// Command server runs the CDP bulker -- Kafka consumer that batches events
// into ClickHouse (and other warehouses, when configured).
package main

import (
	"context"
	"encoding/json"
	"errors"
	"log"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/go-chi/chi/v5"
	"go.uber.org/zap"

	"github.com/dbiz/cdp/ingestion/bulker/internal/batcher"
	"github.com/dbiz/cdp/ingestion/bulker/internal/config"
	"github.com/dbiz/cdp/ingestion/bulker/internal/consumer"
	"github.com/dbiz/cdp/ingestion/bulker/internal/model"
	"github.com/dbiz/cdp/ingestion/bulker/internal/writer"
)

func main() {
	if err := run(); err != nil {
		log.Fatal(err)
	}
}

func run() error {
	cfg, err := config.Load()
	if err != nil {
		return err
	}
	logger, err := newLogger(cfg.LogLevel)
	if err != nil {
		return err
	}
	defer func() { _ = logger.Sync() }()

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	// ---- ClickHouse -------------------------------------------------------
	ch, err := writer.New(ctx, cfg.ClickHouseAddr, cfg.ClickHouseDB, cfg.ClickHouseUser, cfg.ClickHousePassword, cfg.ClickHouseSecure)
	if err != nil {
		return err
	}
	defer func() { _ = ch.Close() }()

	// ---- Batcher ---------------------------------------------------------
	b := batcher.New(cfg.BatchSize, cfg.BatchInterval,
		func(ctx context.Context, evs []*model.IngestedEvent) error {
			_, err := ch.WriteEvents(ctx, evs)
			return err
		}, logger)

	go b.Run(ctx)

	// ---- Consumer --------------------------------------------------------
	cons, err := consumer.New(consumer.Config{
		Brokers:     cfg.KafkaBrokers,
		Group:       cfg.KafkaGroup,
		IngestTopic: cfg.KafkaTopicIngest,
		DLQTopic:    cfg.KafkaTopicDLQ,
	}, b, ch, logger)
	if err != nil {
		return err
	}
	defer cons.Close()

	consumerErr := make(chan error, 1)
	go func() { consumerErr <- cons.Run(ctx) }()

	// ---- HTTP (health) ---------------------------------------------------
	r := chi.NewRouter()
	r.Get("/health", func(w http.ResponseWriter, _ *http.Request) {
		writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
	})
	r.Get("/ready", func(w http.ResponseWriter, _ *http.Request) {
		writeJSON(w, http.StatusOK, map[string]string{"status": "ready"})
	})

	srv := &http.Server{
		Addr:              cfg.HTTPAddr,
		Handler:           r,
		ReadHeaderTimeout: 5 * time.Second,
	}

	httpErr := make(chan error, 1)
	go func() {
		logger.Info("bulker http listening", zap.String("addr", cfg.HTTPAddr))
		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			httpErr <- err
		}
	}()

	// ---- Signals ---------------------------------------------------------
	sigCh := make(chan os.Signal, 1)
	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
	select {
	case <-sigCh:
		logger.Info("shutdown signal received")
	case err := <-consumerErr:
		logger.Error("consumer stopped unexpectedly", zap.Error(err))
	case err := <-httpErr:
		logger.Error("http stopped unexpectedly", zap.Error(err))
	}

	shutCtx, shutCancel := context.WithTimeout(context.Background(), cfg.ShutdownTimeout)
	defer shutCancel()
	cancel() // stop consumer + batcher
	_ = srv.Shutdown(shutCtx)
	_ = b.FlushNow(shutCtx)
	return nil
}

func writeJSON(w http.ResponseWriter, status int, body any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(body)
}

func newLogger(level string) (*zap.Logger, error) {
	lvl, err := zap.ParseAtomicLevel(level)
	if err != nil {
		lvl = zap.NewAtomicLevelAt(zap.InfoLevel)
	}
	cfg := zap.NewProductionConfig()
	cfg.Level = lvl
	cfg.EncoderConfig.TimeKey = "ts"
	cfg.EncoderConfig.MessageKey = "msg"
	return cfg.Build()
}