func (server *Server) dumpCache() {
+	ticker := time.NewTicker(1 * time.Hour)
+
+	for range ticker.C {
+		if !server.kamus.isChanging() {
+			continue
+		}
+		err := server.kamus.store()
+		if err != nil {
+			log.Println("server.dumpCache: ", err)
+		}
+	}
+}
+
+func (server *Server) handleDefinisi(
+	httpRes stdhttp.ResponseWriter,
+	httpReq *stdhttp.Request,
+	reqBody []byte,
+) (resBody []byte, err error) {
+	paramKata := httpReq.Form.Get(paramNameKata)
+	if len(paramKata) == 0 {
+		return []byte(emptyResponse), nil
+	}
+
+	inputs := strings.Split(paramKata, ",")
+	res := make(DefinisiResponse, len(inputs))
+
+	for _, in := range inputs {
+		in = strings.TrimSpace(in)
+		if len(in) == 0 {
+			continue
+		}
+
+		kata := server.kamus.get(in)
+		if kata != nil {
+			res[in] = kata
+			continue
+		}
+
+		if server.offline {
+			continue
+		}
+
+		// The word does not exist in cache, retrieve it from official
+		// website.
+		fwRes, err := server.forwardc.CariDefinisi([]string{in})
+		if err != nil {
+			kata.err = err
+			continue
+		}
+
+		for k, v := range fwRes {
+			if k == in {
+				res[in] = v
+				server.kamus.set(k, v)
+				delete(fwRes, k)
+				break
+			}
+		}
+	}
+
+	if len(res) == 0 {
+		return []byte(emptyResponse), nil
+	}
+
+	resBody, err = res.pack()
+	if err != nil {
+		return nil, err
+	}
+
+	return resBody, nil
+}
+
+//
+// registerEndpoints register the API endpoints.
+//
+func (server *Server) registerEndpoints() (err error) {
+	epDefinisi := &http.Endpoint{
+		Method:       http.RequestMethodGet,
+		Path:         pathAPIDefinisi,
+		RequestType:  http.RequestTypeQuery,
+		ResponseType: http.ResponseTypeJSON,
+		Call:         server.handleDefinisi,
+	}
+	return server.http.RegisterEndpoint(epDefinisi)
+}