Adding frontend, backend connectors, processors and some basic tests (#…

…1049)

This PR:
- adds `go.mod`
- moves core api from `v2` to `v2/core`
- adds remaining components (frontend, backend connectors, processors)
- adds basic tests

v2/backend_connectors/mysql_backend_connector.go

@@ -0,0 +1,77 @@
+package backend_connectors
+
+import (
+	"context"
+	"database/sql"
+	_ "github.com/go-sql-driver/mysql"
+	quesma_api "quesma_v2/core"
+)
+
+type MySqlRows struct {
+	rows *sql.Rows
+}
+
+func (p *MySqlRows) Next() bool {
+	return p.rows.Next()
+}
+
+func (p *MySqlRows) Scan(dest ...interface{}) error {
+	return p.rows.Scan(dest...)
+}
+
+func (p *MySqlRows) Close() {
+	err := p.rows.Close()
+	if err != nil {
+		panic(err)
+	}
+}
+
+func (p *MySqlRows) Err() error {
+	return p.rows.Err()
+}
+
+type MySqlBackendConnector struct {
+	Endpoint   string
+	connection *sql.DB
+}
+
+func (p *MySqlBackendConnector) GetId() quesma_api.BackendConnectorType {
+	return quesma_api.MySQLBackend
+}
+
+func (p *MySqlBackendConnector) Open() error {
+	conn, err := sql.Open("mysql", p.Endpoint)
+	if err != nil {
+		return err
+	}
+	err = conn.Ping()
+	if err != nil {
+		return err
+	}
+	p.connection = conn
+	return nil
+}
+
+func (p *MySqlBackendConnector) Close() error {
+	if p.connection == nil {
+		return nil
+	}
+	return p.connection.Close()
+}
+
+func (p *MySqlBackendConnector) Query(ctx context.Context, query string, args ...interface{}) (quesma_api.Rows, error) {
+	rows, err := p.connection.QueryContext(context.Background(), query, args...)
+	if err != nil {
+		return nil, err
+	}
+	return &MySqlRows{rows: rows}, nil
+}
+
+func (p *MySqlBackendConnector) Exec(ctx context.Context, query string, args ...interface{}) error {
+	if len(args) == 0 {
+		_, err := p.connection.ExecContext(context.Background(), query)
+		return err
+	}
+	_, err := p.connection.ExecContext(context.Background(), query, args...)
+	return err
+}

v2/backend_connectors/postgres_backend_connector.go

@@ -0,0 +1,45 @@
+package backend_connectors
+
+import (
+	"context"
+	"github.com/jackc/pgx/v4"
+	quesma_api "quesma_v2/core"
+)
+
+type PostgresBackendConnector struct {
+	Endpoint   string
+	connection *pgx.Conn
+}
+
+func (p *PostgresBackendConnector) GetId() quesma_api.BackendConnectorType {
+	return quesma_api.PgSQLBackend
+}
+
+func (p *PostgresBackendConnector) Open() error {
+	conn, err := pgx.Connect(context.Background(), p.Endpoint)
+	if err != nil {
+		return err
+	}
+	p.connection = conn
+	return nil
+}
+
+func (p *PostgresBackendConnector) Close() error {
+	if p.connection == nil {
+		return nil
+	}
+	return p.connection.Close(context.Background())
+}
+
+func (p *PostgresBackendConnector) Query(ctx context.Context, query string, args ...interface{}) (quesma_api.Rows, error) {
+	return p.connection.Query(context.Background(), query, args...)
+}
+
+func (p *PostgresBackendConnector) Exec(ctx context.Context, query string, args ...interface{}) error {
+	if len(args) == 0 {
+		_, err := p.connection.Exec(context.Background(), query)
+		return err
+	}
+	_, err := p.connection.Exec(context.Background(), query, args...)
+	return err
+}

