package main

import (
	"context"
	"encoding/json"
	"io"
	"log"
	"net"
	"net/http"

	"git.tornberg.me/go-otel/internal/collector"
	"git.tornberg.me/go-otel/internal/websocket"
	"go.opentelemetry.io/collector/pdata/plog"
	"go.opentelemetry.io/collector/pdata/pmetric"
	"go.opentelemetry.io/collector/pdata/ptrace"
	logsgrpc "go.opentelemetry.io/proto/otlp/collector/logs/v1"
	metricsgrpc "go.opentelemetry.io/proto/otlp/collector/metrics/v1"
	tracegrpc "go.opentelemetry.io/proto/otlp/collector/trace/v1"
	"google.golang.org/grpc"
	"google.golang.org/protobuf/proto"
)

type traceService struct {
	tracegrpc.UnimplementedTraceServiceServer
	collector *collector.Collector
}

func (s *traceService) Export(ctx context.Context, req *tracegrpc.ExportTraceServiceRequest) (*tracegrpc.ExportTraceServiceResponse, error) {
	log.Printf("Received gRPC traces %d", len(req.ResourceSpans))

	// Convert protobuf to bytes then to pdata
	data, err := proto.Marshal(req)
	if err != nil {
		log.Printf("failed to marshal trace request: %v", err)
		return nil, err
	}

	unmarshaler := &ptrace.ProtoUnmarshaler{}
	traces, err := unmarshaler.UnmarshalTraces(data)
	if err != nil {
		log.Printf("failed to unmarshal traces: %v", err)
		return nil, err
	}

	if err := s.collector.ConsumeTraces(ctx, traces); err != nil {
		log.Printf("failed to consume traces: %v", err)
		return nil, err
	}

	return &tracegrpc.ExportTraceServiceResponse{}, nil
}

type metricsService struct {
	metricsgrpc.UnimplementedMetricsServiceServer
	collector *collector.Collector
}

func (s *metricsService) Export(ctx context.Context, req *metricsgrpc.ExportMetricsServiceRequest) (*metricsgrpc.ExportMetricsServiceResponse, error) {
	log.Printf("Received gRPC metrics %d", len(req.ResourceMetrics))

	// Convert protobuf to bytes then to pdata
	data, err := proto.Marshal(req)
	if err != nil {
		log.Printf("failed to marshal metrics request: %v", err)
		return nil, err
	}

	unmarshaler := &pmetric.ProtoUnmarshaler{}
	metrics, err := unmarshaler.UnmarshalMetrics(data)
	if err != nil {
		log.Printf("failed to unmarshal metrics: %v", err)
		return nil, err
	}

	if err := s.collector.ConsumeMetrics(ctx, metrics); err != nil {
		log.Printf("failed to consume metrics: %v", err)
		return nil, err
	}

	return &metricsgrpc.ExportMetricsServiceResponse{}, nil
}

type logsService struct {
	logsgrpc.UnimplementedLogsServiceServer
	collector *collector.Collector
}

func (s *logsService) Export(ctx context.Context, req *logsgrpc.ExportLogsServiceRequest) (*logsgrpc.ExportLogsServiceResponse, error) {
	log.Printf("Received gRPC logs %d", len(req.ResourceLogs))

	// Convert protobuf to bytes then to pdata
	data, err := proto.Marshal(req)
	if err != nil {
		log.Printf("failed to marshal logs request: %v", err)
		return nil, err
	}

	unmarshaler := &plog.ProtoUnmarshaler{}
	logs, err := unmarshaler.UnmarshalLogs(data)
	if err != nil {
		log.Printf("failed to unmarshal logs: %v", err)
		return nil, err
	}

	if err := s.collector.ConsumeLogs(ctx, logs); err != nil {
		log.Printf("failed to consume logs: %v", err)
		return nil, err
	}

	return &logsgrpc.ExportLogsServiceResponse{}, nil
}

func main() {

	// Configure history size (default 100, can be made configurable)
	historySize := 100
	coll := collector.New(nil, historySize) // Temporary nil for wsServer
	wsServer := websocket.New(coll)
	// Update collector with wsServer
	coll.SetBroadcaster(wsServer)

	// Start gRPC server
	go func() {
		lis, err := net.Listen("tcp", ":4317")
		if err != nil {
			log.Fatal("failed to listen for gRPC", err)
		}

		s := grpc.NewServer()
		tracegrpc.RegisterTraceServiceServer(s, &traceService{collector: coll})
		metricsgrpc.RegisterMetricsServiceServer(s, &metricsService{collector: coll})
		logsgrpc.RegisterLogsServiceServer(s, &logsService{collector: coll})

		log.Print("Starting gRPC server on port 4317")
		if err := s.Serve(lis); err != nil {
			log.Fatalf("failed to serve gRPC: %v", err)
		}
	}()

	// OTLP HTTP endpoints
	http.HandleFunc("/v1/traces", handleTraces(coll))
	http.HandleFunc("/v1/metrics", handleMetrics(coll))
	http.HandleFunc("/v1/logs", handleLogs(coll))

	// History API endpoints
	http.HandleFunc("/api/history", handleHistory(coll))
	http.HandleFunc("/api/history/traces", handleHistoryByType(coll, "traces"))
	http.HandleFunc("/api/history/metrics", handleHistoryByType(coll, "metrics"))
	http.HandleFunc("/api/history/logs", handleHistoryByType(coll, "logs"))

