feat: Implement initial Go backend and React frontend project structure for the gotail application.

backend/internal/handlers/handlers.go

@@ -0,0 +1,166 @@
+package handlers
+
+import (
+	"bufio"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"os"
+	"strconv"
+	"strings"
+
+	"github.com/rs/zerolog/log"
+	"github.com/seu-usuario/go-react-web-tail/internal/broker"
+	"github.com/seu-usuario/go-react-web-tail/internal/models"
+)
+
+// Handler contém os handlers HTTP da aplicação
+type Handler struct {
+	broker   *broker.Broker
+	logFiles []string
+}
+
+// New cria uma nova instância do Handler
+func New(broker *broker.Broker, logFiles []string) *Handler {
+	return &Handler{
+		broker:   broker,
+		logFiles: logFiles,
+	}
+}
+
+// HandleSSE gerencia conexões Server-Sent Events para streaming de logs
+func (h *Handler) HandleSSE(w http.ResponseWriter, r *http.Request) {
+	flusher, ok := w.(http.Flusher)
+	if !ok {
+		http.Error(w, "Streaming unsupported", http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("Content-Type", "text/event-stream")
+	w.Header().Set("Cache-Control", "no-cache")
+	w.Header().Set("Connection", "keep-alive")
+
+	clientChan := h.broker.Subscribe()
+	defer h.broker.Unsubscribe(clientChan)
+
+	log.Info().Str("remote_addr", r.RemoteAddr).Msg("SSE client connected")
+
+	for {
+		select {
+		case entry := <-clientChan:
+			data, err := json.Marshal(entry)
+			if err != nil {
+				log.Error().Err(err).Msg("Failed to marshal log entry")
+				continue
+			}
+			fmt.Fprintf(w, "data: %s\n\n", data)
+			flusher.Flush()
+
+		case <-r.Context().Done():
+			log.Info().Str("remote_addr", r.RemoteAddr).Msg("SSE client disconnected")
+			return
+		}
+	}
+}
+
+// HandleFiles retorna a lista de arquivos de log monitorados
+func (h *Handler) HandleFiles(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	if err := json.NewEncoder(w).Encode(h.logFiles); err != nil {
+		log.Error().Err(err).Msg("Failed to encode log files")
+		http.Error(w, "Internal server error", http.StatusInternalServerError)
+	}
+}
+
+// HandleLastLines retorna as últimas N linhas de um arquivo
+func (h *Handler) HandleLastLines(w http.ResponseWriter, r *http.Request) {
+	file := r.URL.Query().Get("file")
+	nParam := r.URL.Query().Get("n")
+
+	n := 200
+	if nParam != "" {
+		if parsed, err := strconv.Atoi(nParam); err == nil && parsed > 0 {
+			n = parsed
+		}
+	}
+
+	// Validar que o arquivo está na lista permitida
+	allowed := false
+	for _, f := range h.logFiles {
+		if f == file {
+			allowed = true
+			break
+		}
+	}
+
+	if !allowed {
+		log.Warn().Str("file", file).Str("remote_addr", r.RemoteAddr).Msg("Attempted access to unauthorized file")
+		http.Error(w, "Invalid file", http.StatusBadRequest)
+		return
+	}
+
+	entries, err := h.getLastLines(file, n)
+	if err != nil {
+		log.Error().Err(err).Str("file", file).Msg("Failed to read last lines")
+		http.Error(w, "Failed to read file", http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	if err := json.NewEncoder(w).Encode(entries); err != nil {
+		log.Error().Err(err).Msg("Failed to encode entries")
+	}
+}
+
+// getLastLines lê as últimas N linhas de um arquivo
+func (h *Handler) getLastLines(filename string, n int) ([]models.LogEntry, error) {
+	f, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	buf := make([]string, 0, n)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		if len(buf) == n {
+			buf = buf[1:]
+		}
+		buf = append(buf, line)
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	entries := make([]models.LogEntry, 0, len(buf))
+	for _, line := range buf {
+		entry := models.NewLogEntry(filename, strings.TrimRight(line, "\r"))
+		entries = append(entries, entry)
+	}
+
+	return entries, nil
+}
+
+// HandleHealth retorna o status de saúde da aplicação
+func (h *Handler) HandleHealth(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	json.NewEncoder(w).Encode(map[string]string{
+		"status": "healthy",
+	})
+}
+
+// HandleMetrics retorna métricas da aplicação
+func (h *Handler) HandleMetrics(w http.ResponseWriter, r *http.Request) {
+	activeClients, totalBroadcasts := h.broker.GetMetrics()
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(map[string]interface{}{
+		"active_clients":   activeClients,
+		"total_broadcasts": totalBroadcasts,
+		"monitored_files":  len(h.logFiles),
+	})
+}