v2/frontend_connectors/basic_http_frontend_connector.go

@@ -0,0 +1,147 @@
+package frontend_connectors
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	quesma_api "quesma_v2/core"
+	"sync"
+)
+
+type HTTPRouter struct {
+	mux      *http.ServeMux                     // Default HTTP multiplexer
+	handlers map[string]quesma_api.HandlersPipe // Map to store custom route handlers
+	mutex    sync.RWMutex                       // Mutex for concurrent access to handlers
+}
+
+func NewHTTPRouter() *HTTPRouter {
+	return &HTTPRouter{
+		mux:      http.NewServeMux(),
+		handlers: make(map[string]quesma_api.HandlersPipe),
+	}
+}
+
+// AddRoute adds a new route to the router
+func (router *HTTPRouter) AddRoute(path string, handler quesma_api.HTTPFrontendHandler) {
+	router.mutex.Lock()
+	defer router.mutex.Unlock()
+	router.handlers[path] = quesma_api.HandlersPipe{Handler: handler}
+	fmt.Printf("Added route: %s\n", path)
+}
+
+func (router *HTTPRouter) Clone() quesma_api.Cloner {
+	newRouter := NewHTTPRouter()
+	router.mutex.Lock()
+	defer router.mutex.Unlock()
+	for path, handler := range router.handlers {
+		newRouter.handlers[path] = handler
+	}
+	return newRouter
+}
+
+func (router *HTTPRouter) GetHandlers() map[string]quesma_api.HandlersPipe {
+	router.mutex.RLock()
+	defer router.mutex.RUnlock()
+	callInfos := make(map[string]quesma_api.HandlersPipe)
+	for k, v := range router.handlers {
+		callInfos[k] = v
+	}
+	return callInfos
+}
+
+func (router *HTTPRouter) SetHandlers(handlers map[string]quesma_api.HandlersPipe) {
+	router.mutex.Lock()
+	defer router.mutex.Unlock()
+	for path, handler := range handlers {
+		router.handlers[path] = handler
+	}
+}
+
+func (router *HTTPRouter) Lock() {
+	router.mutex.Lock()
+}
+
+func (router *HTTPRouter) Unlock() {
+	router.mutex.Unlock()
+}
+
+func (router *HTTPRouter) Multiplexer() *http.ServeMux {
+	return router.mux
+}
+
+type BasicHTTPFrontendConnector struct {
+	listener *http.Server
+	router   quesma_api.Router
+
+	endpoint string
+}
+
+func NewBasicHTTPFrontendConnector(endpoint string) *BasicHTTPFrontendConnector {
+	return &BasicHTTPFrontendConnector{
+		endpoint: endpoint,
+	}
+}
+
+func (h *BasicHTTPFrontendConnector) AddRouter(router quesma_api.Router) {
+	h.router = router
+}
+
+func (h *BasicHTTPFrontendConnector) GetRouter() quesma_api.Router {
+	return h.router
+}
+
+func (h *BasicHTTPFrontendConnector) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	handlerWrapper, exists := h.router.GetHandlers()[req.URL.Path]
+	if !exists {
+		h.router.Multiplexer().ServeHTTP(w, req)
+		return
+	}
+	dispatcher := &quesma_api.Dispatcher{}
+	http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		metadata, message, _ := handlerWrapper.Handler(req)
+
+		metadata, message = dispatcher.Dispatch(handlerWrapper.Processors, metadata, message)
+		_, err := w.Write(message.([]byte))
+		if err != nil {
+			fmt.Printf("Error writing response: %s\n", err)
+		}
+	}).ServeHTTP(w, req)
+}
+
+func (h *BasicHTTPFrontendConnector) Listen() error {
+	h.listener = &http.Server{}
+	h.listener.Addr = h.endpoint
+	h.listener.Handler = h
+	go func() {
+		err := h.listener.ListenAndServe()
+		_ = err
+	}()
+
+	return nil
+}
+
+func (h *BasicHTTPFrontendConnector) Stop(ctx context.Context) error {
+	if h.listener == nil {
+		return nil
+	}
+	err := h.listener.Shutdown(ctx)
+	if err != nil {
+		return err
+	}
+	return h.listener.Close()
+}
+
+func (h *BasicHTTPFrontendConnector) GetEndpoint() string {
+	return h.endpoint
+}
+
+func ReadRequestBody(request *http.Request) ([]byte, error) {
+	reqBody, err := io.ReadAll(request.Body)
+	if err != nil {
+		return nil, err
+	}
+	request.Body = io.NopCloser(bytes.NewBuffer(reqBody))
+	return reqBody, nil
+}

