Added http server.

3 files changed, 293 insertions, 0 deletions

diff --git a/http-server/database.go b/http-server/database.go
new file mode 100644
index 0000000..d13e8c1
--- /dev/null
+++ b/http-server/database.go
@@ -0,0 +1,67 @@
+package main
+
+import (
+	"database/sql"
+	_ "github.com/mattn/go-sqlite3"
+)
+
+type SQLConnection struct {
+	db *sql.DB
+}
+
+func (conn *SQLConnection) init(dbpath string) error {
+	var err error
+	conn.db, err = sql.Open("sqlite3", dbpath)
+	return err
+}
+
+func (conn *SQLConnection) registerUser(username string, key string) error {
+	_, err := conn.db.Exec("INSERT INTO users (username, key) VALUES (?, ?)", username, key)
+	return err
+}
+
+func (conn *SQLConnection) checkUserRegistered(username string) (bool, error) {
+	result, err := conn.db.Query("SELECT username FROM users WHERE username = ?", username)
+	if err != nil {
+		return false, err
+	}
+	for result.Next() {
+		_ = result.Close()
+		return true, nil
+	}
+	return false, nil
+}
+
+func (conn *SQLConnection) saveMessage(message Message) error {
+	var err error
+
+	query := `INSERT INTO messages (userId, data, timestamp) values (
+		(SELECT id FROM users WHERE username = ?), ?, ?
+	)`
+	_, err = conn.db.Exec(query, message.User, message.Data, message.Timestamp)
+
+	return err
+}
+
+func (conn *SQLConnection) getMessagesSince(timestamp int64) ([]Message, error) {
+	var err error
+	var msg []Message
+
+	query := `SELECT username, data, timestamp FROM users JOIN messages
+	WHERE users.id = messages.userId AND timestamp > ?
+	ORDER BY timestamp;`
+
+	result, err := conn.db.Query(query, timestamp)
+	if err != nil {
+		return msg, err
+	}
+
+	for result.Next() {
+		var message Message
+		_ = result.Scan(&message.User, &message.Data, &message.Timestamp)
+		msg = append(msg, message)
+	}
+	_ = result.Close()
+
+	return msg, err
+}
diff --git a/http-server/go.mod b/http-server/go.mod
new file mode 100644
index 0000000..3ada4ae
--- /dev/null
+++ b/http-server/go.mod
@@ -0,0 +1,5 @@
+module vasthecat.ru/coursework/http-server
+
+go 1.16
+
+require github.com/mattn/go-sqlite3 v1.14.7
diff --git a/http-server/main.go b/http-server/main.go
new file mode 100644
index 0000000..af7d4be
--- /dev/null
+++ b/http-server/main.go
@@ -0,0 +1,221 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"strconv"
+	"time"
+)
+
+type Response struct {
+	Message string
+}
+
+type Request struct {
+	User string
+	Data string
+}
+
+type Message struct {
+	User      string
+	Data      string
+	Timestamp int64
+}
+
+func parseRequest(w http.ResponseWriter, r *http.Request) (Request, error) {
+	var resp Request
+
+	body, _ := io.ReadAll(r.Body)
+	err := json.Unmarshal(body, &resp)
+	if err != nil {
+		_ = badRequest(w)
+		return resp, err
+	}
+	return resp, nil
+}
+
+func jsonResponse(w http.ResponseWriter, resp Response) error {
+	data, err := json.Marshal(resp)
+	if err != nil {
+		return err
+	}
+	_, err = w.Write(data)
+	return err
+}
+
+func methodNotAllowedResponse(w http.ResponseWriter) error {
+	w.WriteHeader(http.StatusMethodNotAllowed)
+	return jsonResponse(w, Response{
+		Message: "К серверу разрешены обращения только по методу POST",
+	})
+}
+
+func badRequest(w http.ResponseWriter) error {
+	w.WriteHeader(http.StatusBadRequest)
+	return jsonResponse(w, Response{