	// WebSocket server for visualization
	http.HandleFunc("/ws", wsServer.HandleConnections)
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
		w.Write([]byte("OTel Debug Receiver is running"))
	})

	log.Printf("Starting HTTP server on port 8080")
	log.Printf("OTLP HTTP endpoints:")
	log.Printf("  Traces: http://localhost:8080/v1/traces")
	log.Printf("  Metrics: http://localhost:8080/v1/metrics")
	log.Printf("  Logs: http://localhost:8080/v1/logs")
	log.Printf("OTLP gRPC endpoints:")
	log.Printf("  Traces: localhost:4317")
	log.Printf("  Metrics: localhost:4317")
	log.Printf("  Logs: localhost:4317")
	log.Printf("WebSocket: ws://localhost:8080/ws")

	if err := http.ListenAndServe(":8080", nil); err != nil {
		log.Fatalf("failed to start HTTP server: %v", err)
	}
}

func handleTraces(coll *collector.Collector) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		log.Printf("Received traces request: method=%s, content-type=%s", r.Method, r.Header.Get("Content-Type"))
		if r.Method != http.MethodPost {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}

		body, err := io.ReadAll(r.Body)
		if err != nil {
			log.Printf("failed to read request body: %v", err)
			http.Error(w, "failed to read request body", http.StatusInternalServerError)
			return
		}

		log.Printf("Received traces body, size=%d", len(body))

		var unmarshaler ptrace.Unmarshaler
		contentType := r.Header.Get("Content-Type")
		switch contentType {
		case "application/x-protobuf":
			unmarshaler = &ptrace.ProtoUnmarshaler{}
		case "application/json":
			unmarshaler = &ptrace.JSONUnmarshaler{}
		default:
			unmarshaler = &ptrace.JSONUnmarshaler{} // default to JSON
		}

		traces, err := unmarshaler.UnmarshalTraces(body)
		if err != nil {
			log.Printf("failed to unmarshal traces: %v", err)
			http.Error(w, "failed to unmarshal traces", http.StatusBadRequest)
			return
		}

		log.Printf("Successfully unmarshaled traces, span_count=%d", traces.SpanCount())

		if err := coll.ConsumeTraces(context.Background(), traces); err != nil {
			log.Printf("failed to consume traces: %v", err)
			http.Error(w, "failed to consume traces", http.StatusInternalServerError)
			return
		}

		w.WriteHeader(http.StatusOK)
	}
}

func handleMetrics(coll *collector.Collector) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}

		body, err := io.ReadAll(r.Body)
		if err != nil {
			log.Printf("failed to read request body: %v", err)
			http.Error(w, "failed to read request body", http.StatusInternalServerError)
			return
		}

		var unmarshaler pmetric.Unmarshaler
		contentType := r.Header.Get("Content-Type")
		switch contentType {
		case "application/x-protobuf":
			unmarshaler = &pmetric.ProtoUnmarshaler{}
		case "application/json":
			unmarshaler = &pmetric.JSONUnmarshaler{}
		default:
			unmarshaler = &pmetric.JSONUnmarshaler{} // default to JSON
		}

		metrics, err := unmarshaler.UnmarshalMetrics(body)
		if err != nil {
			log.Printf("failed to unmarshal metrics: %v", err)
			http.Error(w, "failed to unmarshal metrics", http.StatusBadRequest)
			return
		}

		if err := coll.ConsumeMetrics(context.Background(), metrics); err != nil {
			log.Printf("failed to consume metrics: %v", err)
			http.Error(w, "failed to consume metrics", http.StatusInternalServerError)
			return
		}

		w.WriteHeader(http.StatusOK)
	}
}

func handleLogs(coll *collector.Collector) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}

		body, err := io.ReadAll(r.Body)
		if err != nil {
			log.Printf("failed to read request body: %v", err)
			http.Error(w, "failed to read request body", http.StatusInternalServerError)
			return
		}

		var unmarshaler plog.Unmarshaler
		contentType := r.Header.Get("Content-Type")
		switch contentType {
		case "application/x-protobuf":
			unmarshaler = &plog.ProtoUnmarshaler{}
		case "application/json":
			unmarshaler = &plog.JSONUnmarshaler{}
		default:
			unmarshaler = &plog.JSONUnmarshaler{} // default to JSON
		}

		logs, err := unmarshaler.UnmarshalLogs(body)
		if err != nil {
			log.Printf("failed to unmarshal logs: %v", err)
			http.Error(w, "failed to unmarshal logs", http.StatusBadRequest)
			return
		}

		if err := coll.ConsumeLogs(context.Background(), logs); err != nil {
			log.Printf("failed to consume logs: %v", err)
			http.Error(w, "failed to consume logs", http.StatusInternalServerError)
			return
		}

		w.WriteHeader(http.StatusOK)
	}
}

func handleHistory(coll *collector.Collector) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}

		history := coll.GetHistory()

		w.Header().Set("Content-Type", "application/json")
		if err := json.NewEncoder(w).Encode(history); err != nil {
			log.Printf("failed to encode history: %v", err)
			http.Error(w, "failed to encode history", http.StatusInternalServerError)
			return
		}
	}
}

func handleHistoryByType(coll *collector.Collector, dataType string) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}

		history := coll.GetHistory()

		// Filter by type
		var filteredHistory []websocket.HistoryEntry
		for _, entry := range history {
			if string(entry.Type) == dataType {
				filteredHistory = append(filteredHistory, entry)
			}
		}

		w.Header().Set("Content-Type", "application/json")
		if err := json.NewEncoder(w).Encode(filteredHistory); err != nil {
			log.Printf("failed to encode filtered history: %v", err)
			http.Error(w, "failed to encode history", http.StatusInternalServerError)
			return
		}
	}
}