v2/frontend_connectors/basic_tcp_connection_handler.go

@@ -0,0 +1,44 @@
+package frontend_connectors
+
+import (
+	"fmt"
+	"io"
+	"net"
+	quesma_api "quesma_v2/core"
+)
+
+type BasicTcpConnectionHandler struct {
+	processors []quesma_api.Processor
+}
+
+func (h *BasicTcpConnectionHandler) SetHandlers(processors []quesma_api.Processor) {
+	h.processors = processors
+}
+
+func (h *BasicTcpConnectionHandler) HandleConnection(conn net.Conn) error {
+	fmt.Println("Handling connection")
+	defer conn.Close()
+
+	// Example: Read data from the connection
+	buffer := make([]byte, 1024)
+	for {
+		n, err := conn.Read(buffer)
+		if err != nil {
+			if err == io.EOF {
+				fmt.Println("Connection closed")
+			} else {
+				fmt.Println("Error reading from connection:", err)
+			}
+			return err
+		}
+		for _, processor := range h.processors {
+			if processor != nil {
+				processor.Handle(nil, buffer[:n])
+			}
+		}
+		fmt.Printf("Received data: %s\n", string(buffer[:n]))
+
+		// Echo the data back (for demonstration purposes)
+		conn.Write(buffer[:n])
+	}
+}

v2/frontend_connectors/basic_tcp_connector.go

@@ -0,0 +1,72 @@
+package frontend_connectors
+
+import (
+	"context"
+	"fmt"
+	"net"
+	quesma_api "quesma_v2/core"
+	"sync/atomic"
+)
+
+type TCPListener struct {
+	listener   net.Listener
+	Endpoint   string
+	handler    quesma_api.TCPConnectionHandler
+	isShutdown atomic.Bool
+}
+
+func NewTCPConnector(endpoint string) *TCPListener {
+	return &TCPListener{
+		Endpoint: endpoint,
+	}
+}
+
+func (t *TCPListener) Listen() error {
+	ln, err := net.Listen("tcp", t.Endpoint)
+	if err != nil {
+		return fmt.Errorf("failed to start TCP listener: %v", err)
+	}
+	t.listener = ln
+
+	// Start listening for incoming connections in a goroutine
+	go func() {
+		for {
+			conn, err := ln.Accept()
+			if err != nil {
+				if t.isShutdown.Load() {
+					return
+				}
+				fmt.Println("Failed to accept connection:", err)
+				continue
+			}
+			// Handle each connection in a separate goroutine to allow concurrent handling
+			go func() {
+				err := t.GetConnectionHandler().HandleConnection(conn)
+				if err != nil {
+					fmt.Println("Error handling connection:", err)
+				}
+			}()
+		}
+	}()
+	return nil
+}
+
+func (t *TCPListener) GetEndpoint() string {
+	return t.Endpoint
+}
+
+func (t *TCPListener) AddConnectionHandler(handler quesma_api.TCPConnectionHandler) {
+	t.handler = handler
+}
+
+func (t *TCPListener) GetConnectionHandler() quesma_api.TCPConnectionHandler {
+	return t.handler
+}
+
+func (t *TCPListener) Stop(ctx context.Context) error {
+	t.isShutdown.Store(true)
+	if t.listener != nil {
+		return t.listener.Close()
+	}
+	return nil
+}