+		Message: "Не удалось обработать запрос",
+	})
+}
+
+func serverError(w http.ResponseWriter) error {
+	w.WriteHeader(http.StatusInternalServerError)
+	return jsonResponse(w, Response{
+		Message: "Произошла внутренняя ошибка",
+	})
+}
+
+func index(w http.ResponseWriter, r *http.Request) {
+	_, _ = fmt.Fprintf(w, "Hello there")
+}
+
+func register(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		_ = methodNotAllowedResponse(w)
+		return
+	}
+
+	req, err := parseRequest(w, r)
+	if err != nil {
+		return
+	}
+
+	userRegistered, err := db.checkUserRegistered(req.User)
+	if err != nil {
+		_ = serverError(w)
+		return
+	}
+
+	// TODO(andrew): Добавить проверку действительности ключа
+	if false {
+		w.WriteHeader(http.StatusBadRequest)
+		_ = jsonResponse(w, Response{
+			Message: "Указанный ключ не является действительным",
+		})
+		return
+	}
+
+	if userRegistered {
+		w.WriteHeader(http.StatusBadRequest)
+		_ = jsonResponse(w, Response{
+			Message: "Пользователь с таким именем уже зарегистрирован",
+		})
+		return
+	}
+
+	err = db.registerUser(req.User, req.Data)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		_ = jsonResponse(w, Response{
+			Message: fmt.Sprintf("%s", err),
+		})
+		return
+	}
+
+	_ = jsonResponse(w, Response{
+		Message: "Пользователь успешно зарегистрирован",
+	})
+}
+
+func sendMessage(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		_ = methodNotAllowedResponse(w)
+		return
+	}
+
+	req, err := parseRequest(w, r)
+	if err != nil {
+		return
+	}
+
+	// TODO(andrew): Добавить аутентификацию
+	if false {
+		w.WriteHeader(http.StatusForbidden)
+		_ = jsonResponse(w, Response{
+			Message: "Запрос не прошёл аутентификацию",
+		})
+		return
+	}
+
+	msg := Message{
+		User:      req.User,
+		Data:      req.Data,
+		Timestamp: time.Now().Unix(),
+	}
+
+	err = db.saveMessage(msg)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		_ = jsonResponse(w, Response{
+			Message: fmt.Sprintf("%s", err),
+		})
+		return
+	}
+
+	_ = jsonResponse(w, Response{
+		Message: "Сообщение успешно сохранено",
+	})
+}
+
+func pollMessages(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		_ = methodNotAllowedResponse(w)
+		return
+	}
+
+	req, err := parseRequest(w, r)
+	if err != nil {
+		return
+	}
+
+	// TODO(andrew): Добавить аутентификацию
+	if false {
+		w.WriteHeader(http.StatusForbidden)
+		_ = jsonResponse(w, Response{
+			Message: "Запрос не прошёл аутентификацию",
+		})
+		return
+	}
+
+	timestamp, err := strconv.ParseInt(req.Data, 10, 64)
+	if err != nil {
+		w.WriteHeader(http.StatusBadRequest)
+		_ = jsonResponse(w, Response{
+			Message: "Указана неверная временная отметка",
+		})
+		return
+	}
+
+	messages, err := db.getMessagesSince(timestamp)
+	if err != nil {
+		_ = serverError(w)
+		return
+	}
+
+	data, _ := json.Marshal(messages)
+	_ = jsonResponse(w, Response{
+		Message: string(data),
+	})
+}
+
+var db SQLConnection
+
+func main() {
+	err := db.init("chat.sqlite3")
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+
+	http.HandleFunc("/", index)
+	http.HandleFunc("/api/register", register)
+	http.HandleFunc("/api/sendMessage", sendMessage)
+	http.HandleFunc("/api/pollMessages", pollMessages)
+	err = http.ListenAndServe("localhost:8080", nil)
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+}